Assessing the Relationships Among the Phase Angle, Body Water Distribution, and Depressive Symptoms: A Cross‐Sectional Investigation of a Population of Adults and Older Individuals

Cellular health and integrity, measured by phase angle (PhA) and extracellular water‐to‐total body water ratio (ECW/TBW), may vary between age groups and be associated with depressive symptoms. This study aimed to evaluate these relationships in adults and older adults separately. A cross‐sectional analysis was conducted on 8018 participants, including 6631 adults (< 65 years) and 1387 older adults (≥ 65 years). Depression symptoms were assessed using the Beck Depression Inventory‐II (BDI‐II) and a three‐factor model. In adults under 65, higher PhA values were linked to lower depressive symptom severity (OR = 0.746; 95% CI: 0.575–0.969), while elevated ECW/TBW ratios increased severity (OR = 1.323; 95% CI: 1.024–1.712). PhA was inversely associated with somatic symptoms in both adults (OR = 0.592; 95% CI: 0.511–0.687) and older individuals, in whom a significant linear trend was observed ( p trend = 0.008) though the highest quartile alone did not reach significance (OR = 0.711; 95% CI: 0.463–1.089). ECW/TBW showed a direct association with somatic symptoms in adults (OR = 1.551; 95% CI: 1.341–1.794) and older adults (OR = 1.554; 95% CI: 1.139–2.121). Cognitive symptoms were positively associated with ECW/TBW in adults (OR = 1.216; 95% CI: 1.054–1.403) and older participants (OR = 1.375; 95% CI: 1.015–1.864). Among individuals under 65, affective symptoms were inversely related to PhA (OR = 0.757; 95% CI: 0.650–0.882) and positively associated with ECW/TBW (OR = 1.299; 95% CI: 1.119–1.509). PhA and ECW/TBW were inversely and directly associated with depressive symptom severity, respectively, only in adults, whereas no significant associations were observed in individuals aged ≥ 65 years. These findings highlight age‐related differences in the relationship between cellular health indicators and depressive outcomes and warrant confirmation in longitudinal studies.