Magnetic resonance imaging study of the gray matter changes in behavioral variant of frontotemporal dementia

Abstract

Objective To investigate the brain gray matter atrophy in behavioral variant of frontotemporal dementia (bvFTD) in order to provide an objective basis for early diagnosis. Methods High-resolution 3D structural brain images of 39 probable bvFTD and 46 controls were acquired by 3.0 Tesla MRI scanner. Neuropsychiatric Inventory (NPI), MMSE, Logical Memory Subtest of the Wechsler Memory Scale-Chinese Revision, Consortium to Establish a Registry for Alzheimer's Disease drawing and WCST were administered to assess cognitive function and psychological and behavioral symptoms. Then voxel-based morphometry and diffeomorphic anatomical registration through exponentiated lie algebra (VBM-DARTEL) was used to compare the structural difference between bvFTD and control groups. Partial correlation analysis was deployed to examine the relationship between the whole brain volume and the total score of the NPI. Results Compared with the control group, bvFTD patients showed abnormalities in most of the neuropsycological tests (all P<0.01), including the higher scores in NPI (Z=-6.545) , and the poor performance in global cognitive function (t=-8.621) , execution function (t=4.776) , episodic memory (t=-7.990) and visuospatial skills (Z=-4.909) . In addition, the volume of specific regions, including notably bilateral prefrontal and pre-temporal cortex, insula and subcortical structures, were significantly reduced in bvFTD group (t=4.89-10.95, P<0.05, FWE-corrected). Most prominent atrophy was observed in bilateral caudate nucleus, amygdala, pallidum, putamen, insula, and rectus gyrus. Moreover, the atrophy of left precuneus (cluster size=193 voxels, peak MNI coordinates x=-7.5, y=-66.0, z=67.5) was significantly associated with the total score of NPI (ρ=-0.515, P<0.05, AlphaSim corrected). Conclusions It indicates that the structure of cortico-striatal-thalamic circuits is compromised in bvFTD. The atrophy of bilateral striatum may be most prominent. Besides, the volume of left precuneus may be associated with the severity of psychological and behavioral symptoms. These findings suggest the atrophy of bilateral striatum and left precuneus might be considered as potential imaging markers of bvFTD. Key words: Frontotemporal dementia; Magnetic resonance imaging; Corpus striatum; Precuneus; Voxel-based morphometry