Regulation of alcohol intake with advancing age

Regulation of alcohol intake with advancing age

Alcohol 36 (2005) 41–46 Regulation of alcohol intake with advancing age James L. York*, John Welte, Judith Hirsch State University of New York at Buf...

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Alcohol 36 (2005) 41–46

Regulation of alcohol intake with advancing age James L. York*, John Welte, Judith Hirsch State University of New York at Buffalo, Research Institute on Addictions, 1021 Main Street, Buffalo, NY 14203, USA Received 13 September 2004; received in revised form 22 December 2004; accepted 5 April 2005

Abstract Previous surveys of alcohol use in the general population have not gathered sufficient data to allow for estimations of the blood alcohol levels (BACs) routinely achieved in survey participants. Our goal was to assess the influence of age on the estimated peak BAC achieved on typical drinking occasions in a representative sample (n 5 2,626) of the U.S. adult population. Variables related to the quantity and duration of alcohol consumption on typical drinking occasions were assessed by computer-assisted telephone interview. In addition, the height, weight, age, and gender of subjects were ascertained to be used in equations to predict the volume of distribution of ethanol (total body water). Prediction equations were used to estimate the probable peak BACs achieved during the typical drinking occasion. The survey identified 1,833 subjects (‘‘current drinkers’’) of 18–89 years, who reported alcohol consumption within the past 12 months. Linear regression analyses performed on data from these ‘‘current drinkers’’ revealed that, for both men and women, there was an age-related decrease in the predicted peak BAC achieved on typical drinking occasions. The approaches used to modify the BAC with advancing age differed slightly for men and women, but both relied heavily upon a reduction in the quantity of consumption. Ó 2005 Elsevier Inc. All rights reserved. Keywords: Alcohol; Drinking; Gender; Age; Blood alcohol concentration

1. Introduction The blood alcohol levels (BACs) that are achieved during drinking occasions represent the most direct measure of the biological impact of alcohol consumption on tissue exposures and toxicities. Our goal in the current study was to use methodology that would allow for the prediction of the BACs that are typically achieved on drinking occasions to gain insight into the variation of BACs that are expected with advancing age. For instance, surveys of alcohol consumption practices in the general population have consistently reported that alcohol consumption on drinking occasions decreases with advancing age (Clark & Hilton, 1991; Clark & Midanik, 1982; Dawson et al., 1995). Moreover, studies in laboratory animals and humans have demonstrated that older subjects are more intoxicated by any given BAC than younger subjects (Jones & Jones, 1980; Jones & Neri, 1985; Vogel-Sprott & Barrett, 1984; Wood & Elias, 1982; York & Chan, 1993). If older people are more impaired by alcohol than younger subjects, then it might be predicted that older subjects would reduce their ethanol consumption to keep their blood ethanol levels from reaching the values that were

* Corresponding author. Tel.: 11-716-887-2540; fax: 11-716-887-2477. E-mail address: [email protected] (J.L. York). 0741-8329/05/$ – see front matter Ó 2005 Elsevier Inc. All rights reserved. doi: 10.1016/j.alcohol.2005.06.001

targeted at a younger age. The current study sought evidence supporting this hypothesis by using a cross-sectional approach that documented the quantities of alcohol consumed and the amount of time required for consumption on typical drinking occasions in a national general population sample. The methodology allowed for the prediction of the peak BACs achieved on typical drinking occasions in a nationally representative sample of subjects 18–89 years.

2. Materials and methods A computer-assisted telephone survey of the national general population (delete ‘‘survey’’) was conducted on an adult member of 2,626 households across the United States, yielding a subsample of 1,833 subjects of 18–89 years who reported alcohol use within the past 12 months. The survey methodology has been outlined in detail elsewhere (Welte et al., 2001; York et al., 2003) and was approved by the institutional review board of the SUNY Buffalo Research Institute on Addictions. The data were collected by means of a confidential telephone survey. Therefore, verbal informed consent was obtained. Respondents were read a carefully prepared informed consent script that stipulated that their participation would be kept confidential and was


