People who drink light to moderate amounts of alcohol in later life are less likely to develop dementia than people who abstain from alcohol consumption, a study from The Australian National University has found.

The meta-analysis analysed the outcomes of 15 research studies meeting rigorous scientific criteria exploring links between drinking and dementia, drawing on the results for more than 10,000 people worldwide.

"We looked at the results of studies that followed up with participants at intervals over two to eight years," said study leader Prof Kaarin Anstey from the Centre for Mental Health Research (CMHR) at ANU. "We then used statistical analysis to synthesise the results and to weight the studies according to their sample size.

"We found that light to moderate drinkers were 28 per cent less likely to develop Alzheimer's than non-drinkers, 25 per cent less likely to develop vascular dementia, and 26 per cent less likely to develop 'any dementia'."

Dr Anstey said that some of the research projects considered in the ANU synthesis study only reported whether participants were 'drinkers' or 'non-drinkers' without exploring the extent of people's drinking. In these studies drinkers had 44 per cent reduced risk of developing Alzheimer's and 47 per cent reduced risk of developing 'any dementia'.

The meta-analysis also found that the relationship between drinking and dementia was the same for men and women, with light to moderate drinkers showing decreased incidence of dementia regardless of sex.

"It should be noted that the studies we found on this topic nearly all focussed on older adults and their drinking habits," Prof Anstey said. "There is not yet enough scientific data published to draw conclusions about how early life alcohol consumption affects later dementia risk. We also did not analyse the type of alcohol beverages consumed as there are not enough studies that reported results separately for beer, wine etc."

Prof Anstey, who heads the Ageing Research Unit at the CMHR, said that it wasn't clear why light to moderate drinkers were less likely to develop dementia, but suggested that it could be to do with a protective effect of alcohol in reducing inflammation and heart disease, the benefits of social interactions associated with alcohol consumption, or Characteristics of individuals recruited into the studies.