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Lifestyle and dietary correlates of dispositional optimism in men: The Zutphen Elderly Study
Journal of Psychosomatic Research 63 (2007) 483 – 490
Lifestyle and dietary correlates of dispositional optimism in men: The Zutphen Elderly Study Erik J. Giltay a,⁎, Johanna M. Geleijnse b , Frans G. Zitman a , Brian Buijsse b , Daan Kromhout b a
Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands b Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
Received 9 March 2007; received in revised form 24 June 2007; accepted 17 July 2007
Abstract Objective: Dispositional optimism has been associated with a lower risk of cardiovascular mortality, but the underlying mechanisms are still largely unknown. We therefore studied whether dispositional optimism was associated with healthy lifestyle and dietary habits. Methods: In 773 (87.1%) of 887 Dutch elderly community-living men with complete data in 1985, the associations of dispositional optimism with lifestyle and dietary factors were assessed at baseline and during follow-up every 5 years up to 15 years using multilevel regression models. Measurements: Dispositional optimism was assessed using a fouritem questionnaire, and the participants' food consumption was assessed by a cross-check dietary history method that estimates the usual food consumption pattern of the participants. Lifestyle
factors were assessed by questionnaires, while weight and height were measured to calculate body mass index. Results: A high level of dispositional optimism was associated with more physical activity (Pb.001), nonsmoking (P=.02), and higher intakes of alcohol (P=.046), fruit (P=.01), vegetables (P=.01), and wholegrain bread (P=.01), independently from age, education, living arrangement, self-rated health, cardiovascular disease, diabetes mellitus, cancer, and body mass index, as well as total energy intake (for dietary factors). Conclusion: Dispositional optimism in elderly men is associated with healthy lifestyle and dietary habits. A low level of optimism may indirectly affect proneness to cardiovascular death via unhealthy behavioral choices. © 2007 Elsevier Inc. All rights reserved.
Keywords: Dispositional optimism; Dietary factors; Lifestyle factors; Elderly men; Epidemiology
Introduction An individual's level of dispositional optimism—defined in terms of generalized positive outcome expectancies, life engagement, and a future orientation—is related to physical well-being and to lower cardiovascular disease (CVD) morbidity [1,2] and mortality [3,4]. The mechanism through which dispositional optimism appears to prevent CVD is still unclear, but may be partially mediated through prudent lifestyle and dietary behavior. It is well established that a low body mass index (BMI), moderate alcohol use, physical ⁎ Corresponding author. Department of Psychiatry, Leiden University Medical Center, Leiden, P.O. Box 9600, 2300 RC, Leiden, The Netherlands. Tel.: +31 (0)71 5263784; fax: +31 (0)71 5248156. E-mail address: [email protected] (E.J. Giltay). 0022-3999/07/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2007.07.014
activity, and nonsmoking are associated with a lower risk of CVD mortality [5–8]. In addition, dietary patterns rich in fruits and vegetables [9,10], fiber and wholegrain cereals [10,11], and fatty fish and fish fatty acids [12,13], and low in saturated and trans fatty acids [14,15] have convincingly been associated with reduced risks of CVD morbidity and mortality. Cocoa intake may also protect against CVD [16]. Especially for older subjects, it is important to adopt healthy lifestyle and dietary behaviors that reduce these risks in order to increase life expectancy [7,8]. Studies have indicated that the combined effects of lifestyle and dietary factors yield the largest protective effects; for example, a low risk pattern of lifestyle and dietary factors was associated with a 60% lower relative risk of all-cause mortality [6]. Few studies (particularly in older subjects) have related positive psychological factors to dietary and lifestyle factors.
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A cross-sectional study among 8690 Finnish adults aged 31 years old found that optimism was positively associated with eating more fresh vegetables, salads, berries, fruit, foods rich in fiber, and low-fat cheese and milk [17]. Optimism was inversely associated with current smoking. In women, optimism was positively associated with fish intake, while men with a heavy alcohol intake were less optimistic than other men. Because dietary intake was assessed through postal questionnaires concerning the previous 6 months, this may have reduced accuracy and may also have introduced bias. In another cross-sectional study among 128 elderly subjects (aged 65–80 years old), dispositional optimism was related to nonsmoking, moderate alcohol consumption, brisk walking, and vigorous physical activities (in older women only) [18]. Dietary factors, however, were not assessed. The Zutphen Elderly Study, in which data were collected at four time points with 5-year intervals, provided the opportunity to assess longitudinally the potential lifestyle and dietary correlates of dispositional optimism in community-dwelling, elderly men. We hypothesized that one's level of optimism was related to healthy lifestyle (i.e., physical activity, smoking, and alcohol consumption) and dietary behaviors. We focused on the consumption of fruit, vegetables, fiber, saturated fat, trans fatty acid, and fish fatty acids, which are part of dietary guidelines [7,8]. We adjusted for sociodemographic factors, such as age, education, living arrangement, self-rated health, and morbidity, that are known correlates of dispositional optimism [3,19,20] and because lifestyle and dietary factors may be confounded by health status (especially at old age).
Methods Study population The Zutphen Elderly Study is an extension of the Zutphen Study that was initiated in 1960, in which 555 men were still alive in 1985. The Zutphen Study started as the Dutch contribution to the Seven Countries Study on lifestyle, biological risk factors, and CVD in middle-aged men in Finland, Italy, Greece, the former Yugoslavia, Japan, the United States, and the Netherlands. In 1985, an additional random sample of 711 men of the same age also living in Zutphen but not belonging to the original cohort were invited to participate. This invitation resulted in a total target population of 1266 men aged 64 to 84 years, of whom 887 (response rate 70.1%) participated in the study in 1985. All cohort members who were still alive were invited during each consecutive survey wave. Of the 887 men in 1985, 560 of 799 surviving men were reexamined (response rate 78.0%) in 1990, 343 of 463 men (response rate 74.1%) in 1995, and 171 of 235 men (response rate 72.8%) in 2000. Since we only analyzed men with complete data, 800 (90.2%) of 887 men were included in the analyses: 773 men (87.1%) in 1985, 489 (87.3%) in 1990, 256 (74.6%) in 1995,
