Treatment resistance in severe unipolar depression: no association with psychotic or melancholic features.

BACKGROUND

Depressive subtypes generally have been neglected in research on treatment efficacy. We studied a sample of 699 severe unipolar depressed patients to detect any association between depressive features and treatment resistance.

METHODS

Participants were divided into psychotic (PSY, n = 90), melancholic (MEL, n = 430) and non-melancholic (n = 179) subjects according to clinical features. Formal diagnostic criteria (Mini International Neuropsychiatric Interview items), and items from 17-item Hamilton Rating Scale for Depression (HRSD17) were compared across groups. Non-responders were defined by a HRSD17 cut-off score of ≥17 after the last adequate antidepressant treatment. Treatment-resistant depression (TRD) was defined as the failure to respond to ≥2 adequate antidepressant trials. Non-linear regression models were designed to detect associations between depressive subtypes and TRD.

RESULTS

PSY and MEL patients appeared to be more severely affected and to share some "core" melancholic symptoms. Both PSY and MEL patients reported a higher rate of seasonality. However, we found no clinical or illness course variable associated with TRD.

CONCLUSIONS

Our results indicate that psychotic and melancholic depression share some "core" melancholia symptoms, while no distinguishing psychopathological feature appears to be associated with TRD in severely depressed patients.