Lifecourse Traumatic Events and Cognitive Aging in the Health and Retirement Study

Abstract

Introduction: Much of the heterogeneity in the rate of cognitive decline and the age of dementia onset remains unexplained, and there is compelling data supporting psychosocial stressors as important risk factors. However, the literature has yet to come to a consensus on whether there is a causal relationship and, if there is, its direction and strength. This study estimates the relationship between lifecourse traumatic events and cognitive trajectories and predicted dementia incidence.

Methods: Using data on 7,785 participants aged ≥65 years from the Health and Retirement Study, this study estimated the association between lifecourse experience of 10 traumatic events (e.g., losing a child) and trajectories of Telephone Interview for Cognitive Status from 2006 to 2016 using linear mixed-effects models and predicted incident dementia from 2006 to 2014 using cumulative incidence functions (data analysis was in 2020-2022). Inverse probability weights accounted for loss to follow-up and confounding by sex, education, race/ethnicity, and age.

Results: Experiencing 1 or more traumatic events over the lifecourse was associated with accelerated decline compared with experiencing no events (e.g., β= -0.05 [95% CI= -0.07, -0.02] Health and Retirement Study-Telephone Interview for Cognitive Status units/year; 1 vs 0 events). In contrast, experiencing traumatic events was associated with better cognitive function cross-sectionally. Furthermore, the impact of trauma on cognitive decline was of greater magnitude when it occurred after the age of 64 years. However, the magnitude and direction of association varied by the specific traumatic event. There were no associations with predicted incident dementia.

Conclusions: These results suggest that researchers and clinicians should not aggregate traumatic events for understanding the risk of accelerated cognitive decline.

Figure 1.. Fixed Effects Associations Between Lifecourse Experiences of Traumatic Events and Mean Population Cognitive Function and Cognitive Decline.

This figure shows the fixed effects beta estimates and 95% confidence intervals for the exposure (main effect) and exposure*age (slope) terms from linear mixed effects models assessing the association between lifecourse traumatic events (accumulation and sensitive period models, specified on the y-axis) and cognitive function (HRS-TICS, specified on the x-axis; higher score is equivalent to higher cognitive function). E.g. Compared to those who experienced no traumatic events during early life, those who experienced one or more traumatic events before age 19 had a mean HRS-TICS score 0.59 (95%CI: 0.24, 0.94) points higher. For each year of age, experiencing one or more traumatic events after age 64 (Late Life) was associated with 0.07 (95%CI: 0.04, 0.10) fewer HRS-TICS points indicating an accelerated rate of cognitive decline compared to those who did not experience any traumatic events later in life

Figure 2.. Cumulative Predicted Dementia incidence by Lifecourse Traumatic Events.

This figure depicts the cumulative predicted dementia incidence, IP-weighted to account for censoring and confounding, for each form of the exposure. Panels show incidence stratified by (a) cumulative lifecourse traumatic events (0, 1, 2, or 3+ events); (b) early-life events; (c) young-adulthood events; (d) mid-life events; and (e) late-life events. Cumulative incidence functions were estimated using the Aalen-Johansen estimator. There is significant difference between the predicted incidence of dementia by number of lifecourse traumatic events overall or during specific life periods, except for later life events. In small window (ages 84 to 97), there is a slightly lower predicted incidence of dementia for those who experience traumatic events in late-life.

Figure 3.. Fixed Effects Associations Between Individual Traumatic Events and Mean Population Cognitive Function and Cognitive Decline.

This figure shows the fixed effects beta estimates and 95% confidence intervals for the exposure (main effect) and exposure*age (slope) terms from linear mixed effects models assessing the association between each specific traumatic event (specified on the y-axis) and cognitive function (HRS-TICS, specified on the x-axis).