Short-term course of the neuropsychological profile in myotonic dystrophy type 1: a 12-month longitudinal study

Myotonic dystrophy type 1 (DM1) is a complex, multisystemic neuromuscular disorder that affects various systems, including the muscular and central nervous systems. The natural history of DM1 includes a cognitive decline over time across multiple cognitive functions. However, the course of the cognitive profile remains unknown over short follow-up intervals. The study aimed to document the course of the neuropsychological profile in adults with DM1 over 12 months using classic paper-pencil tests and computerized cognitive tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB®). Adult participants with a genetically confirmed diagnosis of juvenile, adult, or late-onset phenotype of myotonic dystrophy type 1 (DM1) underwent a battery of traditional paper-and-pencil tests alongside four assessments from the computerized cognitive battery, CANTAB®. Cognitive functions were evaluated at baseline and at two follow-up points, each 6 months apart. Repeated measures ANOVAs were conducted, followed by post hoc analyses to compare results across the different time points. Significant changes were interpreted in relation to the measurement error. Forty-four participants with DM1 (m = 45.5 ± 11.2 years) were assessed (50% juvenile, 38.6% adult, 11.4% late-onset). Results showed an overall stability in cognitive functions at both 6 and 12 months. However, verbal memory (California Verbal Learning Test) and multitasking skills (CANTAB®) exhibited an improvement outside of the measurement error, likely reflecting a learning effect. Short-term progression studies are essential to improve trial readiness by documenting the best outcome measures to assess treatment effectiveness and gathering a comprehensive overview of the cognitive profile progression in DM1.