Personality, behavior, family environment, family social status and hypertension risk factors in children

J Chron Dis Vol. 38. No. 2, pp. 187-194, 1985 Printed in Great Britain. All rights reserved

Copyright

002 l-968 Ij85 $3.00 + 0.00 cc 1985 Pergamcn Press Ltd

PERSONALITY, BEHAVIOR, FAMILY ENVIRONMENT, FAMILY SOCIAL STATUS AND HYPERTENSION RISK FACTORS IN CHILDREN THE MINNEAPOLIS RICHARD F. GILLUM,

CHILDREN’S

BLOOD PRESSURE

STUDY

RONALD J. PRINEAS, ORLANDO GOMEZ-MARIN,

STEPHEN FINN

and PI-NIAN CHANG’

Division of Epidemiology and ‘Program in Health Care Psychology, School of Public Health, University of Minnesota, Minneapolis, MN 5545.5, U.S.A. (Received

in revised form

9 April 1984)

Abstract-To assess the relationship of psychosocial variables to risk factors for hy~rt~sion in children, we administered instruments designed to measure aspects of children’s personality, behavior, family environment and family social status to 1505 school children aged 7-10 years. Children’s blood pressure was significantly related only to mother’s occupation, the children of unskilled employees having higher blood pressure than children of higher status workers. Children’s body mass index was directly related to scores on the conformity scale of the personality inventory and inverseiy related to scores on the intellectual-cultura1 orientation scale of the family environment instrument and to social class. Social status but not measured dimensions of children’s personality, behavior and family environment may influence the risk of hypertension in children.

INTRODUCTION THE BEST combination of physical variables is estimated to account for 20-40x of the individual variability in blood pressure in children, leaving over half of the variance unaccounted for [I, 21. In follow-up studies, baseline blood pressure level is the best predictor of future hypertension [3]. Blacks are known to have twice the prevalence and greater incidence of hypertension compared to whites in the adult population [4]. Black adolescents have higher blood pressures than whites even though no blood pressure differences are seen at younger ages in most studies [l, 21. Although the reasons for these racial differences are not known [4], black children as a group may be considered to be at high risk for hypertension as adults. Low socioeconomic status is associated with higher blood pressure levels and greater hypertension prevalence in U.S. adults accounting for some of the racial differences [4]. Among the many variables which have been related to prevalence of hypertension in adults are personality traits such as repressed hostility, neuroticism, anxiety, and submissiveness [S, 61. Because of methodologi~ problems in many studies, conclusions as to the importance of personality variables in hypertension remain equivocal. Although probably not major etiologic factors in essential hypertension, personality variables may assume importance as they interact with physiological factors in high risk individuals [5]. Little information exists about the relationship of children’s behavior, family environment and family social status to children’s blood pressure. Supported by National Institutes of Health Grant #HL19877 and Research Career Development Award # lK04HL-00329 (Dr Gillum) from the National Institutes of Health, Bethesda, MD, U.S.A. and a grant from the Graduate School, University of Minnesota. Reprint requests should be addressed to: Dr Ronald J. Prineas, Division of Epidemiology, School of Public Health, University of Minnesota, 611 Beacon St, S.E., Minneapolis, MN 55455, U.S.A. 187

188

RICHARD F. G~LLUM et al.

The following hypotheses governed the present investigation of the relationship of psychosocial variables and BP in children: (1) Personality traits associated with high blood pressure in adults-repressed hostility, inhibition of emotions, submissiveness, and anxiety-are also positively related to blood pressure in children. (2) This relationship is strongest in those children at risk for developing hypertension, based on black race, obesity, and family history of hypertension. METHODS

Subjects During the 1977-78 school year, all children in grades 1, 2, and 3 of the Minneapolis Public School System were contacted and asked to participate in an initial BP screening at their schools [7,8]. Approximately 99% of the children participated in the initial school screening, yielding a popualtion of 10,423 children (3% native American, 18% black, 78% white, and 1% other races). From this group, a cohort of 2640 children aged 6, 7 and 8 years were selected for long term follow-up as follows: all children in the top and bottom 5 percentiles of the systolic blood pressure distribution, plus a random sample of 1 in 2 of the remaining black children, plus a random sample of 1 in 9 of the remaining white children, plus all remaining children of other races. In the summer of 1979, 1508 of these children and their parents were interviewed in their homes. Characteristics at the initial school survey of respondents and non respondents to home interview are shown in Table 1. The reproducibility of the initial blood pressure values was high, as documented in detail elsewhere [7-91. Children with blood pressure > 130/90 mmHg at initial screening and at a confirmation visit (n = 26) were referred to their family physicians. Of these, ten were available for special studies and had data described below collected [9, lo]. However, all 26 are excluded from all analyses presented here except for a paired comparison of scores of the 10 with complete data with 19 age-sex-matched controls. The analyses in this paper are otherwise limited to 1505 children, for whom complete psychosocial data were obtained. Tests

