People are living longer because of better health care and increasing wealth. But the report says dementia is not a normal part of growing old.

Shekhar Saxena is the director of mental health and substance abuse research at the WHO.

SHEKHAR SAXENA: "Dementia is often not recognized. It is commonly mistaken for an age-related decline in functioning because it can mimic age-related problems, and also it progresses slowly. Even in high-income countries, only one-fifth to one-half of the cases of dementia are routinely recognized. This percentage is obviously much lower in middle and low-income countries."

Martin Prince is a professor at Kings College London. He says many people wrongly believe that dementia and Alzheimer's disease are not problems in poorer countries.

MARTIN PRINCE: "There have been some more studies done recently in western Africa, which, I think give the lie to the notion that Alzheimer's disease is very rare amongst all the people in Africa. There are fewer older people because life expectancy is shorter, particularly with the ravages of HIV. But, amongst people who live into old age, the prevalence of dementia looks quite similar to high-income countries."

The world currently spends more than six hundred billion dollars a year to treat and care for people with dementia. Yet the WHO says only eight countries currently have national programs in place to deal with dementia.

It urges greater efforts to identify dementia early, educate the public and provide better care. Dementia may be incurable, but health officials say much can be done to improve the lives of people who have it, and support their families and caregivers.