People who are pessimistic about what life is like during old age may be helping to make their fears come true.
A new study finds that older Americans with negative beliefs about aging were significantly more likely to develop dementia than their peers who embraced their senior years with zeal.
The difference was hardly trivial: Study participants who had positive beliefs about aging were 44 percent less likely to develop dementia over the next four years than were their counterparts with negative beliefs.
Even after the researchers accounted for other risk factors for dementia — including smoking, diabetes and cardiovascular disease — they still found that the odds for the condition were lower among those with a positive attitude toward aging.
Also striking: The apparent benefits of positivity were even greater among the subgroup of adults whose genes put them at greater risk of dementia. In fact, the researchers said, a positive attitude toward aging could essentially erase the handicap associated with carrying a risky variant of the APOE gene.
The findings, published Wednesday in the journal PLOS One, suggest that fighting negative stereotypes about aging could have broad benefits for public health.
A host of earlier research shows that attitudes about growing older may influence cognitive performance, most likely because they affect levels of stress. There's even some evidence that the brains of people who are pessimistic are more likely to have the amyloid plaques and neurofibrillary tangles associated with Alzheimer's disease.
Stereotypes aren't easy to overcome. But considering that there are no treatments that can cure dementia (or even do much to slow it down), researchers are eager to spot any risk factor that people can actually change.
For the new research, a team led by Becca Levy of the Yale School of Public Health used survey results from the Health and Retirement Study, which is conducted every other year by the University of Michigan Institute of Social Research.
Levy and her team focused on a cohort of 4,765 older Americans (their average age was 72) who answered five questions about their attitudes toward aging. For instance, participants were asked whether they were as happy now as they were when they were younger, whether they felt that things got better or worse with age, and whether they felt less useful as the years piled on.
The cognitive status of the study participants was assessed by a standard test conducted over the phone. Among other things, they were asked to count backward from 20, to name the president and vice president and to recall a list of 10 items. Only people who did not have dementia when they entered the study were included in the analysis. Participants retook the test every two years.
Finally, most of the study participants provided saliva samples that were sent off to the National Institutes of Health to see whether they had a version of the APOE gene that put them at increased risk of getting Alzheimer's disease. Among those who were tested, 26 percent had an e4 variant of the gene, which makes the disease more likely.
In the four years after joining the study, 4.6 percent of the adults with negative beliefs about aging went on to develop dementia. So did 2.6 percent of the adults with positive beliefs.
Among those with an e4 variant of the APOE gene, 6.14 percent of adults with negative beliefs about aging developed dementia, compared with 2.7 percent of those with positive beliefs.
Both of the differences remained statistically significant after the researchers controlled for age, sex, educational history, initial cognitive performance, health conditions and other factors that influence dementia risk. In the entire group, having a positive attitude toward aging was associated with a 19 percent reduced risk of dementia; in the high-risk group, those with a positive attitude were 31 percent less likely to develop dementia.
"Age beliefs tend to be internalized early in life and then remain stable over the lifespan, without interventions," Levy and her colleagues wrote. "Our finding could provide a rationale for a public-health campaign to combat the societal sources of negative age beliefs."
The study was funded by the National Institute on Aging.