and 115 (76.3%) in 2000 (with a total of 1633 time points). When using the 1985 data, nonparticipants (due to mortality, nonparticipation, or incomplete data) at follow-up in 1990 were older, less optimistic, less healthy (subjectively and objectively), less physically active, less often using alcohol, and eating less fruit, vegetables, whole grain bread, and cocoa than participants in 1990. In 1985 and 1990, the study was approved by the Medical Ethics Committee of the University of Leiden, The Netherlands, and in 1995 and 2000, by the Medical Ethics Committee of the Netherlands Organisation for Applied Scientific Research (TNO). Informed consent was obtained from all participants. Questionnaire on dispositional optimism In 1985, 1990, 1995, and 2000, dispositional optimism was assessed using a questionnaire, consisting of the following four items—“I still expect much from life,” “I do not look forward to what lies ahead for me in the years to come,” “My days seem to be passing by slowly,” and “I am still full of plans” (our translations)—and was previously shown to be inversely associated with the risk of CVD mortality [4]. The Central Bureau of Statistics had previously collected data on these four items in life situation surveys in the Netherlands in 1976 and 1982 [21]. A sum score (ranging from 0 to 8) was calculated with higher scores indicating greater optimism (Cronbach's alpha 0.61 in 1985). The reliability coefficient for dispositional optimism was 0.72 between 1985 and 1990 (n=358 pairs), 0.69 between 1990 and 1995 (n=223 pairs), and 0.70 between 1995 and 2000 (n=122 pairs) (Pb.001 for all). The overall reliability coefficient over four time points was 0.78 (Pb.001; n=115; as previously published [4]). Disease ascertainment, sociodemographic, and lifestyle factors Medical examinations and dietary surveys were conducted between March and June in 1985, 1990, 1995, and 2000. The medical history on CVD, diabetes, and cancer was obtained using standardized questionnaires. Since the association between optimism and behavior may be confounded by health status in the elderly, we adjusted for cancer, diabetes mellitus, and CVD, defined as the prevalence of myocardial infarction, stroke, and heart failure in 1985, and updated for incident myocardial infarction and stroke in 1990, 1995, and 2000, and for heart failure only in 1990. These diagnoses were verified with data from hospital registers and written information from general practitioners. Information on education (indicative of socioeconomic status, as income and occupation are less informative in elderly retired men, and education is unlikely to be influenced by the present health status), living arrangement, self-rated health, and physical activity were obtained with a questionnaire that participants were asked to fill out at home. Dichotomous variables were created for education (i.e.,
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Table 1 Sociodemographic, lifestyle, and dietary factors in 773 elderly men in 1985 with follow-up in 1990, 1995, and 2000 Variable
1985
1990
1995
2000
Pa
Number of men (n) Mean age (years) Mean dispositional optimism score Education Lower education Higher education Living arrangement Living with wife/partner/others Living alone Self-rated health Feeling healthy Feeling rather healthy or unhealthy Cardiovascular disease Absent Present Diabetes mellitus Absent Present Cancer Absent Present Body mass index (kg/m2) Physical activity (min/week) Smoking status Nonsmoker Current smoker Alcohol use Nonuser Current user Dietary intake Fruit (g/day) Vegetables (g/day) Whole grain bread Nonuser Current user Cocoa (g/day) Saturated fat (g/day) Trans fatty acids (g/day) Fish fatty acids (EPA+DHA; mg/day)
773 72.1±5.2 5.90±1.80
489 75.9±4.6 5.70±1.79
256 80.2±4.3 5.31±1.89
115 84.0±3.5 4.94±1.81
– – b.001
526 (68.0) 247 (32.0)
321 (65.6) 168 (34.4)
162 (63.3) 94 (36.7)
72 (62.6) 43 (37.4)
–
696 (90.0) 77 (10.0)
398 (81.4) 91 (18.6)
192 (75.0) 64 (25.0)
75 (65.2) 40 (34.8)
b.001
362 (46.8) 411 (53.2)
245 (50.1) 244 (49.9)
92 (35.9) 164 (64.1)
41 (35.7) 74 (64.3)
.002
614 (79.4) 159 (20.6)
388 (79.3) 101 (20.7)
192 (75.0) 64 (25.0)
84 (73.0) 31 (27.0)
.060
724 (93.7) 49 (6.3)
439 (89.8) 50 (10.2)
221 (86.3) 35 (13.7)
97 (84.3) 18 (15.7)
b.001
711 (92.0) 62 (8.0) 25.5±3.2 440 (72; 1.332)
433 (88.5) 56 (11.5) 25.5±3.0 460 (60; 1.170)
215 (84.0) 41 (16.0) 25.1±3.3 298 (30; 886)
93 (80.9) 22 (19.1) 25.7±3.1 180 (0; 831)
b.001
542 (70.1) 231 (29.9)
323 (66.1) 166 (33.9)
209 (81.6) 47 (18.4)
108 (93.9) 7 (6.1)
b.001
224 (27.1) 602 (72.9)
137 (25.5) 400 (74.5)
63 (22.8) 213 (77.2)
16 (13.2) 105 (86.8)
.002
136 (36; 365) 161 (97; 260)
173 (72; 413) 147 (90; 239)
194 (82; 419) 150 (97; 243)
191 (86; 426) 121 (74; 200)
b.001 b.001
493 (63.8) 280 (36.2) 1.17 (0; 6.0) 42 (26; 62) 9.1 (3.9; 18.6) 73 (10; 370)
296 (60.5) 193 (39.5) 1.47 (0; 6.9) 35 (22; 54) 6.0 (2.9; 11.4) 75 (9; 368)
159 (62.1) 97 (37.9) 1.42 (0; 7.3) 37 (23; 54) 4.1 (2.3; 6.7) 86 (7; 533)
69 (60.0) 46 (40.0) 1.85 (0; 10.1) 33 (22; 53) 2.7 (1.4; 5.1) 75 (7; 582)
.348
.191 b.001
.001 b.001 b.001 .516
Data are n (%), mean±S.D., or median (percentiles P10; P90), when appropriate. a P value for continuous variables (using logarithmically transformed data, except for dispositional optimism, BMI, and saturated fat intake) by multilevel analysis (for differences between time points), and for categorical variables by chi-squared test (for linear term for trend over time).
lower education vs. vocational or general education, higher vocational training, college, or university), living arrangement (i.e., living with wife, partner, or others vs. living alone), self-rated health (i.e., feeling healthy vs. feeling rather healthy, moderately healthy, or not healthy), and cigarette smoking (i.e., nonsmoker vs. current smoker at that moment). A validated questionnaire on physical activity designed for retired men was used to calculate the total minutes spent in physical activity per week [of an intensity of more than 2 kcal/(kg·h), e.g., fishing or playing billiards] [22,23]. The questionnaire included questions on the frequency, duration, and intensity of bicycling and taking a walk during the previous week, and the average amount of time spent on gardening in summer and winter, sports, hobbies, and odd jobs. Open-ended questions were used to assess the duration and frequency of activities and the kind of
hobbies and sports. The BMI (kg/m2) was calculated from height and weight measured by trained physicians. Dietary factors Information about habitual consumption of foods, including alcoholic beverages, and nutrients was collected in 1985, 1990, 1995, and 2000 by using the cross-check, dietary history method, adapted to the Dutch food consumption pattern [24]. Participants, together with the person who prepared the meals, were interviewed about their usual food consumption pattern during weekdays and weekends for the 2 to 4 weeks preceding the interview. A checklist of foods and quantities of food bought per week was used to calculate and verify the participant's food consumption pattern. Nutrient intake [saturated fat, trans fatty acids, and the fish
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Table 2 Dispositional optimism according to sociodemographic factors in 773 elderly men in 1985, and at 1633 time points from 1985 till 2000 1985
From 1985 till 2000
Variable
n
Unadjusted
Age (years) Education Lower education Higher education Living arrangement Living with wife/ partner/ others Living alone Self-rated health Feeling healthy Feeling rather healthy or unhealthy Cardiovascular disease Absent Present Diabetes mellitus Absent Present Cancer Absent Present Body mass index (kg/m2)
773 −0.27 (−0.34 to −0.20) b.001 526
5.79 (5.64 to 5.94)
247
6.13 (5.90 to 6.35)
696
5.98 (5.85 to 6.11)
77
5.17 (4.77 to 5.57)
362
6.43 (6.25 to 6.61)
411
5.43 (5.26 to 5.60)
614 159
6.00 (5.86 to 6.14) 5.50 (5.22 to 5.78)
724 49 711 62 773
P
.015
Adjusted
a
nb
P
Unadjusted
P
Adjusted a
P
1633 −0.33 (−0.40 to −0.26) b.001 5.80 (5.65 to 5.95)
.022 1081
5.10 (4.94 to 5.26)
.004 5.48 (5.31 to 5.65)
6.11 (5.89 to 6.32)
552
5.46 (5.25 to 5.68)
5.82 (5.60 to 6.03)
5.95 (5.82 to 6.08)
.015 1361
5.37 (5.22 to 5.52)
b.001 5.68 (5.52 to 5.84)
5.44 (5.04 to 5.83)
272
4.79 (4.56 to 5.02)
5.25 (5.00 to 5.49)
740
5.72 (5.55 to 5.89)
b.001 6.08 (5.91 to 6.26)
5.44 (5.28 to 5.60)
893
4.94 (4.80 to 5.09)
5.30 (5.14 to 5.46)
.002
5.97 (5.84 to 6.11) 5.61 (5.34 to 5.88)
.019 1278 355
5.35 (5.20 to 5.50) 4.89 (4.68 to 5.10)
b.001 5.68 (5.52 to 5.84) 5.32 (5.09 to 5.54)
.001
5.91 (5.78 to 6.04) 5.72 (5.22 to 6.22)
.476
5.91 (5.79 to 6.04) 5.71 (5.22 to 6.19)
.422 1481 152
5.25 (5.11 to 5.40) 4.96 (4.64 to 5.28)
.084 5.63 (5.47 to 5.79) 5.33 (5.01 to 5.65)
.063
5.90 (5.77 to 6.04) 5.84 (5.40 to 6.29) 0.02 (−0.05 to 0.09)
.806
.496 1452 181 .884 1633
5.23 (5.09 to 5.38) 5.13 (4.86 to 5.41) 0.05 (0.00 to 0.11)
.485 5.59 (5.43 to 5.75) 5.62 (5.34 to 5.90) .053 0.03 (−0.03 to 0.08)
.828
b.001
b.001
6.42 (6.25 to 6.59)
5.89 (5.76 to 6.01) 6.04 (5.61 to 6.48) .620 −0.01 (−0.07 to 0.06)
b.001
.004
b.001
b.001
.307
Data are standardized beta-coefficients or estimated marginal means of dispositional optimism (with 95% CIs). a b
Adjusted for age. Number of observations.
