LONDON - The number of young and middle-aged people in Britain stricken with Alzheimer's disease has doubled in the past decade. The disease, formerly thought to afflict only the elderly, is now being found in people as young as 30 who are otherwise healthy.
The condition is particularly debilitating in younger people, leading to emotional isolation, absent-mindedness, aggression, inability to swallow, blindness and eventually death.
Dr Richard Harvey, director of research at the Alzheimer's Society, said: ''The number of young people diagnosed has increased dramatically. It's doubled, or more than that, in 10 years.''
However, doctors are baffled by the cause of the increase.
Previously, health authorities thought there were only a handful of young Alzheimer's cases . But research suggests there are now 17,000 people under the age of 65 with Alzheimer's in Britain.
It is thought that, in your thirties, you have a one in 3,000 chance of getting the disease, and a one in 1,000 chance of getting it before you are 60. In your sixties, the probability rises to one in a hundred, and then up to one in four by your eighties.
Doctors say they don't know whether the rise is due to better diagnosis or a real increase in risk. Dr. Graham Stokes, director of mental health at private health insurer BUPA, said there was more awareness of the condition now but warned: ''There could be a greater vulnerability among young people than ever before. It's a mystery. Could there be some environmental factor - some toxins? We don't know.''
Cary Cooper, professor of psychology at the University of Manchester Institute of Science and Technology, said: ''Maybe stress, or something else in their life, starts the process off, maybe it's a trigger mechanism. Are we leading the kind of lifestyle that is stimulating the onset of a condition that before we didn't get until our seventies?''
Another factor could be that young cases were previously sent to psychiatric asylums and forgotten about, but the asylums have now been closed, so the cases are being more openly dealt with.
Having a head injury, smoking, high alcohol intake and strokes all increase the risk of Alzheimer's, and in young people there is a greater chance it will have a genetic cause.
There is no cure for Alzheimer's, but there are now drugs that can suppress early symptoms.
Alzheimer's is often seen as an inevitable part of aging. But in younger people its effects can be particularly acute. It is totally unexpected, victims can be otherwise physically healthy, and they will often have families dependent on them. The disease itself is also more severe.
''The rate of deterioration is faster - it takes four or five years, rather than twice as long in an older person,'' said Stokes. ''Someone who is 45 doesn't expect to become absent-minded, so the psychological trauma is greater.''
John Hodges, professor of behavioral neurology at the University of Cambridge, said: ''In young people, it is more often associated with unusual clinical features, such as severe language impairment.''
(Distributed by Scripps Howard News Service. For more Observer news go to http://www.guardian.co.uk/.)