Older adults living in low-income census tracts are significantly less likely to respond to depression treatment than are their counterparts in middle- and high-income census tracts, researchers reported.
Alex Cohen, Ph.D., of Harvard Medical School, Boston, and his associates analyzed pooled data from the open-label phases of two Pittsburgh-based clinical trials funded by the National Institute of Mental Health.
In the first of these studies, nortriptyline hydrochloride combined with interpersonal psychotherapy was studied for the treatment of depression in 169 subjects aged 59 and older. The second study evaluated the combination of paroxetine and interpersonal psychotherapy among 116 subjects aged 69 and older (Arch. Gen. Psychiatry 2006;63:50–6).
Using the 17-item Hamilton Rating Scale for Depression, the investigators found that subjects living in low-income census tracts were less likely to respond to treatment. For example, participants in the higher-income tracts were far less likely to report suicidal ideation. The investigators found no association between socioeconomic status and remission.
One possible explanation for the gap between low- and middle-income subjects, the researchers said, is that “the persistence of depressive episodes was more pronounced among individuals with lower socioeconomic status.” Comorbid conditions also had some effect on antidepressant response, but they did not negate the effects of socioeconomic status when investigators adjusted for that variable.
Dr. Cohen and his colleagues also pointed to the “nonlinearity” of the findings. Educational level is usually a principal component of socioeconomic status, but in this study, higher educational status did not correlate with better treatment outcome. Subjects in the higher-income census tracts were not always the most likely to respond.
In an interview, Dr. Cohen said he would be cautious about drawing clinical implications from this research for two reasons: The work needs to be replicated, and he is not a psychiatrist. However, he said he would assume that research showing predictors of response to treatment does have clinical implications.
“If it is true that residents of low-income neighborhoods are relatively less likely to respond to efficacious interventions and more likely to experience suicidal ideation during treatment, then it would follow that treatment for such patients might need to be more intense, of longer duration, or possibly, augmented with other psychosocial interventions,” he said.
Dr. Cohen, an anthropologist, is affiliated with the Harvard Medical School's department of social medicine.