Short Term Variability in Affect and Rest Activity Rhythms in Long Term Chronic and Highly Variable Suicidal Ideation in Depressed Older Adults

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ABSTRACT Our ongoing research (R01 MH085651) aims to identify long-term suicide risk factors in older depressed adults. In this supplement, we propose to study a new line of research focusing on how proximal risk factors, such as severity and fluctuation of affect, inter-daily stability of the 24-hour rest-activity rhythm, and sleep health relate to suicide risk in depressed older adults. Poor sleep health and disruption of the 24-hour rest-activity rhythm (RAR) are linked to numerous indices of morbidity and mortality in older adults, including suicidal ideation. Affect dysregulation is also linked to contemplation of suicide and suicidal behavior in younger age groups. While there are complex, bi-directional relationships between suicide risk, sleep/activity, and mood, these relationships have yet to be measured using actigraphy and digital monitoring in well-defined suicide risk groups. We propose an Administrative Supplement for a 3- week pilot study measuring daily affect and rest-activity rhythms (via digital monitoring and actigraphy) to provide a real-time assessment of potential suicide risk factors so far unevaluated in the parent study. Data on participants’ clinical and cognitive characterization, including suicidal ideation trajectories, will be provided by the parent study. Participants will be aged 60 years and older, enrolled in the parent grant, and have met criteria for unipolar major depressive episode. Building on our data that indicated that both chronic severe and highly variable ideators had a higher risk of suicidal behavior than low/non-ideators, groups will include two high suicide risk groups (chronic severe ideators: N=20, highly variable ideators: N=20) and one low suicide risk group (no/minimal ideation: N=20). Affect ratings and digital sleep diaries will be collected twice daily over 3 consecutive weeks, and RAR metrics (using objective activity count patterns) will be collected during the same period, with interdaily stability as the primary RAR measure. The proposed research aligns with RDoC category of Arousal/Regulatory Systems including constructs such as Circadian Rhythms and Sleep/Wakefulness. We build on the complementary expertise of our research team: Dr. Szanto (late-life suicide, prevention and intervention studies with high suicide risk groups), Dr. Franzen (circadian rhythms and sleep and their relationship to suicide risk in adolescents and young adults), Dr. Stahl (digital monitoring, geriatric depression, intervention development to improve circadian rhythmicity and sleep), Dr. Galfalvy (analyses of suicide data, including digital monitoring and time series data), and Dr. Gujral (geriatric depression and physical activity). The proposed work complements our current work on long-term suicide risk factors by identifying modifiable proximal behavioral risk factors that can be used to improve suicide prevention.