fatty acids eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3)] was calculated with corresponding Dutch food tables [Dutch Nutrient Database, NEVO (stichting NEderlands VOedingsstoffenbestand), The Hague] [25]. Time-specific tables with trans fatty acid content of consumed foods were compiled [15]. The intake of cocoa was estimated from the consumption of cocoa-containing foods [16]. Dietary factors were considered as continuous variables, except for whole grain bread intake that was dichotomized (nonuser/current user). Statistical analysis In Table 1, age, dispositional optimism, BMI, physical activity, alcohol use, and several dietary factors are continuous variables, whereas other variables are categorical. For positively skewed variables, back-transformed geometric mean values (with percentiles P10; P90) are
presented (i.e., physical activity, alcohol use, and intake of fruit, vegetables, cocoa, trans fatty acids, and fish fatty acids). All other data presented are numbers (with percentages) or means (with S.D.). For categorical variables, changes over time were analyzed by the linear term for trend by chi-squared test. For continuous variables, changes over time were analyzed by multilevel analysis using an unstructured covariance model (i.e., mixed models in SPSS). Multilevel analysis was used to analyze associations between dispositional optimism and potential sociodemographic confounding variables (Table 2), as well as lifestyle and dietary factors (Table 3) using an unstructured covariance model. Subjects were measured up to four times, and the outcome variable dispositional optimism was used as a continuous variable. The two-level structure consists of the observations (i.e., lower level) and the subject (i.e., higher level). All variables were time dependent, except for education which was a time-independent dichotomous
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Table 3 Dispositional optimism according to lifestyle and dietary factors in 773 elderly men in 1985, and at 1633 time points from 1985 till 2000 1985 Variable Smoking status Nonsmoker Current smoker Physical activity (min/ week) Alcohol (g/day) Fruit (g/day) Vegetables (g/day) Whole grain bread Nonuser User Cocoa (g/day) Saturated fat (g/day) Trans fatty acid (g/day) Fish fatty acids (EPA +DHA; mg/d)
n
From 1985 till 2000 Unadjusted
542 5.91 (5.76 to 6.06) 231 5.87 (5.64 to 6.10) 773 0.29 (0.22 to 0.36)
P .780 b.001
773 0.13 (0.06 to 0.20) b.001 773 0.05 (−0.02 to 0.12) .138 773 0.17 (0.10 to 0.24) b.001 493 280 773 773 773
5.77 (5.61 to 5.92) 6.13 (5.92 to 6.34) 0.04 (−0.03 to 0.11) 0.05 (−0.02 to 0.12) 0.01 (−0.06 to 0.08)
.007
773 0.04 (−0.03 to 0.12)
.212
.242 .174 .875
Adjusted
a
5.91 (5.53 to 6.28) 5.69 (5.28 to 6.09) 0.21 (0.14 to 0.27)
P
nb
Unadjusted
.096 1182 5.26 (5.11 to 5.40) 451 5.10 (4.89 to 5.30) b.001 1633 0.20 (0.16 to 0.25)
0.08 (0.01 to 0.14) .025 1633 0.09 (0.04 to 0.14) 0.03 (−0.03 to 0.10) .300 1633 0.07 (0.02 to 0.12) 0.14 (0.08 to 0.21) b.001 1633 0.07 (0.02 to 0.12) 1633 5.77 (5.39 to 6.14) .050 1017 5.13 (4.98 to 5.28) 6.01 (5.60 to 6.42) 616 5.40 (5.22 to 5.57) −0.03 (−0.09 to 0.04) .458 1633 0.04 (0.00 to 0.09) 0.00 (−0.09 to 0.09) .941 1633 0.01 (−0.04 to 0.06) −0.04 (−0.11 to 0.04) .364 1633 0.00 (−0.05 to 0.06) 0.01 (−0.05 to 0.08)
.682 1633 0.05 (0.00 to 0.10)
P .118
Adjusted a
P
b.001
5.62 (5.38 to 5.85) 5.40 (5.13 to 5.66) 0.15 (0.10 to 0.19)
b.001
.001 .003 .003
0.05 (0.00 to 0.10) 0.06 (0.01 to 0.10) 0.06 (0.01 to 0.10)
.046 .013 .010
.003
.023
5.48 (5.24 to 5.72) 5.69 (5.44 to 5.94) .073 0.01 (−0.04 to 0.05) .598 0.00 (−0.06 to 0.07) .968 −0.01 (−0.07 to 0.05)
.014
.040
.149
0.03 (−0.01 to 0.08)
.720 .873 .736
Data are standardized beta-coefficients or estimated marginal means of dispositional optimism (with 95% CIs). a Adjusted for all sociodemographic factors (age, education, living arrangement, self-rated health, CVD, diabetes mellitus, cancer, and BMI) and total energy intake (for dietary factors only). b Number of observations.
variable. For continuous independent variables, standardized beta-coefficient [with 95% confidence intervals (CIs)] and, for categorical data, estimated marginal means of dispositional optimism (with 95% CIs) are given. The effect size measures in relation to sociodemographic factors were adjusted for age (Table 2), while the effect size measures in relation to lifestyle factors were adjusted for age, education, living arrangement, self-rated health, CVD, diabetes mellitus, cancer, and body mass index (Table 3). Moreover, for dietary factors, we additionally adjusted for tertiles of total energy intake (Table 3). A two-tailed Pb.05 was considered statistically significant. The software used was SPSS for Windows version 13.0 (SPSS Inc., Chicago, IL, USA).
Results Table 1 shows sociodemographic, lifestyle, and dietary factors at baseline and after 5, 10, and 15 years of follow-up. At baseline, the 773 men were on average 72.1 (S.D. 5.2) years old (range 64 to 84). The mean dispositional optimism score statistically significantly decreased over 15 years of time. The proportion of men living alone and having CVD (of borderline statistical significance), diabetes mellitus, and cancer increased, while the proportion of men feeling healthy and the number of current smokers decreased statistically significantly over 15 years of time. There was a strong statistically significantly decline in the total time spent on physical activity over 15 years of follow-up. The average intake of fruit and cocoa increased statistically significantly, and the average intake of vegetables, saturated fat, and trans fatty acids decreased over time.
Associations with dispositional optimism are shown in Table 2 (for sociodemographic factors) and Table 3 (for lifestyle and dietary factors). At baseline in 1985, a higher level of dispositional optimism was positively associated with younger age, higher education, living together, higher self-rated health, absence of CVD, higher physical activity, being a nonsmoker, higher alcohol intake, and a higher dietary intake of vegetables and the use of whole-grain bread (all statistically significantly; Tables 2 and 3). Diabetes mellitus, cancer, BMI, and intake of fruit, cocoa, saturated fat, trans fatty acids, and fish fatty acids were not statistically significantly associated with dispositional optimism at baseline. With the use of all 1633 time-points combined from 1985 till 2000, largely similar results were found, except for eating fruit, which was also positively associated with dispositional optimism (P=.01; Table 3). Although fish fatty acid intake was not associated with dispositional optimism (Table 3), eating ≥400 mg of EPA plus DHA per day (n=168) was statistically significantly associated with a higher mean dispositional optimism score as compared to those eating b400 mg/day (n=1465), independent of sociodemographic factors (P=.048). The analyses were repeated using 1049 time points, while excluding the 584 time points for men who had prevalent CVD, diabetes mellitus, and/or cancer. Largely similar results were obtained, with a higher level of dispositional optimism being associated with more physical activity (beta-coefficient 0.10; 95% CI 0.04–0.16; Pb.001) and higher intakes of alcohol (beta-coefficient 0.06; 95% CI 0.00–0.12; of borderline significance P =.051), fruit (betacoefficient 0.11; 95% CI 0.05–0.16; Pb.001), vegetables
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(beta-coefficient 0.09; 95% CI 0.03–0.14; P=.002), wholegrain bread [nonuser vs. current user: 0.21 (S.E. 0.10); P=.048], independent of sociodemographic factors. Fish fatty acid intake became statistically significantly associated with dispositional optimism (beta-coefficient 0.06; 95% CI 0.00–0.12; P=.039), but being a nonsmoker was no longer statistically significantly associated with a higher level of optimism [nonsmoker vs. current smoker: 0.18 (S.E. 0.12); P=.12].
