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#apaperaday: A Longitudinal Follow-Up Study of Intellectual Function in Duchenne Muscular Dystrophy over Age: Is It Really Stable?

In today’s #apaperaday, Prof. Aartsma-Rus reads and comments on the paper titled: A Longitudinal Follow-Up Study of Intellectual Function in Duchenne Muscular Dystrophy over Age: Is It Really Stable?

Today’s paper is from Journal of Clinical Medicine by Chieffo et al on the longitudinal intellectual function of Duchenne patients DOI: 10.3390/jcm12020403 

It was already reported in 19th century that some Duchenne patients appeared to have cognitive problems and in 1981 Victor Dubovitz studied this formally reporting that Duchenne patients on average have an IQ that is 1 standard deviation below the mean.

The cognitive problems were reported to be stable with age. However, this was never formally followed up. Here authors did a systematic, retrospective longitudinal follow up of intellectual function in a cohort of Duchenne patients.

Of the 77 Duchenne patients included, 70 could perform the intellectual function test. They were assessed 2->4 times over a period of 6 months – 6 years with a total of 194 assessments.

26 patients missed only fulllength dystrophin, 23 patients also missed Dp140 (reported to be associated with more cognitive impairment) & 5 missed all isoforms (reported to be associated with even more cognitive impairment). For 16 it was not clear if they could produce Dp140.

Out of 70 tested patients, 43 had normal IQ, 18 were borderline intellectual functioning, 5 & 4 had mild & moderate intellectual disability. Over time the mean IQ was stable. Authors report variability for patients over time, especially for those with behavior or attention disorders

The variability did not vary between different IQ groups, or between groups who missed only full length dystrophin or also additional isoforms. Authors discuss that the variability in IQ between different measurements likely reflects the attention given by the patient to the test.

They stress this outlines the need for standardizing how the test is conducted. They also discuss the limitations of the study: it was retrospective, and the intervals between different measurements was not the same for all patients.As this was a first study of this kind, more work is needed. However, it is good to have the first study done and published. As I’ve mentioned multiple times already in my papers, the BIND project aims to study the brain involvement in dystrophinopathy patients (Duchenne, Becker, females with dystrophinopathy symptoms). Authors are involved in this network.