AUTHOR=Lin Szu-Ying , Lin Po-Chen , Lin Yi-Cheng , Lee Yi-Jung , Wang Chen-Yu , Peng Shih-Wei , Wang Pei-Ning 

TITLE=The Clinical Course of Early and Late Mild Cognitive Impairment

JOURNAL=Frontiers in Neurology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.685636

DOI=10.3389/fneur.2022.685636

ISSN=1664-2295

ABSTRACT=Introduction: Amnestic mild cognitive impairment (MCI) can be classified as either early MCI (EMCI) or late MCI (LMCI) according to the severity of memory impairment. The aim of the present study was to compare the prognosis and clinical course between EMCI and LMCI.
Methods: Between January 2009 and December 2017, a total of 418 patients with MCI and 146 subjects with normal cognition were recruited from a memory clinic. All the patients received at least two series of neuropsychological evaluations each year and were categorized as either EMCI or LMCI according to Alzheimer’s Disease Neuroimaging Initiative 2 (ADNI2) criteria.
Results: In total, our study included 161 patients with EMCI, 258 with LMCI, and 146 subjects with normal cognition as controls (NCs). The mean follow-up duration was 3.55 ± 2.18 years (range: 1–9). As first year follow-up assessment, 54 cases (32.8%) of EMCI and 16 (5%) of LMCI showed a normal cognitive status. There was no significant different between the first year EMCI reverter and NCs in terms of dementia-free survival and further cognitive decline. However, first-year LMCI reverters still had higher risk of cognitive decline during following evaluations. Until the last follow-up, annual dementia conversion rates were 1.74%, 4.33%, and 18.6% in the NC, EMCI, and LMCI groups, respectively. The EMCI and LMCI groups showed a higher rate of progression to dementia (log-rank test, p<0.001) then normal subjects. Compared with NCs, patients in the LMCI group showed a significantly faster annual decline in global cognition (annual rate of change for the mini-mental status examination [MMSE] score: −1.035, p<0.001) and all cognitive domains, while those in the EMCI group showed a faster rate of decline in global cognitive function (annual rate of change for the MMSE score: −0.299, p=0.001).
Conclusion: It is important to arrange follow-up visits for MCI patients, even in the EMCI stage. One-year short-term follow-up may provide clues about progression of cognitive function and help to identify relative low risk EMCI subjects.