Effects of Longitudinal Changes in Neuroticism and Stress on Cognitive Decline

The relationships among depression, personality factors, stress, and cognitive decline in the elderly are complex. Depressed elders score higher in neuroticism than nondepressed older individuals. Independently, the presence of neuroticism and the number of stressful life events are each associated with worsening cognitive decline in depressed older adults. Yet little is known about combined effects of changes in neuroticism and changes in stress on cognitive decline among older depressed adults.

Longitudinal observational study.

Academic Health Center.

The authors examined 62 participants in the Neurobiology of Late-life depression (NBOLD) study to test the hypothesis that, compared with older depressed subjects who experience improved neuroticism and lower psychosocial stressors over time, those with worsening neuroticism and greater psychosocial stressors will demonstrate more cognitive decline.

The authors measured neuroticism using the NEO-Personality Inventory-Revised at baseline and 1 year. Study psychiatrists measured depression using the Montgomery-Ǻsberg Depression Rating Scale. At annual assessments, subjects reported the number of psychosocial stressors in the prior year and completed a neuropsychological evaluation. Participants completed a detailed neuropsychological battery at baseline and annually over 3 years. The battery included a test of delayed story memory (Logical Memory-2 or LMII). The outcome 3-year change in cognitive scores was regressed against 3-year change scores of neuroticism and number of psychosocial stressors, plus their interaction, while adjusting for sex, age, race, education, baseline cognitive score, and 3-year change in MADRS score as covariates.

In multivariable linear regression analysis with the above covariates, the interaction effect of 3-year change in Total Neuroticism score and 3-year change in Total Stressors on change in LMII performance was statistically significant (B = -0.080[95%CL: -0.145 to -0.015], T = -2.48, df = 52, p = 0.017). Further exploration of this finding showed that 1) when total stressors increased by 2 or more over 3 years, LMII change was inversely associated with neuroticism change; and 2) when neuroticism improved less, LMII change score was inversely associated with total stressor change. There were no other significant interactions between stress and neuroticism on cognition.

Our findings document the importance of tracking change in neuroticism and monitoring psychosocial stress over the long-term course of treatment in geriatric depression. Both factors exert important combined effects on memory over time. Future studies in larger samples are needed to confirm our results and to extend them to examine both cognitive change and development of dementia.