MedWire News: While major depression patients starting treatment will spend three quarters of the next decade in euthymia, the remaining quarter will be spent in subthreshold or threshold depression, Japanese study findings indicate.
Previously, major depression was seen as an episodic, remitting and relapsing disorder with essentially asymptomatic intervals. It has been shown, however, that residual subthreshold depression between episodes is linked to functional impairment and very rapid relapse into a full depressive episode.
To examine the long-term course of depressive symptomatology and threshold and subthreshold levels, Toshi Furukawa, from Nagoya City University, and colleagues studied data from the Group for Longitudinal Affective Disorders Study of patients with previously untreated mood episodes serially assessed for 10 years.
In all, 94 patients had major depressive disorder, of whom 66 had single episode and 28 recurrent depression. The average age of the two groups was 44.1 years and 44.3 years, respectively. The follow-up rate was 70% for the 11,280 person-months.
The team found that, of the follow-up months, 77% were spent in euthymia, while 16% were spent in subthreshold depression and 7% in major depression, at 75%, 19%, and 6%, respectively, for single-episode patients and 81%, 11%, and 8%, respectively, for recurrent patients.
The results, published in the journal Acta Psychiatrica Scandinavica, show that the only predictor of the proportion of time spent in euthymia over the 10 years of follow-up was duration of index episode, at an r value of -0.63.
The team writes: "Clinically, we need to pay closer attention to lingering depression in mood disorders and make the best use of the available randomized evidence. There is growing awareness that we also need some non-pharmacological approaches to this problem such as cognitive-behavioural therapy and its combination with pharmacotherapy."
By Liam Davenport