A long-term study of more than 9,000 people, which tracked the health of civil servants working in London, found that people who drank over the recommended limits for men and women and also those who have been teetotal in midlife were at an increased risk of the disease.
The study, published in the British Medical Journal (BMJ), followed participants who were aged between 35 and 55 when it began in the mid-1980s. Abstinence in midlife was associated with a 45% higher risk of dementia compared with people who consumed between one and 14 units of alcohol per week. Long-term abstainers and those who reported a decrease in alcohol consumption also appeared to have an increased risk.
Alcohol consumption was measured during assessments between 1985 and 1993, when the participants had an average age of 50. They were followed up for an average of 23 years, with cases of dementia identified through hospital, mental health service and mortality records. A total of 397 cases of dementia were recorded.
The team of French and British researchers suggested that part of the excess risk of dementia in abstainers could be attributable to the greater risk of cardiometabolic disease reported in this group.
Among excessive drinkers, defined as those who consumed more than 14 units per week, experts found a heightened risk of dementia that increased the more a person drank, noting that with every seven-unit-per-week increase there was a 17% rise in dementia risk.
“These results suggest that abstention and excessive alcohol consumption are associated with an increased risk of dementia, although the underlying mechanisms are likely to be different in the two groups,” the authors said.
Guidance from the UK chief medical officer states that men and women should drink no more than 14 units of alcohol each week – the equivalent of six pints of average strength beer.
Commenting on the study, Dr Sara Imarisio, the head of research at Alzheimer’s Research UK, said: “As this study only looked at people’s drinking in midlife, we don’t know about their drinking habits earlier in adulthood, and it is possible that this may contribute to their later life dementia risk.
“People who completely abstain from alcohol may have a history of heavy drinking and this can make it difficult to interpret the links between drinking and health. Future research will need to examine drinking habits across a whole lifetime, and this will help to shed more light on the relationship between alcohol and dementia.”
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