The number of dementia cases in developing countries could be twice the one previously estimated, says a study involving about 15,000 participants, which might be related to the lack of standard techniques for diagnosing dementia in these particular areas. The findings come in contradiction with similar studies that have previously pointed out that dementia cases in developing countries could be half as common, or even less than half, as compared to the number in high income countries.

The study was carried out by the 10/60 Dementia Research Group under the leadership of Martin Prince of the King's College London, and involved people over 65 from seven countries around the world with low and middle incomes. Using the '10/60 algorithm', that is presumably more sensitive to cultural differences, the research team found that the occurrence of dementia cases is double the one suggested by the Diagnostic and Statistical Manual of Mental Disorders.

According to Prince, this effect can be accounted for through the fact that the DSM manual was created with the presumption that the education standards in developing countries are high, thus failing to take into consideration the population that received relatively low education. The biggest discrepancies have been found in rural and underdeveloped areas, where people have high respect towards the elders.

"If you're elderly, you don't shop, don't cook, don't clean the house, don't go shopping. All these things are done for you," said Price about the elderly people living in the rural areas of India and China, which is unlikely to lead to any social and occupational problems.

"In many cultures, with high degrees of support and respect for older people, relatives might not perceive dementia as a problem," said Eric Larson and Kenneth Langa of the Group Health Center for Health Studies, respectively from the University of Michigan.

Estimates indicate that developing countries might house up to 60 percent of the people suffering from dementia, and the percent is likely to rise since such countries usually focus more on diseases that lead to early mortality.