Moderate consumption of wine could reduce the risk of contracting Alzheimer's disease among those over 75, according to a study revealed at a conference in Vienna.
Excessive consumption, on the other hand, can increase the risk, researchers at Wake Forest University in North Carolina found.
Kaycee Sink, one of the authors of the report, said they monitored 3,069 people of 75 and upwards over six years, asking them to note their alcohol consmption.
For those already suffering minor memory problems who drank more than two glasses a day, the risk was twice that of non-drinkers with similar impairment.
Another study released by researchers at a California medical centre for war veterans showed that those who had suffered post-traumatic stress disorder were twice as likely to contract Alzheimer's than other ex-soldiers.
The study covered 181,093 veterans aged 55 and over, who were monitored between 2001 and 2007.
Characterized by forgetfulness, agitation and dementia, Alzheimer's is caused by a massive loss of cells in several regions of the brain. The disease occurs most frequently in old age.
An estimated 37 million people worldwide live with dementia, with Alzheimer's disease causing the majority of cases, according to the World Health Organization (WHO).
With the aging of populations, this figure is projected to increase rapidly over the next decades, rising from 7.1 million in 2000 to 16.2 million in 2050 in Europe alone.
The Alzheimer's Association 2009 international conference in Vienna is attended by some 6,000 scientists, doctors and other experts on the disease. It runs until July 16.