Early cognitive impairment in patients with leukoaraiosis and its relation with diffusion tensor imaging

Abstract

Objective To analyze the characteristics of early cognitive impairment in leukoaraiosis (LA) patients and fractional anisotropy (FA) changes by diffusion tensor imaging (DTI) in various regions of interest (ROIs), and explore the relationship between FA values and cognitive impairment. Methods A total of 38 chronic ischemic LA patients, admitted to our hospital from August 2015 to August 2016, and 20 healthy elderly controls were chosen in our study. Comprehensive assessment of cognitive functions, and MRI and DTI examinations were performed in subjects from these two groups. The cognitive functions, and FA values in ROIs were compared between the two groups; the FA values in ROIs of mild, moderate, and severe ischemic LA patients were compared. The correlations between FA values in ROIs and cognitive functions in LA patients were analyzed. Results As compared with the healthy control group, the patient group had significantly lower Mimi Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores, statistically longer time of Stroop test C, lower scores of verbal fluency test (VFT), digit span (DS)-inverted sequence, word similarity test in Chinese Revision of Wechsler Intelligence Scale for Children (WISC-CR), auditory verbal learning test (AVLT), clock drawing test and block testing, and significantly longer time of Trail Marking Test A (TMTA) and Stroop test B (P<0.05), suggesting that the overall cognitive function, executive function, memory, visual-spatial ability, information processing capability of LA patients decreased greatly. Significantly decreased FA values in bilateral anterior horn of lateral ventricle, left superior frontal gyrus, left inferior frontal gyrus, bilateral frontal orbital gyrus, right deep temporal lobe, right cingulate gyrus, and genu of corpus callosum in the LA patient group were noted as compared with those in the control group (P<0.05). In mild, moderate and severe LA patients, the FA values of these ROIs decreased in turn, with statistically significant differences (P<0.05). In the LA patient group, correlation analysis showed that the scores of auditory verbal learning test were positively correlated with FA values in the brain regions of left anterior horn of lateral ventricle, bilateral frontal orbital gyrus, deep white of right temporal lobe, right cingulate gyrus, and genu of corpus callosum (P<0.05), and negatively correlated with FA values in left inferior frontal gyrus (P<0.05); the scores of trail making test A were negatively related with FA values in right anterior horn of lateral ventricle (P<0.05); the Stroop test B scores were negatively correlated with FA values in deep white matter of the right temporal lobe (P<0.05); the Stroop test C scores were negatively related with FA values in left orbital frontal cortex, deep white of right temporal lobe, right cingulate gyrus, and genu of corpus callosu (P<0.05); and the block testing scores were positively related with FA values in left frontal orbital gyrus, right temporal lobe deep, and genu of corpus callosu (P<0.05). Conclusions The early cognitive impairment and decreased FA values are noted in LA patients. FA values are related to cognitive impairment. DTI contributes to diagnose early cognitive impairment in LA patients. Key words: Leukoaraiosis; Diffusion tensor imaging; Cognitive function; Region of interest; Fraction antisotropy