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Abstract
Objective: We sought to understand the trajectory of mild cognitive impairment (MCI) better by examining longitudinally different MCI subtypes and progression to dementia and reversion to normal cognition in a community sample.
Methods: We evaluated the stability of MCI subtypes and risk of dementia over 4 biennial assessments as part of an ongoing prospective cohort study, the Sydney Memory and Ageing Study.
Results: While prevalence of MCI and different MCI subtypes remains relatively stable across all assessments, reversion from MCI and transitions between different MCI subtypes were common. Up to 46.5% of participants classified with MCI at baseline reverted at some point during follow-up. The majority (83.8%) of participants with incident dementia were diagnosed with MCI 2 years prior to their dementia diagnosis. Both reverters and participants with stable MCI were at an increased risk of progression to dementia compared to those without MCI at baseline (HR 6.4, p = 0.02, and HR 24.7, p < 0.001, respectively); however, the risk of dementia in participants with MCI who did not revert was higher than in reverters (HR 2.5, p = 0.01). This effect was specific to amnestic subtypes (MCI reverters vs nonreverters: amnestic MCI HR 3.3, p = 0.006; nonamnestic MCI: HR 1.3, p = 0.67).
Conclusion: Our findings indicate that the relevance of reversion for progression risk depends on the MCI subtype. Subtype specificity and longitudinal characterization are required for the reliable identification of individuals at high risk of developing dementia.
GLOSSARY
- aMCI=
- single-domain amnestic mild cognitive impairment;
- amdMCI=
- multiple-domain amnestic mild cognitive impairment;
- CI=
- confidence interval;
- DSM-IV=
- Diagnostic and Statistical Manual of Mental Disorders, 4th edition;
- HR=
- hazard ratio;
- IADL=
- instrumental activities of daily living;
- MCI=
- mild cognitive impairment;
- MMSE=
- Mini-Mental State Examination;
- NM=
- no mild cognitive impairment;
- nMCI=
- single-domain nonamnestic mild cognitive impairment;
- nmdMCI=
- multiple-domain nonamnestic mild cognitive impairment
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Supplemental data at Neurology.org
- Received December 23, 2016.
- Accepted in final form March 16, 2017.
- © 2017 American Academy of Neurology
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