People who abstain from alcohol or consume more than 14 units per week during middle age are at increased risk of developing dementia, according to a study published online ahead of print August 1 in BMJ. However, the underlying mechanisms are likely to be different in the two groups.
Continuously increasing life expectancy and, according to World Health Organization estimates, an expected tripling of dementia prevalence by 2050 have increased the importance of understanding the impact of alcohol consumption on aging outcomes. Previous studies have indicated that moderate drinking is associated with a reduced risk of dementia, whereas abstinence and heavy drinking are associated with an increased risk. The evidence is far from conclusive, however, and the reasons underlying these associations remain unclear.
Drinking Patterns Analyzed
A team of researchers from France and the United Kingdom investigated the association between midlife alcohol consumption and risk of dementia into early old age. They also examined whether cardiometabolic disease affects this association. Their findings are based on data from 9,087 British civil servants who were between ages 35 and 55 in 1985 and took part in the ongoing Whitehall II Study, which is looking at the impact of social, behavioral, and biologic factors on long-term health.
Participants’ alcohol consumption and alcohol dependence were assessed at regular intervals between 1985 and 1993 (average age, 50). Alcohol consumption trajectories between 1985 and 2004 were also used to examine the association of long-term alcohol consumption and risk of dementia from midlife to early old age. Admissions for alcohol-related chronic diseases and cases of dementia from 1991 to 2017, and the role of cardiometabolic disease, were identified from hospital records.
Among the 9,087 participants, 397 cases of dementia were recorded over an average follow-up period of 23 years. Average age at dementia diagnosis was 76.
After adjusting for sociodemographic, lifestyle, and health-related factors that could have affected the results, the researchers found that abstinence in midlife or drinking more than 14 units per week was associated with a higher risk of dementia, compared with drinking one to 14 units of alcohol per week. Among those drinking more than 14 units per week of alcohol, every seven-unit-per-week increase in consumption was associated with a 17% increase in dementia risk.
History of hospital admission for alcohol-related chronic diseases was associated with a quadrupled risk of dementia. The researchers showed that some of the excess dementia risk in abstainers resulted from a greater risk of cardiometabolic disease.
Alcohol consumption trajectories showed similar results, with long-term abstainers, those reporting decreased consumption, and long-term consumers of more than 14 units per week at a higher risk of dementia, compared with long-term consumers of one to 14 units per week.
Further analyses to test the strength of the associations produced broadly consistent findings, suggesting that the results are robust. Taken together, these results suggest that abstention and excessive alcohol consumption are associated with an increased risk of dementia, said lead author Séverine Sabia, PhD, a research associate at Inserm, U1018, Centre for Research in Epidemiology and Population Health, Université Paris-Saclay, France and Hôpital Paul Brousse in Villejuif, France, and colleagues.
According to the researchers, no firm conclusions regarding cause and effect can be drawn from this observational study, and the researchers said they cannot rule out the possibility that some of the risk may result from confounding factors. However, the findings “strengthen the evidence that excessive alcohol consumption is a risk factor for dementia” and “encourage use of lower thresholds of alcohol consumption in guidelines to promote cognitive health at older ages,” they said. The findings “should not motivate people who do not drink to start drinking, given the known detrimental effects of alcohol consumption for mortality, neuropsychiatric disorders, cirrhosis of the liver, and cancer,” they added.