A new window on neurocognitive dysfunction in the childhood form of myotonic dystrophy type 1 (DM1).

Not much is known about the neurocognitive deficits in the childhood phenotypic expression of DM1. Twenty-four children and adolescents with no mental retardation were administered an extensive neuropsychological battery to investigate cognition in terms of memory, executive functions and visuo-spatial abilities. The results showed discrepancies between Wechsler's indexes with higher scores in Verbal Comprehension than Perceptive Organization and Speed of Processing. Memory assessment using Signoret's Memory Battery revealed a clear difference between verbal and visuospatial memory but no impairment between short and long-term memory. Concerning executive abilities, DM1 subjects showed greater deficits in processing speed than in mental flexibility, inhibition or working memory. This pattern of deficits could implicate a frontoparietal circuit in accordance with the neural networks involved in the adult form of DM1 and reopens the question of a continuum between childhood and adulthood neurocognitive impairments.