In a recent Addiction journal paper researchers perform an in-depth analysis of the alcohol-dementia relationship and determine whether certain levels of alcohol consumption increases the risk of dementia.
Dementia generally affects the elderly and geriatric patients. This condition is categorized by numerous symptoms, some of which include diminished cognition, memory, attention, communication, reasoning, and visual perception. Dementia impairs the patient's quality of life and imposes severe physical, psychological, social, and economic burdens.
The global prevalence of dementia has been rising over the last two decades, with the number of dementia patients expected to reach 152 million by 2050. Although there remains a lack of effective treatments for dementia, certain behaviors have been shown to increase the risk of its development. In fact, according to the 2020 Lancet Commission for Dementia Prevention, Intervention, and Care, up to 40% of dementia cases could be prevented or delayed if 12 distinct risk factors were avoided.
Excessive alcohol consumption in mid-life, for example, can cause significant neurotoxic effects on the brain. As compared to other risk factors, such as high blood pressure and diabetes, harmful alcohol use is one of the strongest risk factors for the development of dementia.
Population-based studies have reported conflicting results on the alcohol-dementia relationship. For example, some reports suggest that light-to-moderate alcohol use can reduce dementia risk as compared to those who have abstained from alcohol. In contrast, other studies report that alcohol use does not impact the risk of dementia.
Despite these different reports, reviews of population-based observational studies indicate that the alcohol-dementia relationship is J-shaped. More specifically, low levels of alcohol use may provide some benefit in reducing the risk of dementia, whereas excessive alcohol consumption likely increases the risk of dementia in a dose-dependent manner.
About the Study
The researchers in the current review aimed to provide a more concise understanding of the alcohol-dementia relationship while addressing the limitations of previous studies. Some of these limitations included a lack of standardization regarding how alcohol use was categorized and the scarcity of representation from low- to middle-income countries.
Moreover, the researchers collected data from 15 prospective epidemiological cohort studies conducted across six continents to examine the relationship between alcohol and dementia. Most of the cohorts were based in high-income countries; however, representation from low- and middle-income countries was provided by cohorts from Brazil and the Republic of Congo.
The study included individuals above 60 years of age. Individuals with dementia diagnosis at baseline, those without follow-up after dementia assessment, and those with no alcohol use records were excluded.
For each study cohort, alcohol use was converted into average grams of pure ethanol daily (g/day) based on the type of alcoholic beverage reported. From these values, the researchers categorized none, occasional, light-moderate, moderate-heavy, and heavy alcohol users as individuals who were currently abstaining from alcohol or consumed less than 1.3 g/day, 1.3-24.9 g/day, 25-44.9 g/day, and over 45 g/day, respectively.
A total of 24,478 individuals were included in the current study, with a mean age of 71.8 years at baseline. Among these, 58.3% were females, and 54.2% were current drinkers.
The risk of dementia was greater among alcohol abstainers than occasional, light-moderate-, and moderate-heavy drinkers, as well as among men. Notably, this result was consistent among female subjects when fully adjusted and competing risk models were employed. However, in fully adjusted models and those adjusted for competing for risk of death, no association was found between alcohol use and dementia among females.
Neither lifetime abstainers nor previous drinkers had a different dementia risk, regardless of their sex, demographic, or clinical characteristics.
Moderate drinkers were associated with a reduced risk of dementia compared to lifetime abstainers. These findings were consistent among men and women and in the adjusted models.
The dose-response analysis conducted among current drinkers did not show any significant variation in dementia risk based on the amount of alcohol consumed. Furthermore, based on current alcohol intake status, neither men nor women showed any variation in dementia susceptibility after adjusting for demographic and clinical characteristics.
Furthermore, dementia risk did not differ between daily drinkers and occasional drinkers. The same was true in comparison between lifetime abstainers and current drinkers.
Continent-wise analyses for the association between alcohol use and dementia risk, including Europe, Oceania (Australia), North America, and Asia (Korea), revealed non-linear relationships for Europe, North America, and Asia; however, these differences were not statistically significant. Meanwhile, results from Oceania depicted a protective effect of alcohol use against dementia compared to lifetime abstainers.
Among current drinkers, light-moderate alcohol consumption was associated with a reduced risk of dementia among Europeans compared to occasional drinkers. Alcohol consumption does not impact the risk of dementia in Asia.
The study findings suggest that abstaining from alcohol may increase the risk for all-cause dementia. Furthermore, there was no evidence to suggest that the amount of alcohol consumed impacts the dementia risk.
The current study's researchers emphasize that their findings must be balanced against existing literature reporting the association between moderate alcohol use and poor brain health, as well as other health conditions like cancer. Thus, the current study findings are not meant to encourage alcohol consumption and instead question whether current guidelines on reducing alcohol consumption in individuals over the age of 60 is an effective approach to preventing the development of dementia.
Nevertheless, the current study is associated with certain limitations that must be considered. The cohort participants, for example, self-reported their daily alcohol intake, which may be under-reported. Furthermore, the type of alcoholic drink was not consistently assessed in each cohort. Finally, the presence of healthy survivor bias may also limit the applicability of the study findings, particularly considering the older age of the cohorts.