Alzheimer’s disease can be diagnosed sooner than you thought. Australian and British researchers say it can be detected in brains of healthy people as early as in their 40s.

431 healthy Canberrans aged from 44 to 48 were taken for study. Those who scored less in the cognitive tests were more likely to have higher risks.

The lesions in their brain showed up in MRI scans too, however they didn’t show any early symptoms.

“It’s one of the first studies to demonstrate that these white-matter lesions exist in such a young group… Secondly, we have been able to predict these lesions through fairly simple-to-administer cognitive tasks,” David Bunce, a research fellow at the Centre for Mental Health Research at the Australian National University.

In the cognitive test, researches asked participants to react as fast as they can. Those who reached in 200 milliseconds at one attempt, and took 450 milliseconds the next, tended to have these lesions.

“In the same way that middle-aged people go to the GP and have a blood pressure test, potentially it might be possible to use some people's reaction times, measured on a laptop or a PC (to gauge their risk of later dementia)…However, at the moment we don’t know how to head off dementia and Alzheimer's later on,” said Professor Bunce.