Since qualitative CT studies have suggested decreased cerebellar size in pa
tients with bipolar disorder, we performed a quantitative analysis of the c
erebellum in patients with bipolar disorder to determine whether high-resol
ution, thin slice magnetic resonance imaging (MRI) morphometry would reveal
similar results. Bipolar patients hospitalized for a first manic episode (
n = 16), bipolar patients with prior manic episodes hospitalized for a mani
c episode (n = 14), and normal volunteers (n = 15) matched for age, sex, ra
ce, and education were recruited and anatomic brain scans were acquired usi
ng a Picker 1.5 Tesla MRI scanner. Right and left cerebellar hemisphere vol
umes and vermal areas V1 (lobules I-V), V2 (lobules VI-VII), and V3 (lobule
s VIII-X) were measured. ANCOVA comparing each ROI, adjusting for race, sex
, age, total cerebral volume, and substance abuse duration, revealed a sign
ificant group effect for vermal V3 area. Specifically, V3 area was signific
antly smaller in multiple-episode patients than in first-episode patients o
r healthy volunteers. Number of previous episodes of depression may contrib
ute to this finding. These results suggest that cerebellar vermal atrophy m
ay be a later neurodegenerative event in patients with bipolar disorder who
have had multiple affective episodes. The confounding effects of medicatio
ns are considered. (C) 1999 American College of Neuropsychopharmacology. Pu
blished by Elsevier Science Inc.