Mild myotonic dystrophy is associated with memory impairment in the context of normal general intelligence.

Abstract

Previous investigations of cognitive function in myotonic dystrophy (DM) suggested that DM subjects have impairment of general intelligence and severe defects in executive function. These studies had to neglect patients with mild clinical disease, since they were generally performed before the availability of DNA testing for DM. We have investigated a group of milder DM cases (defined both by their degree of disability and CTG expansion size) and have not found any defect in general intelligence using the National Adult Reading Test, Standard Progressive Matrices, and Mini-Mental State examination. Three executive function tests were used. The cognitive estimates test and the Wisconsin Card Sorting Test showed tendencies towards impairment, which were of borderline significance, but the verbal fluency task was performed normally. However, in the face of normal general intelligence, mild DM subjects as a group show impairment of memory function. This suggests that memory function may be more sensitive to small CTG repeat expansions than general intelligence.

Relationship between pulmonary and cognitive functions in myotonic dystrophy type 1: a preliminary study

“…Rubinsztein et. al has shown that memory was influenced in early stages of the disease course, rather than executive functions 23 , however, in our study, tests of verbal and memory functions were not found different in control group contrarily.…”

Cerebral involvement in myotonic dystrophies

“…Several authors tried to correlate neuropsychological and neuroimaging findings. 6,24,27,28,45,62,101 Meola et al 71,72 confirmed a selective impairment on tests of frontal lobe function in DM1 and suggested that this type of deficit does not correlate with cortical atrophy and white matter hyperintense lesions, but might be associated with fronto-temporal lobe hypoperfusion on PET studies.…”

“…Whether measurements of global intelligence correlate with CTG size is a controversial issue. Some authors have concluded that CTG size correlates with IQ or MMSE scores and thus may be of predictive value, 23,47,65,88,101,122 but others have not found any correlation. 71,72,78 Visual-Spatial Deficits.…”

Myotonic Dystrophy Type 1 (DM1): From the Genetics to Molecular Mechanisms

“…Alterations of personality associated with DM1 include avoidant personality, obsessive-compulsive, passive-aggressive, and schizotypic traits, whose occurrence is not attributable to the patients' disabling condition (Delaporte 1998;Winblad et al, 2005). Other studies have found severe impairment in all measurements of general intelligence and verbal fluency (Rubinsztein et al, 1997).…”