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You are here: Home > Journals > Journal of the American Geriatrics Society > The Relationship Between Alcohol Consumption,...
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The Relationship Between Alcohol Consumption, Cognitive
Performance, and Daily Functioning in an Urban Sample of
Older Black Americans
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Journal of the American Geriatrics Society - Volume 44, Issue 10 (October 1996) - Add Journals Issue Alert
Copyright © 1996 American Geriatrics Society - About This Journal
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Abstract
P1158
Full Text
Frontmatter
METHODS
The Sample
Community
Screening Interview
for Dementia (CSID)
Test Measurements
Alcohol
Consumption
CLINICAL INVESTIGATION
The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily
Functioning in an Urban Sample of Older Black Americans
Hugh C. Hendrie MB, ChB
Sujuan Gao PhD
Kathleen S. Hall PhD
Siu L. Hui PhD
Frederick W. Unverzagt PhD
Departments of Psychiatry
Statistical Analysis
RESULTS
Medicine
DISCUSSION
References
Find Similar Articles
Regenstrief Institute for Health Care, Indiana University School of Medicine,
Indianapolis, Indiana.
OBJECTIVE:To report on moderate alcohol consumption and
measurements of cognitive function and activities of daily living in an
older, urban, community-dwelling sample of black Americans.
DESIGN:As part of a community prevalence study of dementia,
information on alcohol consumption and cognitive performance was
collected on 2040 randomly selected black subjects living in
Indianapolis.
MEASUREMENTS:From questions in the screening interview, alcohol
consumption was grouped into four categories: lifetime abstainers,
regular drinkers less than 4 drinks per week, 4 to 10 drinks per week,
and more than 10 drinks per week. Current and past drinkers were
analyzed separately. Three measurements were used: (1) a total
cognitive score; (2) the delayed recall score from the East Boston
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
Memory Test; (3) a score for daily functioning based upon information
from the informant. Multiple regression models were fitted with drinking
variables as the major predictor, including covariates of age, gender,
education, history of stroke, hypertension, being treated for depression,
and a family history of dementia.
MAIN RESULTS:In all analyses, there was a very consistent pattern for
both current and past drinkers. There was a small but significant dose
effect of drinking for the drinkers, with subjects in the heaviest drinking
category scoring poorest, i.e., lowest scores in cognitive tests and
highest scores in scales of daily functioning indicating more impairment.
The scores of abstainers were worse than those of subjects in the
lightest drinking category. The pattern of scores for cognitive
performance and daily functioning was similar between current and past
drinkers. These patterns remained the same even after potential
confounders were included.
CONCLUSIONS:Previous research on effects of alcohol on health indices
have suggested a J-shaped relationship between amounts of alcohol
consumption and measurements of heart disease, stroke, and mortality
rates. Our study provides some support for the concept of a similar Jshaped relationship between cognitive performance and alcohol
consumption, but the differences between drinking categories were
modest and the clinical significance of these findings uncertain.
Supported by NIA Grant R01 AG 00956 and Alzheimer's Association Grant IIRG-95-084.
Address correspondence to Hugh C. Hendrie, MB, ChB, Indiana University School of
Medicine, Department of Psychiatry, 541 Clinical Drive, Room 298, Indianapolis, IN 462025111.
