Differences in the pattern of cognitive impairments between juvenile and adult onset myotonic dystrophy type 1

To understand the different patterns of neuropsychological dysfunction observed between juvenile onset (jDM1) and adult onset (aDM1) myotonic dystrophy type 1.

We enrolled 19 genetically confirmed DM1 patients, and neuropsychological tests-Wechsler Adult Intelligence Scale-Revised short form; Rey-Kim memory test; and Executive Intelligence Test for evaluating intelligence, memory, and executive function-were performed. Clinical parameters including cytosine-thymine-guanine (CTG) repeats, creatinine kinase level, pulmonary function test, six-minute walk test, motor scales, and cardiac function were evaluated.

Verbal intelligence was significantly lower in the jDM1 than the aDM1 group (7.50 ± 1.64 vs. 11.00 ± 2.54, respectively; p = 0.009), while no difference was observed in performance intelligence. There was significant differences between the two groups (p = 0.022) with respect to memory function, as specifically revealed by the pattern of lower function in the verbal memory of the jDM1 group. However, the executive function test showed no intergroup differences.

Verbal memory impairment significantly deteriorated in the jDM1 group as compared to the aDM1 group, reflecting a more profound neurodevelopmental change in the juvenile type.