Discussion This population-based, prospective study shows that optimism is positively associated with health-promoting behavior in elderly men. Men with a relatively high level of dispositional optimism were physically more active, avoiding smoking more often, using alcohol more often, and having more healthful diets (dietary patterns richer in fruit, vegetables, fiber, and fatty fish) than men with lower levels of optimism. Low optimism may be an underlying predisposing factor to explain why unhealthy behaviors tend to cluster in individuals [26], while the accumulation of these modifiable risk factors dramatically increases the risk of CVD [5,6]. Dispositional optimism was related to several healthpromoting behaviors. First, optimists were physically more active than pessimists, as has previously been found [3,18,27]. This relationship may have a bidirectional nature; people low in optimism may be less inclined to engage in moderate-to-vigorous physical activity, but may also become less optimistic because of immobility. Second, nonsmokers were more optimistic than smokers, which is in accordance with previous data [17,18,27]. Optimists may be more willing to quit smoking when taking into account future health risks. Moreover, smoking dependence may be rooted in an underlying (genetic) vulnerability that may also predispose to low optimism, and smoking has direct ‘compensatory’ enhancing effects on negative moods (presumably by binding to neuronal nicotinic acetylcholine receptors, inhibiting monoamine oxidase activity, and stimulating dopamine release) [28,29]. Third, dispositional optimism was positively associated with the moderate use of alcohol, in accordance with previous findings [18,27]. Depression has been associated with a low intake of alcohol [30], but also with higher [31] and excessive [32] alcohol consumption (defined as three or more drinks per day). The absence of a J-shaped relationship may be explained by the fact that alcohol was hardly excessively consumed in our study cohort (i.e., 95% percentile: 43 g/day). Fourth, optimism was positively associated with the intake of fruit, vegetables, and whole-grain bread, which are important components of a healthy diet preventing CVD and other morbidity [5–11]. The associations with dietary factors were largely unaffected after adjustment for sociodemographic variables. Similar associations with fruit, vegetables,
fiber, and fish have recently been described in a group of young adults [17]. However, we did not find any association with saturated fat intake, whereas depression was found to be associated with higher dietary intakes of cholesterol and saturated fat [30]. We found some associations between the intake of fish fatty acids and dispositional optimism. EPA and DHA are the main n-3 long-chain polyunsaturated fish fatty acids, and DHA is an essential and abundant building block of the human brain. Although depression is not simply the reverse of optimism, circulating levels of fish fatty acids (or their ratio to n-6 fatty acids) are inversely associated with depression [33,34] and depressive symptoms [35]. However, controlled trials that examined the effects of EPA and/or DHA administration on depression showed limited beneficial effects and considerable heterogeneity [36]. If the personality trait of optimism is an antecedent of healthy lifestyles and diets, our findings would have important implications for health promotion programs. Our findings indeed suggest that optimists are more health conscious. Programs that target behaviors such as physical activity, smoking, and food consumption have resulted in reductions in a variety of CVD endpoints on the group level. In many individuals, however, health promotion programs are ineffective [28]. A personality trait of low optimism may form a barrier. For example, quitting smoking will be impossible for someone who holds little optimism that any such action will be successful. Less optimistic individuals may prefer to enjoy the benefits of unhealthy habits now without considering possible future health, while optimists may be more motivated to attempt to change their behavior to obtain future beneficial effects on health. The effectiveness of behavioral interventions is likely to be affected by how people perceive the future. Risk reduction strategies therefore may not only need to target the specific behavioral change, but also need to be goal-oriented and establish understanding about its future effects. It may require face-toface counseling techniques to reduce negative ideas and to motivate to pursue the goal (i.e., to facilitate initiatives for physical activity and dietary change in one's own way) [28]. Although we analyzed longitudinal data following the same men over 15 years, the direction of the relationship cannot be unraveled. We largely performed cross-sectional analyses, since dispositional optimism is a stable trait over many years apart, with a reliability coefficient of about 0.7 [4,37], and we were less interested in determinants of relatively small fluctuations in dispositional optimism over time. So, no definite conclusions can be drawn about causality, and our data are in line with the idea that healthy behavior causes optimism, or, vice versa, that optimistic men tend to have healthier lifestyles, or that other mediating variables are involved. Their relationship with CVD mortality may be even more complex, since both optimism and lifestyle may be influenced by suffering from CVD morbidity and/or an underlying atherosclerotic pathophysiological process. Optimism has previously been associated with adaptive, problem-focused coping responses [37]. Since
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coping style encompasses behavioral choices, optimism may facilitate the avoidance of unhealthy habits while engaging in more healthy behaviors, such as adopting dietary recommendations and making health-promoting food choices because of positive expectations and beliefs in their future benefits. By indirect causation—through a combination of healthy habits—optimism would then lead to a lower risk of CVD mortality. Some limitations concerning methodology and interpretation of the present study need to be discussed. First, we tested only a single four-item scale that focused on a future orientation, since our study was initiated before the ‘Life Orientation Test’ (LOT and LOT-Revised) [37] or ‘Scale of Subjective Well-being for Older persons’ [3] were created and validated. Questionnaires were kept similar across the waves to avoid introducing method variation bias. Our optimism scale has not been validated against the LOT (Revised) [37]. Another limitation is potential residual confounding and the biasing effects of optimism, since optimists may also be more likely to report positive aspects of health and behavior. Moreover, the attrition rate was approximately 25% in the surveys carried out during 15 years of follow-up and men with a higher level of optimism were less likely to drop out. The strengths of the present study were its size and the fact that optimism and its correlates were assessed during long-term follow-up. Moreover, dietary factors were assessed repeatedly using a standardized dietary history method, which has reduced misclassification of exposure. In summary, we showed that dispositional optimism is associated with healthy lifestyle and dietary habits in community-dwelling elderly men. Maintenance of healthy lifestyles and diets (less atherogenic) may therefore partly explain the link between dispositional optimism and a lower risk of CVD morbidity [1,2] and mortality [3,4]. The effectiveness of behavioral interventions may be influenced by personality characteristics of the individual. It remains to be elucidated whether optimism contributes to prudent lifestyle and dietary behavior, or, vice versa, whether healthy lifestyles and diets contribute to one's level of optimism or are due to third mediating variables. Acknowledgments We thank Dr. H.C. Boshuizen, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands, for her assistance in the statistical analyses. The Zutphen Elderly Study was funded by the Netherlands Prevention Foundation and the National Institute of Aging, Bethesda, MD, USA. References [1] Scheier MF, Matthews KA, Owens JF, et al. Optimism and rehospitalization after coronary artery bypass graft surgery. Arch Intern Med 1999;159:829–35.
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[23] Westertorp KR, Saris WHM, Bloemberg BPM, Kempen K, Caspersen CJ, Kromhout D. Validation of the Zutphen Physical Activity Questionnaire for the Elderly with doubly labeled water. Med Sci Sports Exerc 1992;24:S68 [Abstract 403]. [24] Bloemberg BP, Kromhout D, Obermann-De Boer GL, Van KampenDonker M. The reproducibility of dietary intake data assessed with the cross-check dietary history method. Am J Epidemiol 1989;130: 1047–56. [25] Voskuil DW, Feskens EJ, Katan MB, Kromhout D. Intake and sources of alpha-linolenic acid in Dutch elderly men. Eur J Clin Nutr 1996;50:784–7. [26] Laaksonen M, Prattala R, Karisto A. Patterns of unhealthy behaviour in Finland. Eur J Public Health 2001;11:294–300. [27] Ylöstalo PV, Ek E, Laitinen J, Knuuttila ML. Optimism and life satisfaction as determinants for dental and general health behavior-oral health habits linked to cardiovascular risk factors. J Dent Res 2003;82:194–9. [28] Rozanski A. Integrating psychologic approaches into the behavioral management of cardiac patients. Psychosom Med 2005;67(Suppl 1): S67–S73. [29] Brody AL. Functional brain imaging of tobacco use and dependence. J Psychiatr Res 2005. [30] Payne ME, Hybels CF, Bales CW, Steffens DC. Vascular nutritional correlates of late-life depression. Am J Geriatr Psychiatry 2006;14: 787–95.
