Weight loss in women may be a precursor for Alzheimer's

Scientists in the U.S. say they suspect that women who develop Alzheimer's disease or other forms of dementia may start losing weight at least a decade before being diagnosed with the condition.

The researchers at the Mayo Clinic in Rochester, Minnesota say women who developed dementia began losing weight between 11 and 20 years before their diagnosis with the weight loss accelerating in the decade before the diagnosis.

The researchers led by Dr. David Knopman found by the time women were diagnosed they weighed 12 pounds (5.4 kg) less on average than those who did not develop Alzheimer's or dementia.

For the study Knopman's team examined medical records, including detailed weight information, on 219 women from 1990 to 1994 who eventually were diagnosed with Alzheimer's or dementia.

They also tracked the same number of women who did not develop any form of dementia who were of similar age and lived in the same area.

A similar process tracking men who developed dementia and men who did not, did not find any differences in weight.

With a brain disorder such as dementia a persons ability to perform daily activities becomes undermined and the most common form among the elderly is Alzheimer's.

This slow progressive disease begins with mild memory problems and ends with severe brain damage.

Dr. Knopman says the findings suggest that certain behaviours develop in women who are destined to develop Alzheimer's that predate the appearance of the disease by years and supports the suspicion that dementia and Alzheimer's disease have a very long presymptomatic time course and do not develop overnight.

Dr. Knopman suggests that behavioural rather than biological reasons lie behind the weight loss and merely losing weight should not be seen as a diagnostic indicator of dementia.

He says as the dementia progresses changes in personality such as apathy and loss of initiative begin to emerge and this leads to women losing interest in meals, particularly when combined with the loss of the sense of smell that may accompany the onset of cognitive impairment.

This may make women less likely to prepare nutritious meals and more likely to skip meals altogether.

Men may not lose weight because in general they are not responsible for preparing meals which would lessen the effect of the apathy, loss of initiative, and loss of sense of smell.

The research is published in the journal Neurology.