Onset of Depression Inventory (ODI)—Assessment of the speed of onset of depressive episodes

Background velopment of a full blown depressive episode may be very rapid, taking less than one hour, or be very slow, taking up to months. In a previous study with outpatients it was found that the majority (58%) of depressive episodes within bipolar affective disorders (BD) develop within one week whereas this is rarely the case (7.4%) in unipolar depression (UD). Apart from a replication of these findings, the present study aimed to investigate the speed of onset in patients with BD compared to UD patients with either a depressive episode (DE) or recurrent depressive disorder (RD). s of onset of depression was assessed using the structured patient interview “Onset of Depression Inventory” (ODI). In total, 24 BD patients, 42 patients with a DE and 80 patients with a RD within unipolar affective disorders were included. s eed of onset of depressive episodes differed significantly between the three patient groups (Kruskal–Wallis-test: Chi²=12.493, p=0.002): 50% of the BD patients developed a depressive episode within a week, compared with only 16.7% of DE patients and 25.0% of RD patients. tions I has not yet been validated. sions rlier finding of a faster onset of depressive episodes in BD compared to UD patients is replicated. Clinicians should consider the possibility of a hidden bipolarity in patients who develop a depressive episode within a few days.