[31] Hakkarainen R, Partonen T, Haukka J, Virtamo J, Albanes D, Lonnqvist J. Food and nutrient intake in relation to mental wellbeing. Nutr J 2004;3:14. [32] van Gool CH, Kempen GI, Penninx BW, Deeg DJ, Beekman AT, van Eijk JT. Relationship between changes in depressive symptoms and unhealthy lifestyles in late middle aged and older persons: results from the Longitudinal Aging Study Amsterdam. Age Ageing 2003;32:81–7. [33] Maes M, Smith R, Christophe A, Cosyns P, Desnyder R, Meltzer H. Fatty acid composition in major depression: decreased omega 3 fractions in cholesteryl esters and increased C20: 4 omega 6/C20:5 omega 3 ratio in cholesteryl esters and phospholipids. J Affect Disord 1996;38:35–46. [34] Peet M, Murphy B, Shay J, Horrobin D. Depletion of omega-3 fatty acid levels in red blood cell membranes of depressive patients. Biol Psychiatry 1998;43:315–9. [35] Tiemeier H, van Tuijl HR, Hofman A, Kiliaan AJ, Breteler MM. Plasma fatty acid composition and depression are associated in the elderly: the Rotterdam Study. Am J Clin Nutr 2003;78:40–6. [36] Appleton KM, Hayward RC, Gunnell D, et al. Effects of n-3 longchain polyunsaturated fatty acids on depressed mood: systematic review of published trials. Am J Clin Nutr 2006;84:1308–16. [37] Scheier MF, Carver CS, Bridges MW. Distinguishing optimism from neuroticism (and trait anxiety, self-mastery, and self-esteem): a reevaluation of the Life Orientation Test. J Pers Soc Psychol 1994; 67:1063–78.
Lifestyle and dietary correlates of dispositional optimism in men: The Zutphen Elderly Study Erik J. Giltay a,⁎, Johanna M. Geleijnse b , Frans G. Zitman a , Brian Buijsse b , Daan Kromhout b a
Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands b Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
Received 9 March 2007; received in revised form 24 June 2007; accepted 17 July 2007
Abstract Objective: Dispositional optimism has been associated with a lower risk of cardiovascular mortality, but the underlying mechanisms are still largely unknown. We therefore studied whether dispositional optimism was associated with healthy lifestyle and dietary habits. Methods: In 773 (87.1%) of 887 Dutch elderly community-living men with complete data in 1985, the associations of dispositional optimism with lifestyle and dietary factors were assessed at baseline and during follow-up every 5 years up to 15 years using multilevel regression models. Measurements: Dispositional optimism was assessed using a fouritem questionnaire, and the participants' food consumption was assessed by a cross-check dietary history method that estimates the usual food consumption pattern of the participants. Lifestyle
factors were assessed by questionnaires, while weight and height were measured to calculate body mass index. Results: A high level of dispositional optimism was associated with more physical activity (Pb.001), nonsmoking (P=.02), and higher intakes of alcohol (P=.046), fruit (P=.01), vegetables (P=.01), and wholegrain bread (P=.01), independently from age, education, living arrangement, self-rated health, cardiovascular disease, diabetes mellitus, cancer, and body mass index, as well as total energy intake (for dietary factors). Conclusion: Dispositional optimism in elderly men is associated with healthy lifestyle and dietary habits. A low level of optimism may indirectly affect proneness to cardiovascular death via unhealthy behavioral choices. © 2007 Elsevier Inc. All rights reserved.
Keywords: Dispositional optimism; Dietary factors; Lifestyle factors; Elderly men; Epidemiology
Introduction An individual's level of dispositional optimism—defined in terms of generalized positive outcome expectancies, life engagement, and a future orientation—is related to physical well-being and to lower cardiovascular disease (CVD) morbidity [1,2] and mortality [3,4]. The mechanism through which dispositional optimism appears to prevent CVD is still unclear, but may be partially mediated through prudent lifestyle and dietary behavior. It is well established that a low body mass index (BMI), moderate alcohol use, physical ⁎ Corresponding author. Department of Psychiatry, Leiden University Medical Center, Leiden, P.O. Box 9600, 2300 RC, Leiden, The Netherlands. Tel.: +31 (0)71 5263784; fax: +31 (0)71 5248156. E-mail address: [email protected] (E.J. Giltay). 0022-3999/07/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2007.07.014
activity, and nonsmoking are associated with a lower risk of CVD mortality [5–8]. In addition, dietary patterns rich in fruits and vegetables [9,10], fiber and wholegrain cereals [10,11], and fatty fish and fish fatty acids [12,13], and low in saturated and trans fatty acids [14,15] have convincingly been associated with reduced risks of CVD morbidity and mortality. Cocoa intake may also protect against CVD [16]. Especially for older subjects, it is important to adopt healthy lifestyle and dietary behaviors that reduce these risks in order to increase life expectancy [7,8]. Studies have indicated that the combined effects of lifestyle and dietary factors yield the largest protective effects; for example, a low risk pattern of lifestyle and dietary factors was associated with a 60% lower relative risk of all-cause mortality [6]. Few studies (particularly in older subjects) have related positive psychological factors to dietary and lifestyle factors.
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A cross-sectional study among 8690 Finnish adults aged 31 years old found that optimism was positively associated with eating more fresh vegetables, salads, berries, fruit, foods rich in fiber, and low-fat cheese and milk [17]. Optimism was inversely associated with current smoking. In women, optimism was positively associated with fish intake, while men with a heavy alcohol intake were less optimistic than other men. Because dietary intake was assessed through postal questionnaires concerning the previous 6 months, this may have reduced accuracy and may also have introduced bias. In another cross-sectional study among 128 elderly subjects (aged 65–80 years old), dispositional optimism was related to nonsmoking, moderate alcohol consumption, brisk walking, and vigorous physical activities (in older women only) [18]. Dietary factors, however, were not assessed. The Zutphen Elderly Study, in which data were collected at four time points with 5-year intervals, provided the opportunity to assess longitudinally the potential lifestyle and dietary correlates of dispositional optimism in community-dwelling, elderly men. We hypothesized that one's level of optimism was related to healthy lifestyle (i.e., physical activity, smoking, and alcohol consumption) and dietary behaviors. We focused on the consumption of fruit, vegetables, fiber, saturated fat, trans fatty acid, and fish fatty acids, which are part of dietary guidelines [7,8]. We adjusted for sociodemographic factors, such as age, education, living arrangement, self-rated health, and morbidity, that are known correlates of dispositional optimism [3,19,20] and because lifestyle and dietary factors may be confounded by health status (especially at old age).
