We investigated the 15-item Geriatric Depression Scale (GDS-15) with regard to its factors and, reproducibility, as well as its relationship to activities of daily living, social factors, medical conditions, and quality of life for community-dwelling elderly people in Japan. The study population consisted of 736 community-dwelling elderly participants aged 65 or older. Exploratory factor analysis of the data and correlation coefficients between factors and activities of daily living, quality of life, social factors, and medical conditions were calculated for two consecutive years. The reproducibility of the results was also evaluated. As the result, GDS-15 had three reproducible factors specified as follows: factor I, "energy loss and pessimistic outlook"; factor II, "positive mental status (reversed)"; and factor III, "empty feeling." Comparing our findings with a review of research in this area, positive items (excluding "feel full of energy") seem to compose an universal factor. Factor I correlated best with quality of life, factor II with activities of daily living, and factor III with subjective cognitive function. These results suggest the GDS-15 can be used to assess the functional ability and quality of life, as well as depressive mood in older adults.
Keywords: Activities of daily living (ADLs); Cognitive function; Depression; Factor analysis; Geriatric Depression Scale (GDS-15); Quality of life (QOL).
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