The evaluation of Amygdala volumes in adolescents with Bipolar disorder type I

Purpose: The aim of the present study is to investigate whether the variables of the disorder effect amygdala volumes in the adolescents with Bipolar Disorder type I and to compare the possible amygdala volume changes with healthy adolescents.Method: Seventeen adolescents aged between 13 and 19 with Bipolar Disorder type I according to DSM-IV criteria that either already been followed up or got the diagnosis after their admission to Dokuz Eylül University, Department of Child and Adolescent Psychiatry between May 2008 and October 2008 were included in the study. The diagnosis of all cases was established using K-SADS P-L and affective module of WASH-U-K-SADS. Twelve adolescents between 13 and 19 years old and without any psychiatric diagnosis were included in the healthy control group selected from epidemiologic catchment area of the university. The MRI scans of all participants were made by using an MRI machine with 1.5 Tesla power (Gyroscan Intero, Philips, Netherlands) and standard head coils. The amygdala volumes were evaluated according to coronal planes and volume boundaries were controlled according to reformatted axial and saggital planes. After the identification of the limits with serial planes manually, volume variables were recorded in cubic millimeters using the present program. The MRI scans of the cases were made during euthymic phase. The phase of euthymia was defined according to YMRS (Young Mania Rating Scale) and HAM-D (Hamilton Depression Rating Scale) and the scores below 7 were considered as euthymia in both scales.Findings: The evaluation and comparison of both right and left amygdala volumes between the patient and the control group revealed no significant difference. However in the patient group, negative correlation was found between right and left amygdala volumes and the duration of the disorder (for the right amygdala P = 0.026; for the left amygdala P = 0.031).Result: The differences detected in amygdala volumes by structural MRI scans in adolescent and adult Bipolar Disorder samples may reflect underlying pathophysiologic differences between the early onset and the late onset of the disorder. The questions concerning the results of the present study and whether there is a volume decrease in amygdala of the adolescents with Bipolar Disorder or not, need further investigations with structural and functional imaging studies, especially in more homogeneous groups and in drug naive patients.Key Words: Bipolar disorder, Adolescent, Amygdala, MRI