Diagnosis of Alzheimer's years before clinical signs emerge

Brain researchers are developing tests that can identify the beginnings of Alzheimers years before the first clinical signs of the disease emerge.

The researchers, who presented their results on 14 November at the annual meeting of the Society for Neuroscience in Washington DC, say the tests allowed them to single out people who went on to develop the condition. If those results are repeated using larger study groups, doctors could start using the tests straight away.

One test uses brain scans to spot the first hints of problems that will later cause dementia. William Jagust of the University of California, Berkeley, and his group tracked about 60 healthy old people for around three years, using two brain imaging techniques and exercises designed to probe memory and cognition.

Six of the group developed forms of dementia and several others started to suffer from the cognitive impairments that precede full blown Alzheimers. When Jagust looked back at the scans taken at the start of the project, he found that several brain areas showed tell tale signs in these subjects. Neural activity in temporal and parietal lobes, for example, was below average in people that later scored poorly in cognitive tests.

Were picking up signs of Alzheimers before a neurologist would diagnose it, says Jagust.

Brain shrinkage:

Catherine Myers at Rutgers University in Newark, New Jersey, and her colleagues have taken a different approach. Researchers already know that the hippocampus, a brain area involved in the formation of new memories, shrinks as Alzheimers progresses. Myer decided to see whether she could pick up problems in the same area before the disease could be diagnosed.

Using an adapted version of a psychological test known to measure hippocampal damage in animals, together with a test for remembering words, she was able to identify seven of the 19 people from a group of around 60 who went on to develop Alzheimers or cognitive impairments in the two years of the study. The subjects, aged around 70, were all healthy at the start of the project.

There is no test now that is good at predicting Alzheimers, says Myers. This will give families a couple of years to prepare.

Early warning:

Both Myers and Jagust say the long-term aim of their work is to tie the tests in with future drug treatments. Several drugs are being developed to inhibit the build up of the plaques and tangles of protein that build up in the brain and cause Alzheimers, and these treatments are likely to be most effective if they can be applied before clinical signs of the disease emerge.

A molecular treatment for Alzheimers will be possible in the future, predicts Jagust, so there has been a surge of interest in diagnosis.

Neither predictive test is ready to deploy, however. Myers wants first to replicate her results using a group two or three times bigger than the one she has been working with. Jagust plans to repeat his tests while using a new technique that allows researchers to measure, using a brain scan, levels of the molecules that cause plaques and tangles.