[Correlates of cognitive impairment in patients with leukoaraiosis by magnetic resonance spectroscopy].

Objective: To explore the pathological changes in patients with leukoaraiosis (LA) by magnetic resonance spectroscopy (MRS) and examine its relationship with cognitive function.
Methods: Twenty-three LA patients and 23 age and gender-matched healthy subjects were recruited from the Department of Neurology, Beijing Chaoyang Hospital, Capital Medical University between August 2010 and November 2010. All participants underwent the neuropsychological tests. Multi-voxel chemical shift imaging was performed and the regions of interest were positioned in bilateral frontal white matter. The relative metabolite ratios, involving N-acetyl aspartate/choline ratio (NAA/Cho), N-acetyl aspartate/creatine (NAA/Cr) and choline/creatine (Cho/Cr), were estimated. The correlation of the MRS data and the performance of cognitive function was analyzed.
Results: The LA patients were associated with a worse performance of mini mental state examination (MMSE) versus the healthy controls (24 ± 3 vs 28 ± 1, P < 0.05). Univariate analysis of the MRS data revealed the ratios of NAA/Cho and NAA/Cr significantly decreased in bilateral frontal white matter lesions in the LA group versus the control group (1.72 ± 0.20 vs 1.96 ± 0.36, 1.67 ± 0.17 vs 1.85 ± 0.21, P < 0.05). The values of NAA/Cr and NAA/Cho in normal appearing white matter increased versus the LA group (1.83 ± 0.24 vs 1.72 ± 0.20, 1.78 ± 0.28 vs 1.67 ± 0.17) and decreased versus the control group (1.83 ± 0.24 vs 1.96 ± 0.36, 1.78 ± 0.28 vs 1.85 ± 0.21). But no significant differences were found (P > 0.05). The ratio of Cho/Cr did not differ among 3 groups (P > 0.05). The pathological change of NAA/Cr in white matter lesion in LA patients was markedly correlated with the performance of MMSE (r = 0.47, P < 0.05).
Conclusion: NAA may be a marker of axonal loss/dysfunction in LA patients. And the changes of NAA/Cr have a positive correlation with cognitive impairment.