BACKGROUND: There is a lack of studies that assess whether the DSM-IV criteria for Major Depressive Episode (MDE) that use a diagnostic threshold are valid for the elderly and whether each symptom of depression contributes equally to impairment in this group. METHOD: The Australian National Survey of Mental Health and Wellbeing is a population-based epidemiological survey which utilized the Composite International Diagnostic Instrument to diagnose MDE. Analyses were based on the survey respondents who endorsed either (or both) the "depressed mood" or "loss of interest" core MDE symptoms (60+ years, n=278; 40+ years, n=1020). A series of multivariate linear regression analyses were run to assess the relationship between the number and the type of depressive symptoms and five measures of impairment. RESULTS: For those aged 60+ years, a linear relationship alone was observed for the relationship between the number of depressive symptoms and each of the five measures but not all symptoms of depression were equal predictors of impairment; loss of energy was the most consistent predictor. When the regression analyses were repeated using respondents aged 40+ years, consistent significant interactions between age and individual symptoms of depression were not observed. LIMITATIONS: The dimensionality of MDE is assessed focusing solely on symptoms. CONCLUSIONS: Our data illustrate the apparent dimensional structure of MDE and the differential impact of depressive symptoms on impairment in an elderly sub-sample. There was little support for systematic age-dependent changes. Adjustments to the diagnostic criteria of MDE may not require age-dependent distinctions.
BACKGROUND: There is a lack of studies that assess whether the DSM-IV criteria for Major Depressive Episode (MDE) that use a diagnostic threshold are valid for the elderly and whether each symptom of depression contributes equally to impairment in this group. METHOD: The Australian National Survey of Mental Health and Wellbeing is a population-based epidemiological survey which utilized the Composite International Diagnostic Instrument to diagnose MDE. Analyses were based on the survey respondents who endorsed either (or both) the "depressed mood" or "loss of interest" core MDE symptoms (60+ years, n=278; 40+ years, n=1020). A series of multivariate linear regression analyses were run to assess the relationship between the number and the type of depressive symptoms and five measures of impairment. RESULTS: For those aged 60+ years, a linear relationship alone was observed for the relationship between the number of depressive symptoms and each of the five measures but not all symptoms of depression were equal predictors of impairment; loss of energy was the most consistent predictor. When the regression analyses were repeated using respondents aged 40+ years, consistent significant interactions between age and individual symptoms of depression were not observed. LIMITATIONS: The dimensionality of MDE is assessed focusing solely on symptoms. CONCLUSIONS: Our data illustrate the apparent dimensional structure of MDE and the differential impact of depressive symptoms on impairment in an elderly sub-sample. There was little support for systematic age-dependent changes. Adjustments to the diagnostic criteria of MDE may not require age-dependent distinctions.