Heavy alcohol consumption has well known and well documented serious deleterious
consequences for both general health and cognitive status. [1] Alcoholic subjects perform
more poorly on cognitive testing than nonalcoholic subjects, and this poor performance
persists even after prolonged periods of sobriety. [2] Heavy alcohol consumption has
been identified as a risk factor for dementia [3] as well as leading to the more
circumscribed deficit in memory seen in the Korsakoff-Wernicke's syndrome. [4] [5]
The effects of more moderate levels of drinking on health and cognitive performance are
more controversial. Moderate alcohol consumption, variously defined, has been
associated with a reduced risk for coronary artery disease, ischemic stroke, and mortality
rates when compared with lifetime abstention from alcohol. [6] [7] [8] [9] [10] [11] [12] [13]
[14] This relationship between alcohol consumption and indices of disease has been
described as J-shaped. [14] Some possible biological mechanisms have been proposed
for this apparent protective effect of moderate alcohol consumption, including favorable
increase in high density lipoprotein cholesterol (HDL-C) and its subfractions [15] [16] [17]
and increased levels of plasma concentration of endogenous tissue-type plasminogen
activator. [18]
In studies on currently employed subjects, a correlation between reduced abstraction
ability and increasing quantity of alcohol consumed per occasion has been reported,
whereas other studies involving younger adult or college age subjects have suggested
that mild to moderate alcohol consumption in social situations has little effect on cognitive
performance when the subjects are sober when tested. [19] [20] [21] [22] [23] [24] In studies
involving low-to-moderate alcohol consumption in older subjects, Hebert et al. [25]
reported no relationship between alcohol consumption and changes in cognitive scores
over time in a population-based study. They did report, however, that subjects in the
lightest drinking category had slightly but significantly better change scores in one of
three cognitive tests than did abstainers. In a sample of healthy volunteers, Goodwin et
al. [26] found that subjects who reported consuming alcohol during a 3-day period
performed slightly better in tests of cognitive function than subjects reporting no alcohol
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
P1159
consumption during that period, but the correlation between alcohol consumption and
cognitive performance was weak. No relationship between alcohol consumption and cognitive
scores were reported for patients attending a glaucoma clinic [27] or in a small sample of
subjects attending general practitioner clinics, although this latter study did report that the
median Mini-Mental State Exam (MMSE) scores of occasional drinkers was slightly but
significantly lower than the median MMSE scores of regular drinkers. [28] A recent study
involving the twin panel of US veterans has reported little or no effect of moderate drinking
compared with no drinking on scores on the telephone version of the MMSE and also
reported that past drinkers who are now abstaining had slightly but significantly lower MMSE
scores than the lifetime abstainers. [29]
As part of a two-stage prevalence study of Alzheimer's disease and other dementias, a
screening interview, the Community Screening Interview for Dementia, consisting of a
cognitive evaluation of the subject and information regarding functional abilities obtained
from a family member, was administered to a community-dwelling random sample of
2212 older ( 65 years) blacks living in Indianapolis. [30] Lifestyle questions, including
questions about alcohol consumption, were incorporated into the questionnaire. The
purpose of this paper is to report on the association between alcohol consumption and
cognitive performance and functional abilities based on the results from these
questionnaires.
METHODS
The Sample
The geographic study area comprised 29 contiguous census tracts, selected on the
basis of demographic and economic factors reported in the 1990 US Census to ensure
that the sampled area had a demographic composition similar to that of the black
population of the city of Indianapolis. A simple random sample of residential addresses
was constructed by the Indianapolis Water Company using all residential addresses in
the area as the sampling frame. Interviewers visited sampled addresses and recruited all
eligible residents at each address. To be eligible individuals had to reside at the sampled
address, be black, and be 65 years of age or older. A total of 2212 subjects completed
interviews, 121 (4.7%) eligible subjects were too ill to participate, 249 (9.6%) eligible
subjects refused, 4915 households were ineligible because there were no residents aged
65 years or older, and 383 households had no black members. Of the 2212 subjects
interviewed, 2040 had complete data on alcohol intake and the other variables analyzed
in this study, and 1381 of the 2040 subjects had informants, usually spouses or children,
who also completed the informant section, including all the questions about alcohol
consumption. [30]
Community Screening Interview for Dementia (CSI-D)
The CSI-D consists of two parts: a cognitive and risk factor section, which takes
approximately 20 minutes to administer, and an informant section, which provides
information about daily functioning and takes approximately 15 minutes to administer.
