Over a mean follow-up period of 23 years, researchers found that people who abstained from alcohol in midlife or consumed more than 14 units per week were at higher risk for dementia.
However, the mechanisms underlying these associations in the two groups may not be the same, according to the findings published in BMJ.
“Most previous studies on the association between alcohol consumption and risk of dementia are based on elderly populations where drinking habits may have been modified at older ages,” Séverine Sabia, PhD, from the French Institute of Health and Medical Research, Inserm, and the department of epidemiology and public health, University College London, told Healio Psychiatry. “Given the long latent phase of dementia, it is important to consider how alcohol consumption over adulthood shapes the risk of dementia.”
To evaluate the relationship between alcohol consumption and dementia risk, researchers conducted a prospective cohort study of data from 9,087 British civil servants aged between 35 and 55 years in 1985 who were taking part in the Whitehall II Study, which looks at the impact of social, behavioral and biological factors on long-term health.
Sabia and colleagues assessed alcohol consumption over the follow-up period by administering questionnaires to the participants several times from 1985 to 2016. The researchers then converted measures on frequency and number of drinks consumed to units of alcohol consumed per week. They categorized alcohol consumption as abstinence, one to 14 units per week and more than 14 units per week. In addition, incident dementia was identified through linkage to hospital, mental health services and mortality registers until 2017.
Researchers found that people who abstained from alcohol in midlife or consumed more than 14 units per week were at higher risk for dementia.
There were 397 cases of dementia recorded over a mean follow-up of 23 years. Participants who abstained from alcohol in midlife were at higher risk for dementia than those who consumed one to 14 units per week (HR = 1.47; 95% CI, 1.15-1.89). Among participants who drank more than 14 units per week, every 7-unit increase in alcohol consumption per week was linked to a 17% higher risk for dementia (95% CI, 4-32). Furthermore, those who had scores of more than 2 on the CAGE alcohol assessment (HR = 2.19; 95% CI, 1.29-3.71) and alcohol-related hospital admission (HR = 4.28; 95% CI, 2.72-6.73) were also at increased risk for dementia.
“We also found an excess risk of dementia in abstainers, but this should not motivate people who do not drink to start drinking alcohol,” Sabia said. “These findings should be considered along with other results that show a detrimental effect of alcohol consumption on mortality and neuropsychiatric disorders, cirrhosis of the liver and cancer. In addition, we cannot exclude the possibility that persons abstaining from alcohol in midlife may have been previous drinkers.”
Based on 17-year alcohol consumption trajectories measured from midlife to early old age, long-term abstinence (HR = 1.74; 95% CI, 1.31-2.3), reduction in consumption (HR = 1.55; 95% CI, 1.08-2.22) and long-term drinking of more than 14 units per week (HR = 1.4; 95% CI, 1.02-1.93) were tied to a higher dementia risk compared with long-term alcohol consumption of one to 14 units each week.
Multistate models showed that part of the elevated risk of dementia in abstainers was attributable to the greater risk of cardiometabolic disease in this group over the follow-up.
“Excessive alcohol consumption is not included in the current dementia prevention guidelines,” Sabia told Healio Psychiatry. “Our results show it to be a risk factor for dementia. Our results also highlight the need for downward revision of guidelines in countries that use a higher threshold than 14 units per week.”
However, Sevil Yasar, MD, PhD, associate professor at Johns Hopkins School of Medicine, wrote in a related editorial that current recommendations on alcohol use should not change based exclusively on findings from epidemiological studies.
“The next steps should include confirmation of findings in other long-term cohort studies and ideally a randomized clinical trial, to answer pressing questions about the possible protective effects of light to moderate alcohol use on risk of dementia and the mediating role of cardiovascular disease,” she wrote. “Such a trial would be of long duration and ethically challenging. It would have to be funded exclusively by government agencies to avoid bias.” – by Savannah Demko
Disclosure: The authors and Yasar report no relevant financial disclosures.