Delusional and psychotic disorders in juvenile myotonic dystrophy type-1.

We investigated the clinically derived hypothesis of a relatively high incidence of delusional and psychotic disorders in adolescents with juvenile Myotonic Dystrophy type-1 (DM1). Twenty-seven subjects of age 16-25 with juvenile DM1 and their parents were invited to have a clinical psychiatric interview, and to complete an ASEBA behavior checklist (YSR, ASR, CBCL, and ABCL). We diagnosed a Delusional Disorder in 19% of our patients and a Psychotic Disorder not otherwise specified in another 19%. These two groups of patients had a significantly worse level of clinically defined general functioning. It is clinically relevant to investigate in patients with juvenile DM the symptom of delusions and the presence of a delusional and psychotic disorder, and to consider the presence of juvenile DM in youngsters presenting with such a thought disorder. These disorders compromise the general functioning of the subjects and are often to some extent treatable.