The instrument was designed as a screening instrument for dementia that could be used
in different cultures with differing degrees of education so that it specifically excludes
literacy-dependent items. The development, content scoring, and psychometric properties
of the CSI-D have been published previously. [31] [32] The items were selected from
several widely used geriatric assessment scales including the CAMDEX, [33] the MMSE,
[34] Dementia Rating Scale, [35] the CARE, [36] and the East Boston Memory Test. [37]
The items test cognitive function across multiple domains and include language,
memory, recall, orientation, judgment, comprehension, and construction as well as
activities of daily living. Each cognitive item is scored between 0 and 1, and the total
cognitive score ranges from 0 to 33. There are five items in which scores of fractions of
1 are possible: naming animals (23 animals = 1), naming three objects (repeat and
remember), following instructions, East Boston Story repeat (each item remembered =
1/6). When sampling for the subsequent clinical assessment stage, a cognitive score
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
<28.5 was considered poor performance by itself when no informant data was available.
Approximately one-third of the subjects in the poor performance category were
subsequently diagnosed as suffering from dementia. As a way of determining the
potential clinical significance of our findings, the percent of subjects scoring in the poor
performance category were calculated for each drinking group. We compared the scores
of the CSI-D cognitive section and the MMSE on 309 (53 demented, 96 cognitively
impaired, 160 normal) older black subjects as part of the clinical assessment procedures
of our prevalence study. The CSI-D and the MMSE were highly intercorrelated (Pearson
rho=.77, P < .001), and the distribution of scores was nearly identical (both highly
negatively skewed). Descriptive statistics were calculated for the CSI-D cognitive section
(mean = 27.81, SD = 4.50, range = 26.65) and the MMSE mean = 23.17, SD = 5.87,
range = 30). Based on these descriptive data, we estimated that 1 point on the CSI-D
cognitive section is roughly equivalent to 1.3 points on the MMSE. The score for daily
functioning is very similar to the scores from the Blessed dementia rating scale, where 0
= perfect functioning. High interrater reliability was obtained among lay interviewers after
a 2-week training course (kappa = 1 for 96% of the items). The intraclass correlation for
test-retest reliability after a 2- week interval was 0.93. In the East Boston Memory Test,
the subject is asked to repeat the following story immediately and again after an interval
in which the subject draws overlapping circles and pentagons. The story is as follows:
"Three children were alone at home and the house caught on fire. A brave man
managed to climb in a back window and carry them to safety. Aside from minor cuts and
bruises all were well." Scoring ranges from 0 to 6 items recalled.
Test Measurements
Three measurements were used for this study following the interviews with the subjects
and with the informants: (1) The total cognitive score (range 0-33) as a measure of
global cognitive function involving multiple domains; (2) the delayed recall score from the
East Boston Memory test (range 0-6) as a more specific measurement of memory
function; the immediate recall score from this test, but not the delayed recall score, is
incorporated in the total cognitive score; and (3) A score for daily functioning based upon
the information from the relative on Activities of Daily Living (perfect score = 0).
Alcohol Consumption
There were six questions regarding alcohol consumption: (1) Do or did you drink
alcoholic beverages? (2) Was
P1160
there ever a period when you drank alcoholic beverages regularly, and, if "yes", (3) At what
age did you begin drinking alcohol? (4) Do you still drink alcoholic beverages? (5) How often
do/did you drink alcohol beverages (daily or almost every day, 3-4 times per week, once or
twice per week, once or twice per month)? and (6) On those days that you have or had
alcohol drinks, about many drinks do/did you usually have (more than 5, 3-5, 1-2)? One drink
was defined as one glass of wine, one bottle of beer, or one mixed drink.
Information from items 5 and 6 were combined to provide an estimate for number of
drinks per week and grouped into three categories: less than 4 drinks per week, 4 to 10
drinks per week, and more than 10 drinks per week. These categories were chosen to be
consistent with the methods of classification employed by Hilton and Clark in some
analyses of the National Alcohol Survey data. [38] When questions comprised a range of
possibilities, the median score was utilized. The category "more than five drinks" was
scored as six. Information about alcohol consumption was collected independently from
both subject and informant. The Spearman rank correlation between the subject and
informant data for the calculated number of drinks per week was 0.43 ( P < .001). The
Kappa value comparing the subject and informant data was low (0.2); however, kappa
only measures the exact agreement between the categories of the two variables.
