Cognitive performance declines naturally with age, but the results of the new study, published in the American Journal of Epidemiology (Vol. 164, pp. 898-906) suggests that eating curries "often or very often" had significantly better cognitive performance than those who "never or rarely" ate the dish.
The study adds to previous laboratory-based studies that showed that curcumin could boost the body's ability to clear the build up of plaques in the brain that are linked to Alzheimer's disease.
Although the mechanism of Alzheimer's is not clear, significant data exists supporting the build-up of plaque from beta-amyloid deposits. Recent research (Journal of Alzheimer's Disease, Vol. 10, pp. 1-7) from the US appeared to indicate that curcumin could help the body's immune system clear away these deposits and reduce the risk of developing the disease.
The Singapore National Mental Health Survey of the Elderly, led by Tze-Pin Ng from the National University of Singapore, recruited 1,010 elderly Asian subjects (average age 68.9) and compared scores for the Mini-Mental State Examination (MMSE).
The researchers report that for three different categories of curry consumption - "often or very often", "occasionally" and "never or rarely" - and compared this with MMSE performance.
Ng and co-workers report that 43 per cent of the cohort consumed curry at least once a month to daily, while16 per cent never or rarely consumed the dish.
When the researchers looked at the consumption of curry with measures of cognitive impairment (scores below 23 on the MMSE), it was reported that those who consumed curry "often or very often" were associated with a 49 per cent reduced risk of cognitive impairment, compared to those who never or rarely consumed.
Eating curry "occasionally" was associated with a 38 per cent reduced risk.
"These findings present the first epidemiological evidence supporting a link between curry consumption and cognitive performance that was suggested by a large number of earlier experimental evidence," wrote the researchers.
The study has several limitations, including not taking into account vegetable and fat intake, which form part of curries, and the accuracy of the self-reporting of curry consumption.
Given these limitations, the researchers noted that the results should be "interpreted with caution," and stated that dietary intakes may have changed as a result of the onset of dementia in some of the subjects.
Despite such comments, the researchers point at turmeric as the potential source of the observed benefits.
"Interestingly, it has also been purported that the prevalence of Alzheimer's disease in India among elderly between 70 and 79 years of age is four-fold less than that of the United States," said Ng.
"The results reported here are therefore significant, as they point to a significant beneficial effect on cognitive functioning with even low-to-moderate levels of curry consumption."
Curcumin has increasingly come under the scientific spotlight in recent years, with studies investigating its potential benefits for reducing cholesterol levels, improving cardiovascular health and cancer-fighting abilities.
Some experts recommend however that consumers wishing to make use of curcumin's properties consume it in supplement form rather than eating more curries, which tend to be rather high in fat in their Western form.