RELATIONSHIP BETWEEN T2-WEIGHTED HYPERINTENSITIES (UNIDENTIFIED BRIGHT OBJECTS) AND LOWER IQS IN CHILDREN WITH NEUROFIBROMATOSIS-1

To address the controversy regarding the relationship between cognitiv e impairment (lowering of IQ) and magnetic resonance imaging (MRI) cha racteristics (T2-weighted hyperintensities or unidentified bright obje cts [UBOs]) in children with neurofibromatosis-1 (NP-1), we used a pai rwise NF-1/sibling design; we set out to predict the lowering of IQ in each child with NF-1 as a discrepancy from the IQ of an unaffected si bling (D-SIQ). Our multiple regression model included the age of the c hild with NF-1, familial or sporadic nature of the NF-1, number of loc ations in the child's brain occupied by T2-weighted hyperintensities ( UBOs), and the volumetric percentage of brain tissue occupied by T2-we ighted hyperintensities (UBOs). Only the number of locations occupied by UBOs accounted for IQ lowering (D-SIQ) in children with NF-1 (42% o f the variance in D-SIQ). This is the first report to confirm that a c ontinuum of lowered IQs in NF-l-affected children exists in relation t o the distribution of UBOs (range 0-7), not just presence (vs. absence ) of any UBOs. (C) 1996 Wiley-Liss, Inc.