Considering the sensitive nature of the alcohol consumption questions and that the
number of drinks per week is an estimate from median values of the original questions,
Spearman's rank correlation, which does not decrease with a systematic shift in scores
between two measurements, is in our opinion a better indicator of association between
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
the two variables fluctuations.
Statistical Analysis
The means and standard deviations of the three test scores were calculated. Analysis of
variance was used to compare means among groups, and chi-square tests were used to
compare proportions. We fitted multiple regression models for the test scores with
drinking variables as the major predictors and potential confounders as covariates.
Because the test scores have skewed distributions, we used the minus log
transformation (-log(maximum+1-score) for the total cognitive score and the East Boston
delayed story recall score and -log(minimum+1-score) for the daily functioning score) to
normalize those scores in the linear statistical models.
The drinking categories in our data represent an ordinal grouping, and the crude mean
scores of the drinking groups, along with the abstainers, follow a J-shape. Therefore, we
used two drinking variables to represent alcohol consumption in the multiple regression
model to test if the pattern would remain after controlling for potential confounding
variables. The two variables are: (1) drinkers versus abstainers, and (2) a linear dose
variable coded 0 (for abstainers) to 3 (for heavy drinkers). This coding scheme allowed
abstainers to deviate from the drinkers' linear response. To assess if the abstainers'
deviation was large enough to form a J-shape, we tested whether the predicted cognitive
scores of the abstainers were worse than those of the lightest drinkers based on the
regression models using one-sided Wald statistics. To control for potential confounding
variables between alcohol consumption and cognitive function, demographic factors such
as age, years of education, gender, and smoking were included in the linear models. In
addition, the following medical historical factors were included: cancer, Parkinson's
disease, diabetes, hypertension, angina, heart attack, stroke, period of unconsciousness
following head injury, being treated for "nerves," being treated for depression, with
electroshock, and a family history of dementia. Variables significantly related to the test
scores, as well as alcohol consumption, were included in the final models.
Separate models were fitted with the transformed log scores of cognitive function,
delayed memory recall, and daily functioning as the dependent variables for current
drinkers and past drinkers, with abstainers included in each analysis.
RESULTS
The mean age of the 2040 subjects in our study was 74.1 years (±7.0 SD), with 1199
(59%) aged 65 to 74 years, 652 (32%) aged 75 to 84, and 189 (9%) aged 85 years and
older. This age distribution is similar to that reported for the black population in
Indianapolis in the 1990 US Census. Sixty-five percent of the sample were women, and
the mean years of education was 9.6 years (±3.1 years).
Eight hundred thirty-six (41.0%) of the subjects reported that they were lifetime
abstainers. A total of 1204 subjects (59.0%) reported using alcoholic beverages regularly
at some time during their life. Of these, 712 subjects (34.9% of the total sample)
reported that they had stopped drinking.
The average number of years of reported drinking for subjects currently drinking was
51.8 years (±10.6), and for subjects who had now stopped drinking the average was 33.1
years (±16.0). Only five subjects (0.6%) in the currently drinking category had drunk for
less than 5 years. The average number of years that previous drinkers had stopped
drinking was 20.7 (±14.9 years). Only nine subjects (1.1%) had stopped drinking in the
past year.
The demographic characteristics and history of medical illness of the current and past
drinkers classified by the three alcohol consumption levels, as well as abstainers, are
shown in Table 1 . Past drinkers and current drinkers were similar in all characteristics
except for a slightly higher proportion of women in the past drinking category. Abstainers
were older and more likely to be women and had a lower percentage of smokers than
the drinking categories. The relationship to education was more variable between the
categories, but the heaviest drinking category tended to be less well educated.
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
When the history of medical conditions between current and past drinkers are compared,
past drinkers had a significantly higher percentage of reported cancer, diabetes,
hypertension, angina, heart attack, stroke, and ever having been treated for "nerves."
