342. Anatomical MRI study of basal ganglia in bipolar disorder patients

Abstract

Findings from MRI studies suggested basal ganglia abnormalities in unipolar depression. In bipolar disorder, the available results have been mostly inconclusive. This study examined further the possibility of anatomical basal ganglia abnormalities in bipolar subjects. 7 DSM-IV drug-free bipolar patients (mean ± S.D. age = 37.4 ± 6.3), 15 lithium-treated bipolar patients (mean ± S.D. age = 34.9 ± 9.4) and 16 healthy controls (mean ± S.D. age = 36.0 ± 9.3) were studied. A 1.5T GE Signa magnet with Signa 5.4.3 software (General Electrics, Inc. Milwaukee, WI) was used. 3D gradient echo imaging (SPGR) was used (TR = 25 ms, TE = 5 ms, nutation angle = 40°, FOV = 24 cm, slice thickness = 1.5 mm, NEX = 1, matrix size = 256 × 192). Image analysis was conducted blindly on the semi-automated software Scion Image (Scion Corporation, Inc., Frederick, MD). No significant differences were found among groups for caudate and putamen gray matter volumes (ANOVA, p > 0.05). However, significant inverse correlation with age was found for right caudate, and right and left putamen gray matter volumes in patients (r = −0.488, p = 0.021; r = −0.453, p = 0.034; r = −0.546, p = 0.009), but not in controls. A significant inverse correlation between length of illness and left putamen gray matter volumes was also found in patients (Spearman Coefficient = −0.427, p = 0.048). MRI anatomical abnormalities in basal ganglia may be more characteristic of unipolar than bipolar disorder. However, our results suggest that age and length of illness could be relevant factors leading to increased loss of gray matter volume in basal ganglia structures, and part of the brain mechanisms that may be implicated in the pathophysiology of bipolar disorder.