Background: Early age at onset of bipolar disorder is clinically important since it predicts a more severe course of illness and a poorer prognosis. Recently the age at onset (AAO) of bipolar disorder (BPD) has been reported different in samples from the USA and Europe (Bipolar Collaborative Network). We have examined the AAO of first major affective episode in major depressive disorder (MDD) and bipolar disorder in a sample of patients consecutively admitted to an affective ward in Norway. We also examined the relation between AAO and affective temperaments.
Methods: Semi-structured interview of 119 patients consecutively admitted to an affective ward. Patients were diagnosed according to DSM-IV criteria for major affective disorders and affective temperaments were assessed using Akiskal Mallya criteria.
Results: Childhood-onset of BPD (before age 13) was found in 13.5% of patients, and early onset BPD (before age 20) in 61.6%. The AAO of first major affective disorder was significantly higher in MDD (n=67) compared to BPD (n=52); (28 Years Median (Min 10-Max 57) vs. 18 Years Median (Min 8-Max 41), p<0.001, Mann-Whitney U). Comparing patients with and without affective temperaments, showed that patients with such temperaments had an earlier AAO in both MDD and BPD (MDD: 20 Years Median (Min 10-Max 56), vs. 30 Years Median (Min 12-Max 57) p=0.006, Mann-Whitney U); BPD: 16 Years Median (Min 8-Max 30) vs. 20 Years Median (Min 12-Max 41, p=0.011, Mann-Whitney U).
Conclusion: Our Norwegian data are more in line with the US than the European data regarding age at onset of bipolar disorders. The presence of an affective temperament presents an additional affirmation of the early occurrence of mood symptoms in early onset forms of both MDD and BPD.