Fractional Anisotropy and Radial Diffusivity: Diffusion Measures of White Matter Abnormalities in the Anterior Limb of the Internal Capsule in Schizophrenia

J. Levitt, J. Alvarado, P. Nestor, L. Rosow, P. Pelavin, R. McCarley, M. Kubicki, M. E. Shenton
Schizophrenia Research
Volume 136, Pages 55 - 62
2012

Abstract

INTRODUCTION: Higher cognitive functioning is mediated by frontal-subcortical cognitive and limbic feedback sub-loops. The thalamo-cortical projection through the anterior limb of the internal capsule (ALIC) serves as the final step in these feedback sub-loops. We evaluated abnormalities in the ALIC fiber tract in schizophrenia using both structural MRI and diffusion tensor imaging (DTI).

METHODS: 20 chronic schizophrenia patients and 22 male, normal controls group matched for handedness, age, and parental SES, underwent structural and DTI brain imaging on a 1.5 Tesla GE system. We manually measured ALIC volume normalized for intracranial contents (ICC) using structural brain images and then registered these high resolution structural brain scan derived ALIC label maps to DTI space allowing for the measurement in the ALIC of diffusion indices including, fractional anisotropy (FA) mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD).

RESULTS: We found in the ALIC of chronic schizophrenia subjects, compared with normal controls, bilaterally lower FA and bilaterally higher RD, but no differences in AD, MD, or relative volume. Cognitive correlations in schizophrenia patients showed, in particular, that higher left ALIC FA correlated positively with better verbal and nonverbal declarative/episodic memory performance.

DISCUSSION: Using a novel approach to assess both diffusion and volume measures in the ALIC in schizophrenia, we found abnormalities in measures of diffusion, but not volume, supporting their importance as sensitive indices of abnormalities in white matter fiber bundles in schizophrenia. Our findings also support the role of ALIC white matter tract FA abnormalities in declarative/episodic memory in schizophrenia.


Reference

Levitt J, Alvarado J, Nestor P, Rosow L, Pelavin P, McCarley R, Kubicki M, Shenton ME. Fractional anisotropy and radial diffusivity: Diffusion measures of white matter abnormalities in the anterior limb of the internal capsule in schizophrenia. Schizophrenia Research 2012;136:55 - 62.

Grants

K05 MH 700047, R01 MH 40799, R01 MH 50747, R03 MH068464-01

Research areas

dti, schizophrenia
© 2013 Psychiatry Neuroimaging Laboratory | Last updated 04.15.2013