OBJECTIVES: To investigate the correlation between neuropsychological and MRI findings in children with the childhood cerebral (CCALD) and asymptomatic forms of X-linked adrenoleukodystrophy (ALD) and to identify early cognitive markers that may predict disease progression in asymptomatic children with ALD. BACKGROUND: The few published neuropsychological studies on CCALD suggest a correlation between the pattern of cognitive deficit and lesion site; however, neuropsychological performance in asymptomatic children with ALD has not been investigated. METHODS: The authors assessed cognitive function and cerebral MRI findings in seven CCALD and eight asymptomatic ALD children. RESULTS: The CCALD children's cognitive skills were severely compromised, especially Wechsler and executive functions. Visual perception, short-term memory, and language were generally preserved, except that naming was severely impaired. All had extensive posterior white matter deterioration. The asymptomatic children had relatively intact neuropsychological performance, but their verbal fluency was compromised and naming severely impaired. All except one had mild white matter alterations. For all the children, the majority of neuropsychological test performance correlated significantly with extent of white matter lesions. CONCLUSIONS: The pattern of cognitive deterioration in children with CCALD and the significant correlation of neuropsychological test performance with extent of white matter lesions indicate a white matter dementia similar to that observed in adults with demyelinating diseases. The deficits found in asymptomatic children, despite their normal intelligence, suggest that careful neuropsychological investigation can identify early signs of malfunction. These may be markers of disease progression useful for selecting children for bone marrow transplant, although this will require confirmation by prospective longitudinal studies.