Why should neuropsychological assessment always be considered in Myotonic Dystrophy Type 2? An overview of patients' cognitive profile

Overview & Synopsis

Objectives and background: Myotonic Dystrophies (DM) are hereditary, multisystem, slowly progressive myopathies that also affect the central nervous system. In contrast to the well-established cognitive profile of Myotonic Dystrophy Type 1 (DM1), only few studies investigated cognitive dysfunction in Myotonic Dystrophy Type 2 (DM2), and their findings are inconsistent. We have therefore performed a formal comprehensive review of available studies in DM2 to identify the most commonly affected cognitive domains. Methods: An advanced search was conducted on PubMed with the terms "myotonic dystrophy type 2" AND "cognitive deficits", "cognitive", "cognition", "neuropsychological", "neurocognitive", "neurobehavioral" in all fields. All available original research articles (13) and 1 case study, 14 in total, were included and thoroughly studied. Results: Most research studies indicate primary cognitive deficits in executive functions (dysexecutive syndrome), memory (short term nonverbal, verbal episodic memory), visuo-spatial/constructivemotor functions and attention while language is rarely reported to be affected. Cognitive profile is associated with brain abnormalities in several secondary and high-order cortical and subcortical regions and associative white matter tracts based on the few neuroimaging and/or multimodal studies. The limited sample size of DM2 patients is the most prominent limitation on current literature. Conclusions: The multifaceted profile of cognitive deficits highlights the need for routine neuropsychological evaluation in DM2 that could unveil patients' strengths and impairments at baseline and to be carefully monitored over time.