Cognitive function in early adult and adult onset myotonic dystrophy

Introduction - Most studies revealing intellectual deficits in myotonic dystrophy (MyD) involved heterogeneous groups of patients with respect to intelligence and onset of disease. The present study was undertaken to investigate whether patients with early adult and adult MyD show subtle cognitive deficits despite a normal intelligence. Materials and methods - We compared 26 MyD patients of normal intelligence with mild symptoms and early adult and adult onset to 25 matched control subjects (CS) on a range of neuropsychological tests and a number of motor tasks of increasing complexity, which required increasing cognitive control. Results - The groups did not differ as far as the neuropsychological tests were concerned, with the exception of the Stroop Color Word Test. With respect to motor performance, the MyD patients were poorer scorers on simple and automatic motor tasks than CS, but the difference disappeared as the complexity of the tasks increased and required correspondingly more cognitive control. Conclusion - We found hardly any evidence of cognitive dysfunction in our group of MyD patients with early adult and adult onset.