Old people are absent-minded.

Old people are grouchy.

Old people can’t learn new things.

If you believe these stereotypes, you may be at higher risk for Alzheimer’s disease, two new studies show. The studies, published Monday in a paper in the journal Psychology and Aging, show that people who have negative beliefs about aging are more likely to have brain changes associated with Alzheimer’s.

Looking at healthy, dementia-free subjects from the Baltimore Longitudinal Study of Aging, the nation’s longest-running scientific study of aging, researchers found that the volume of the hippocampus — a part of the brain important for memory, measured by an MRI exam — declined by three times as much among those who hold negative stereotypes about aging, compared with those who do not.

The researchers also looked at brain autopsies of subjects from the same group, and among those with negative aging stereotypes, they found significantly more of two markers associated with Alzheimer’s: amyloid plaques, which are protein clusters that build up between brain cells; and neurofibrillary tangles, protein strands that build up between brain cells.

The subjects were interviewed about their views on aging long before the onset of dementia: The first group’s views were measured when they were, on average, in their early 40s, and the second group’s views were measured an average of 28 years later, when most were in their late 50s or early 60s.

The link between negative views and brain changes is probably because of an increased stress response, said Becca R. Levy, an associate professor at the Yale School of Public Health and the paper’s lead author.

In an earlier study Levy conducted, people exposed to negative beliefs about aging had an increased heart rate and blood pressure response when talking about stressful events in their life. Positive age stereotypes, on the other hand, can act as a buffer for stress, she said. Studies have shown that stress can contribute to pathological changes in the brain.

The new research is the first to show that a culture-based psychosocial risk factor relates to these Alzheimer’s biomarkers, and could have profound implications about the messages U.S. society sends regarding old people.

“Children as young as 4 take in the stereotypes of their culture,” Levy said. “It would be great to start quite young, in kindergarten or even pre-k, to start reinforcing positive stereotypes, bringing older role models into classrooms.”

The finding could also change the way scientists interpret culture-related Alzheimer’s disease data. The difference in diet has been suggested as an explanation for why the Alzheimer’s rate in the United States is five times that of India, but the discrepancy might alternatively be explained by a cultural comparison, the paper said, noting that “India has a tradition of venerating elders . . . whereas the United States has a prevalence of negative age stereotypes.”