Cognition and psychopathology in myoclonus-dystonia

Objective (1) To study the neuropsychological and psychopathological profile in myoclonus-dystonia (M-D) patients with and without a mutation in the DYT11 gene. (2) To explore whether cognitive and psychiatric impairments are related to severity and duration of motor symptoms. Herewith, this study may help to clarify whether neuropsychological and psychiatric symptoms are associated with the DYT11 mutation or are secondary to the burden of motor impairments that originated in early childhood.

Methods Extensive batteries of neuropsychological tests and psychiatric questionnaires were administered to DYT11 gene mutation-carrying (MC) M-D patients (n=31), non-mutation-carrying (NMC) M-D patients (n=20) and a healthy control group (n=36).

Results MC M-D patients demonstrated mild impairments in executive functions. On the contrary, with the exception of one type of verbal fluency, no evident cognitive impairments were found in NMC M-D patients. Further, increased rates of anxiety disorders were found only in MC M-D patients, whereas increased rates of depressive symptoms were observed in both M-D groups. Correlation analyses yielded modest associations between severity of myoclonus and executive functions. No relationships were found between neuropsychological test performance and scores on the psychiatric assessments.

Conclusions The findings of this study suggest that anxiety disorders and executive dysfunctions may be part of the phenotype of M-D patients with a DYT11 mutation, whereas depressive symptoms and semantic fluency impairments may be secondary to suffering from a chronic movement disorder, regardless of DYT11 gene mutation.