Abstract

Background: Family history is one of the most important known risk factors for the occurrence of bipolar disorder (BD). Identifying clustering factors in BD families may facilitate the identification of the hereditary sub-phenotypes of the disorder and might reveal the underlying genetic features. This retrospective study aimed to investigate the effect of family history and gender on the clinical features of the disease in a large BD sample followed in a specialized mood center in Turkey.
Methods: Research was carried out by reviewing the medical files of patients diagnosed with bipolar disorder who were followed up in the Raşit Tahsin Mood Clinic. Family histories and other demographic and clinical information of the patients were retrieved from the Mood Disorders Patient Registration Form (SKIP-TURK) completed for each patient. A patient’s family history was considered positive if any diagnosis of mood disorders and/or psychotic disorders was present in their first and/or second-degree relatives.
Results: Family history was positive in 64.5% (n = 474) of 735 patients whose family history was recorded. Female patients made up 59.9% of the sample. Eighty point three percent (n = 590) of the patients were diagnosed with type 1 BD, 8.4% (n = 62) with type 2 BD, 11.3% (n = 83) with bipolar disorder not otherwise specified (BD-NOS). In the sample divided into 4 groups according to gender and family history, differences in the age at onset of the illness (F = 3.662, p = .012) were found to be statistically significant. In post hoc analysis, a significant difference was obtained between female patients without a positive family history and patients with a relevant family history. Regardless of family history status, the type of first episode in male patients tended to be hypomania/mania. Regarding treatment preferences, there was no significant difference between patients with and without a positive family history.
Conclusions: In the literature, some studies evaluating the familial burden only included first-degree relatives, while others considered first- and second-degree relatives, and some studies defined the family history including only relatives with mood disorders, while others would include any psychiatric disease. In the present study, family history of those diagnosed with mood disorders and/or psychotic disorders in their first- and/or second-degree relatives was considered positive. This study provides valuable information by evaluating the effect of family history and gender on the clinical features of the disease in a large BD sample in Turkey.

Key words: Bipolar disorder, family history, genetic transmission, familial aggregation