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Diffusion-weighted magnetic resonance imaging of white matter in bipolar disorder: a pilot study
William T Regenold1, Christopher A D'Agostino, Narayanan Ramesh
1Geriatric Division, Department of Psychiatry, University of Maryland School of Medicine, VA Maryland Healthcare System, Baltimore, MD 21201, USA.
Objective:
Diffusion-weighted magnetic resonance imaging (MRI) has shown increased sensitivity in detecting brain white matter disease compared to traditional T2-weighted MRI. Diffusion-weighted imaging (DWI) can quantitatively assess the microstructural integrity of white matter using the average apparent diffusion coefficient (ADC(av)), a measure of the extent to which water molecules move freely within tissue. On the basis of numerous studies suggesting white matter disease in bipolar patients, particularly patients with more severe illness, this study aimed to test the utility of DWI in assessing the white matter integrity of bipolar patients with severe illness.
Methods:
The existing MRI scans of eight bipolar patients and eight age-matched controls with neurological illness were examined retrospectively. ADC(av) values for pixels within white matter regions of interest (ROIs) were calculated and used to plot ADC(av) frequency histograms for each ROI. Mean ADC(av) values for the two groups were then compared by ANCOVA.
Results:
The bipolar mean ADC(av) (0.855 +/- 0.051 x 10(-3) mm2/s) for combined white matter ROIs significantly exceeded that of controls (0.799 +/- 0.046 x 10(-3) mm2/s), while covarying for age (F = 4.47, df = 3, p = 0.025).
Conclusions:
This is the first report of an elevated ADC(av) in the white matter of a group of patients with bipolar disorder. In this group of patients with severe illness, increased white matter ADC(av) suggests microstructural changes consistent with decreased white matter integrity. DWI may be an additional, useful tool to assess white matter abnormalities in bipolar disorder.
Insights
Diffusion-weighted imaging (DWI) reveals decreased white matter integrity in severe bipolar disorder. This magnetic resonance imaging (MRI) technique may help assess brain abnormalities in bipolar patients.
Area of Science:
- Neuroimaging
- Neurology
- Psychiatry
Background:
- Diffusion-weighted imaging (DWI) offers enhanced sensitivity for detecting brain white matter disease compared to traditional MRI.
- White matter disease is increasingly implicated in bipolar disorder, particularly in severe cases.
- The average apparent diffusion coefficient (ADC(av)) quantifies white matter microstructural integrity.
Purpose of the Study:
- To evaluate the effectiveness of DWI in assessing white matter integrity in bipolar patients with severe illness.
- To compare ADC(av) values between bipolar patients and age-matched controls.
Main Methods:
- Retrospective analysis of MRI scans from eight bipolar patients and eight controls.
- Calculation of ADC(av) values within white matter regions of interest (ROIs).
- Comparison of mean ADC(av) values between groups using ANCOVA, controlling for age.
Main Results:
- Bipolar patients exhibited significantly higher mean ADC(av) values in white matter ROIs compared to controls (0.855 vs. 0.799 x 10(-3) mm2/s).
- The difference remained significant after covarying for age (F = 4.47, df = 3, p = 0.025).
Conclusions:
- This study is the first to report elevated ADC(av) in the white matter of bipolar disorder patients.
- Increased white matter ADC(av) suggests reduced microstructural integrity in severe bipolar disorder.
- DWI shows promise as a tool for assessing white matter abnormalities in bipolar disorder.
