The prognostic value of thought disorder in psychotic depression.

Thirty-eight patients with psychotic depression were compared to 40 patients with severe, nonpsychotic depression. Psychiatric variables, along with demographic data, were used to predict relapse over a 7-year period in a multiple regression model. Initial formal thought disorder was a strong predictor of relapse during the follow-up (F = 43, p < .001). The predictive value of this symptom in psychotic depression was not enhanced by the addition of other symptomatic or demographic variables. It appears that individuals with psychotic depression who experienced formal thought disorder are much more likely to have a relapse within a 7-year period than other people with depression.