Alcohol, aging, and cognitive performance: a cross-cultural comparison

Alcohol in the Aging Brain - The Interplay Between Alcohol Consumption, Cognitive Decline and the Cardiovascular System

As our society grows older new challenges for medicine and healthcare emerge. Age-related changes of the body have been observed in essential body functions, particularly in the loco-motor system, in the cardiovascular system and in cognitive functions concerning both brain plasticity and changes in behavior. Nutrition and lifestyle, such as nicotine intake and chronic alcohol consumption, also contribute to biological changes in the brain. This review addresses the effect of alcohol consumption on cognitive decline, changes in brain plasticity in the aging brain and on cardiovascular health in aging. Thus, studies on the interplay of chronic alcohol intake and either cognitive decline or cognitive preservation are outlined. Because of the inconsistency in the literature of whether alcohol consumption preserves cognitive functions in the aging brain or whether it accelerates cognitive decline, it is crucial to consider individual contributing factors such as culture, health and lifestyle in future studies.

Alcohol, Gender, and Cognitive Performance

Background: Recent data demonstrate that moderate consumption of alcohol may be beneficial to cognition. Design: Longitudinal growth curve analyses controlling for variables related to cognition were used to examine the relationship between alcohol consumption, ethnic differences, gender, and cognition over a 4-year-follow-up period. Sample: The sample included 1,836 Japanese American and 2,581 Non-Hispanic White American community-dwelling adults age 65 and older who were cognitively intact at baseline and participated in at least one follow-up examination. Measurement: Cognitive performance was measured using the Cognitive Abilities Screening Instrument (CASI) and reaction time. Results: Current drinkers scored significantly higher on CASI over time than past drinkers or abstainers. The same association between alcohol and CASI was observed in both genders and both ethnic groups. Conclusion: This study provides support regarding the potential beneficial outcomes associated with alcohol consumption and cognition and that these benefits were not modified by gender or ethnicity.

Alcohol consumption in mild cognitive impairment and dementia: harmful or neuroprotective?

OBJECTIVE

In several longitudinal studies, light-to-moderate drinking of alcoholic beverages has been proposed as being protective against the development of age-related changes in cognitive function, predementia syndromes, and cognitive decline of degenerative (Alzheimer's disease, AD) or vascular origin (vascular dementia). However, contrasting findings also exist.

METHOD

The English literature published in this area before September 2011 was evaluated, and information relating to the various factors that may impact upon the relationship between alcohol consumption and dementia or predementia syndromes is presented in the succeeding texts.

RESULTS

Light-to-moderate alcohol consumption may be associated with a reduced risk of incident overall dementia and AD; however, protective benefits afforded to vascular dementia, cognitive decline, and predementia syndromes are less clear. The equivocal findings may relate to many of the studies being limited to cross-sectional designs, restrictions by age or gender, or incomplete ascertainment. Different outcomes, beverages, drinking patterns, and study follow-up periods or possible interactions with other lifestyle-related (e.g., smoking) or genetic factors (e.g., apolipoprotein E gene variation) may all contribute to the variability of findings.

CONCLUSION

Protective effects of moderate alcohol consumption against cognitive decline are suggested to be more likely in the absence of the AD-associated apolipoprotein E ε4 allele and where wine is the beverage. At present, there is no indication that light-to-moderate alcohol drinking would be harmful to cognition and dementia, and attempts to define what might be deemed beneficial levels of alcohol intake in terms of cognitive performance would be highly problematic and contentious.

Diet and Alzheimer's disease risk factors or prevention: the current evidence

Preventing or postponing the onset of Alzheimer's disease (AD) and delaying or slowing its progression would lead to a consequent improvement of health status and quality of life in older age. Elevated saturated fatty acids could have negative effects on age-related cognitive decline and mild cognitive impairment (MCI). Furthermore, at present, epidemiological evidence suggests a possible association between fish consumption, monounsaturated fatty acids and polyunsaturated fatty acids (PUFA; in particular, n-3 PUFA) and a reduced risk of cognitive decline and dementia. Poorer cognitive function and an increased risk of vascular dementia (VaD) were found to be associated with a lower consumption of milk or dairy products. However, the consumption of whole-fat dairy products may be associated with cognitive decline in the elderly. Light-to-moderate alcohol use may be associated with a reduced risk of incident dementia and AD, while for VaD, cognitive decline and predementia syndromes, the current evidence is only suggestive of a protective effect. The limited epidemiological evidence available on fruit and vegetable consumption and cognition generally supports a protective role of these macronutrients against cognitive decline, dementia and AD. Only recently, higher adherence to a Mediterranean-type diet was associated with decreased cognitive decline, although the Mediterranean diet (MeDi) combines several foods, micro- and macro-nutrients already separately proposed as potential protective factors against dementia and predementia syndromes. In fact, recent prospective studies provided evidence that higher adherence to a Mediterranean-type diet could be associated with slower cognitive decline, reduced risk of progression from MCI to AD, reduced risk of AD and a decreased all-cause mortality in AD patients. These findings suggested that adherence to the MeDi may affect not only the risk of AD, but also of predementia syndromes and their progression to overt dementia. Based on the current evidence concerning these factors, no definitive dietary recommendations are possible. However, following dietary advice for lowering the risk of cardiovascular and metabolic disorders, high levels of consumption of fats from fish, vegetable oils, nonstarchy vegetables, low glycemic index fruits and a diet low in foods with added sugars and with moderate wine intake should be encouraged. Hopefully this will open new opportunities for the prevention and management of dementia and AD.

