The brain is involved in myotonic dystrophy, leading to increased daytime sleepiness, fatigue and lack of initiative. This can lead to difficulties with planning ahead, making decisions and processing visual and spatial information. This may hamper social interactions and communication, for example at work or in relationships. Therefore proper attention needs to be paid to social functioning and participation, already in an early phase of the disease.

Patients with the congenital or juvenile form of myotonic dystrophy often have cognitive impairment. Attention deficit disorder with or without hyperactivity and behavioral abnormalities may occur. Children may have difficulty with social interactions. Therefore, evaluation by a (neuro)psychologist, special education strategies and counseling can be helpful. Specialised advice and counseling can be provided by the Centre for Neurological Learning & Development Disabilities. Speech problems can be caused by the combination of muscle weakness and delayed mental development. Speech therapy may be indicated.