Attention and corpus callosum volumes in individuals with mucopolysaccharidosis type i

OBJECTIVE: Previous research suggests attention and white matter (WM) abnormalities in individuals with mucopolysaccharidosis type I (MPS I); this cross-sectional comparison is one of the first to examine the relationship of WM structural abnormalities as measured by corpus callosum (CC) volumes with attention scores to evaluate this relationship in a larger sample of patients with MPS I.

METHODS: Volumetric MRI data and performance on a computerized measure of sustained attention were compared for 18 participants with the severe form of MPS I (MPS IH), 18 participants with the attenuated form of MPS I (MPS I ATT), and 60 typically developing age-matched controls.

RESULTS: The MPS I groups showed below-average mean attention scores ( p < 0.001) and smaller CC volumes ( p < 0.001) than controls. No significant associations were found between attention performance and CC volume for controls. Attention was associated with posterior CC volumes in the participants with MPS IH ( p = 0.053) and total ( p = 0.007) and anterior ( p < 0.001) CC volumes in participants with MPS I ATT.

CONCLUSIONS: We found that attention and CC volumes were reduced in participants with MPS I compared to typically developing controls. Smaller CC volumes in participants with MPS I were associated with decreased attention; such an association was not seen in controls. While hematopoietic cell transplantation used to treat MPS IH may compound these effects, attention difficulties were also seen in the MPS I ATT group, suggesting that disease effects contribute substantially to the clinical attentional difficulties seen in this population.