Moderate alcohol consumption and cognitive risk

We reviewed 143 papers that described the relationship between moderate drinking of alcohol and some aspect of cognition. Two types of papers were found: (1) those that provided ratios of risk between drinkers and nondrinkers (74 papers in total) and (2) those that, although they did not provide such ratios, allowed cognition in drinkers to be rated as "better," "no different," or "worse" than cognition in nondrinkers (69 papers in total). The history of research on moderate drinking and cognition can be divided into two eras: 1977-1997 and 1998-present. Phase I (1977-1997) was the era of neuropsychological evaluation involving mostly young to middle-aged (18-50 years old) subjects. Although initial studies indicated moderate drinking impaired cognition, many later studies failed to confirm this, instead finding no difference in cognition between drinkers and nondrinkers. Phase II (1998-present) was and is the era of mental status exam evaluation involving mostly older (≥55 years old) subjects. These studies overwhelmingly found that moderate drinking either reduced or had no effect on the risk of dementia or cognitive impairment. When all the ratios of risk from all the studies in phase II providing such ratios are entered into a comprehensive meta-analysis, the average ratio of risk for cognitive risk (dementia or cognitive impairment/decline) associated with moderate "social" (not alcoholic) drinking of alcohol is 0.77, with nondrinkers as the reference group. The benefit of moderate drinking applied to all forms of dementia (dementia unspecified, Alzheimer's disease, and vascular dementia) and to cognitive impairment (low test scores), but no significant benefit against cognitive decline (rate of decline in test scores) was found. Both light and moderate drinking provided a similar benefit, but heavy drinking was associated with nonsignificantly higher cognitive risk for dementia and cognitive impairment. Although the meta-analysis also indicated that wine was better than beer or spirits, this was based on a relatively small number of studies because most studies did not distinguish among these different types of alcohol. Furthermore, a number of the studies that did make the distinction reported no difference among the effects of these different types of alcohol. Therefore, at present this question remains unanswered. Analysis also showed that the presence of the apolipoprotein E epsilon 4 allele eliminated the benefit of moderate drinking. However, this was based on a relatively small number of studies and several other studies have found a beneficial effect of the epsilon e4 allele. Further studies are necessary to settle this question. The benefit of moderate alcohol for cognition was seen in both men and women, although the amount and pattern of drinking is very different between the two sexes. Lastly, the finding of unaffected or significantly reduced cognitive risk in light to moderate drinkers was seen in 14/19 countries for which country-specific ratio data were available, with three of the five remaining countries showing nonsignificant reductions as well. Overall, light to moderate drinking does not appear to impair cognition in younger subjects and actually seems to reduce the risk of dementia and cognitive decline in older subjects.

Race moderates age-related cognitive decline in type 2 diabetes

The age-related rate of cognitive decline in patients with diabetes mellitus has received relatively little attention. In this cross-sectional study, Caucasian (N = 145) and African American (N = 25) males with diabetes mellitus were recruited to examine age-related changes in cognitive performance. It is known that African Americans with diabetes mellitus are at increased risk for more frequent and more severe diabetes-related complications. It was hypothesized that such complications may accelerate age-related cognitive decline in African Americans. Three timed tests varying in complexity assessed attention, mental flexibility, and learning. Advancing age was uniformly associated with decreasing cognitive performance but only on more complex tasks did race moderate this relationship. A steeper age-related decline was observed in African Americans on more complex cognitive tests. Diabetes may be an accelerated form of aging that impacts cognition and race appears to differentially moderate this relationship.

