Brain magnetic resonance imaging of structural abnormalities in bipolar disorder

Background: The neuropathogenesis of bipolar disorder remains poorly descri bed. Previous work suggests that patients with bipolar disorder may have ab normalities in neural pathways that are hypothesized to modulate human mood states. We examined differences in brain structural volumes associated wit h these pathways between patients with bipolar disorder hospitalized with m ania and healthy community volunteers. Methods: Twenty-four patients with bipolar disorder and mania were recruite d from hospital admission records. Twenty-two healthy volunteers were recru ited from the community who were similar to the patients in age, sex, race, height, handedness, and education. All subjects were scanned using a 3-dim ensional radiofrequency-spoiled Fourier acquired steady state acquisition s equence on a 1.5-T magnetic resonance imaging scanner. Scans were analyzed using commercial software. Prefrontal, thalamic, hippocampal, amygdala, pal lidal, and striatal volumetric measurements were compared between the 2 gro ups. Results: Patients with bipolar disorder demonstrated a significant (Lambda = 0.64; F-6,F-37 = 3.4; P = .009) overall difference in structural volumes in these regions compared with controls. In particular, the amygdala was en larged in the patients. Brain structural volumes were not significantly ass ociated with duration of illness, prior medication exposure, number of prev ious hospital admissions, or duration of substance abuse. Separating patien ts into first-episode (n = 12) and multiple-episode (n = 12) subgroups reve aled no significant differences in any structure (P>.10). Conclusion: Patients with bipolar disorder exhibit structural abnormalities in neural pathways thought to modulate human mood.