Cognitive and psychiatric evaluation of 40 patients with myotonic dystrophy.

We evaluated 40 patients suffering from a severe form a myotonic dystrophy (MD) with neuropsychological (WAIS-R, MMSE) and psychiatric tests (SADS, SRT) for the assessment of cognitive and psychiatric symptoms. We tested 20 normal volunteers as control group. Patients with MD scored significantly, lower on WAIS Full Scale (p less than 0.001), Verbal Scale (p less than 0.001), and Performance Scale (p less than 0.001) and on the MMSE (p less than 0.05) than the controls. 35% of patients met the Research Diagnostic Criteria for a psychiatric diagnosis; 17.5% of them had a depressive disorder. The scores on SADS subscales and on the SRT scale of depression were also significantly higher in patients than in controls. Our data confirm that mental impairment and psychiatric disorders are important clinical manifestations of CNS dysfunction in the severe form on MD.