Table 2 presents the mean cognitive score (and percent of subjects with poor
performance), East Boston delayed score, and daily functioning score for current drinkers
by three alcohol consumption levels as well as for abstainers. Similar data for past
drinkers are presented in Table 3 . In all comparisons, drinkers scored progressively
worse, with the level of drinking (i.e., heaviest drinkers had the lowest scores in cognitive
tests, highest scores in daily functioning), and abstainers scored intermediately (i.e.,
poorer than the lightest drinking category but better than the heaviest drinking category).
The pattern of the scores suggests that, among drinkers, there is a linear dose-response
relationship between level of
P1161
TABLE 1 -- Demographics and History of Medical Conditions of Current Drinkers, Past
Drinkers and Abstainers Classified by Alcohol Consumption Category
P
P
Values Values
Current
Drinkers
Past Drinkers
Drinks per week
>10
4-10
<4
>10
4-10
<4
Number of subjects
n=
93
n=
71
n=
328
n=
158
n=
140
n=
414
Abstainers
71.58 71.94 73.12 72.82 72.56 73.94 75.39
SD
(6.25) (6.16) (6.54) (6.39) (6.34) (6.67) (7.41)
10.11 10.04 8.92
8.78
9.62
*
n = 836
Age
Years of Education 8.78
*
9.80
<0.001
<0.001
0.006
<0.001
SD
(3.23) (2.94) (3.18) (3.18) (2.97) (3.03) (3.12)
% Women
22.58 36.62 54.88 32.28 43.57 64.73 85.29
<0.001
<0.001
% Smokers
87.10 81.69 77.74 89.87 84.29 73.12 35.93
<0.001
<0.001
Cancer
4.30
8.45
6.71
11.39 16.43 9.91
10.07
0.119
0.139
Parkinson's
disease
0.00
1.41
0.30
1.91
0.72
0.571
0.446
Diabetes
10.75 11.27 13.72 29.75 32.14 21.50 24.88
<0.001
0.039
Hypertension
40.86 50.70 55.18 64.56 62.86 63.68 63.59
<0.001
0.992
Angina
17.20 16.90 14.94 25.32 22.14 17.96 18.27
0.608
0.142
Heart attack
13.98 8.45
8.87
17.83 19.42 12.38 13.70
0.097
0.108
Stroke
13.98 9.86
7.01
17.83 10.79 12.08 10.46
0.163
0.067
Unconcious
15.05 9.86
9.17
11.39 8.57
<0.001
0.003
Nerves
17.20 21.13 14.02 24.68 23.57 21.26 20.98
0.05
0.702
Depression
6.45
8.45
4.88
8.23
9.35
5.31
8.41
0.210
0.210
Electroshock
4.30
0.00
2.13
4.43
2.14
1.94
2.04
0.295
0.291
Family history of
dementia
6.45
8.45
5.81
6.33
10.00 7.04
8.39
0.479
0.560
% History of
1.43
0.72
7.97
4.56
* P Values are given using one-way ANOVA comparisons for continuous variables and chi-square tests for
categorical variables.
Analysis included current drinkers and abstainers.
Analysis included past drinkers and abstainers.
TABLE 2 -- Comparisons of Scores by Drinking Categories (Current Drinkers) for Total
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
Cognitive Score, East Boston Delayed Recalls, Scores of Daily Functioning and Percent of
Subjects scoring Below Cut-Off Score
Drinks per week
Number of subjects
>10
4-10
n = 93
<4
n = 71
n = 328
Abstainers
P Values
n = 836
Mean cognitive scores
29.93
30.42
30.93
30.18
SD
(3.23)
(2.58)
(2.11)
(3.08)
Mean delayed recall scores
4.38
4.72
4.92
4.74
SD
(1.92)
(1.61)
(1.48)
(1.58)
Mean daily functioning scores
3.97
2.09
2.43
2.84
SD
(4.00)
(2.58)
(2.91)
(3.61)
<0.001
0.028
*
0.010
*
*
* P Values are given using one-way ANOVA comparisons.
drinking and various measures of functioning. To ensure that these were not spurious
findings attributable to confounding factors, we modeled each test score as a function of the
alcohol levels, with potential confounders as covariates, using multiple regression. The
cognitive scores were log transformed so that the dependent variable was normally
distributed. We screened all of the available demographic and medical history variables for
potential confounders and found that age, years of education, gender, history of stroke,
hypertension, depression, and family history of dementia were significantly related to
cognitive scores as well as drinking. Hence these variables were included in the final model.
