Association of diffusion tensor imaging abnormalities with executive dysfunction in patients with leukoaraiosis

Objective To explore abnormal microstructural changes of white matter using diffusion tensor imaging (DTI) in patients with leukoaraiosis (LA), and to determine the association of such abnormalities of DTI parameters with cognitive function, especially executive function. Methods A total of 44 patients with LA and 36 healthy controls were recruited from the department of Neurology, Beijing Chaoyang Hospital, Capital Medical University between July 2010 and June 2011. The two groups were matched for age, sex, education, and vascular risk factors. All the subjects underwent the scans of conventional magnetic resonance imaging (MRI), DTI and neuropsychological assessment. The values of mean diffusivity (MD) and fractional anisotropy (FA) were measured within white matter lesions (WML) and normal appearing white matter (NAWM). Three regions of interest (ROIs) were located in the white matter of centrum semiovale, anterior periventricular white matter and posterior periventricular white matter. The relationships between the cognitive function and the abnormalities of DTI parameters were analyzed. Results (1) Patients with LA performed significantly worse cognitive function, especially in the fields of executive function. The results of our study showed that patients with LA were associated with comprehensive cognitive function deficits, including mini mental state examination (MMSE) (24.4±3.2 vs 28.3±1.2), montreal cognitive assessment (MoCA) (21.2±3.4 vs 25.7±1.7), Stroop B (69.2±13.5 vs 43.3±5.0), Stroop C (141.2±42.6 vs 64.8±10.0), Stroop (C-B) (72.0±41.9 vs 21.5±9.4), trail making test (TMT)-A (73.4±15.4 vs 31.1±7.1), TMT-B (126.2±17.5 vs 81.4±5.7), digit symbol test (25.2±5.4 vs 36.7±5.1) (all P<0.05). (2) The values of FA were lower, and MD were higher in WML than NAWM and controls in all the three ROIs (P<0.05). The values of FA in NAWM located in centrum semiovale and posterior periventricular white matter were lower than controls (P<0.05). The values of MD in NAWM located in anterior periventricular white matter were higher than controls (P<0.05). (3) The values of FA of NAWM located in anterior periventricular correlated inversely with the Z scores of executive function (r=-0.311, P=0.04). Conclusions Patients with LA are related with significant cognitive impairment, especially in the domains of executive dysfunction. Microstructural integrity of both white matter lesions and NAWM is associated with executive function. The underlying executive dysfunction in LA may attribute to the damage of the prefrontal-subcortical circle. Key words: Leukoaraiosis; Executive function; Diffusion tensor imaging