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entirely voluntary. Respondents were briefly informed of the nature and funding of the study and told that the information would be kept confidential and that they could refuse to answer any particular question or could withdraw from the study at any time during the interview. The questions related to alcohol use that was reported here were part of a larger survey designed to examine the co-occurrence of gambling, alcohol, and drug abuse (Welte et al., 2001). These questions assessed, among other things, the quantity and the duration of alcohol consumption on typical drinking occasions, using the past 12 months as the reference period. The quantity of alcohol consumption was assessed by asking the respondents how much they consumed, which is expressed as units of a ‘‘standard drink,’’ defined as 12 oz. of beer, malt liquor, or wine cooler; 4 oz. of wine, a 1.5 oz. shot of liquor; or a mixed drink containing a shot of liquor (e.g., ‘‘on a typical day when you drink beer, how many 12 oz. cans or bottles do you drink?’’). The duration of the typical drinking episode was assessed by asking subjects how long (minutes, hours) they usually required to consume the number of drinks they had just described. For calculation purposes, the standard drink (for instance, 12 oz. of beer containing 4% alcohol) was defined in this study to contain 0.5 oz. (15 ml), or 12 g of ethanol. Questions pertaining to the weight and height of subjects were included in the survey so that prediction equations (Watson et al., 1980) based upon subject gender, age, height, and weight could be used to estimate the total body water (TBW) of subjects. Because of the water solubility of ethanol, TBW is, theoretically, the volume of distribution of ingested ethanol (Harger & Hulpieu, 1956) and is the body composition variable that most directly determines the blood concentrations of ingested ethanol (blood is approximately 81% water). Ethanol is considered to become equally distributed throughout the body water, including the water in whole blood. The approach used here to estimate the probable peak BAC relied upon the principle that, for an individual of given TBW, the peak blood ethanol level is a function of the number of standard drinks consumed (12 g of ethanol per drink) and the amount of time over which drinks are consumed. We used an approach similar to that used by many others to predict blood alcohol concentrations after social drinking (Breslin et al., 1997; Greenberg, 1968; Kapur, 1991; Stowell & Stowell, 1998). This approach essentially calculates the dilution of the number of grams of ingested ethanol in the number of liters of TBW, and makes a correction (subtraction) for the time allowed for metabolism of ethanol (the duration of the drinking episode; York et al., 2003). An average disappearance rate of 0.015 g of ethanol per 100 ml of blood per hour, due primarily to hepatic metabolism, was used for both genders (Greenberg, 1968; Markham et al, 1993; Stowell & Stowell, 1998; Watson, 1989). There is no correction for age in the metabolism of ethanol because the

preponderance of evidence does not support such an approach at this time (York et al., 2003). Thus, the following equation was used to estimate the peak BAC for subjects, where the BAC is expressed in grams of ethanol per 100 ml of blood, N is equal to the number of hours over which the alcohol is consumed, and TBW is expressed in deciliters BAC 5 ½ð12 3 Total number of standard drinks=TBWÞ 3 0:8065 2 0:015N Because blood is only approximately 80.65% water, by volume, multiplication by 0.8065 converts the concentration from TBW to conventional BAC units. A detailed description of the BAC calculation procedure has been presented elsewhere (York et al., 2003). SPSS linear regression software was used to perform the statistical analyses presented below. The regressions of age vs. peak BAC, TBW, duration, or quantity were first performed, then the independent contributions of quantity, duration, and TBW to the relationship of peak BAC to age were estimated for each variable by holding the other two constant in the calculation of the peak BAC.

3. Results The survey obtained a response rate of 65.1% and produced a sample that closely approximated the age and race/ethnicity distribution of the general population. Of the 1,539 women interviewed, 1,028 (prevalence of 67.2%) reported current drinking (past 12-month window), compared to 805 of the 1,096 men (prevalence 73.4%). Additional details regarding the sample characteristics may be found in the publications by Welte et al. (2001) and York et al. (2003). The data in Table 1 clearly outline the decline with age in the quantity of alcohol consumed by both men and women on drinking occasions. The decline with age in the duration of the drinking episode was more pronounced in women than in men. The volume of distribution for ethanol (total body water, TBW) remained relatively unchanged for women across the decades, but declined by about 20% in men, a finding similar to previous reports (Chumlea et al., 2001; Schoeller, 1989; Watson et al., 1980). Predicted peak BACs were nearly identical for men and women in their 20s and 30s, but appeared to decline more in women than in men with advancing age. The group mean BAC for subjects of all ages combined was similar for men and women. Linear regressions using age as a continuous variable vs. the dependent variables of TBW, BAC, quantity (drinks per drinking day), and duration (minutes spent drinking) were performed to determine the relative contribution of the variables quantity, duration, and TBW to the decline in BAC with age (Fig. 1).

