Association between affective temperaments and bipolar spectrum disorders: Preliminary perspectives from a controlled family study

Background: The study aimed at determining the temperamental underpinnings of bipolar spectrum disorders (BSD) in the first-degree relatives (FDR) of patients with bipolar I disorder in comparison with control subjects. Sampling and Methods: The sample consisted of 198 subjects: 33 bipolar I probands and their 33 FDR in the experimental group, 33 schizophrenia probands and their 33 FDR in the patient control group, and 33 normal healthy controls and their 33 FDR. The affective temperament and the BSD were assessed using the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire and the criteria of Ghaemi et al. [Can J Psychiatry 2002;47:125-134], respectively. Results: Among the FDR of bipolar I probands, 27.3% satisfied the diagnosis of BSD, which was significantly higher than in the other groups (relative risk = 6, 95% CI = 1.74-20.69). Bipolar probands were significantly more hyperthymic as compared to controls (relative risk = 2, 95% CI = 1.34-2.98), and both the FDR of the bipolar and the FDR of the patient control groups were significantly more hyperthymic as compared to the FDR of the normal controls (relative risk = 1.52, 95% CI = 0.93-2.51). FDR (of bipolar patients) with BSD had a significantly higher total irritable temperament score as compared to FDR (of bipolar patients) without BSD (mean difference = 2.07, 95% CI = 0.64-3.50). Conclusions: Our findings support the fact that the whole spectrum of bipolarity is transmitted in susceptible families. The graded distribution of hyperthymia suggests it to be a milder expression of bipolarity in the FDR of bipolar patients. The irritable temperament appears to be a specific vulnerability marker for the development of BSD.