Combating negative stereotypes about aging might help protect against Alzheimer's disease (AD).
Findings from a longitudinal study show that individuals who held more negative views toward aging showed a steeper decline in hippocampal volume and greater accumulation of amyloid plaques and neurofibrillary tangles associated AD than their peers who held more positive views toward aging.
This is the first study to demonstrate that a culture-based risk factor predicts the development of AD-related pathologic changes in the brain, the researchers note.
"It would be great to bolster these positive age stereotypes in everyday life; that may be a way to help with cognitive health, and particularly because we know they are taken in from the culture at a very young age," first author Becca R. Levy, PhD, associate professor of public health and psychology, Yale University School of Public Health, in New Haven, Connecticut, told Medscape Medical News.
The findings were published online December 7 in the journal Psychology and Aging.
Negative stereotypes toward aging have been shown to predict various adverse outcomes among older individuals, but whether the influence of stereotypes extends to brain changes associated with AD was unclear until now.
The findings of Dr Levy and colleagues stem from the Baltimore Longitudinal Study of Aging (BLSA).
In the first part of the study, they assessed changes in hippocampal volume over time in relation to attitudes on aging in 52 men and women who underwent an MRI assessment annually over a 10- year period. The average age at which participants began undergoing MRIs was 68 years. At baseline, they were free of dementia and tended to rate themselves as being in good health. Most had completed high school. Attitudes toward aging was assessed with the 16-item age-stereotype subscale of the BLSA's Attitudes Toward Old People Scale.
As predicted, those with more negative attitudes toward aging were found to have a significantly steeper decline in hippocampal volume (P = 007) after adjusting for age, sex, education, self-rated health, well-being, number of chronic conditions, and intracranial volume.
The rate of decline in hippocampal volume in the negative-age-stereotype group was three times the rate of decline in the positive-age-stereotype group. "That is, participants holding more- negative age stereotypes tended to have the same hippocampal-volume decline in three years that participants holding more-positive age stereotypes tended to have in nine years," the authors report.
In the second part of the study, they assessed amyloid plaques and neurofibrillary tangles at autopsy in 74 BLSA participants for whom baseline data on age stereotypes were available. Their average age was 88 years at the time of autopsy.
As predicted, adults who held more negative age stereotypes, in comparison with their peers who had more positive age stereotypes, had significantly higher composite scores with regard to plaques and tangles (P = .046), after adjusting for age, sex, education, self-rated health, well-being, and number of chronic conditions, the researchers say.
They note that several factors support their assumption that negative age stereotypes contribute to the AD biomarkers, rather than the reverse.
"First, the baseline measurement of stereotypes occurred more than 20 years before the measurement of hippocampal volume, as well as plaques and tangles. Second, all participants were dementia-free at baseline, and members of the neuroimaging subsample were dementia-free at the initial MRI scans. Third, previous studies have demonstrated that negative age stereotypes increased stress, but the reverse did not occur; the negativity of age stereotypes held by older individuals did not significantly change over a 10-year period, despite encounters with highly stressful life events," they explain in their article.
"We speculate that stress is likely involved," Dr Levy told Medscape Medical News.
"In experimental research, we have found that in older adults, if we activate negative age stereotypes, they have a greater stress response, and if we activate positive age stereotypes, it acts as a stress buffer; they don't have as much of a cardiovascular response to stress," she explained. "Animal research has found that stress can lead to biomarkers that we looked at in this study; in rodents, hippocampal volume declines, and there is greater accumulation of plaques and tangles with stress."
Reached for comment, Steven F. Huege, MD, assistant clinical professor of psychiatry at the University of Pennsylvania Perelman School of Medicine, in Philadelphia, said, "There has been some past studies looking at stress with linkages to Alzheimer's disease. It's not implausible that viewing things in a negativistic sort of way could certainly lead to stress and affect brain health, similar to cardiovascular health."
He also noted that attitudes about aging are "starting to evolve slowly as we see a larger cohort enter into a geriatric population age. We are really reaching an inflection point where for the first time, there are more older people in this country than there are younger people, and I think that attitudes are going to naturally shift. Hopefully, it will have a positive impact. Certainly there is more discussion about aging, dementia, and Alzheimer's disease than a decade or two ago," said Dr Huege.
The study was supported by the National Institute on Aging, the Yale School of Public Health, and the Johns Hopkins University Alzheimer's Disease Research Center. The authors have disclosed no relevant financial relationships.
Psychol Aging. Published online December 7, 2015. Abstract
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Cite this: Combating Ageism May Help Prevent Alzheimer's Disease - Medscape - Dec 14, 2015.