Individuals who hold negative views about aging are more likely to show brain changes associated with Alzheimer’s disease, a new study finds.

It’s estimated that 5.1 million Americans have Alzheimer’s disease, and this number is rising as the population ages.

Yale School of Public Health researchers conducted the study, which involved healthy, dementia-free subjects from the Baltimore Longitudinal Study of Aging, the nation's longest-running scientific study of aging.

Based on MRIs, participants who held more negative beliefs about aging, such as elderly people are decrepit, showed a greater decline in the volume of the hippocampus, a part of the brain crucial to memory, the researchers say. Reduced hippocampus volume is an indicator of Alzheimer's disease.

Then researchers used brain autopsies to examine two other indicators of Alzheimer's disease: amyloid plaques, which are protein clusters that build up between brain cells; and neurofibrillary tangles, which are twisted strands of protein that build up within brain cells.  Participants holding more negative beliefs about aging had a significantly greater number of plaques and tangles. The age stereotypes were measured about 28 years before the plaques and tangles, the study found.

In both stages of the study, the researchers adjusted for other known risk factors for Alzheimer’s disease, including health and age.

This is the first to link the brain changes related to Alzheimer's disease to a cultural-based psychosocial risk factor, the researchers say. They are hoping that coming up with ways to generate positive thoughts about aging could help mitigate the negative ones and lead to a new way to prevent the disease.

The study appears online in Psychology and Aging.