Natural history of cognitive deficits and their relationship to MRI T2-hyperintensities in NF1
S L Hyman1, D S Gill, E A Shores
1Neurogenetics Research Unit, The Children's Hospital at Westmead (Royal Alexandra Hospital for Children), NSW, Sydney, Australia.
Background:
Cognitive impairment is the most common complication of neurofibromatosis type 1 (NF1) in childhood. Current research suggests a strong relationship between cognitive deficits and brain T2-hyperintensities. The majority of these lesions disappear as the child ages. Cross-sectional data suggest that there also are improvements in intellect.
Objective:
To determine the natural history of cognitive functioning and MRI T2-hyperintensities from childhood into adulthood, and whether changes in MRI T2-hyperintensities over time are predictive of changes in cognitive functioning.
Methods:
The authors conducted a prospective longitudinal study of a cohort of 32 patients with NF1 and 11 unaffected sibling controls. All patients underwent neuropsychological assessments and 27 children underwent MRI examinations. The patients were then reassessed after an 8-year period.
Results:
and
Conclusions:
There was no improvement in cognitive ability as the children with NF1 developed into adulthood compared with controls. Despite significant decreases in the number, size, and intensity of the T2-hyperintensities over the 8-year period, these changes were not associated with changes in cognitive ability. T2-hyperintensities in the cortex or subcortical or deep white matter are more frequent with age and these lesions are likely to have a different pathology than basal ganglia lesions. The best predictor of cognitive dysfunction in adulthood was the presence of T2-hyperintensities in childhood, rather than current lesion status. There is a limited time window (<18 years) in which the presence of T2-hyperintensities can be used as biologic markers of cognitive dysfunction.
