Coexistence of somatic and psychological symptoms of depression among community-dwelling older adults is associated with the incidence of dementia.

Abstract

Background: Depression in old age is associated with the incidence of dementia. However, whether a combination of somatic and psychological symptoms influences the risk of dementia has not been fully investigated.

Objective: We aimed to determine the association between the combination of psychological and somatic symptoms of depression and the incidence of dementia.

Methods: This prospective cohort study included 2111 community-dwelling older adults (median age = 73 years, interquartile range = 68-78 years, 39.5% male). Participants were evaluated for 5 years from baseline to assess the incidence of dementia. Somatic symptoms were defined as the presence of one or more symptoms of fatigue, weight loss, sleep disturbances, and abnormal appetite. Psychological symptoms were assessed using the 15-item Geriatric Depression Scale. Participants were stratified into four groups based on the presence or absence of somatic and psychological symptoms. A Cox proportional hazards model was used to examine the associations with the incidence of dementia, adjusted for potential confounders.

Results: The hazard ratios for the incidence of dementia in the somatic (HR 1.42, 95% CI: 0.96-2.09) and psychological symptoms-only groups (HR 1.47, 95% CI: 0.83-2.59) were not significantly different; however, they were significantly higher in the coexistent group than in the normal group (HR 1.91, 95% CI: 1.24-2.94).

Conclusions: The coexistence of somatic and psychological symptoms of depression increases the risk of dementia. Therefore, interventions should consider both somatic and psychological symptoms to prevent or delay dementia.