People's socio-economic status was once a major area of interest for scientists researching the effectiveness of drugs and psychotherapy but little work has been done on this in the last 25 years as race and ethnicity have taken centre stage. Yet people with lower socio-economic status tend to have more stress in their lives and less resources to cope with it than better-off people. Lydia Falconnier from the University of Illinois in Chicago looked at how socio-economic status affected the effectiveness of cognitive-behaviour therapy, interpersonal psychotherapy and drug therapy using data from the Treatment of Depression Collaborative Research Program (TDCRP) run by the National Institute of Mental Health. They found that socio-economic status was associated with worse outcomes for all three treatments although it was not associated with attrition (dropping out of treatment).
Falconnier, Lydia - Socioeconomic status in the treatment of depression American Journal of Orthopsychiatry 79(2), 148-158