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Table 1 Alcohol consumption variables on typical drinking occasions (mean, S.E.M.) Age (years) 18–29







All ages

Men Quantity Duration BAC TBW N

3.90 (0.22) 123 (6) 0.051 (0.004) 47.5 (0.4) 207

3.34 (0.24) 138 (9) 0.035 (0.004) 48.0 (0.4) 191

3.33 (0.23) 135 (8) 0.036 (0.004) 47.6 (0.4) 183

2.46 (0.17) 115 (11) 0.025 (0.002) 46.2 (0.5) 108

2.23 (0.19) 99 (12) 0.025 (0.003) 44.9 (0.6) 62

2.38 (0.41) 123 (20) 0.029 (0.009) 41.8 (0.6) 42

1.92 (0.23) 86 (20) 0.026 (0.003) 38.1 (0.7) 12

3.21 (0.10) 126 (4) 0.037 (0.002) 46.8 (0.2) 805

Women Quantity Duration BAC TBW N

3.09 (0.15) 158 (7) 0.055 (0.004) 32.0 (0.3) 238

2.23 (0.11) 128 (6) 0.037 (0.003) 32.1 (0.2) 226

2.05 (0.11) 123 (7) 0.032 (0.003) 32.3 (0.3) 218

1.65 (0.09) 101 (7) 0.024 (0.002) 33.6 (0.4) 171

1.52 (0.08) 87 (7) 0.025 (0.002) 32.5 (0.3) 100

1.42 (0.11) 91 (11) 0.021 (0.002) 32.2 (0.5) 57

1.06 (0.06) 60 (13) 0.017 (0.002) 32.3 (0.8) 18

2.16 (0.05) 122 (3) 0.036 (0.001) 32.4 (0.1) 1028

Quantity 5 standard drinks per drinking days (one drink 5 12 g ethanol), duration 5 minutes spent drinking on drinking days, BAC 5 blood alcohol level in g/100 ml blood, TBW 5 total body water in kilograms or liters, N 5 number of subjects. Values in parentheses are standard errors.

The linear regressions presented in Fig. 1 illustrate the changes in BAC with age and also the changes with age in the variables that enter into the peak BAC calculation equation. Note that the estimated peak BACs declined with age in both men and women (Fig. 1A). The 20% decline in TBW with age in men indicates that older men have available a smaller volume of distribution for ethanol. The decline with age in the quantity of consumption for men closely paralleled that for women. At the same time, the duration of the drinking episode fell more sharply with age for women compared to men. All of the correlations depicted in the figure were significant except for the duration variable in men. The correlations were higher in women for all of the variables except TBW. A test of gender interaction effects indicated that the slopes of the regression lines for men differed from those for women only for the variables of duration (P !.001) and TBW (P !.001). To demonstrate quantitatively the relative contributions of the quantity, duration, and TBW variables to the decline in peak BAC with age, the influence of each of those variables alone on the slope of the BAC vs. age function was examined. Table 2 presents statistical evidence to support the visual evidence that is obtained from inspection of the regression slopes of Fig. 1. The aim of Table 2 was to present a statistical approach for estimating the extent to which each of the variables in the BAC equation (TBW, quantity, and duration) contribute to the change in slope of the BAC with age. This was accomplished for each variable by holding the other two variables constant in the calculation of BAC. For instance, to determine the influence of quantity alone on the slope of BAC vs. age, the variables of duration and TBW were held constant by assigning the group mean value (Table 1, all ages) for those variables to all subjects, allowing only quantity to vary as originally assessed. The effect of this approach on the slope of the BAC vs. age regression is demonstrated in the second line of Table 2. The first line of the table presents the slope as

