Factors Of Cognitive Dysfunction Research Articles

Cerebral metabolism, magnetic resonance spectroscopy and cognitive dysfunction in early multiple sclerosis: an exploratory study

Objectives: Positron emission tomography (PET) studies have shown that cortical cerebral metabolic rate of glucose (CMRglc) is reduced in multiple sclerosis (MS). Quantitative magnetic resonance spectroscopy (MRS) measures of N-acetyl-aspartate (NAA) normalized to creatine (NAA/Cr) assess neuronal deterioration, and several studies have shown reductions in MS. Furthermore, both PET and MRS reductions correlate with cognitive dysfunction in MS. Our aim was to determine if changes in cortical CMRglc in early MS correlate with NAA/Cr measurements of neuronal deterioration, as well as cognitive dysfunction and neurological disability.Methods: We studied 20 recently diagnosed, clinically definite, relapsing–remitting MS patients. Global and cortical CMRglc was estimated using PET with 18-F-deoxyglucose and NAA/Cr ratio was measured using multislice echo-planar spectroscopic imaging. All subjects were neuro-psychologically tested and a cognitive dysfunction factor (CDF) was calculated.Results: Cortical CMRglc correlated with cortical NAA/Cr (r = 0·45; P<0·05), but there were no correlation between CMRglc and other NAA/Cr measurements, conventional magnetic resonance imaging measurements, or CDF. Stepwise regression analysis showed association between cortical NAA/Cr and CMRglc of the left ventrolateral prefrontal cortex (P<0·001), left putamen (P = 0·010), and left hippocampus (P = 0·011). Furthermore, CDF was related to CMRglc in the left cerebellum (P = 0·001) and the left caudate nucleus (P = 0·013). The results of the statistical analysis should be regarded as exploratory, since we did not correct for multiple comparisons.Conclusion: Our findings suggest that reductions in cortical CMRglc are associated with reductions in cortical NAA/Cr in early MS. These changes affect cortical and subcortical neural circuits of importance to cognitive function.

Cognitive deficits in multiple sclerosis: correlations with T2 changes in normal appearing brain tissue

Although disease load in multiple sclerosis (MS) often is based on T2 lesion volumes, the changes in T2 of normal appearing brain tissue (NABT) are rarely considered. By means of magnetic resonance, (MR) we retrospectively investigated whether T2 changes in NABT explain part of the cognitive impairment seen in MS and constitute a supplement to traditional measurement of T2 lesion volume. Fifty patients with clinically definite MS were included (38 women, 12 men). Patients were MR scanned, neuropsychologically tested, and evaluated clinically with the Kurtzke Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Impairment Scale (MSIS). Voxel-wise T2 estimates and total T2 lesion volume were tested for correlations with eight cognitive domains, a general cognitive dysfunction factor (CDF), and the two clinical scales. We found distinct clusters of voxels with T2 estimates correlating with CDF, mental processing speed, complex motor speed, verbal fluency, and MSIS. A significant negative correlation was found between total lesion volume and CDF (r = -0.34, P = 0.02), verbal intelligence (r = -0.40, P = 0.005), mental processing speed (r = -0.34, P = 0.03), visual problem solving (r = -0.40, P = 0.01), and complex motor speed (r = -0.39, P = 0.01). No significant correlation was detected between total lesion load and the clinical measures EDSS and MSIS. Our results suggest that even in the NABT MR detects changes likely to be associated with an underlying pathology and possibly contributes to the cognitive impairment in MS.