Spanish version of the Geriatric Depression Scale: reliability and validity in persons with mild-moderate dementia

Background: Depressive symptoms are prevalent among persons with dementia (PWD). Our aim was to assess the psychometric properties of the Spanish version of the Geriatric Depression Scale (GDS-15 and GDS-5) in PWD. Methods: In this cross-sectional study, five healthcare centers providing care for PWD from two cities in Spain participated. Ninety-six community-dwelling PWD aged 55 years and older, living with a known caregiver, completed a battery of scales including the GDS-15 and GDS-5, the Cornell Scale Depression in Dementia (CSDD), a list of self-reported chronic health conditions (yes/no), severity of dementia (Mini-Mental State Examination), functional status (Barthel Index), generic quality of life (WHOQOL-BREF), and sociodemographic information. Results: Cronbach's a coefficients were 0.81 and 0.72 for GDS-15 and GDS-5, respectively, providing evidence for acceptable internal consistency. Significant associations between the GDS-15/GDS-5, the Barthel Index, CSDD, and the WHOQOL-BREF were found. No significant differences were found on GDS-15/GDS-5 scores among dementia diagnostic groups (Alzheimer's disease, vascular dementia, mixed dementia, other dementia) or between mild (MMSE 21-26) and moderate (MMSE 10-20) dementia. Participants self-reporting depression on the comorbid condition list (yes) scored significantly higher on the GDS-15 and GDS-5 compared to those who reported not having depression. Exploratory factor analyses suggested a two-factor structure on GDS-15 which accounted for 41.6% of the variability, while the one-factor structure on the GDS-5 accounted for 48.1% of the variability. Conclusions: In general, this study provides evidence that GDS-15 and GDS-5 are suitable measures for screening depressive symptoms in community-dwelling PWD.