Research has shown the similar symptoms of depression and early Alzheimer's can be more easily distinguished through a new multi-tasking test.
Someone developing Alzheimer's often exhibits low levels of impaired reasoning and memory, which are sometimes mistaken for signs of depression.
Currently, up to two thirds of people with dementia never receive a formal diagnosis and it is often misdiagnosed as depression. But one way to tell the conditions apart is to ask patients to perform two mental tasks at the same time, scientists have now found.
A team led by Professor Sergio Della Sala, from the University of Edinburgh, 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.
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."