Researchers found abstinence was associated with a 45 per cent increase in the chances of getting dementia by early old age, compared to those who drank within recommended limits – up to a bottle and a half of wine a week.
People who drank above the 14 unit guideline were also at increased risk, the team from University College London and French institute for health, Inserm, found. Their risk of developing dementia increased incrementally the more alcohol they were consuming.
“We show that both long term alcohol abstinence and excessive alcohol consumption may increase the risk of dementia,” the authors of the study, published in the British Medical Journal, wrote. “Given the number of people living with dementia is expected to triple by 2050 and the absence of a cure, prevention is key.”
Among abstainers, the study also found increased risks of diabetes and cardiovascular disease. These are both conditions which could contribute to dementia, a collective term for the loss of memory, thinking and other cognitive functions, and the leading cause of death in the UK.
Moderate alcohol consumption has previously been shown to help protect against these conditions, by reducing cholesterol and blood pressure levels, and it may be this which is responsible for the dementia protecting benefit.
However the authors said it would be nearly impossible to find a definitive cause without a much larger and impractical trial where participants are randomly allocated to quit drinking or drinking more heavily.
It could also be that people with higher levels of these types of metabolic diseases were more likely to quit drinking, or healthier and more well off people were more likely to be moderate drinkers. The authors said they would not encourage anyone currently abstaining to change their habits.
Of the 9,087 participants, who took part in a British study between 1985 and 1993 and were followed for 23 years on average, there were 397 cases of dementia recorded.
The study found long-term abstainers were at the most extra risk of dementia (67 per cent), compared to those who were abstinent in midlife (45 per cent) and those cutting down (50 per cent).
“The most intriguing finding from this study was the significantly increased risk of dementia among abstainers… and that association was only present in those who abstained from wine,” said Dr Sevil Yasar from John Hopkins School of Medicine in Baltimore, who was not involved in the study.
“Wine, in addition to alcohol, contains polyphenolic compounds, which have been associated with neuroprotective effects on both neurodegenerative and vascular pathways, and with cardioprotective effects through inflammation reduction, inhibition of platelet aggregation, and alteration of lipid profile.”
However she added that we should remain cautious about the findings.
Dr Sara Imarisio, head of research at Alzheimer’s Research UK, agreed, adding: “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.”