Visuoconstructional impairment in DM1: exploring underlying cognitive processes through the Rey complex figure.

Introduction: Among the cognitive difficulties shown by myotonic dystrophy type 1 (DM1) patients, visuoconstructional impairment - specifically measured with the Rey-Osterrieth Complex Figure Test (RCFT) - is particularly notable. This study aimed to analyze the performance of DM1 patients and healthy controls (HC) in the RCFT, using different correction systems in order to explore the cognitive processes underlying the poor performance and its associations with other signs and symptoms.

Methods: Data from 66 DM1 patients and 68 HC were included in this study. All participants had a comprehensive neuropsychological assessment, including the RCFT, which was scored using both the traditional Osterrieth and the Boston Qualitative Scoring System (BQSS) procedures. ANCOVA and Spearman's correlation analyses were conducted.

Results: DM1 Patients obtained significantly poorer scores than HC on the RCFT using both correction systems. Regarding BQSS, patients performed worse than HC in both main indexes (Copy Presence Accuracy-CPA and Organization-ORG), and specifically on scores of Configural accuracy, Planning, and Perseveration. Both main indexes - but especially CPA - showed significant and strong correlations with several clinical and cognitive variables.

Conclusions: Both visuoconstruction and organizational impairments underlie the poor RCFT performance in DM1. Moreover, visuoconstruction ability appears to be sensitive to the clinical hallmarks of DM1 patients. The RCFT is proposed as a gold standard in DM1 assessment and the merits of using alternative scoring systems are discussed.