Separate models were fitted to current and past drinkers, with abstainers included in
each analysis. Parameter estimates from the regression model for the cognitive score of
current drinkers are presented in Table 4 . From the model we can see that older age,
lower education, female gender, depression, and history of stroke were associated with
lower cognitive scores, whereas, surprisingly, hypertension and family history of dementia
were positively associated with cognitive scores in this sample. Both the indicator
variable for drinking and the level of drinking were also significant predictors of cognitive
scores. From the parameter estimates, each increasing level of drinking is associated
with a decrease of .0902 ( P = .006) in the predicted log cognitive score, but the
abstainers scored .1556 ( P = .008) lower in the log transformed cognitive scores than
the predicted zero dose response. Relative to the abstainers, the light drinkers had a
higher predicted mean log cognitive score of .0654 (= .1556-0.0902, P = .006).
The same conclusions were reached when the regression model was fitted to past
drinkers and abstainers. The indicator variable for drinking and the dose effect had
parameter estimates of .2260 ( P < .001) and -.1012 ( P < .001), respectively.
P1162
TABLE 3 -- Comparisons of Scores by Drinking Categories (Past Drinkers) for Total
Cognitive Score, East Boston Delayed Recalls, Scores of Daily Functioning and Percent of
Subjects scoring Below Cut-Off Score
Drinks per week
Number of subjects
Mean cognitive scores
>10
4-10
<4
n=
158
n=
140
n=
414
29.96
30.61
30.88
Abstainers P Values
n = 836
30.18
SD
(3.08)
(2.40)
(2.23)
(3.08)
Mean delayed recall scores
4.58
4.68
5.12
4.74
SD
(1.65)
(1.62)
(1.36)
(1.58)
Mean daily functioning scores
3.44
2.54
2.59
2.84
SD
(3.36)
(2.32)
(3.11)
(3.61)
<0.001
*
<0.001
*
0.139
*
* P Values are given using one-way ANOVA comparisons.
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
TABLE 4 -- Parameter Estimates from the Multiple Regression for Current Drinkers and
Abstainers. Log Transformed Cognitive Scores are Used as the Dependent Variable
Parameter
Estimate
Standard
Error of
Estimate
t Statistics
P Value
Current drinkers
vs abstainers
0.1556
0.0585
2.66
0.008
Dose effect of
drinking
-0.0902
0.0327
-2.76
0.006
Age
-0.0207
0.0023
-9.19
<0.001
Years of
education
0.0806
0.0051
15.81
<0.001
Female
-0.0952
0.0385
-2.47
0.014
Being treated for -0.1345
depression
0.0597
-2.25
0.024
Stroke
-0.2032
0.0520
-3.90
<0.001
Hypertension
0.0813
0.0321
2.53
0.012
Family history of
dementia
0.1311
0.0582
2.25
0.024
The abstainers deviate significantly from the predicted zero dose response by .2260 on the
log transformed scale, and this is .1248 (0.2260-0.1012) lower than the light drinkers ( P <
.001). This again puts the mean cognitive score of the abstainers near that of the moderate
drinkers and between the light and heavy drinkers. The adjusted mean log cognitive scores
by alcohol consumption from these two models are displayed in Figure 1a. The J-shaped
relationship between alcohol and cognitive score was still observed after accounting for
confounders.
The same regression analyses were run separately for current and past drinkers,
including abstainers in each analysis, with the East Boston delayed scores and the daily
functioning scores as the dependent variables. The linear dose effect for the drinkers
was significant at the .05 level in all four models. However, the abstainer's deviation from
the predicted zero dose response was only significant for the East Boston delay story
score when past drinkers were included in the model ( P < .001). P values from the
other three models for the abstainers' deviation ranged from 0.098 to 0.141.
