Toronto, Jan 22 (IANS): Abnormal hyperactivation in the brain could be an early biomarker of Alzheimer's disease, a new study suggests.

The study indicates that hyperactivation in certain brain areas in people not yet diagnosed with Alzheimer's but who were worried about their memory loss and who exhibited risk factors for the disease.

"Alzheimer's disease is progressive and may emerge in the brain 20 to 30 years before diagnosis," said researcher Sylvie Belleville from the Universite de Montreal in Canada.

"It is therefore, very important to pinpoint biomarkers -- that is, physical and detectable signs of the disease -- and to understand better the initial effects on the brain. Hyperactivation could therefore represent one of the first signs of Alzheimer's disease," Belleville added.

For their study, published in the journal Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring, the team used data from the Consortium for the Early Identification of Alzheimer's Disease to study brain activation in groups of individuals at a high risk of developing Alzheimer's disease who had performed a memory task while being scanned with MRI.

One group consisted of 28 individuals who were concerned about their memory, but who did not show cognitive impairments on traditional clinical tests.

The other group included 26 individuals with mild cognitive impairments.

The researchers found that individuals in the first group, or those with memory complaints but who did not show objective cognitive impairments, had abnormally high levels of activation in multiple key regions of the brain affected by Alzheimer's disease.

Individuals with mild cognitive impairments, who are considered to be at a more advanced stage of the disease, tended to show decreased activation in these brain regions, the researcher said.