Do white matter changes contribute to the subsequent development of dementia in patients with mild cognitive impairment? A longitudinal study

Objective. White matter lesions on brain CT or MRI are a frequent finding i n patients with Alzheimer's disease. However, little is known about the pro gnostic significance of these changes in cognitively impaired individuals w ho are at risk for subsequent development of dementia. This study aims at i nvestigating the potential impact of white matter lucencies (WML) on brain CT on the course of mild cognitive impairment. Patients and Methods. Twenty-seven patients (mean age 72. SD 4.03) with mil d cognitive impairment (MCI) and no signs of cerebrovascular disease were p rospectively examined. At their initial presentation, all patients underwen t a structured interview for the diagnosis of dementia (SIDAM) and a brain CT. Linear measures of atrophy and visual ratings of white matter changes w ere performed. At follow-up (mean interval 29 months), these patients were re-examined with the SIDAM. Eight patients had developed dementia and met c linical criteria for Alzheimer's disease (crossover group). Results. Evaluation of the initial CT scans revealed significantly more fre quent and extended white matter abnormalities and a higher degree of tempor al lobe atrophy in the crossover group as compared to the cognitively stabl e group. In the crossover group, high WML severity initially was associated with a lesser degree of temporal lobe atrophy and higher global cognitive performance. Conclusion. We conclude that WML play a role in the dementia process and th at they might accelerate cognitive decline in individuals with mild cogniti ve impairment. WML should be included in prospective studies of MCI as pote ntial predictor variables. Copyright (C) 2000 John Wiley & Sons, Ltd.