As the more than 10 drinks/week drinking category of subjects may contain subjects with
greatly different levels of alcohol consumption, we subcategorized subjects into 10 to 14
drinks/week, 14 to 42 drinks/week and more than 42 drinks/week. No significant
differences in any comparisons were seen between these groups.
DISCUSSION
Our study provides information about alcohol consumption in one of the largest
community-based random samples of older blacks yet recorded. The drinking patterns
reported by these older subjects is very similar to those reported for black subjects aged
60 years and older (n = 395) in the 1984 National Alcohol Survey. [39] In that study, 60%
of the population were reported to be current abstainers, and 14% were infrequent
drinkers, compared with 75.9% of our sample who reported not currently drinking (41%
lifetime abstainers and 34.9% former drinkers). In the National Alcohol Survey, older
black subjects reported lower alcohol consumption than older white subjects. This
relatively low reported use of alcohol is consistent with the culture and mores of the
subjects in our study, most of whom express strong religious beliefs and are active
church goers. Despite these similarities, the validity of the reporting of alcohol
consumption is always a concern. In our study, we had the opportunity to compare
information on alcohol consumption from subjects as well as from informants. This
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
showed a modest correlation (Spearman rank order correlation 0.43, P < .001). It is also
possible that the calculated amount of drinking was underestimated in our study. For the
highest category of amounts of drinking per session (>5 drinks) the drinking units were
scored at six in our calculation. It must also be remembered that all of our calculations
were estimates based on median values. Thus, any direct extrapolation from our results
to determine an absolute level of alcohol intake for preservation or enhancement of
cognitive function would be difficult if not impossible. Although many of the the
differences between the alcohol consumption categories reported here reach
significance, levels are very modest, approximately .5 point in the East Boston Delayed
Recall, >1 point in the daily functioning scale (equivalent to scores in the Blessed scale),
and approximately
P1163
Figure 1. Mean log-transformed cognitive total scores and alcohol consumption
adjusted for confounding variables.
1 point in our total cognitive score from the CSI-D (equivalent to 1.3 points on the MMSE).
Despite these modest differences, the pattern of our results in all measurements of
cognitive functioning and of activities of daily living is remarkably consistent and very
similar to those of other studies that explore the relationship between alcohol
consumption and disease indices such as stroke and heart disease and mortality rates.
[6] [7] [8] [9] [10] [11] [12] [13] In subjects who report drinking at any time in their lives,
there is a significant linear relationship between increasing amounts of alcohol
consumption and poorer cognitive performance. The relationship in our study remains
significant even when potentially confounding variables such as age, gender, education,
history of stroke hypertension, being treated for depression, and a family history of
dementia are entered into the model.
In our study, the heaviest drinking category (>10 drinks per week) would certainly not be
considered heavy drinking by some standards. For example the Royal College of
General Practitioners, Psychiatrists and Physicians has recommended a "sensible"
weekly limit of 21 small drinks for men and 14 for women. [40] Our heaviest drinking
category probably contains a very wide range of drinking habits and is most likely the
category associated with underreporting due, in part, to limiting the maximum number of
drinks recorded to six. We did attempt to subdivide the heaviest drinking category further
to determine whether the differences we report are the result of a small number of very
heavy drinkers. However we could find no significant differences in cognitive functioning
between these subdivisions, even with the small number of subjects who reported
drinking more than 42 drinks per week. This surprising finding may be attributable to the
fact that self-report is most unreliable in subjects who drink the heaviest, but we are
unable to demonstrate this from our current data. Despite these caveats, it is still
somewhat disconcerting to observe the relationship between reduced cognitive scores,
albeit modest, and alcohol consumption at this level in this older population.
