Prevalence of depression in an elderly community sample: a comparison of GMS-AGECAT and DSM-IV diagnostic criteria

Background. Prevalence rates of depression based on the GMS-AGECAT system a re markedly higher than rates of major depression diagnosed using DSM-III a nd DSM-III-R criteria. Interpreting this finding is difficult since AGECAT diagnostic criteria have not been published. Methods, We conducted a survey in Edmonton, Canada, in which 1119 community residents aged 65 years or older were administered the Geriatric Mental St ate (GMS) questionnaire. Depression was diagnosed using AGECAT and also acc ording to criteria for DSM-IV major depression and minor depression. We ide ntified 57 items in the GMS relating to major and minor depression which we re then grouped into dysphoric, somatic and cognitive categories. The relat ionship of these symptoms to AGECAT depression was investigated by recoding symptoms to absent (nullifying) and recalculating the number of AGECAT cas es. Data were weighted to reflect the underlying population. Results. There were 143 cases of AGECAT depression (prevalence rate = 11.4 %), 14 cases of major depression (prevalence rate = 0.86 %) and 44 cases of minor depression (prevalence rate = 3.6 %). Of the 154 subjects with eithe r AGECAT or DSM-IV depression, only 47 (31%) were depressed according to bo th diagnostic systems. Nullifying all dysphoric symptoms reduced the number of AGECAT cases to eight, whereas nullifying somatic and cognitive symptom s reduced the numbers of cases only to 138 and 142, respectively. By themse lves, dysphoric symptoms accounted for 77 of the 143 cases of AGECAT depres sion, while somatic and cognitive symptoms alone accounted for no cases. Conclusions. AGECAT depression is more inclusive than DSM-IV major or minor depression and AGECAT case status is determined mainly by the proportion o f dysphoric symptoms.