Alcohol consumption is not a direct cause of cognitive impairment in older men later in life, a study conducted by the University of Western Australia has found.
The study, published in the Journal of Neurology, used Mendelian randomisation to analyse the genetic data from 3,542 men between the ages of 65 and 83 years.
The scientists measured the participants' cognitive function three to eight years after recording their alcohol consumption.
Lead author, Western Australian Centre for Health and Ageing Director and UWA Professor Osvaldo Almeida says the team investigated the triangular association between alcohol consumption, cognitive impairment and a genetic polymorphism that modulates the efficiency of a critical enzyme of alcohol metabolism.
"We found a genetic variation that increases absenteeism and decreases the total amount of alcohol consumed," Prof Almeida says.
"If alcohol were a cause of cognitive impairment, one would expect that this genetic variation would be associated with lower risk of cognitive impairment in later life [because people with this genetic variation drink less or not at all].
"That was not the case. Hence, we concluded that the association between alcohol use and cognitive impairment is not due to a direct effect of alcohol."
The study also presented results that are consistent with the possibility, but do not necessarily prove, that regular moderate drinking decreases the risk of cognitive impairment in older men.
Prof Almeida says the reasons for these results were unclear.
"But evidence from a randomised trial looking at the effect of the Mediterranean diet [which includes nuts, olive oil, vegetables and wine] on health outcomes is supportive of this hypothesis," he says.
"One may argue that people who drink in moderation have a lifestyle where, in general, things are done in moderation.
"This approach to life may decrease health hazards in general."
Prof Almeida says that although the results didn't show alcohol affecting cognitive impairment, other studies have found excessive alcohol use to be associated with worse physical health, widowhood and poor social support.
"[These studies] led to the assumption that alcohol must directly damage the brain and cause cognitive impairment," he says.
"This study shows that such an assumption is wrong.
"It also suggests that alcohol may have a small protective effect that we need to understand better in order to develop new interventions that might contribute to prevent dementia without all the bad outcomes associated with alcohol."
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"Alcohol consumption and cognitive impairment in older men: A mendelian randomization study." Almeida OP1, Hankey GJ, Yeap BB, Golledge J, Flicker L. Neurology. 2014 Feb 19. [Epub ahead of print] www.ncbi.nlm.nih.gov/pubmed/24553426