Direct comparisons between the results of our study and other previous studies are
difficult. Studies in younger populations have reported a subtle, if any, effect of alcohol
consumption on cognitive function. Our subjects' average length of alcohol consumption
was 20 to 30 years. It is possible, as suggested by Bates and Tracy, [19] that the effects
of alcohol on cognitive functioning are magnified as subjects age. The previous studies
on older subjects have also reported little if any effect of alcohol consumption in older
subjects, but these studies differed in a number of ways from our current study, e.g., in
the population studied and in the methods for determining alcohol consumption. Only one
previous study, Hebert et al., [25] was conducted on a population basis. This study was
longitudinal in design, excluded subjects who scored poorly on the initial evaluation, and
the subjects were primarily white. Our study was cross-sectional in design and included
all subjects regardless of cognitive performance. All of our study subjects were black.
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MD Consult - The Relationship Between Alcohol Consumption, Cognitive Performance, and Daily Functioning in an Urban Sample of Older Black Americans - Journ...
There are few reports supplying any physiological differences in ethanol metabolism
between white and black subjects. However, one study reports that the ADH2 * 3 allele,
which is found in about 25% of blacks, encodes a high activity isozyme subunit of
alcohol dehydrogenase, which may affect the rate of ethanol metabolism. [41]
In our study, lifetime abstainers tended to score more poorly in tests of cognitive function
than subjects in the lightest drinking category. Hebert et al., Goodwin et al., and the
study by Christian et al. on aging twins reported a similar relationship in cognitive
performance between abstainers and light drinkers, but the reported differences were
small and, in the case of the twin study, not significant. [25] [26] [29] Studies of the
relationship between alcohol consumption and health
P1164
indices suggest that alcohol's apparent protective effect may be caused by its biological
effects on cholesterol fractions or plasma levels of plasminogen activator. [15] [16] [17] [18]
Some aspects of our results suggested this hypothesis should be treated with caution.
Significant differences in cognitive function were found only in the very lightest category of
drinkers (<4 drinks per week). However, Ridker et al. [18] did demonstrate significant
differences in plasma concentration of endogenous tissue-type plasminogen activator, even in
those subjects who reported drinking only monthly compared with abstainers.
Perhaps the most surprising finding from our study is the similarity of the pattern of the
relationship between alcohol consumption and cognitive function in both current and past
drinkers, the majority of whom had discontinued drinking an average of 20 years
previously. Within the alcohol-consuming groups, the dose-response relationship
between increasing amounts of alcohol consumption and declining cognitive performance
is perhaps not surprising inasmuch as the effects of prolonged alcohol consumption in
the brain may persist even after prolonged abstinence. [42]
More puzzling is the association between higher cognitive score in the lightest drinking
category compared with abstainers in those subjects who have now stopped drinking. It
is difficult to compare this result with the finding from the twin study, where past drinkers
had poorer cognitive scores than lifelong abstainers. In the twin study, past drinkers
were not further divided into alcohol consumption categories. It is also difficult to attribute
this association to the protective effects of small amounts of alcohol in subjects who had
not consumed alcohol for an average of 20 years.
It is possible that the differences between abstainers and regular drinkers may be
caused by other lifestyle, personality, or genetic factors associated with being an
abstainer. In our study calculations, we tried to control for demographic and other risk
factors that may influence cognitive function. Poikolainen [14] has argued that the large
proportion of abstainers in previous studies (in our study 41% of the sample were
lifetime abstainers) spoke against the possibility that abstainers would be a selective
group deviating in many respects from the general population. We have no other ready
explanation for this finding, although we will continue to explore possible
genetic/environmental differences between the abstainers and the regular drinkers.
Finally, it must be remembered that the data presented here are cross-sectional in
design. It is not possible to draw inferences from these data regarding a causal
relationship between alcohol consumption and cognitive performance. It is hoped that as
our longitudinal study continues, the relationship between alcohol consumption and
cognition will be clarified.
In summary, in this large community-based sample of older black Americans, there is a
consistent but modest linear relationship between increasing levels of alcohol
consumption and poorer cognitive scores in subjects who report having been regular
drinkers at one time in their lives. Light drinkers performed better in cognitive tests than
lifelong abstainers, but the presumption that this association is related to the biological
effects of alcohol is questionable.
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