The authors of this paper do not have any commercial associations that might pose a conflict of interest in connection with this manuscript.
Age at onset in Sardinian bipolar I patients: evidence for three subgroups
Article first published online: 8 APR 2008
© 2008 Blackwell Munksgaard
Volume 10, Issue 3, pages 443–446, May 2008
How to Cite
Manchia, M., Lampus, S., Chillotti, C., Sardu, C., Ardau, R., Severino, G. and Zompo, M. D. (2008), Age at onset in Sardinian bipolar I patients: evidence for three subgroups. Bipolar Disorders, 10: 443–446. doi: 10.1111/j.1399-5618.2007.00572.x
- Issue published online: 8 APR 2008
- Article first published online: 8 APR 2008
- Received 26 February 2007, revised and accepted for publication 3 October 2007
- admixture analysis;
- age at onset;
- bipolar affective disorder;
- isolated population
Objective: We studied age at onset (AAO) in order to assess the presence of different subgroups in a homogeneous genetic population, such as the Sardinian population.
Methods: Admixture analysis was applied in order to identify a model of separate normal distribution of AAO characterized by different means, variances and population proportions to allow for evaluation of different subgroups in a sample of 181 unrelated patients of Sardinian origin with bipolar disorder (BP) type I. The Mann–Whitney test was used to compare the means of AAO between subjects with a history of suicide attempts and subjects with no such history.
Results: The best-fitting model had three components with means (SD) of 18.1 (2.3), 24.3 (5.3) and 41 (11.5) years, comprising 36%, 39% and 25% of the sample, respectively. We obtained two cut-off points at 21 and 33 years, enabling the sample to be divided into three subgroups. The Mann–Whitney test revealed a difference between the mean AAO of subjects with a positive history of suicide attempts and that of subjects with no such history (p = 0.041).
Conclusions: We found three AAO sub-groups in our sample of BP I patients of Sardinian origin. Our findings add further support to the hypothesis whereby AAO acts as a clinical marker of biological heterogeneity in BP.