Methods Study population The Zutphen Elderly Study is an extension of the Zutphen Study that was initiated in 1960, in which 555 men were still alive in 1985. The Zutphen Study started as the Dutch contribution to the Seven Countries Study on lifestyle, biological risk factors, and CVD in middle-aged men in Finland, Italy, Greece, the former Yugoslavia, Japan, the United States, and the Netherlands. In 1985, an additional random sample of 711 men of the same age also living in Zutphen but not belonging to the original cohort were invited to participate. This invitation resulted in a total target population of 1266 men aged 64 to 84 years, of whom 887 (response rate 70.1%) participated in the study in 1985. All cohort members who were still alive were invited during each consecutive survey wave. Of the 887 men in 1985, 560 of 799 surviving men were reexamined (response rate 78.0%) in 1990, 343 of 463 men (response rate 74.1%) in 1995, and 171 of 235 men (response rate 72.8%) in 2000. Since we only analyzed men with complete data, 800 (90.2%) of 887 men were included in the analyses: 773 men (87.1%) in 1985, 489 (87.3%) in 1990, 256 (74.6%) in 1995,
and 115 (76.3%) in 2000 (with a total of 1633 time points). When using the 1985 data, nonparticipants (due to mortality, nonparticipation, or incomplete data) at follow-up in 1990 were older, less optimistic, less healthy (subjectively and objectively), less physically active, less often using alcohol, and eating less fruit, vegetables, whole grain bread, and cocoa than participants in 1990. In 1985 and 1990, the study was approved by the Medical Ethics Committee of the University of Leiden, The Netherlands, and in 1995 and 2000, by the Medical Ethics Committee of the Netherlands Organisation for Applied Scientific Research (TNO). Informed consent was obtained from all participants. Questionnaire on dispositional optimism In 1985, 1990, 1995, and 2000, dispositional optimism was assessed using a questionnaire, consisting of the following four items—“I still expect much from life,” “I do not look forward to what lies ahead for me in the years to come,” “My days seem to be passing by slowly,” and “I am still full of plans” (our translations)—and was previously shown to be inversely associated with the risk of CVD mortality [4]. The Central Bureau of Statistics had previously collected data on these four items in life situation surveys in the Netherlands in 1976 and 1982 [21]. A sum score (ranging from 0 to 8) was calculated with higher scores indicating greater optimism (Cronbach's alpha 0.61 in 1985). The reliability coefficient for dispositional optimism was 0.72 between 1985 and 1990 (n=358 pairs), 0.69 between 1990 and 1995 (n=223 pairs), and 0.70 between 1995 and 2000 (n=122 pairs) (Pb.001 for all). The overall reliability coefficient over four time points was 0.78 (Pb.001; n=115; as previously published [4]). Disease ascertainment, sociodemographic, and lifestyle factors Medical examinations and dietary surveys were conducted between March and June in 1985, 1990, 1995, and 2000. The medical history on CVD, diabetes, and cancer was obtained using standardized questionnaires. Since the association between optimism and behavior may be confounded by health status in the elderly, we adjusted for cancer, diabetes mellitus, and CVD, defined as the prevalence of myocardial infarction, stroke, and heart failure in 1985, and updated for incident myocardial infarction and stroke in 1990, 1995, and 2000, and for heart failure only in 1990. These diagnoses were verified with data from hospital registers and written information from general practitioners. Information on education (indicative of socioeconomic status, as income and occupation are less informative in elderly retired men, and education is unlikely to be influenced by the present health status), living arrangement, self-rated health, and physical activity were obtained with a questionnaire that participants were asked to fill out at home. Dichotomous variables were created for education (i.e.,
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485
Table 1 Sociodemographic, lifestyle, and dietary factors in 773 elderly men in 1985 with follow-up in 1990, 1995, and 2000 Variable
1985
1990
1995
2000
Pa
Number of men (n) Mean age (years) Mean dispositional optimism score Education Lower education Higher education Living arrangement Living with wife/partner/others Living alone Self-rated health Feeling healthy Feeling rather healthy or unhealthy Cardiovascular disease Absent Present Diabetes mellitus Absent Present Cancer Absent Present Body mass index (kg/m2) Physical activity (min/week) Smoking status Nonsmoker Current smoker Alcohol use Nonuser Current user Dietary intake Fruit (g/day) Vegetables (g/day) Whole grain bread Nonuser Current user Cocoa (g/day) Saturated fat (g/day) Trans fatty acids (g/day) Fish fatty acids (EPA+DHA; mg/day)
773 72.1±5.2 5.90±1.80
489 75.9±4.6 5.70±1.79
256 80.2±4.3 5.31±1.89
115 84.0±3.5 4.94±1.81
– – b.001
526 (68.0) 247 (32.0)
321 (65.6) 168 (34.4)
162 (63.3) 94 (36.7)
72 (62.6) 43 (37.4)
–
696 (90.0) 77 (10.0)
398 (81.4) 91 (18.6)
192 (75.0) 64 (25.0)
75 (65.2) 40 (34.8)
b.001
362 (46.8) 411 (53.2)
245 (50.1) 244 (49.9)
92 (35.9) 164 (64.1)
41 (35.7) 74 (64.3)
.002
614 (79.4) 159 (20.6)
388 (79.3) 101 (20.7)
192 (75.0) 64 (25.0)
84 (73.0) 31 (27.0)
.060
724 (93.7) 49 (6.3)
439 (89.8) 50 (10.2)
221 (86.3) 35 (13.7)
97 (84.3) 18 (15.7)
b.001
711 (92.0) 62 (8.0) 25.5±3.2 440 (72; 1.332)
433 (88.5) 56 (11.5) 25.5±3.0 460 (60; 1.170)
215 (84.0) 41 (16.0) 25.1±3.3 298 (30; 886)
93 (80.9) 22 (19.1) 25.7±3.1 180 (0; 831)
b.001
542 (70.1) 231 (29.9)
323 (66.1) 166 (33.9)
209 (81.6) 47 (18.4)
108 (93.9) 7 (6.1)
b.001
224 (27.1) 602 (72.9)
137 (25.5) 400 (74.5)
63 (22.8) 213 (77.2)
16 (13.2) 105 (86.8)
.002
136 (36; 365) 161 (97; 260)
173 (72; 413) 147 (90; 239)
194 (82; 419) 150 (97; 243)
191 (86; 426) 121 (74; 200)
b.001 b.001
493 (63.8) 280 (36.2) 1.17 (0; 6.0) 42 (26; 62) 9.1 (3.9; 18.6) 73 (10; 370)
296 (60.5) 193 (39.5) 1.47 (0; 6.9) 35 (22; 54) 6.0 (2.9; 11.4) 75 (9; 368)
159 (62.1) 97 (37.9) 1.42 (0; 7.3) 37 (23; 54) 4.1 (2.3; 6.7) 86 (7; 533)
69 (60.0) 46 (40.0) 1.85 (0; 10.1) 33 (22; 53) 2.7 (1.4; 5.1) 75 (7; 582)
.348
.191 b.001
.001 b.001 b.001 .516
Data are n (%), mean±S.D., or median (percentiles P10; P90), when appropriate. a P value for continuous variables (using logarithmically transformed data, except for dispositional optimism, BMI, and saturated fat intake) by multilevel analysis (for differences between time points), and for categorical variables by chi-squared test (for linear term for trend over time).
lower education vs. vocational or general education, higher vocational training, college, or university), living arrangement (i.e., living with wife, partner, or others vs. living alone), self-rated health (i.e., feeling healthy vs. feeling rather healthy, moderately healthy, or not healthy), and cigarette smoking (i.e., nonsmoker vs. current smoker at that moment). A validated questionnaire on physical activity designed for retired men was used to calculate the total minutes spent in physical activity per week [of an intensity of more than 2 kcal/(kg·h), e.g., fishing or playing billiards] [22,23]. The questionnaire included questions on the frequency, duration, and intensity of bicycling and taking a walk during the previous week, and the average amount of time spent on gardening in summer and winter, sports, hobbies, and odd jobs. Open-ended questions were used to assess the duration and frequency of activities and the kind of
hobbies and sports. The BMI (kg/m2) was calculated from height and weight measured by trained physicians. Dietary factors Information about habitual consumption of foods, including alcoholic beverages, and nutrients was collected in 1985, 1990, 1995, and 2000 by using the cross-check, dietary history method, adapted to the Dutch food consumption pattern [24]. Participants, together with the person who prepared the meals, were interviewed about their usual food consumption pattern during weekdays and weekends for the 2 to 4 weeks preceding the interview. A checklist of foods and quantities of food bought per week was used to calculate and verify the participant's food consumption pattern. Nutrient intake [saturated fat, trans fatty acids, and the fish
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Table 2 Dispositional optimism according to sociodemographic factors in 773 elderly men in 1985, and at 1633 time points from 1985 till 2000 1985
From 1985 till 2000
Variable
n
Unadjusted
Age (years) Education Lower education Higher education Living arrangement Living with wife/ partner/ others Living alone Self-rated health Feeling healthy Feeling rather healthy or unhealthy Cardiovascular disease Absent Present Diabetes mellitus Absent Present Cancer Absent Present Body mass index (kg/m2)
773 −0.27 (−0.34 to −0.20) b.001 526
5.79 (5.64 to 5.94)
247
6.13 (5.90 to 6.35)
696
5.98 (5.85 to 6.11)
77
5.17 (4.77 to 5.57)
362
6.43 (6.25 to 6.61)
411
5.43 (5.26 to 5.60)
614 159
6.00 (5.86 to 6.14) 5.50 (5.22 to 5.78)
724 49 711 62 773
P
.015
Adjusted
a
nb
P
Unadjusted
P
Adjusted a
P
1633 −0.33 (−0.40 to −0.26) b.001 5.80 (5.65 to 5.95)
.022 1081
5.10 (4.94 to 5.26)
.004 5.48 (5.31 to 5.65)
6.11 (5.89 to 6.32)
552
5.46 (5.25 to 5.68)
5.82 (5.60 to 6.03)
5.95 (5.82 to 6.08)
.015 1361
5.37 (5.22 to 5.52)
b.001 5.68 (5.52 to 5.84)
5.44 (5.04 to 5.83)
272
4.79 (4.56 to 5.02)
5.25 (5.00 to 5.49)
740
5.72 (5.55 to 5.89)
b.001 6.08 (5.91 to 6.26)
5.44 (5.28 to 5.60)
893
4.94 (4.80 to 5.09)
5.30 (5.14 to 5.46)
.002
5.97 (5.84 to 6.11) 5.61 (5.34 to 5.88)
.019 1278 355
5.35 (5.20 to 5.50) 4.89 (4.68 to 5.10)
b.001 5.68 (5.52 to 5.84) 5.32 (5.09 to 5.54)
.001
5.91 (5.78 to 6.04) 5.72 (5.22 to 6.22)
.476
5.91 (5.79 to 6.04) 5.71 (5.22 to 6.19)
.422 1481 152
5.25 (5.11 to 5.40) 4.96 (4.64 to 5.28)
.084 5.63 (5.47 to 5.79) 5.33 (5.01 to 5.65)
.063
5.90 (5.77 to 6.04) 5.84 (5.40 to 6.29) 0.02 (−0.05 to 0.09)
.806
.496 1452 181 .884 1633
5.23 (5.09 to 5.38) 5.13 (4.86 to 5.41) 0.05 (0.00 to 0.11)
.485 5.59 (5.43 to 5.75) 5.62 (5.34 to 5.90) .053 0.03 (−0.03 to 0.08)
.828
b.001
b.001
6.42 (6.25 to 6.59)
5.89 (5.76 to 6.01) 6.04 (5.61 to 6.48) .620 −0.01 (−0.07 to 0.06)
b.001
.004
b.001
b.001
.307
Data are standardized beta-coefficients or estimated marginal means of dispositional optimism (with 95% CIs). a b
Adjusted for age. Number of observations.