depicted in Fig. 1A and reflects the combined influence of all three variables on the peak BAC. The approach, which allows quantity alone to vary (line 2) produced an even steeper slope of the BAC vs. age function in both men and women. In contrast, allowing the duration variable alone to vary, while holding quantity and TBW constant (Table 2, line 3), produced smaller and even positive slopes in both men and women, but more so in women, indicating that the decreases in duration of drinking with age (Fig. 1B) functioned to reduce the negative slope of the BAC vs. age regression. When TBW alone (line 4) was allowed to vary, a slight reduction in the slope was observed in men and a slight increase in the slope was observed in women. Thus, the findings in Table 2 indicate that the decreases in consumption quantities with age contributed overwhelmingly to the decrease in the BAC with age in both men and women. In contrast, the decrease in the duration of the drinking episode with age functioned to raise the BAC more in women than in men. A test of gender interaction effects in these modified regressions indicated that the slopes for men differed from those of women for both the duration and TBW variables (P !.001) but not for the quantity variable (P !.07). 4. Discussion The findings presented here on the age-related reductions of the quantities consumed on drinking occasions agree with those from previous surveys cited above. However, the additional information on the duration of the drinking episode (minutes of drinking, Table 1) collected in this survey has allowed for the construction of a more complete picture of the biological impact of these agerelated changes in drinking patterns, vis-a`-vis their impact on expected blood and tissue alcohol levels on drinking occasions. Moreover, the data in Fig. 1 portray how the


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Fig. 1. Changes with age in the blood alcohol level (BAC) and in the variables that influence the BAC. Linear regression analyses (least squares straight line fits) against age are depicted for the BAC and for each of the variables that enters into the calculation of the BAC (see equation in text). Regression equations, with Y intercepts, slopes, ‘‘r’’ and ‘‘P’’ values are listed for men and women for each variable. (A) Men and women display similar declines in BAC with age. Total body water (TBW) declines with age in men, but remains relatively flat in women. (B) Quantity (drinks consumed per drinking occasion) decreases similarly in both men and women, whereas the duration of the drinking episode decreases more steeply in women than in men. (n 5 805 males, 1,028 females).

approach used by men to control their BACs with age differ from that used by women. For both men and women, a reduction in the quantity consumed is the major adjustment, as witnessed by the reduction in the age vs. BAC correlation when quantity is held constant in the calculation of BAC. The decrease in body water compartment with age in men, but not women, illustrates the need for men to make a larger adjustment in their rate of consumption to maintain a BAC comparable to that observed in women. Men also gain an advantage in lowering their BAC by maintaining a longer duration of drinking throughout the age span, whereas the shorter durations of consumption reported by older women is a factor that would tend to increase the BAC for any given

quantity of consumption. Relevant to the interpretation of these findings are studies that indicate that the degree of impairment produced by any given BAC tends to be similar in men and women (Mumenthaler et al., 1999; Roman, 1988). Thus, it appears that men and women of different age categories are drinking in a fashion such that the degree of impairment, or ‘‘high’’, experienced from their consumption is similar for the genders within the particular age range. In this study, the elimination rate for alcohol for both men and women was taken to be 0.015% per hour, an accepted reference value for the past several decades. However, the issue of the relative ethanol elimination rates for men and women is being debated at this time (York

J.L. York et al. / Alcohol 36 (2005) 41–46 Table 2 Effect of quantity, duration, or total body water (TBW) alone on the slope of the blood alcohol level (BAC) vs. age function Men Slopea BAC vs. age (all variables) BAC vs. age (quantity alone) BAC vs. age (duration alone) BAC vs. age (TBW alone)

Women r



25.6 (1.1) 2.174 .001 27.0 (0.8)



2.269 .001

27.6 (1.3) 2.196 .001 210.5 (1.0) 2.318 .001 11.0 (0.3) 1.103 .003 13.7 (0.4)

1.255 .001

10.9 (0.1) 1.268 .001 20.6 (0.2)

2.085 .01

Each of the three variables used in the prediction of peak BAC was examined for its independent contribution to the slope of the BAC vs. age regression. Line 1 of the table presents the slope, correlation coefficient (r), and statistical significance (P) of the regression when all three variables of quantity, duration, and TBW are allowed to vary, as in Fig. 1A. The slopes obtained when two of the three variables are held constant are depicted in lines 2, 3, and 4. a Slopes and standard errors have been multiplied by 10,000 to convert them into easily readable form. Values in parentheses are standard errors of the mean.

