Age-related cognitive decline in myotonic dystrophy type 1: An 11-year longitudinal follow-up study

Background: Myotonic dystrophy type 1 (DM1) is an inherited multi-systemic disease involving the central nervous system (CNS) and is consequently characterized by a range of cognitive impairments. However, whether this cognitive profile progresses over time is still a matter of debate. The aim of this study was to longitudinally assess a DM1 sample, in order to compare, for the first time, this progression with that of a control group. Clinical and socio-demographic predictive factors potentially implicated in this possible decline are analysed.

Method: Seventy-five DM1 patients with childhood, juvenile, adult, and late-onset, and 54 control participants were re-assessed in an 11-year follow-up with a comprehensive neuropsychological battery. The analyses employed were mixed ANOVA for repeated measures to test intergroup comparisons over time and multiple linear regression for predictive variable analysis.

Results: Myotonic dystrophy type 1 patients significantly worsened in visuospatial/visuoconstructive abilities and visual memory compared with controls. Multiple linear regression revealed that progression of cognitive impairment measured by copy of the Rey-Osterrieth complex figure was predicted by muscular impairment, whilst on the block design test age predicted the change with a cut-off at 31 years of age.

Discussion: A domain-specific progressive cognitive decline was found in DM1, with visuospatial/visuoconstructive abilities showing the greatest vulnerability to the passage of time. In addition to important clinical implications, these results suggest the need for the scientific community to delve deeper into the potential mechanisms underlying early cognitive decline in this population.