Attention and corpus callosum (CC) volumes were found to be lower in patients with mucopolysaccharidosis type I (MPS I) compared with typically developing age-matched control individuals, according to a study published in Neurology.

Data from the multicenter study Longitudinal Studies of Brain Structure and Function in MPS Disorders were used to obtain volumetric magnetic resonance imaging data from a total of 18 patients with MPS I (MPS IH), 18 patients with attenuated form of MPS I (MPS IATT), and 60 typically developing control individuals. A computerized measure of sustained attention was used to compare patient performance. The 21.6-minute Test of Variables of Attention was used to assess attention of participants. The Conners’ Continuous Performance Task II was used in control participants aged ≥10 years to assess attention.

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Both MPS I groups demonstrated significantly below-average mean attention scores (P <.001), as well as smaller CC volumes (P <.001), compared with control individuals. Control individuals showed no association between attention performance and CC volume. Higher scores on omission errors correlated with significantly larger posterior CC volumes in MPS IH participants (35.64 per 1 mL; 95% CI, −0.53 to 71.80 per 1 mL; P =.053). Higher scores on commission errors and consistency of the reaction time were associated with larger central CC volumes (179.92 per 1 mL; 95% CI, 68.27-291.58 per 1 mL; P =.002) and increased central CC volumes (84.06 per 1 mL; 95% CI, 0.03-168.09 per 1 mL; P =.050) in the MPS IH group, respectively.

Limitations of the study include its retrospective design as well as the small sample size in each group.

The authors conclude that this study is one of the first to systematically demonstrate an association between attention deficits and decreased CC volumes in a well-characterized sample of young patients with MPS I. They believe their result “not only further delineates the clinical phenotype but also provides further evidence of [white matter] neuropathology in MPS I.”


King KE, Rudser KD, Nestrasil I, et al. Attention and corpus callosum volumes in individuals with mucopolysaccharidosis type I [published online April 12, 2019]. Neurology. doi:10.1212/WNL.0000000000007496