The Missouri Children’s Picture Series (MCPS), a 238-item objective personality inventory, was given to each child [l 11. The scales of the MCPS are (1) Conformity, (2) Masculinity/Femininity, (3) Maturity, (4) Aggression, (5) Inhibition, (6) Activity Level, (7) Sleep Disturbance, and (8) Somatization [I 11.In the present study, MCPS raw scale scores were converted to age-sex-specific T-scores using published means and standard deviations [ll]. In addition, children were classified according to 36 MCPS prototype patterns, defined using all 8 scales (J. 0. Sines, personal communication, D. R. Owen, unpublished doctoral dissertation, University of Iowa, 1972). Prototype prevalence ranged from 0 to 9.2%. TABLE 1. CHARACTERISTICS AT BASELINE SCHOOLSURVEYOF RESWNDENTS AND NON RESPONDENTS Non respondents

Respondents

AS

Sex(% female) Height (cm) Weight (kg) Body mass index (kg/m*) Pulse (bpm) Systolic blood pressure (mmHg) Fourth phase diastolic blood pressure (mmHg) Fifth phase diastolic blood pressure (mmHg) N of subjects

Mean

SD

Mean

SD

7.73 49.6 125.80 26.46 16.66 83.79 104.59

0.7 I

0.72

7.35 6.16 5.00 10.72 11.90

7.69 48.1 125.69 26.61 16.78 82.22 103.90

7.40 6.18 4.39 10.69 10.93

67.24

11.82

66.07

12.85

56.53

13.94

55.29

16.01

1508

1132

Hypertension

Risk Factors in Children

189

The Missouri Children’s Behavior Checklist (MCBC) was completed by the mother of the study child. The MCBC is an inventory of 70 items describing possible child behaviors [12]. The scales generated are (1) Aggression, (2) Inhibition, (3) Activity, (4) Sleep Disturbance, (5) Somatization, and (6) Sociability. Age-sex-specific T-scores were computed for the MCBC using our sample means and standard deviations. The Family Environment Scale of Moos (FES) was also completed by the mother. This instrument consists of a series of 90 statements describing the family environment, to which the respondent replies true or false [13]. The scales of this test are (1) Cohesion, (2) Expressiveness, (3) Conflict, (4) Independence, (5) Achievement, (6) Intellectual/Cultural orientation, (7) A~tive~Re~reational, (8) Moral/Religious~ (9) Organization, and (10) Control. T-scores were computed using norms from Moos 1131. All FES and MCPS findings were verified using T-scores computed from means and standard deviations from our own sample. The procedure for the home interview was as follows: Children and their parents were visited at home. The MCBC, FES, and a recent life events questionnaire were given to the mother, if present, to complete; of the 1506 children for whom these data were collected, 1416 had mothers complete these instruments, 61 had fathers, and the rest had another adult complete the instruments. While the mother completed these questionnaires, the MCPS was administered to the index child. The following physical measurements were also obtained: two blood pressure readings were recorded on the right arm with the child in the supine position, after 5 min rest. Trained blood pressure technicians used a random zero blood pressure device, and selected cuff size to encircle 90% of the upper arm with the cuff bladder. The onset of first (SBP), fourth (D4) and fifth (D5) Korotkoff phases were recorded as described elsewhere 171. Agelsex specific blood pressure Z scores were computed for use in these analyses. Weight and height were not measured in the home, but were taken as the average of the preceding and following school screening measurements. Weight was measured with calibrated scales with the child wearing only light indoor clothing. Height was measured to the nearest centimeter without shoes. Body Mass Index (BMI) was computed as weight divided by height squared (kg/m2). Parents completed a questionnaire which included demographic, socioeconomic, and family medical history questions. Parents’ occupation and education were used to compute Hollingshead’s two-factor index of social position [14]. This was done for each parent and for the head of the household, arbitrarily defined as the father if present, otherwise the mother. Homemakers and students were arbitrarily grouped with occupation category 6 unless otherwise noted. Statistical methods

