High levels of perceived chronic stress are associated with an increased risk of incident amnestic mild cognitive impairment (aMCI), according to the Einstein Aging Study, conducted by a group of researchers affiliated with Albert Einstein School of Medicine, Bronx, New York, and published in the December 11, 2015, issue of Alzheimer Disease and Associated Disorders.
The researchers undertook the study based on previous research in animals demonstrating that chronic stress plays an important role in Alzheimer-related neuropathology. Moreover, chronic or sustained exposure to stress is necessary for these harmful effects to occur. The researchers hypothesized that chronic stress might have the same impact in human subjects. For this reason, they used the 14-item Perceived Stress Scale (PSS), which measures global life stress experienced during the 30-day period preceding administration of the test.
The PSS was administered annually to participants (N = 507) aged 70 and older, for an average of 3.6 years. Participants were included if they completed at least one annual follow-up assessment. The highest stress group was more likely to be female (76% vs 61%), less educated, and more depressed. There was no significant relationship between global cognition and level of stress.
Of the 507 subjects, 71 (14%) were diagnosed with an incident aMCI. The researchers used a series of nested Cox proportional hazard models for the association of continuous PSS to incident aMCI, examining demographics and presence of APOE e4, the gene that has been associated with increased risk of Alzheimer’s disease. In all 3 models, PSS had a statistically significant hazard ratio, while demographic factors and depression were not significant. For every 5-point increase in PSS score, the risk of developing aMCI increased by 30% in the fully adjusted model (P = .007).
Similar results were obtained when participants were divided categorically into quintiles that were based on their PSS scores. Participants in the high-stress quintile were nearly 2.5 times more likely to develop incident aMCI than were those in the combined lower-stress quintiles.
The researchers concluded that their study demonstrated that “perceived stress is an independent predictor of aMCi, the preclinical stage of Alzheimer disease.” They called stress a “modifiable risk factor” and recommended that perceived stress should be “targeted in preventive interventions, including mindfulness-based stress reduction, cognitive-behavioral therapies, and pharmacologic interventions that aim to reduce cognitive decline.” The investigators noted that perceived stress can be measured using self-report instruments, making evaluation of stress and implementation of stress-reduction strategies easy to incorporate in the clinical setting.