Since a neuropsychological study in 2008 (Ekström et al., 2008), there have been few studies of pediatric cohorts to assess potential links between congenital and childhood-onset DM1 with autism spectrum disorders. The Ekström analysis of 57 children and adolescents with DM1 showed that 53% exhibited autism spectrum or other neuropsychiatric disorders (e.g., attention deficit hyperactivity disorder or Tourette's syndrome). The authors concluded that awareness of potential autism spectrum disorder comorbidity in DM1 was essential to patient care. There has been little literature on this issue since 2008.
A New Cohort Study of Autism and Childhood DM1
Dr. Nathalie Angeard (Paris Descartes University and Institut de Myologie) and colleagues recently published a review of nine studies focused on cognitive disorders in childhood DM1, compromising 175 cases (Angeard et al., 2017).
Emotional and behavioral disorders were prominent among reports in childhood DM1—the earlier study by Ekström and colleagues found that 36% of a cohort containing congenital (CDM) and juvenile-onset DM1 had autism spectrum disorders, although other studies did not report that high a prevalence. Angeard suggests that the association between and difficulties in the differential diagnoses of intellectual disability and autism spectrum might contribute to differences in reports of autism spectrum in CDM and juvenile DM1.
Cognitive function studies in CDM have reported moderate to severe intellectual disability in greater than half of patients studied. Considerable information is available regarding the characterization of specific cognitive function deficits and is reported in this meta-analysis. Patients with autism spectrum comorbidity did not fit a narrow profile, but rather exhibited a range of severity of symptoms, cognitive abilities and functional adaptations. The authors suggest that a considerable gap exists in understanding executive function and social cognition in childhood DM1, making it difficult to compare these patients with those with autism spectrum disorder. Likewise, a dearth of neuroanatomic and brain function studies in childhood DM1 also makes it difficult to compare their profile with that of autism spectrum disorder children. Where comparisons can be made based on available publications, the authors compare and contrast the social/communication, cognitive function and brain abnormality profiles between the two disorders (Table 2 in Angeard et al., 2017).
It’s Not Yet Clear Whether Childhood DM1 and Autism Spectrum Disorders are Comorbid
Overall, Angeard and colleagues note that only the Ekström paper reports high prevalence of autism spectrum disorder in childhood DM1 (36% versus 1% in the general population). Most publications agree, however, upon moderate prevalence of autism spectrum disorders in CDM. An evolving definition of autism spectrum over the time of the publications assessed here complicates any clear conclusion regarding comorbidity. The authors note that the prevalence of intellectual disability among childhood DM1 and autism spectrum may lead to biases in diagnosis. Taken together, they regard the question of comorbidity of childhood DM1 and autism as still open, requiring more careful cross-sectional and longitudinal natural history studies of the cognitive and behavioral phenotype of childhood DM1. For now, earlier attention to the cognitive, developmental, and social/emotional profiles of those at risk for CDM and juvenile-onset DM1 is warranted.
Autism spectrum conditions in myotonic dystrophy type 1: a study on 57 individuals with congenital and childhood forms.
Ekström AB, Hakenäs-Plate L, Samuelsson L, Tulinius M, Wentz E.
Am J Med Genet B Neuropsychiatr Genet. 2008 Sep 5;147B(6):918-26. doi: 10.1002/ajmg.b.30698.
Childhood-onset form of myotonic dystrophy type 1 and autism spectrum disorder: Is there comorbidity?
Angeard N, Huerta E, Jacquette A, Cohen D, Xavier J, Gargiulo M, Servais L, Eymard B, Héron D.
Neuromuscul Disord. 2017 Dec 15. pii: S0960-8966(17)31337-8. doi: 10.1016/j.nmd.2017.12.006. [Epub ahead of print]