Moderation and Mediation Analysis of the Relationship between Total Protein Concentration and the Risk of Depressive Disorders in Older Adults with Function Dependence in Home Care

Due to its devastating consequences, late-life depression is an important public health problem. The aim of the study was an analysis of variables which may potentially influence the risk of depression (GDS-SF). Furthermore, the aim was to study possible mediating effects of given variables on the relationship between the total protein concentration and the risk of depression in older adults with chronic diseases, and physical function impairment. The research sample included 132 older adults with chronic conditions and physical function impairments, residing in a long-term care in residential environment. In the studied group of sensory organs, diseases proved to be a significant moderator of the relationship between GDS-SF and total serum protein concentration. A stronger relationship was observed in subjects suffering from diseases of sensory organs (b = −6.42, 95% CI= −11.27; −1.58). The Barthel index and 25(OH)D vitamin were the most significant mediators of the examined relationship. Cohort research is suggested to confirm the hypothesis.