Researchers in Scotland have developed a novel diagnostic test that can help distinguish between symptoms of depression and early Alzheimer's.

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

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

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

The findings 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.

"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 aging and depression," The Scotsman quoted Dr Susanne Sorensen, head of research at the Alzheimer's Society, as saying.

"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," he added.