fatty acids eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3)] was calculated with corresponding Dutch food tables [Dutch Nutrient Database, NEVO (stichting NEderlands VOedingsstoffenbestand), The Hague] [25]. Time-specific tables with trans fatty acid content of consumed foods were compiled [15]. The intake of cocoa was estimated from the consumption of cocoa-containing foods [16]. Dietary factors were considered as continuous variables, except for whole grain bread intake that was dichotomized (nonuser/current user). Statistical analysis In Table 1, age, dispositional optimism, BMI, physical activity, alcohol use, and several dietary factors are continuous variables, whereas other variables are categorical. For positively skewed variables, back-transformed geometric mean values (with percentiles P10; P90) are
presented (i.e., physical activity, alcohol use, and intake of fruit, vegetables, cocoa, trans fatty acids, and fish fatty acids). All other data presented are numbers (with percentages) or means (with S.D.). For categorical variables, changes over time were analyzed by the linear term for trend by chi-squared test. For continuous variables, changes over time were analyzed by multilevel analysis using an unstructured covariance model (i.e., mixed models in SPSS). Multilevel analysis was used to analyze associations between dispositional optimism and potential sociodemographic confounding variables (Table 2), as well as lifestyle and dietary factors (Table 3) using an unstructured covariance model. Subjects were measured up to four times, and the outcome variable dispositional optimism was used as a continuous variable. The two-level structure consists of the observations (i.e., lower level) and the subject (i.e., higher level). All variables were time dependent, except for education which was a time-independent dichotomous
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487
Table 3 Dispositional optimism according to lifestyle and dietary factors in 773 elderly men in 1985, and at 1633 time points from 1985 till 2000 1985 Variable Smoking status Nonsmoker Current smoker Physical activity (min/ week) Alcohol (g/day) Fruit (g/day) Vegetables (g/day) Whole grain bread Nonuser User Cocoa (g/day) Saturated fat (g/day) Trans fatty acid (g/day) Fish fatty acids (EPA +DHA; mg/d)
n
From 1985 till 2000 Unadjusted
542 5.91 (5.76 to 6.06) 231 5.87 (5.64 to 6.10) 773 0.29 (0.22 to 0.36)
P .780 b.001
773 0.13 (0.06 to 0.20) b.001 773 0.05 (−0.02 to 0.12) .138 773 0.17 (0.10 to 0.24) b.001 493 280 773 773 773
5.77 (5.61 to 5.92) 6.13 (5.92 to 6.34) 0.04 (−0.03 to 0.11) 0.05 (−0.02 to 0.12) 0.01 (−0.06 to 0.08)
.007
773 0.04 (−0.03 to 0.12)
.212
.242 .174 .875
Adjusted
a
5.91 (5.53 to 6.28) 5.69 (5.28 to 6.09) 0.21 (0.14 to 0.27)
P
nb
Unadjusted
.096 1182 5.26 (5.11 to 5.40) 451 5.10 (4.89 to 5.30) b.001 1633 0.20 (0.16 to 0.25)
0.08 (0.01 to 0.14) .025 1633 0.09 (0.04 to 0.14) 0.03 (−0.03 to 0.10) .300 1633 0.07 (0.02 to 0.12) 0.14 (0.08 to 0.21) b.001 1633 0.07 (0.02 to 0.12) 1633 5.77 (5.39 to 6.14) .050 1017 5.13 (4.98 to 5.28) 6.01 (5.60 to 6.42) 616 5.40 (5.22 to 5.57) −0.03 (−0.09 to 0.04) .458 1633 0.04 (0.00 to 0.09) 0.00 (−0.09 to 0.09) .941 1633 0.01 (−0.04 to 0.06) −0.04 (−0.11 to 0.04) .364 1633 0.00 (−0.05 to 0.06) 0.01 (−0.05 to 0.08)
.682 1633 0.05 (0.00 to 0.10)
P .118
Adjusted a
P
b.001
5.62 (5.38 to 5.85) 5.40 (5.13 to 5.66) 0.15 (0.10 to 0.19)
b.001
.001 .003 .003
0.05 (0.00 to 0.10) 0.06 (0.01 to 0.10) 0.06 (0.01 to 0.10)
.046 .013 .010
.003
.023
5.48 (5.24 to 5.72) 5.69 (5.44 to 5.94) .073 0.01 (−0.04 to 0.05) .598 0.00 (−0.06 to 0.07) .968 −0.01 (−0.07 to 0.05)
.014
.040
.149
0.03 (−0.01 to 0.08)
.720 .873 .736
Data are standardized beta-coefficients or estimated marginal means of dispositional optimism (with 95% CIs). a Adjusted for all sociodemographic factors (age, education, living arrangement, self-rated health, CVD, diabetes mellitus, cancer, and BMI) and total energy intake (for dietary factors only). b Number of observations.
variable. For continuous independent variables, standardized beta-coefficient [with 95% confidence intervals (CIs)] and, for categorical data, estimated marginal means of dispositional optimism (with 95% CIs) are given. The effect size measures in relation to sociodemographic factors were adjusted for age (Table 2), while the effect size measures in relation to lifestyle factors were adjusted for age, education, living arrangement, self-rated health, CVD, diabetes mellitus, cancer, and body mass index (Table 3). Moreover, for dietary factors, we additionally adjusted for tertiles of total energy intake (Table 3). A two-tailed Pb.05 was considered statistically significant. The software used was SPSS for Windows version 13.0 (SPSS Inc., Chicago, IL, USA).
Results Table 1 shows sociodemographic, lifestyle, and dietary factors at baseline and after 5, 10, and 15 years of follow-up. At baseline, the 773 men were on average 72.1 (S.D. 5.2) years old (range 64 to 84). The mean dispositional optimism score statistically significantly decreased over 15 years of time. The proportion of men living alone and having CVD (of borderline statistical significance), diabetes mellitus, and cancer increased, while the proportion of men feeling healthy and the number of current smokers decreased statistically significantly over 15 years of time. There was a strong statistically significantly decline in the total time spent on physical activity over 15 years of follow-up. The average intake of fruit and cocoa increased statistically significantly, and the average intake of vegetables, saturated fat, and trans fatty acids decreased over time.
