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 in patients with Alzheimer's disease. However, little is known about the prognostic significance of these changes in cognitively impaired individuals who are at risk for subsequent development of dementia. This study aims at investigating 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 mild cognitive impairment (MCI) and no signs of cerebrovascular disease were prospectively examined. At their initial presentation, all patients underwent a structured interview for the diagnosis of dementia (SIDAM) and a brain CT. Linear measures of atrophy and visual ratings of white matter changes were performed. At follow-up (mean interval 29 months), these patients were re-examined with the SIDAM. Eight patients had developed dementia and met clinical criteria for Alzheimer's disease (crossover group). RESULTS: Evaluation of the initial CT scans revealed significantly more frequent and extended white matter abnormalities and a higher degree of temporal lobe atrophy in the crossover group as compared to the cognitively stable 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 that they might accelerate cognitive decline in individuals with mild cognitive impairment. WML should be included in prospective studies of MCI as potential predictor variables.

The prognosis of mild cognitive impairment in the elderly.

PURPOSE: To determine whether or not subtypes of intellectual functioning are suitable to predict further cognitive decline in individuals with mild cognitive impairment. DESIGN: Naturalistic longitudinal study (mean interval 2.7 years). PATIENTS: 41 subjects with mild cognitive impairment who attended a memory clinic. METHODS: SIDAM, CT, SPECT, and ApoE genotype. RESULTS: At follow-up, 8 out of 41 patients (19.5%) with MCI had progressed to dementia, 8 patients (19.5%) had improved to normal levels of cognitive functioning, 25 patients (61%) had remained stable within the MCI group. At baseline the two prognostic groups differed significantly with regard to age, memory functions, orientation, and the degree of atrophy of the left medial temporal lobe on CT scan. CONCLUSION: The majority of MCI patients in this study remained cognitively stable within the observation period. Patients with older age, poorer test performance on memory tasks and orientation deficits are at higher risk of progressive decline to dementia. CT measures of medial temporal lobe atrophy may be a sensitive parameter of group discrimination.