Background: This study investigates the frequency of hyperintensities, which are common in bipolar disorder, in sufferers' siblings who are free of bipolar disorder and to ascertain whether these lesions reflect any familial characteristics. It offers an assessment of the relationship between these lesions and clinical characteristics.
Methods: The study group consisted of 12 patients with bipolar disorder, their siblings who had no history of mental disorder, and a matched control group. All three groups were assessed using SCID-I (Structured Clinical Interview for DSM-IV Axis I Disorders) for diagnosis, and MRI (magnetic resonance imaging) for signal hyperintensity.
Results: No periventricular white matter lesions were encountered in any groups. It was found that in the patients and siblings, the location was in the right cerebral hemisphere in the deep white matter, whereas it was in the left cerebral hemisphere for the control group. Only in the patient group were lesions detected in subcortical white matter in the right cerebral hemisphere. The lesions were localized in the fronto-parietal area. Considering the brain as a whole, more hyperintensities were detected in the patient group compared to the other two groups. The onset of the disorder with a manic episode was increasing probably in the presence of hyperintensities.
Conclusions: Despite being alike in terms of age, more hyperintensities were detected in the patient group than in the siblings and control groups. Contrary to the control group, however, hyperintensities were localized in the right cerebral hemisphere in both the patients and the siblings groups. Hyperintensities seen in the left cerebral hemisphere yield a nonspecific impression. Siblings who have hyperintensities in the right cerebral hemisphere should be followed up and investigated with regard to bipolar disorder.