Is mild cognitive impairment prodromal for vascular dementia like Alzheimer's disease?
OBJECTIVE
Individuals with mild cognitive impairment (MCI) are at increased risk of Alzheimer's disease (AD) and probably other forms of dementia. Some subtypes of vascular dementia (VaD) may possess minor neuropathological changes of AD that may contribute to cognitive impairments. It was posited that MCI, identified by criteria described here, might present as a prodrome for VaD and AD.


METHODS
Serial Mini-Mental State Examination was administered at 3- to 6-month intervals, and neuroimaging was performed annually. Subtle cognitive dysfunctions were weighted and measured according to MCI criteria defined here. Subjects identified with MCI were then followed up for an additional 3.88+/-3.01 years. Diagnoses of VaD and AD were made according to established criteria.


RESULTS
During 3.72+/-2.94 years of follow-up of the original normative subjects, 73 of 291 (25.1%) developed MCI. Of the 27 subjects who developed VaD, 15 (55.6%) had prodromal MCI. Of these, two thirds were subclassified as having small-vessel dementia. The remaining 12 patients with VaD (44.4%) were diagnosed directly from a cognitively normal status without preceding MCI. These were predominantly multi-infarct or strategic-infarct dementia (66.7%). An additional 35 MCI subjects (47.9%) developed AD. Both VaD and AD diagnosed after MCI prodromes manifested similar spectral domains of cognitive impairments, which included memory, during their MCI stages.


CONCLUSIONS
In some VaD subtypes, particularly those caused by subcortical microvascular disease, dementia may be preceded by MCI, which has similar domains of cognitive impairment and a similar progressive course that may mimic AD.
Meyer
John Stirling
JS
Department of Neurology, Baylor College of Medicine, Veterans Administration Medical Center, Houston, Tex 77030, USA. jmeyer@bcm.tmc.edu
Xu
Gelin
G
Thornby
John
J
Chowdhury
Munir H
MH
Quach
Minh
M
D000368:Aged; D000544:Alzheimer Disease / Q000453:epidemiology*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D015331:Cohort Studies; D015897:Comorbidity; D015140:Dementia, Vascular / Q000145:classification / Q000453:epidemiology*; D003710:Demography; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011237:Predictive Value of Tests; D015995:Prevalence; D012306:Risk; D013781:Texas / Q000453:epidemiology