A study by researchers in Canada has concluded that memory tests are more effective than brain scans or other cognitive tests.

They suggested doctors should use memory tests on patients who present with possible symptoms of the disease.

Early diagnosis of Alzheimer's is considered vital if we are to offer a fully effective treatment for the disease

Harriet Millward, Alzheimer's Research Trust

Early diagnosis of Alzheimer's can enable early medical intervention which can slow down the progression of the disease.

Dr Konstantine Zakzanis and colleagues at the University of Toronto based their findings on a review of 31 previous studies.

They examined how effective verbal tests were compared to brain scans.

Verbal tests

They concluded that the so-called California Verbal Learning Test was the most effective.

It is used to diagnose Alzheimer's by asking patients a series of questions. Patients are scored on how long it takes to answer and on how many answers are correct.

The authors said the test can be used to distinguish between those patients with the disease and those whose memory is just showing signs of ageing.

Addressing the American Psychological Association annual convention in Chicago, they said that a positive diagnosis depends on the extent of the memory loss.

Harriet Millward, deputy chief executive of the UK's Alzheimer's Research Trust, said early diagnosis was important.

"Accurate, early diagnosis of Alzheimer's is considered vital if we are to offer a fully effective treatment for the disease.

"The Alzheimer's Research Trust is funding major UK research to find an accurate, non-invasive and cheap way of diagnosing Alzheimer's early.

"However, there is still a long way to go before we can find an answer to this awful disease."