One-way analysis of variance was used for comparing means [15]. Student’s unpaired t-test was used for comparing the group of hypertensive children with a normotensive comparison group [ 151. Pearson product-moment correlations were computed for blood pressure and test scale scores, with significance assessed by 2-tailed t test [15]. Multiple regression analysis was used to assess the simultaneous relationship of several variables to blood pressure [ 151. In most analyses the age-sex specific blood pressure Z-score was used, thereby controlling for effects of age and sex. Because of the large number of tests performed, results were not considered of even borderline significance unless the p value was cO.01.

RESULTS

Demographic characteristics

Table 2 presents participant children. Median educational income category was

the age-sex distribution and mean blood pressures of the 150.5 The sample was 60% white, 29% black, 7% Indian and 5% other. levels of fathers and mothers were 12 years each. Median family ~l5,00~19,999/year. Table 3 shows the distribution of Hollingshead

190

RICHARD

F. GILLUM et al

Mean home blood pressure Diastolic 4th

(SD) Diastolic

Age

N

Systolic

7 8 9 IO

91 279 291 85

104.33 (10.35) 103.99 (9.88) 104.55 (9.94) 104.82 (9.02)

57.70(18.t2) 6i.O9(15.42) 61.49f16.18) 62.40(15.41)

44.64 50.39 50.33 50.08

7 8 9 10 Totai

100 302 293 64 1505

105.19 104.75 106.1 I 105.17

61.87(15.50) 62.43 (15.48) 63.19(15.26) 60.59 (18.42)

49.14(21.11) 50.50 (18.89) 51.87(17.40) 48.59 (22.04)

5th

Girls (19.20) (17.87) (19.20) (19.71)

Boys (9.67) (8.71) (8.98) (8.53)

social class for black and white children. Of special interest was the high proportion (5 1%) of children in the sample from homes where the biological father was permanently absent.

None of the Pearson correlation coefficients of MCPS, MCBC or FES scale scores with age-sex adjusted systolic or diastolic home blood pressure attained statistical significance (Table 4). Change in blood pressure between baseline (before psychologic testing) and fall 1978 (after testing) was significantly correlated with FES expressiveness scale score (SBP, r =0.07, p ~0.01; D4, r =0.07, p 0.05) related to the child’s blood pressure at home visit. The social position score was not significantly correlated to home blood pressure (SBP, r = 0.02; D4, r = 0.01; D5, r = 0.01) Between fall 1978 and fall 1980, diastolic blood pressure of children from households in the lowest social class (V) increased less than that of other children (D4, p = 0.02; D5, p = 0.003). Educational attainment of parents was not related to children’s blood pressure. Children whose mothers were unskilled employees had higher home systolic blood pressure than children whose mothers held higher status jobs or were homemakers (Table 5). This association persisted after adjusting for the child’s BMI (JJ = 0.02). Mother’s occupation was not related to the child’s diastolic blood pressure. Father’s occupation was not related to children’s home blood pressure. Family income was not related to children’s home blood pressure.

TABLE 3. DSTRIBUTION OF HOLLINGSHEAD SOCIAL CLASSOF HEAD OF HOUSEHOLD BY RACE Black

White

Class

n

%

n

I II III IV V Total

13 37 79 165 61 355*

4 10 22 47 17 100

99 165 228 306 42 840*

-.y; _-12 20 27 36 5 100

*Subjects with missing data on parents’ occupation, or education are excluded.

Hypertension TABLE 4. CORRELATION MATRIX OF MCPS,

MCBC

191

Risk Factors in Children

AND FES SCALE SCORESWITH BLOOD PRESSUREiN 434 BLACK CHUBREN AND 897 WHITE CHILDREN

SBP -_..--___

D4BP ---..

_-_-

B*

W*’

Both?

B

W

DSBP ____ B

Both

-

_.

