Alzheimer's disease explained

Alzheimer's disease is probably the best-known illness associated with advanced age. Find out how to recognise the warning signs.

Alzheimer's disease is a progressive, mysterious illness that robs people of their memory, personality and eventually all cognitive function. The disease is named after Alois Alzheimer, the German physician who first identified the condition during the autopsy of a woman who had suffered what was believed to be a mental illness in 1906.

Dr. Alzheimer discovered the clumps of plaques and twisted fibres of neurofibrillary tangles that resulted from the disease's destruction of nerve cells within the brain.

Incidence

Alzheimer's affects 20 million people worldwide. Around half of the 750,000 people in the UK who suffer from dementia are affected by Alzheimer's. It usually affects those aged 65 or older, but it can affect people young as 40, though this is considered rare.

Who's at risk?

New research from the United States suggests that optimism and a positive emotional outlook in early life may ward off the disease. This study also showed that stroke and head trauma may increase a person's risk for developing the debilitating disease. Diet and deficiencies of the nutrient folate, or folic acid, may also play a role, according to findings from a 1998 study in the UK.

The major risk factor is age. In the UK, five to ten per cent of people aged 65 to 74 and 20 to 25 per cent of people aged over 75 years of age suffer from it. There's some evidence that women are at greater risk than men, but this is probably because women live longer than men. It may be that genes play an important role in determining who will develop Alzheimer's, but only 15 per cent of sufferers have a positive family history.