Cognitive decline in Myotonic dystrophy type 1 (DM1)

Background: Myotonic dystrophy type 1 (DM1) is a disorder associated with deficits in facial emotion recognition ability and social interaction skills 1, 2, 3. This study aimed to explore an important function associated with facial analysis and social interplay - the ability to remember and to recognize faces. Methods: Thirty-three persons with adult onset DM1 and thirty healthy controls performed a facial memory task included in the Rivermead Behavioral Memory Test-Extended (RBMT-E) 4. Scores in this task were correlated with duration of the disease, CTG repeat expansion size as measured in blood and results on neuropsychological tests. Results: Deficits in facial memory ability were significantly (P < 0.05) more prevalent in DM1 and 36% of the patients performed according to a clinical relevant impairment, indicating signs of prosopagnosia (face blindness). In a group of patients with a CTG repeat expansion > 475 repeats, failure in facial memory ability was associated with larger repeats and longer duration of the disease. Furthermore, a significant association between general visuoconstructive ability and facial memory in the DM1 group (but not in healthy controls) indicated the use of compensatory visual analytic strategies. These strategies involved a focus on details in favor of holistic analyses. Conclusions: In summary, this study is the first to show facial memory deficits and prosopagnosia in adult onset DM1. Thus, the ability to recognize faces is a basic prerequisite in social interplay, this finding adds an important clue on understanding social interaction associated with the disease.