It`s known that long-term alcohol abuse is detrimental to memory function and can cause neuro-degenerative disease.
But, the new findings, published in the Oxford University Press journal `Age and Ageing`, suggested that light or moderate consumption of alcohol may decrease the risk of cognitive decline or dementia.
A team of German researchers led by Dr Siegfried Weyere of Central Institute of Mental Health in Mannheim analysed 23 longitudinal studies, involving over 3,300 subjects aged 75 years and older.
They found that the impact of small amounts of alcohol was associated with lower incidence rates of overall dementia and Alzheimer dementia, but not of vascular dementia and cognitive decline.
"Our study suggests that light-to-moderate alcohol consumption is inversely related to incident dementia, also among individuals aged 75 years and older," the researchers wrote.
"It is still an open question whether different alcoholic beverages, such as beer, wine, and spirits, all have a similar effect."
Some studies have shown a positive effect of wine only, which may be due either to the level of ethanol, the complex mixture that comprises wine, or to the healthier life-style ascribed to wine drinkers, they said.
The participants of the study, of whom about 3,202 were without dementia, were interviewed in their homes by trained investigators and reassessed one and a half years and three years later.
Alcohol consumption information was available for 3,180 participants, half of whom (48.6 per cent) drank wine only, 29.0 per cent drank beer only and 22.4 per cent drank mixed alcohol beverages (wine, beer or spirits).
Alcohol consumption was significantly associated with male gender, younger age, higher level of education, not living alone and not being depressed.
During the three-year study period, 301 patients had died and data about their cognitive status was collected from family members, caregivers or primary care physicians.
Within the follow-up period, 217 cases (or 6.8 per cent) of dementia were diagnosed, whereby 111 subjects suffered from Alzheimer dementia.
Due to the relatively small numbers, other subgroups of dementia, such as vascular dementia, Parkinson`s disease, Lewy body dementia, alcohol dementia etc, were not considered in the following analyses.
Univariate and multivariate analyses revealed that alcohol consumption was significantly associated with a lower incidence of overall dementia and Alzheimer dementia.