Danish researchers have identified characteristics in people with psychotic depression that predict an increased risk for conversion to bipolar disorder.
The researchers analyzed data from several Danish registries to identify conversion to bipolar disorder among patients with an initial diagnosis of unipolar psychotic depression between January 1995 and December 2007.
Among the 8588 patients included in the study, 609 were diagnosed with bipolar disorder (defined as a new diagnosis of hypomania, mania, mixed affective episode, or bipolar disorder) during follow-up, giving a conversion rate of 7.1%.
Comparison of patients who did and did not convert to bipolar disorder identified a range of differences, seven of which emerged as significant risk factors in multiple logistic regression analysis.
These were: younger age at onset of unipolar psychotic depression (adjusted odds ratio [AOR]=0.99 per year of increasing age); recurrent depression (AOR=1.02 per episode); living alone (AOR=1.29); receiving a disability pension (AOR=1.55); and the highest educational level being a technical education (AOR=1.55), short-cycle higher education (AOR=2.65), or medium-cycle higher education (AOR=1.75).
Further analysis of the impact of age at psychotic depression onset found that, compared with people aged 20 years or younger at onset, the AOR for bipolar disorder was 1.64 for those aged 20–29 years, 1.58 for age 30–39 years, 1.80 for age 40–49 years, 1.36 for age 50–59 years, 1.19 for age 60–69 years, 0.85 for age 70–79 years, and 0.40 for age 80 years or older.
The researchers said that in comparison to previous studies the risk was underestimated in this latest study. Interestingly people in the age group (40- 49) appear to have a greater risk than younger groups. I was under the impression for some time that bipolar disorder developed much earlier. Perhaps a greater fluctuation in hormones levels might increase the risk as well.
This study was of interest because I have experienced depression since age twelve and also experienced psychotic depression around age 14 and at 39. Despite experiencing some characteristics of bipolar disorder my doctors didn’t think bipolar disorder was likely.