Baseline amnestic severity predicts progression from Amnestic Mild Cognitive Impairment to Alzheimer Disease Dementia at 3 years

Abstract

BACKGROUND: Given the long preclinical disease course of Alzheimer disease (AD) pathology, novel treatments may be more efficacious if administered before the emergence of dementia. Thus, accurate prediction of who will develop AD dementia is of key importance in selecting individuals for trials of treatment and may become crucial for future selection of patients for therapy.

METHODS: As part of the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing, 901 individuals who did not have dementia were recruited. We assigned individuals according to Petersen criteria and Winblad criteria for Mild Cognitive Impairment (MCI) at baseline. We then stratified individuals with amnestic MCI into 2 groups according to the severity of their memory impairment on baseline neuropsychological assessment. Incident diagnosis of AD dementia was established by consensus of an expert panel at 36 months.

RESULTS: At 36 months, 725 (80.5%) participants were followed up, 54 (7.4%) of whom developed AD dementia. Subjects with amnestic MCI according to Petersen criteria were more likely to develop AD dementia [positive predictive value; PPV, 24.1%; 95% confidence interval (CI), 18.4-30.6] than healthy controls (PPV, 1.0%; 95% CI, 0.3-2.3). Winblad criteria were also effective, with multiple domain amnestic MCI being most accurate at predicting AD dementia (PPV, 47.3%; 95% CI, 33.7-61.2). Finally, more severe amnestic impairment below the median was useful for predicting the development of AD dementia in single domain amnestic MCI (PPV, 28.1%; 95% CI, 17.0-41.5) and in multiple domain amnestic MCI (PPV, 65.7%; 95% CI, 47.8-80.9).

CONCLUSIONS: Memory impairment per se, impairment in multiple cognitive domains and severity of memory impairment were all associated with greater risk of developing AD dementia in this sample. Characterizing the severity of memory impairment may provide prognostic stratification within Petersen or Winblad taxonomies of amnestic MCI.

RAS ID

27934

Document Type

Journal Article

Date of Publication

7-1-2018

ISSN

1546-4156

Volume

32

Issue

3

PubMed ID

29561277

School

School of Medical and Health Sciences / Centre of Excellence for Alzheimer’s Disease Research and Care

Copyright

subscription content

Publisher

Lippincott Williams and Wilkins

Comments

Bradfield, N. I., Ellis, K. A., Savage, G., Maruff, P., Burnham, S., Darby, D., ... & Robertson, J. (2018). Baseline Amnestic Severity Predicts Progression From Amnestic Mild Cognitive Impairment to Alzheimer Disease Dementia at 3 Years. Alzheimer Disease & Associated Disorders, 32(3), 190-196. Article is Available here

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Link to publisher version (DOI)

10.1097/WAD.0000000000000252