Late onset dysthymic disorder and major depression differ from early onset dysthymic disorder and major depression in elderly outpatients

Abstract

Background: Age of onset may affect clinical features and prognosis in elderly patients with major depression (MDD), but there is a lack of such data in elderly patients with dysthymic disorder (DD) and systematic comparisons of late onset MDD and DD have not been conducted. Methods: In a Late Life Depression Clinic, patients≥60 years old who met DSM-III-R or DSM-IV criteria for MDD or DD were studied. The 24-item Hamilton Rating Scale for Depression (HRSD) and SCID-P were completed, family history was obtained, and medical illnesses were assessed. Results: In the total sample ( n=370; 211 MDD and 159 DD), compared to early onset patients, late onset (onset≥60 years) patients had a higher rate of cardiovascular disease ( χ 2=4.12, df=1, P<0.05), lower rate of anxiety disorder ( χ 2=4.19, df=1, P<0.05), and a lower rate of family history of affective disorder ( χ 2=9.37, df=1, P<0.002). Late onset DD patients were more likely to have cardiovascular disease than early onset DD patients ( χ 2=5.63, df=1, P<0.02), but the rate of cardiovascular disease did not differ between late and early onset MDD patients ( χ 2=0.35, df=1, P<0.6). Late onset MDD patients were less likely to have a family history of affective disorder than early onset MDD patients ( χ 2=10.71, df=1, P<0.001). Prevalence of anxiety disorders did not differ between the early and late onset MDD patients ( χ 2=0.07, df=1, P<0.79), but was more common in the early onset DD compared to the late onset DD patients (17.98% versus 4.29%, χ 2=6.98, df=1, P<0.01). Late onset DD did not differ from late onset MDD in the rates of cardiovascular disease, anxiety disorders, and family history of affective disorder. Excluding patients with double depression ( n=32) did not alter the cardiovascular or family history findings, but the difference in anxiety disorders between early and late onset DD patients was no longer significant. Limitations: Academic clinic sample results may not generalize to community populations. Conclusions: In the elderly, late-onset DD is typically different from early onset DD. Cerebrovascular disease appears to play a role in the etiology of late onset DD. The similarities between late onset DD and late onset MDD suggest a single condition along a continuum.