Associations with dispositional optimism are shown in Table 2 (for sociodemographic factors) and Table 3 (for lifestyle and dietary factors). At baseline in 1985, a higher level of dispositional optimism was positively associated with younger age, higher education, living together, higher self-rated health, absence of CVD, higher physical activity, being a nonsmoker, higher alcohol intake, and a higher dietary intake of vegetables and the use of whole-grain bread (all statistically significantly; Tables 2 and 3). Diabetes mellitus, cancer, BMI, and intake of fruit, cocoa, saturated fat, trans fatty acids, and fish fatty acids were not statistically significantly associated with dispositional optimism at baseline. With the use of all 1633 time-points combined from 1985 till 2000, largely similar results were found, except for eating fruit, which was also positively associated with dispositional optimism (P=.01; Table 3). Although fish fatty acid intake was not associated with dispositional optimism (Table 3), eating ≥400 mg of EPA plus DHA per day (n=168) was statistically significantly associated with a higher mean dispositional optimism score as compared to those eating b400 mg/day (n=1465), independent of sociodemographic factors (P=.048). The analyses were repeated using 1049 time points, while excluding the 584 time points for men who had prevalent CVD, diabetes mellitus, and/or cancer. Largely similar results were obtained, with a higher level of dispositional optimism being associated with more physical activity (beta-coefficient 0.10; 95% CI 0.04–0.16; Pb.001) and higher intakes of alcohol (beta-coefficient 0.06; 95% CI 0.00–0.12; of borderline significance P =.051), fruit (betacoefficient 0.11; 95% CI 0.05–0.16; Pb.001), vegetables
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(beta-coefficient 0.09; 95% CI 0.03–0.14; P=.002), wholegrain bread [nonuser vs. current user: 0.21 (S.E. 0.10); P=.048], independent of sociodemographic factors. Fish fatty acid intake became statistically significantly associated with dispositional optimism (beta-coefficient 0.06; 95% CI 0.00–0.12; P=.039), but being a nonsmoker was no longer statistically significantly associated with a higher level of optimism [nonsmoker vs. current smoker: 0.18 (S.E. 0.12); P=.12].
Discussion This population-based, prospective study shows that optimism is positively associated with health-promoting behavior in elderly men. Men with a relatively high level of dispositional optimism were physically more active, avoiding smoking more often, using alcohol more often, and having more healthful diets (dietary patterns richer in fruit, vegetables, fiber, and fatty fish) than men with lower levels of optimism. Low optimism may be an underlying predisposing factor to explain why unhealthy behaviors tend to cluster in individuals [26], while the accumulation of these modifiable risk factors dramatically increases the risk of CVD [5,6]. Dispositional optimism was related to several healthpromoting behaviors. First, optimists were physically more active than pessimists, as has previously been found [3,18,27]. This relationship may have a bidirectional nature; people low in optimism may be less inclined to engage in moderate-to-vigorous physical activity, but may also become less optimistic because of immobility. Second, nonsmokers were more optimistic than smokers, which is in accordance with previous data [17,18,27]. Optimists may be more willing to quit smoking when taking into account future health risks. Moreover, smoking dependence may be rooted in an underlying (genetic) vulnerability that may also predispose to low optimism, and smoking has direct ‘compensatory’ enhancing effects on negative moods (presumably by binding to neuronal nicotinic acetylcholine receptors, inhibiting monoamine oxidase activity, and stimulating dopamine release) [28,29]. Third, dispositional optimism was positively associated with the moderate use of alcohol, in accordance with previous findings [18,27]. Depression has been associated with a low intake of alcohol [30], but also with higher [31] and excessive [32] alcohol consumption (defined as three or more drinks per day). The absence of a J-shaped relationship may be explained by the fact that alcohol was hardly excessively consumed in our study cohort (i.e., 95% percentile: 43 g/day). Fourth, optimism was positively associated with the intake of fruit, vegetables, and whole-grain bread, which are important components of a healthy diet preventing CVD and other morbidity [5–11]. The associations with dietary factors were largely unaffected after adjustment for sociodemographic variables. Similar associations with fruit, vegetables,
fiber, and fish have recently been described in a group of young adults [17]. However, we did not find any association with saturated fat intake, whereas depression was found to be associated with higher dietary intakes of cholesterol and saturated fat [30]. We found some associations between the intake of fish fatty acids and dispositional optimism. EPA and DHA are the main n-3 long-chain polyunsaturated fish fatty acids, and DHA is an essential and abundant building block of the human brain. Although depression is not simply the reverse of optimism, circulating levels of fish fatty acids (or their ratio to n-6 fatty acids) are inversely associated with depression [33,34] and depressive symptoms [35]. However, controlled trials that examined the effects of EPA and/or DHA administration on depression showed limited beneficial effects and considerable heterogeneity [36]. If the personality trait of optimism is an antecedent of healthy lifestyles and diets, our findings would have important implications for health promotion programs. Our findings indeed suggest that optimists are more health conscious. Programs that target behaviors such as physical activity, smoking, and food consumption have resulted in reductions in a variety of CVD endpoints on the group level. In many individuals, however, health promotion programs are ineffective [28]. A personality trait of low optimism may form a barrier. For example, quitting smoking will be impossible for someone who holds little optimism that any such action will be successful. Less optimistic individuals may prefer to enjoy the benefits of unhealthy habits now without considering possible future health, while optimists may be more motivated to attempt to change their behavior to obtain future beneficial effects on health. The effectiveness of behavioral interventions is likely to be affected by how people perceive the future. Risk reduction strategies therefore may not only need to target the specific behavioral change, but also need to be goal-oriented and establish understanding about its future effects. It may require face-toface counseling techniques to reduce negative ideas and to motivate to pursue the goal (i.e., to facilitate initiatives for physical activity and dietary change in one's own way) [28]. Although we analyzed longitudinal data following the same men over 15 years, the direction of the relationship cannot be unraveled. We largely performed cross-sectional analyses, since dispositional optimism is a stable trait over many years apart, with a reliability coefficient of about 0.7 [4,37], and we were less interested in determinants of relatively small fluctuations in dispositional optimism over time. So, no definite conclusions can be drawn about causality, and our data are in line with the idea that healthy behavior causes optimism, or, vice versa, that optimistic men tend to have healthier lifestyles, or that other mediating variables are involved. Their relationship with CVD mortality may be even more complex, since both optimism and lifestyle may be influenced by suffering from CVD morbidity and/or an underlying atherosclerotic pathophysiological process. Optimism has previously been associated with adaptive, problem-focused coping responses [37]. Since
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coping style encompasses behavioral choices, optimism may facilitate the avoidance of unhealthy habits while engaging in more healthy behaviors, such as adopting dietary recommendations and making health-promoting food choices because of positive expectations and beliefs in their future benefits. By indirect causation—through a combination of healthy habits—optimism would then lead to a lower risk of CVD mortality. Some limitations concerning methodology and interpretation of the present study need to be discussed. First, we tested only a single four-item scale that focused on a future orientation, since our study was initiated before the ‘Life Orientation Test’ (LOT and LOT-Revised) [37] or ‘Scale of Subjective Well-being for Older persons’ [3] were created and validated. Questionnaires were kept similar across the waves to avoid introducing method variation bias. Our optimism scale has not been validated against the LOT (Revised) [37]. Another limitation is potential residual confounding and the biasing effects of optimism, since optimists may also be more likely to report positive aspects of health and behavior. Moreover, the attrition rate was approximately 25% in the surveys carried out during 15 years of follow-up and men with a higher level of optimism were less likely to drop out. The strengths of the present study were its size and the fact that optimism and its correlates were assessed during long-term follow-up. Moreover, dietary factors were assessed repeatedly using a standardized dietary history method, which has reduced misclassification of exposure. In summary, we showed that dispositional optimism is associated with healthy lifestyle and dietary habits in community-dwelling elderly men. Maintenance of healthy lifestyles and diets (less atherogenic) may therefore partly explain the link between dispositional optimism and a lower risk of CVD morbidity [1,2] and mortality [3,4]. The effectiveness of behavioral interventions may be influenced by personality characteristics of the individual. It remains to be elucidated whether optimism contributes to prudent lifestyle and dietary behavior, or, vice versa, whether healthy lifestyles and diets contribute to one's level of optimism or are due to third mediating variables. Acknowledgments We thank Dr. H.C. Boshuizen, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands, for her assistance in the statistical analyses. The Zutphen Elderly Study was funded by the Netherlands Prevention Foundation and the National Institute of Aging, Bethesda, MD, USA. References [1] Scheier MF, Matthews KA, Owens JF, et al. Optimism and rehospitalization after coronary artery bypass graft surgery. Arch Intern Med 1999;159:829–35.
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