BOSTON—Among elderly persons, high levels of perceived stress may be associated with an increased risk of amnestic mild cognitive impairment (aMCI), according to a study presented at the 2013 Alzheimer’s Association International Conference. High stress levels in this population also may be associated with high levels of anxiety and depression, independent of other risk factors, according to related research presented at the meeting.
In both studies, investigators assessed individuals’ stress levels using the Perceived Stress Scale (PSS). A third study, also presented at the conference, suggested that this scale had satisfactory psychometric properties in nondemented elderly adults and would be a useful tool for examining the influence of perceived stress on aging, incident MCI, and dementia.
High PSS Scores and Age Were Associated With aMCI Risk
To examine whether perceived stress is a risk factor for cognitive decline and aMCI, Mindy J. Katz, MPH, Senior Associate in the Saul R. Korey Department of Neurology at the Albert Einstein College of Medicine, and colleagues examined 528 participants in the Einstein Aging Study who had completed the PSS. Participants with dementia or aMCI at baseline were excluded from these analyses. Subjects underwent annual neurologic examinations, neuropsychologic evaluations, standardized assessments of activities of daily living, and depression screening. Patients also answered structured questions about their memory and cognitive function.
A total of 73 participants developed incident aMCI during the study. At baseline, individuals who later developed incident aMCI were significantly older (mean age, 81.7) than subjects who did not (mean age, 79.6). Participants who later developed aMCI also had higher PSS scores at baseline (19.1 vs 16.8) and higher scores on the Blessed Information-Memory-Concentration Test (2.2 vs 1.6). Subjects with the highest levels of perceived stress were more likely to develop aMCI than subjects with lower levels. When the investigators analyzed the PSS as a continuous score, they found that increasing scores were associated with increasing risk of aMCI. Adjusting for depression did not change the results. “In our study, perceived stress was high prior to the onset of aMCI, and risk increased at higher levels of stress, [thus] suggesting a causal relationship,” said Ms. Katz. We cannot exclude the possibility that people with declining memories experience more stress prior to the onset of aMCI.”
Perceived Stress Correlates With Depresion and Anxiety
Ali Ezzati, MD, a neurology resident at the Albert Einstein College of Medicine, and colleagues examined 706 participants in the Einstein Aging Study to evaluate the influence of cognitive dysfunction, pain, depression, and anxiety on the level of stress. The researchers administered the Geriatric Depression Scale, the Beck Anxiety Inventory, the Total Pain Index, and the Free and Cued Selective Reminding Test (FCSRT)–Immediate Recall to all patients. The investigators examined relationships among stress, depression, anxiety, and FCSRT using Spearman coefficients. The authors also conducted multiple linear regression analysis to evaluate the independent effects of pain, anxiety, depression, and memory on stress while controlling for other variables.
The mean age of subjects with a PSS score lower than 17 was 79, compared with a mean age of 80 for subjects with a PSS score of 17 or higher. Overall, women had more stress than men. Stress was negatively correlated with education level. The mean number of years of education was approximately 14.4 for individuals with a PSS score lower than 17, compared with 13.8 years for patients with a PSS score of 17 or higher.
After controlling for age, gender, and education, the researchers found that the effects of depression, anxiety, pain, and memory were associated with stress. After the investigators adjusted for either anxiety or depression, however, pain and memory had no effect on stress levels. “Future studies should consider the interplay between depression, anxiety, and pain on stress and memory decline in older adults,” said Dr. Ezzati.
The Perceived Stress Scale Demonstrated Its Validity
The PSS has a component that measures subjective distress and a component that measures ability to cope. The scale asks respondents whether their lives seem unpredictable, uncontrollable, or overloaded. Subjects rate their responses to 14 questions on a five-point scale.
Investigators at the Albert Einstein College of Medicine in Bronx, New York, administered the PSS to 768 participants in the Einstein Aging Study to validate the scale in a diverse sample of older adults. Participants were recruited from Medicare and voter registration rolls, 70 or older, and lived in an ethnically or racially diverse community. Individuals with dementia were excluded from the study. Julie M. Jiang, a doctoral candidate at the college, used various statistical methods to define the scale’s underlying factor structure, test the construct validity of its factors, and assess its internal consistency.