Longitudinal Analysis of Bidirectional Relationships Between Nocturia and Depressive Symptoms: The Nagahama Study.
Although the association between nocturia and depressive symptoms has been demonstrated, the causal direction remains unclear. Our aim was to investigate the directional association between nocturia and depressive symptoms using longitudinal data from the general population.This longitudinal analysis was conducted as part of the Nagahama Cohort Project, the population-based cohort study, with baseline and 5-year follow-up investigations. Nocturnal voiding frequency and mental health were measured with self-report questionnaires, the International Prostate Symptom Score (IPSS) and the five-item Mental Health Inventory (MHI-5). Logistic regression analyses and a cross-lagged panel analysis were performed to analyze the bidirectional association between nocturia and depressive symptoms.Of the 9,764 participants at baseline, data from 8,285 were used in this analysis. The median age at baseline was 57.3, and the proportion of men was 32.0%. New-onset depressive symptoms and nocturia was observed among 369 and 793 participants. In the adjusted logistic regression analyses, we observed clear dose-relationship between baseline nocturnal voiding frequency and new-onset depressive symptoms (P for trend<0.001), and weak association between baseline MHI-5 and new-onset nocturia (P for trend=0.0087). In a cross-lagged panel analysis, the path coefficient from nocturnal voiding frequency to MHI-5 (β=-0.06, P<0.001) was stronger than that from MHI-5 to nocturnal voiding frequency (β=-0.02, P=0.047).This longitudinal study demonstrated a bidirectional association between nocturia and depressive symptoms. The cross-lagged path coefficient suggested that nocturia could be more likely a cause than a result of depressive symptoms.