Background. Prevalence rates of depression based on the
GMS-AGECAT system are markedly
higher than rates of major depression diagnosed using DSM-III and 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 State (GMS) questionnaire.
Depression
was diagnosed using AGECAT and also according to criteria for DSM-IV major
depression and
minor depression. We identified 57 items in the GMS relating to major and
minor depression which
were then grouped into dysphoric, somatic and cognitive categories. The
relationship of these
symptoms to AGECAT depression was investigated by recoding symptoms to
absent (nullifying)
and recalculating the number of AGECAT cases. 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 either AGECAT or DSM-IV depression, only 47 (31%)
were depressed
according to both diagnostic systems. Nullifying all dysphoric symptoms
reduced the number of
AGECAT cases to eight, whereas nullifying somatic and cognitive symptoms
reduced the numbers
of cases only to 138 and 142, respectively. By themselves, dysphoric symptoms
accounted for 77 of
the 143 cases of AGECAT depression, 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 of dysphoric
symptoms.