1141 Insomnia and Depressive Symptom Patterns Predict Dementia Incidence in Community-Dwelling Older Adults: A Ten-Year Study

Abstract Introduction Insomnia and depressive symptoms often co-occur in late life and are individually or jointly linked to increased dementia risk. However, heterogeneity in these symptom clusters and their links to dementia remains understudied. This study aims to identify insomnia-depression symptom profiles using latent profile analysis (LPA) and examine their associations with subsequent incident dementia, as well as whether these associations persist after accounting for comorbidity, in community-dwelling older adults. Methods We used data from the National Health and Aging Trends Study (NHATS), a nationally representative longitudinal cohort of U.S. older adults followed annually from 2011 (R1) to 2023 (R13).The analytic sample was restricted to participants from the 2011 (R1) and 2015 (R5) enrollment cohorts. Baseline phenotypes were defined using continuous Patient Health Questionnaire-2 (PHQ-2; range 0-6) scores and a two-item insomnia severity score capturing difficulty initiating sleep and difficulty maintaining sleep, with each item coded on a 1-5 Likert scale and summed (total range 2-10). Dementia was determined using NHATS consensus criteria. To ensure symptoms preceded dementia onset, participants who developed dementia within two years after enrollment were excluded. Dementia incidence was then followed for up to 12 years. LPA identified optimal symptom phenotype profiles using model fit indices (BIC, entropy). Cox proportional hazards models estimated the hazard of incident dementia adjusting for sociodemographic and health characteristics. Results The sample included 4,661 community-dwelling older adults (27.3% aged 65-69, 48.3% aged ≥75, 60.1% female, 71.9% non-Hispanic White), followed for an average of 10.9 years. LPA revealed four profiles: “Insomnia-predominant” (27.5%), “Low-symptom” (10.5%, reference), “Moderate-co-symptom (44.1%), and “Depression-predominant” (17.9%). In Cox proportional hazard models, compared with “Low-symptom", both “Moderate-co-symptom" (HR=1.93, 95% CI: 1.44-2.57) and “Depression-predominant” (HR=1.92, 95% CI: 1.41-2.62) showed nearly two-fold higher dementia risk after full adjustment. The “Insomnia-predominant” profile was not associated with increased dementia risk (HR=1.07, 95% CI: 0.78-1.47). Conclusion Profile marked by moderate insomnia-depressive symptoms or depression-predominance were associated with higher dementia risk over 10 years, even after accounting for comorbidity. These findings highlight the value of evaluating multi-symptom patterns rather than isolated sleep complaints to identify older adults at elevated dementia risk and facilitate targeted interventions. Support (if any)