APATHY AND HYPERSOMNIA ARE COMMON FEATURES OF MYOTONIC-DYSTROPHY

Objectives-Myotonic dystrophy is a disease characterised by myotonia a nd muscle weakness, Psychiatric disorder and sleep problems have also been considered important features of the illness. This study investig ated the extent to which apathy, major depression, and hypersomnolence were present. The objective was to clarify if the apathy reported ane cdotally was a feature of CNS involvement or if this was attributable to major depression, hypersomnolence, or a consequence of chronic musc le weakness. Methods-These features were studied in 36 adults with non -congenital myotonic dystrophy and 13 patients with Charcot-Marie-Toot h disease. gy using patients with Charcot-Marie-Tooth disease as a com parison group the aim was to control for the disabling effects of havi ng an inherited chronic neurological disease causing muscle weakness. Standardised assessment instruments were used wherever possible to fac ilitate comparison with other groups reported in the medical literatur e. Results-There was no excess of major depression an cross sectional analysis in these patients with mild myotonic dystrophy. However, apat hy was a prominent feature of myotonic dystrophy in comparison with a similarly disabled group of patients with Charcot-Marie-Tooth disease (clinician rated score; Mann Whitney U test, p=0.0005). Rates of hyper somnolence were greater in the myotonic dystrophy group, occurring in 39% of myotonic dystrophy patients, but there was no correlation with apathy. Conclusion-These data suggest that apathy and hypersomnia are independent and common features of myotonic dystrophy Apathy cannot be accounted for by clinical depression or peripheral muscle weakness an d is therefore likely to reflect CNS involvement. These features of th e disease impair quality of life and may be treatable.