Deposition of amyloid-beta plaques in the brain may not be always the cause of decline in mental abilities among people suffering from Alzheimer's disease, a new research has suggested.

Amyloid-beta plaques are considered to be the cause of Alzheimer’s. The new study showed that the plaques are, in fact, a just a symptom of the disease. Studies in beagles receiving both dietary and behavioural treatments showed major improvements in cognition, but only minor decreases in amyloid-beta plaques in their brains.

Neuroscientist Viorela Pop, a graduate student at the University of California, Irvine, conducted the research in 24 beagle dogs aged between eight and 12 years.

The dogs were divided in four groups. One group was fed a diet enriched with high-antioxidant foods, like spinach, tomatoes, grapes, carrots and citrus fruit. Behavioural enrichment was the approach to the second group of dogs in which they socialized with other dogs, played with new toys, took long walks and learned new tasks. The third group of dogs received both treatments, while the last group received none. The study lasted for period of about two years and six months.

A detailed analysis of the results indicated that dogs given the combined treatment had the biggest improvement in cognition and moderately reduced plaques in their brains. Dogs given just antioxidants fared better compared to dogs that underwent only enrichment activities.

“The amyloid plaque just does not seem to be the main thing responsible for cognitive decline in dogs and Alzheimer’s disease in humans,” says Pop after publishing he findings in the Journal of Neuroscience.

Pop's was perhaps, the first study to look at antioxidant and behavioural enrichment treatments in dogs that naturally accumulate amyloid-beta plaques. Other recent research also suggests plaque deposits in the brain are not the sole cause of Alzheimer’s.

Humans and dogs immunized against amyloid-beta plaques have no deposition but still continue to experience cognitive decline. Patients continue to deteriorate in spite of all treatments, which tells you the plaques are not the ultimate cause of the disease.