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Mood-state effects on amygdala volume in bipolar disorder
Lara C Foland-Ross1, John O Brooks, Jim Mintz
1Laboratory of Neuro Imaging, Dept. of Neurology, UCLA School of Medicine, Los Angeles, CA, USA.
Journal of Affective Disorders
|April 24, 2012
Summary
Bipolar disorder patients show reduced amygdala volume when depressed compared to euthymic states or healthy controls. Mood state significantly impacts amygdala size in bipolar disorder.
Area of Science:
- Neuroimaging
- Psychiatry
- Brain Anatomy
Background:
- Inconsistent prior findings on amygdala volume in bipolar disorder (BD).
- Mood state variability may explain discrepancies in previous studies.
- Prefrontal cortex volume differences observed between depressed and euthymic BD patients.
Purpose of the Study:
- To investigate mood state-dependent volumetric differences in the amygdala in bipolar disorder.
- To compare amygdala volumes across depressed bipolar, euthymic bipolar, and healthy control groups.
Main Methods:
- Structural MRI scans acquired on a 3T scanner.
- Manual tracing of amygdala volumes.
- Comparison of amygdala volumes across 28 bipolar disorder type I patients (12 depressed, 16 euthymic) and 12 healthy controls, adjusting for sex and total brain volume.
Main Results:
- Significant effect of mood state and hemisphere on amygdala volume.
- Depressed bipolar patients exhibited significantly lower amygdala volumes compared to euthymic bipolar patients (p=0.005).
- Depressed bipolar patients also showed significantly lower amygdala volumes than healthy controls (p=0.043).
Conclusions:
- Mood state significantly influences amygdala volume in individuals with bipolar disorder.
- Findings suggest amygdala volume may serve as a state-dependent biomarker in BD.
- Further longitudinal studies with unmedicated samples are warranted to confirm these results.
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