Correlation among subcortical white matter lesions, intelligence and CTG repeat expansion in classic myotonic dystrophy type 1

Objectives - To analyze the correlation among intelligence, brain magnetic resonance images (MRI) and genotype in classic myotonic dystrophy type 1 (DM1) patients. Materials and methods - Seventeen patients with classic DM1 were administered intelligence and neuropsychological tests and brain MRI focusing on a semi-quantitative rating scale of subcortical white matter lesions (WMLs). Statistical analysis was measured to evaluate the correlation among clinical manifestations, intelligence, brain MRI abnormalities, and CTG repeat expansion. Results - There were statistically significant correlations between intelligence test and insular WMLs for all DM1 patients and between intelligence quotient and temporal WMLs for those patients with less than 400 of the CTG repeat size. We also documented that temporal WMLs were related to the disease course, and frontal WMLs were correlated with aging in all DM1 patients. However, a poor correlation was found among CTG repeat size and clinical pictures, neuropsychological impairments, and brain MRI abnormalities in all DM1 patients. Conclusion - These results suggest that subcortical WMLs are correlated with focal dementia in classic DM1 patients. Temporal and insular WMLs may be responsible for the global intellectual dysfunction of adult DM1 patients.