AUTHOR=Zhang Tianyi , Luo Xiao , Zeng Qingze , Fu Yanv , Li Zheyu , Li Kaicheng , Liu Xiaocao , Huang Peiyu , Chen Yanxing , Zhang Minming , Liu Zhirong ,  the Alzheimer’s Disease Neuroimaging Initiative (ADNI) 

TITLE=Effects of Smoking on Regional Homogeneity in Mild Cognitive Impairment: A Resting-State Functional MRI Study

JOURNAL=Frontiers in Aging Neuroscience

VOLUME=Volume 12 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2020.572732

DOI=10.3389/fnagi.2020.572732

ISSN=1663-4365

ABSTRACT=Background
Smoking is a modifiable risk factor for Alzheimer's disease (AD). However, smoking-related effects on intrinsic brain activity in high-risk AD population is still unclear.
Objective
We aimed to explore differences of smoking effects on brain function between healthy elderly and amnestic MCI (amnestic mild cognitive impairment, aMCI) patients using ReHo mapping.
Methods
We identified 64 healthy elderly controls and 116 aMCI patients, including 98 non-smoking and 18 smoking aMCI. Each subject underwent structural and resting-state functional MRI scanning and neuropsychological evaluations. Regional homogeneity (ReHo) mapping was used to assess regional brain synchronization. Based on ANCOVA, we explored the difference of ReHo among groups in a voxel-wise way, followed by post hoc two-sample analyses (p<0.05, corrected). Further, we correlated the mean ReHo with neuropsychological scales.
Results
Three groups were well-matched in age, gender, and education. Significant ReHo differences were found among three groups, located in the left supramarginal gyrus (SMG) and left angular gyrus (AG). Specifically, non-smoking aMCI had lower ReHo in SMG and AG than smoking aMCI and controls. By contrast, smoking aMCI had greater AG ReHo than healthy controls (p <0.05). Across groups, correlation analyses showed that left AG ReHo correlated with MMSE (r = 0.18), clock drawing test (r = 0.20), immediate recall (r = 0.36), delayed recall (r = 0.34), and auditory verbal learning test (r = 0.20). 
Conclusion
Smoking might pose compensatory or protective effects on intrinsic brain activity in aMCI patients.