According to a comprehensive survey on the prevalence of Alzheimer's disease and related disorders from around the world, published in the British medical journal The Lancet, a new case of dementia arises every 7 seconds, and by the year 2020, 42 million people will suffer from Alzheimer's disease or another form of dementia. Currently, 24 million people have been diagnosed with dementia, with 4.5 million cases in the United States. Alzheimer's disease, the most common form of dementia, accounts for more than half of those cases.

Researchers at Alzheimer's Disease International and the Institute of Psychiatry at King's College, London, pooled data from numerous medical studies and concluded that there are four to five million new cases of dementia around the world each year. By 2040, that global number will increase to 81 million.

The rising prevalence of Alzheimer's disease and other forms of dementia calls attention to the urgent need to find effective means to treat and prevent this memory-robbing illness. The authors of the study cite the need to combat known risk factors for heart and blood vessel disease, including high blood pressure, smoking, diabetes, and high cholesterol.

Source: Ferri C, Prince M, et al. Global prevalence of dementia: a Delphi consensus study. Lancet. 2005 Dec 17;366(9503):2112-2117.