et al., 2003), with some researchers favoring a more rapid elimination rate in women. Nevertheless, the choice of elimination rates for men and women does not affect the function of the age-related decline in peak BACs that is the main thrust of this paper, because any alternate elimination rate would affect the peak BAC value for each subject, within genders, to the same extent. The choice of a different elimination rate for men and women would serve only to separate the mean BAC and the BAC curves for men and women presented in Table 1 and Fig. 1A, but would not affect the age relatedness of the function. Owing to possible cohort effects, true age-related effects are best explored with a longitudinal design, not the crosssectional design of the current study. However, a number of biological and/or social–behavioral factors may be speculated to contribute to, or motivate, the decrease in the BAC with advancing age. One possibility is that documented age-related increases in the acute sensitivity to alcohol intoxication may reduce the amount of alcohol (BAC) needed to produce the desired or tolerated level of intoxication. For example, Jones and Jones (1980) reported that, under the influence of a mean BAC of 0.063, middle aged women experienced a greater impairment in shortterm memory than did young women, but the extent of the impairment was not quantified in their report. Even more helpful in determining the extent of the influence of age-related changes in sensitivity to ethanol on drinking habits is the study of Jones and Neri (1985), who reported that young men (20–29 years) reported significantly lower subjective intoxication scores than did older subjects (30–59 years) tested at the same blood ethanol levels after the administration of an oral dose of ethanol (0.68 g/kg ethanol) as neat whiskey. The intoxication scores for younger subjects (20–29 years) were only about 60% as


great as the those for the oldest subjects (50–59 years) at several measurements taken as alcohol was absorbed and eliminated. These findings suggest that a significant proportion of the roughly 50% smaller predicted peak BAC we found for men and women in the 50–59 age group compared to the 18–29 age group may be motivated by the attempt by older subjects to maintain their level of intoxication at a level that is similar to that experienced by subjects in the youngest age group. Other studies in the literature also help in the estimation of the extent to which changes in sensitivity to ethanol with age may motivate the reductions in BACs we report here. Studies in laboratory rodents of different ages have found that the BAC required to produce hypnosis is approximately 14–24% less in old rats than in young animals (York & Chan, 1993). In a study of the drinking habits of 41 male social drinkers of 19–63 years, Vogel-Sprott and Barrett (1984) reached many of the same conclusions presented in the current study. They reported that older subjects (63 years old) experience nearly twice as much impairment as younger subjects on motor tasks (balance beam, bead stringing) when BACs were controlled for (mean 0.069%). Thus, much of the reduction in peak BAC with age may reflect the attempt to keep the level of intoxication similar to that experienced at a younger age. The above reasoning rests upon the assertion that the peak BAC estimations presented here are based upon consumption patterns that reflect the self-selection of ethanol under free-choice conditions, and that the effects produced by those doses are the effect typically desired by the interviewee. The interaction of variables that influence alcohol consumption over the life span is very complex. A variety of social or behavioral factors may also operate separately or in conjunction with biological changes in sensitivity to motivate the reduction in the peak BACs with age. For instance, increased attention with advancing age to social responsibilities in the family, legal, or occupational realm may lead to a more cautious approach to alcohol consumption (Akers & La Greca, 1991; Beresford & Gomberg, 1995; Mishara & Kastenbaum, 1980). Moreover, the social context in which drinking takes place can be expected to vary with age in a manner that may influence the amount of alcohol typically consumed. A desire for a less intense intoxication or ‘‘high’’ from drinking with advancing age should also be considered as an alternative or supplemental explanation for the findings we report. The extent to which these variables may operate to modify the intake of ethanol has yet to be quantified. However, the information on increased sensitivity to ethanol with age outlined above does permit a semiquantitative approach. The finding that the quantity of alcohol consumption declines, in general, in other nations throughout the world (Fillmore et al., 1993) might be taken as evidence that a factor or factors in common to all the cultures (perhaps biological changes with age) have operated to influence the age-related declines in consumption reported here and by others.


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Acknowledgments This study was supported in part by grants AA 12883 and 11402 from the National Institute on Alcohol Abuse and Alcoholism.

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