-

W

Both

MCPS

I 2 3 4 5 6 1 8

-0.04 0.04 0.05 -0.02 0.07 0.02 0.03 -0.03

-0.02 0.03 -0.00 0.00 -0.04 0.01 0.00 0.00

-0.02 0.03 0.01 -0.01 0.00 0.01 0.0 I 0.01

-0.10 -0.02 0.06 0.05 0.10 0.06 0.08 -0.06

0.06 0.03 0.03 0.00 -0.05 -0.06 -0.06 -0.05

0.01 0.01 0.03 0.02 0.00 -0.01 -0.01 -0.04

-0.13 -0.08 0.05 0.03 0.13 0.1 I 0.10 -0.05

-0.02 0.02 0.04 -0.01 -0.02 -0.00 0.01 -0.07

-0.05 -0.01 0.03 0.01 0.02 0.05 0.03 -0.04

MCBC

1 2 3 4 s 6

-0.02 0.01 0.04 -0.07 -0.03 -0.09

0.01 -0.06 -0.01 0.01 0.02 0.07

-0.00 -0.04 0.01 -0.03 -0.00 0.01

0.00 -0.01 0.00 -0.03 0.03 -0.02

-0.01 -0.01 -0.05 -0.01 -0.03 0.02

0.02 -0.01 -0.03 -0.01 0.00 0.01

-0.02 -0.01 - 0.02 0.02 0.01 0.01

0.00 -0.01 -0.07 0.02 - 0.02 --0.01

0.02 -0.01 -0.04 0.04 0.01 0.01

I 2 3 4 5 6 7 8 9 10

-0.01 -0.04 -0.04 0.01 -0.03 -0.01 0.03 -0.08 0.05 -0.02

0.03 -0.01 -0.07 -0.02 0.02 -0.02 -0.04 0.06 0.05 -0.05

0.01 -0.02 -0.05 -0.02 -0.01 -0.02 -0.02 0.01 0.04 -0.04

0.00 -0.04 -0.00 -0.07 -0.03 -0.04 -0.02 -0.02 0.04 -0.04

0.02 0.00 0.03 0.02 0.03 0.00 0.02 0.00 -0.01 -0.06

0.02 -0.02 0.00 -0.00 0.01 -0.02 -0.01 -0.01 -0.00 -0.04

-0.04 -0.07 -0.02 -0.04 -0.03 -0.07 -0.08 -0.04 0.0 I -0.01

0.09 0.05 0.02 0.03 0.05 0.06 0.04 0.02 -0.00 -0.10

0.07 -0.01 -0.01 0.02 0.04 0.01 -0.01 0.02 0.01 -0.06

FES

*For n = 434, r is significant

at the 5% level if r > 0.09 at the 1% level if r z== 0.12; **For n = 897. r is significant at the 5% level if r z 0.07 at ihe 1% level if r z 0.09; tFor n = 1331. r is significant at the 5% level if r z-0.05 at the 1% level if r > 0.07 Mixed race and children of other races are excluded.

Multiple regressions were performed for each of the following dependent variables: age-sex adjusted systolic BP Z-score as measured at the home visit; age-sex adjusted D4 BP Z-score and age-sex adjusted D5 BP Z-score. Only 5% of the variance in systolic or 2% of the variance in diastolic BP above that explained by BMI and height could be explained by the addition of adjusted scales of the MCPS, MCBC or FES. It was hypothesized, in keeping with the views of Davies [S], that psychosocial predictors of BP would be most potent among those chiidren biologically at risk for hypertension. To test this view, the first high-risk group of children was chosen according to the following criteria: BMI 2 15.0 kg/m2 and at least one parent with a history of hypertension. For the 196 children classified as at risk for hypertension by this procedure, Pearson correlations were computed between MCPS, MCBC and FES scale scores and age-sex specific systolic and diastolic BP Z-scores. All of the correlation coefficients were co.18 and therefore not statistically significant at the 1% level. The correlation analysis was

TABLE 5. MOTHER.S HOLLINGSHEAD OCCUPATIONALCATEGORY AND MEAN CHLLD'SBLOOD PRESSURE(EAMHG) _I. 2. 3. 4. 5. 6. 7. 8.

-________Executives/professionals Managerial personnel Administrative personnel Clerical/sales workers Skilled employees Semi-skilled employees Unskilted employees Homemakers, students F P

*After adjustment

f

D. x3:2

E

-.

