Multi-tasking test spots onset of Alzheimer's

Published on Sunday 8 November 2009 21:40

A DIAGNOSTIC test that can help distinguish between symptoms of depression and early Alzheimer's has been developed by Scottish researchers.

People developing Alzheimer's suffer from mild levels of impaired reasoning and memory that are easily mistaken for signs of depression. This can lead to many patients with dementia being misdiagnosed and missing out on early treatment that could make a difference.

Scientists at the University of Edinburgh found asking patients to perform two mental tasks at the same time can help tell the conditions apart.

A team led by Professor Sergio Della Sala compared the "dual-tasking" ability of 89 Alzheimer's patients, sufferers of chronic depression and healthy elderly individuals with no memory impairment.

The findings, reported in the Journal of Neurology, showed that people with Alzheimer's performed significantly worse than the other two groups. This was true even when allowances were made for individual memory differences.

An estimated 63,000 Scots have dementia out of a total of 700,000 across the UK. More than half suffer from Alzheimer's.

Dr Susanne Sorensen, head of research at the Alzheimer's Society, which funded the study, said: "This is the first piece of research to compare the performance of dual tasks in Alzheimer's disease and depression and could mean that people with dementia are diagnosed earlier. Currently, up to two-thirds of people with dementia never receive a formal diagnosis and it is often misdiagnosed as depression. Dela Sala's team aims to develop a simple screening test that will help GPs discriminate Alzheimer's from normal ageing and depression.

"An early diagnosis is hugely important as it may enable people with dementia to understand their condition, (and] have access to certain drugs that could help relieve some of their symptoms."

The dual task experiment consists of five stages. First the subject's short-term memory capacity is determined, the outcome called the "digit span". Then lists of digits are read to the subject who is asked to repeat the lists. This produces a "task list score". Stage three involves using a pencil to trace a path through a maze, giving a third score. In stage four, the subject repeats digit lists while tracing a path, the dual task. The final stage is a retest of stage four.