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Biomarkers which allow for identification of the underlying aetiology of mild cognitive impairment (MCI) are of prognostic importance. In addition to the amyloid-β and hyperphosphorylated tau pathology, genetic factors such as apolipoprotein E (APOE)-ε4 and neuroinflammation may have additional roles in the pathogenesis of Alzheimer’s Disease (AD). In this study, we investigated the influence of APOE-ɛ4 status, neuroinflammation as measured by high mobility group box 1 protein (HMGB1), and their interaction effect on cortical thickness in MCI. We hypothesised that the interaction between APOE-ɛ4 and HMGB1 would result in a more widespread pattern of cortical thinning compared with either one factor alone.
Fifty-two individuals (27 mild cognitive impairment (MCI) and 25 controls) were recruited from a tertiary neurological centre. MCI was clinically diagnosed using the National Institute on Aging and the Alzheimer’s Association workgroup (NIA-AA) criteria.1 They had a Clinical Dementia Rating (CDR) score of 0.5 and had no other disease that could account for their cognitive deficits. Subjects with active systemic inflammatory states including infections, recent surgery or acute strokes and those receiving anti-inflammatory or cancer treatment were excluded as they could affect the levels of high mobility group box 1 protein (HMGB1). This study was approved by the SingHealth Institutional Ethics Review Board and written informed consent was obtained for all.
Blood samples were collected from all subjects. Genomic DNA was extracted from peripheral blood with QIAamp DNA Blood Maxi Kit (Qiagen, Hilden, Germany). Genotyping for apolipoprotein E (APOE) was performed as described previously.2 Subjects with at least a single copy of …
Footnotes
Contributors HF contributed to the acquisition of data, study design, statistical analyses, interpretation of data, drafting/revising of the manuscript for intellectual content and gave final approval. KPN contributed to the acquisition of data, interpretation of data, drafting/revising of the manuscript for intellectual content and gave final approval. JT contributed to analysis of the blood samples, drafting/revising of the manuscript for intellectual content and gave final approval. LL contributed to the study design, analysis of blood samples, drafting/revising of the manuscript and gave final approval. RJC and TTY contributed to acquisition of data, drafting/revising of the manuscript for intellectual content and gave final approval. NK contributed to the study design, statistical analysis, interpretation of the data, drafting/revising of the manuscript and gave final approval.
Funding This research was supported by the Ministry of Health Healthcare Research Scholarship, Master of Clinical Investigation, Singapore and National Neuroscience Institute, Singapore.
Competing interests None declared.
Patient consent Obtained.
Ethics approval SingHealth Institutional Ethics Review Board.
Provenance and peer review Not commissioned; externally peer reviewed.