Stressed-out Older Adults Risk Memory Woes

Megan Brooks

December 15, 2015

Older adults who live stressful lives are more than twice as likely to develop amnestic mild cognitive impairment (aMCI) than their less-harried peers, suggest findings from a longitudinal study of aging.

"Our study provides strong evidence that perceived stress increases the likelihood that an older person will develop aMCI. Fortunately, perceived stress is a modifiable risk factor for cognitive impairment, making it a potential target for treatment," senior author Richard Lipton, MD, vice chair of neurology, Albert Einstein College of Medicine and Montefiore Health System, New York City, said in a statement.

"Perceived stress reflects the daily hassles we all experience, as well as the way we appraise and cope with these events," added first author Mindy Katz, MPH, also from the Department of Neurology at Einstein. "Perceived stress can be altered by mindfulness-based stress reduction, cognitive-behavioral therapies, and stress-reducing drugs. These interventions may postpone or even prevent an individual's cognitive decline," she noted.

The findings were published online December 11 in Alzheimer Disease and Associated Disorders.

Robust Findings

The results stem from the ongoing Einstein Aging Study, a community-based cohort of adults aged 70 years and older. As part of the study, participants undergo yearly clinical evaluations, a neuropsychological battery of tests, psychosocial measures, and assessments of activities of daily living, and they provide self-reports (or reports by informants) of memory and cognitive problems. In 2005, the study began collecting data on stress using the Perceived Stress Scale (PSS). All participants were free of aMCI at their first PSS assessment.

Among a total of 507 participants, 71 developed aMCI during an average follow-up period of 3.6 years. High levels of perceived stress were associated with a greater risk of developing aMCI. In the fully adjusted model, for every 5-point increase in PSS, the risk for aMCI increased by 30% (hazard ratio [HR], 1.30; 95% confidence interval [CI], 1.08 - 1.58; P = .007).

"The consistency of results after covariate adjustment and the lack of evidence for reverse causation in longitudinal analyses suggest that these findings are robust," the authors write.

Similar results were obtained when participants were divided into quintiles on the basis of their PSS scores. Those in the highest-stress quintile were nearly 2.5 times more likely to develop aMCI than those in the other four quintiles combined (HR, 2.44; 95% CI, 1.32 - 4.54; P = .005).

People in the high-stress group were more apt to be female and to have less education and higher levels of depression. However, depression did not significantly affect the relationship between stress and the onset of aMCI, the authors report. The impact of stress on aMCI was also unaffected by the presence of the APOE-ε4 allele.

Reverse Causality?

The researchers note that the effect of stress on cognitive function may be mediated through multiple physiologic pathways involving the central nervous, neuroendocrine, immune, and cardiovascular systems.

A limitation of the study, they say, pertains to use of the PSS to "operationalize chronic stress. Although it is likely that the predictive power of the PSS derives from its sensitivity to chronic sources of stress, the PSS is a global index that cannot distinguish among other stress effects such as specific major life events in the elderly (eg, residential transitions), appraisal processes, role stressors (eg, caregiving), heightened stressor reactivity, and dispositional traits (eg, tendencies toward worry or rumination)," they note.

Another potential limitation of this study is that stress may increase in response to developing cognitive impairment rather than serve as a risk factor for it.

Reached for comment, Elizabeth Munoz, PhD, postdoctoral scholar, Department of Psychology, University of California, Riverside, told Medscape Medical News that the study "contributes to the growing evidence that psychological stress influences cognitive health."

"Our study in Psychology and Aging showed that perceived stress influences cognitive performance over a short timescale (biannual change), and Katz and colleagues' paper further adds to the chain of evidence that perceived stress may contribute to pathological outcomes over time," Dr Munoz said.

The study was funded by the National Institutes of Health, the National Center for Advancing Translational Sciences, the Leonard and Sylvia Marx Foundation, and the Czap Foundation. The authors have disclosed no relevant financial relationships.

Alzheimer Dis Assoc Disord. Published online December 11, 2015. Abstract

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