Longer duration of untreated depression was associated with increased depression severity after 2 years, according to the results of a study published in PLoS One.

Taiwanese researchers enrolled participants aged 18 to 65 years with major depressive disorder who had been untreated with antidepressants for ≥4 weeks prior to the study (n=155). Participants received venlafaxine extended-release 75 mg/d and zolpidem during the first 4 weeks; control of medication was then discontinued and the patients were treated as general psychiatric patients. At 2-year follow-up, depression severity in patients who were not receiving pharmacotherapy (n=101) was assessed using the Hamilton Depression Rating Scale.

Both the duration of untreated depression and the depression severity at baseline were associated with the depression severity at 2-year follow-up (P <.05 for both). Duration of untreated depression was also inversely correlated with the percentage improvement in depression severity from baseline (P <.05).

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Neither the duration of pharmacotherapy during the 2 years nor the duration of discontinuation of pharmacotherapy during the 2 years were associated with severity or percentage improvement of depression severity from baseline to follow-up.

In regression models, duration of untreated depression and educational years at baseline independently predicted the severity and percentage improvement of depression severity from baseline.

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Based on the results, the study authors concluded that “early treatment might be an important factor related to the prognosis of depression… Therefore, [duration of untreated depression] is a valuable index for prediction of the long-term prognosis of depression and should be assessed in clinical practice.”


Hung C-I, Liu C-Y, Yang C-H. Untreated duration predicted the severity of depression at the two-year follow-up point. PLoS One. 2017;12(9):e0185119.