Cholesterol homeostasis in the developing brain: a possible new target for ethanol

Cholesterol is an essential component of cell membranes and plays an important role in signal transduction. This brief overview presents evidence from the literature that ethanol may affect cholesterol homeostasis and that, in the developing brain, this may be involved in its developmental neurotoxicity. The effects caused by inborn errors of cholesterol synthesis and by in utero ethanol exposure present several similarities in humans (eg, Smith-Lemli-Opitz syndrome and fetal alcohol syndrome), as well as in animal models. Ethanol has a cholesterol-reducing effect on the cardiovascular system, and a protective effect against Alzheimer's disease, whose pathogenesis has been linked to altered cholesterol homeostasis in the brain. In vitro, ethanol affects several functions that are mediated by cholesterol and important for brain development, such as glial cell proliferation, synaptogenesis, neuronal survival and neurite outgrowth. The brain contains high levels of cholesterol, mostly synthesized in situ. Astrocytes produce large amounts of cholesterol that can be released by these cells and utilized by neurons to form synapses. Ethanol up-regulates the cholesterol transporter ATP binding cassette A1 and cholesterol efflux from primary astrocyte cultures without affecting cholesterol synthesis.

Light to moderate alcohol consumption is associated with better cognitive function among older male veterans receiving primary care

Among older persons, the effects of light to moderate alcohol consumption on cognitive function remain inadequately defined. The authors sought to determine whether light to moderate drinking is associated with better cognitive function among older men. Participants included men aged 65 years or older enrolled in a Veteran's Administration (VA) primary care clinic. Current (past 1 year) and lifetime use, cognitive functioning (as determined by the Trail Making Part B, Symbol Digit, FAS, and Hopkins Verbal Learning tests), and demographic, psychosocial, and medical status were obtained using standardized methods. Participants (N = 760) had a mean age of 74 (range, 65-89) years. Current drinkers (n = 509) as compared with never (n = 31) and former (n = 220) drinkers demonstrated significantly better cognitive performance on 3 (Trails B, Symbol Digit, and Hopkins Verbal Learning) of the 4 tests (P < .01 for all comparisons). In multiple linear regression models, current light to moderate drinking (ie, 7 or fewer drinks per week), as compared to a reference group of never and former drinkers, was associated with better performance on the Trails B, Symbol Digit, and Hopkins Verbal Learning tests (P < .01 for all comparisons). The number of years drinking 7 or fewer drinks per week also was independently associated with better cognitive performance. Current consumption of 7 or fewer drinks per week and the number of years drinking at this level are both associated with better cognitive performance in older male veterans receiving primary care. These findings are consistent with the hypothesis that light to moderate drinking confers cognitive benefits to older persons.

Does drinking have effects on mood and cognition in male and female students?

Self-ratings of mood and bodily symptoms were made by groups of IQ and education-matched male and female students [teetotal, low (2-9 units/week for both sexes; 1 UK unit=8 g alcohol) and moderate (12-34 units/week for males; 10-24 units/week for females) drinkers], before the start and at the end of cognitive testing. Multivariate analyses of variance (MANOVAs) showed that there were significant Alcohol x Time interactions, because the teetotal group responded to the cognitive tests with greater increases in the factors of somatic anxiety and aggressive mood than did the other two groups. Thus, the teetotallers had greater ratings of anxiety, sweating, palpitations, irritability, headache, feeling angry, quarrelsome, belligerent, resentful, hostile, spiteful and rebellious. No differences were found in immediate or delayed logical memory, in verbal fluency, trails, clock-drawing or mental flexibility tests. In tests of sustained attention [rapid visual information processing (RVIP)] and planning, males performed better than females. The moderate-alcohol group performed better than the low-alcohol group in RVIP and planning (completed significantly more tasks in the minimum moves), although in the hardest parts of the latter test, they took longer in planning the initial move. In conclusion, there was no evidence that the group drinking moderate levels of alcohol had any cognitive impairment and the teetotal group responded to the cognitive tests with the greatest increases in negative mood.

Directions for unraveling the issue of alcohol and health disparities: findings from the Postmenopausal Health Disparities study

The Postmenopausal Health Disparities Study (PHD Study) is a model for unraveling the underlying factors that may play a role in the health status and life expectancy disparities among racial and ethnic groups, with particular attention to effects of alcoholic beverage consumption. The study is bioepidemiologic; underlying mechanisms, rather than end points per se, are evaluated. The design is cross-sectional with historical prospective elements. Data were collected from responses to three questionnaires and examination findings from a clinic visit. There were significant differences among racial and ethnic groups in patterns of alcoholic beverage consumption and selected demographic factors, body mass index, measures of physical activity and fitness, and nutritional factors. Predictors of body mass index included both moderate drinking and hormonal factors. To address the current controversy about risks and benefits of hormone replacement therapy (HRT) we examined the predictors of control-based categories of estradiol among treated women; predictors included drinking of alcohol, hormonal variables, and being Caucasian. In addition, a substantial proportion of the variables examined differed significantly between alcohol drinkers and abstainers. The significant differences between alcohol drinkers and abstainers, and among racial and ethnic groups, demonstrate the value of studying multiple racial and ethnic groups simultaneously. The PHD Study provides a unique and productive model that can be used in other populations.