Child’s blood pressure I .--Systolic

101.6(10.4) 103.3 (8.1) 104.6 (9.9) 103.9 (9.3) 104.1 (8.4) 104.9 (9.0) 108.4(30.5) 105.9 (9.5) 2.1’ 0.009*

Diastolic

4

61.1 (15.9) 64.1 (12.9) 60.2 (17.2) 62.0(15.5) 63.9 (14.3) 61.4(16.6) 61.4(16.5) 61.8(15.6) 0.75 0.63

for child’s age and sex F = 2.6, p = 0.01,

(SD) Diastolic

5

48.6 (20.6) 50.6 (17.4) 49.1 (20.7) 50.4119.1) 51.7(18.6) S0.S(18.8) 47.9 (19.7) 50.6(18.3) 0.31 0.95

Hypertension

Risk Factors

in Children

193

statistical criteria, requiring p < 0.01 to compensate for the large number of tests done. Two other studies confirm our negative results. Buck, using a different personality instrument, failed to find a significant relationship of blood pressure with assertiveness in children [19]. Shekelle et al. using yet another instrument in a case-control study of hypertensive adolescents failed to find significant differences in scores on 4 of 5 suppressed hostility scales (cases had slightly higher irritability scores) and 5 of 6 personality scales (cases had somewhat higher anxiety scores) [21]. Reporting no cross-sectional association between psychologic status and concomitant blood pressure in adults, Monk suggested that “careful measurement of environmental and social stimuli to which individuals are exposed and the subsequent overt behavior might be valuable in epidemiologic studies of hypertension” [20]. However, the present negative findings with regard to behavior (MCBC) and children’s blood pressure are consistent with the negative findings of Buck using a Type A behavior scale [19] and those of Matthews et al. using the Matthews Youth Test for Health, another Type A behavior rating instrument (unpublished data). Shekelle found no relationship of delinquent behavior or school grade point averages to blood pressure [21]. The finding of higher activity scale scores on MCBC among the 10 hypertensive compared with 19 normotensive children is inconsistent with the results in the larger sample. It may be due to chance, although Insel et al. reported positive correlations of activity scores on a Type A scale and blood pressure. The findings with regard to family environment are consistent with the findings of Shekelle et al., who reported no difference between hypertensive adolescents and controls in frequency of only child status or living with natural parents [21]. However, they and Insel et al. found marked differences in measures of the need for intellectual achievement in school [18, 211, contrasting with our failure to find any positive relationship of family environment, achievement or intellectual/cultural scale scores to blood pressure in either the main sample or in the small group of hypertensive subjects. Insel’s findings of significant correlations of family support, achievement, and religious orientation scale scores with blood pressure in Seventh Day Adventists are inconsistent with our findings; this is probably due to factors peculiar to that conservative religious group. Our findings of inconsistent relationships between various indicators of family social status to children’s blood pressure is consistent with the findings of the Bogalusa Heart Study [22], which found no relationship of children’s blood pressure to parents’ educational level or occupation. The greater consistency and strength of an inverse relationship of poverty to blood pressure in U.S. adults [4] may indicate that longer exposure than our children’s 7-10 years to the environmental stress associated with low social status is necessary to produce blood pressure elevations. Our findings of a strong inverse relationship of family social status and children’s BMI and weight is consistent with other findings in U.S. adult women and children [4,23]. The Bogalusa Heart Study found a significant U-shaped relationship of parents’ educational level to a weight/height index and triceps skinfold in black children but no relationship in white children [21]. Black children of white collar workers had greater skinfolds but similar weight/height index compared to children of blue collar workers. There was no relationship of parents’ ocupation and obesity in white children [22]. The relationship of obesity to social status presumably reflects greater caloric intake from carbohydrate or fat-containing foods among lower social status children. Generalization of the present findings with regard to personality, behavior, family environment, and family social status should be limited to those aspects of each measured by the MCPS, MCBC and FES and to populations similar to that studied. The present findings provide no support for a causal relationship of personality, behavior or family environment to children’s blood pressure or risk of hypertension. Social status may begin in childhood to influence the risk of hypertension.

Acknowledgements-We gratefully Achen,

B.S., MS M. Dunn,

acknowledge the contribution of the technical D. Buckingham and the personnel of the Minneapolis

staff including Public Schools.

Alan

Von

194

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