Distinct Resting-State Functional Connectivity Patterns of Anterior Insula Affected by Smoking in Mild Cognitive Impairment

Abstract

Abstract Background Smoking is a modifiable risk factor for Alzheimer's disease (AD). The insula plays a key role in both smoking and cognition. However, the smoking effects on insula-related networks in cognitively normal controls (CN) and mild cognitive impairment (MCI) patients remain unknown. Methods We recruited 129 CN (85 non-smokers and 44 smokers) and 83 MCI (54 non-smokers and 29 smokers). Each underwent neuropsychological assessment and MRI (structural and resting-state functional). Seed-based functional analyses in anterior and posterior insula were performed to calculate the functional connectivity (FC) with voxels in whole brain. Mixed-effect analyses were performed to explore the interactive effects on smoking and cognitive status. Associations between FCand neuropsychological scales were assessed. Results Mixed-effect analyses revealed the FC differences between the right anterior insula (RAI) with the left middle temporal gyrus (LMTG) and that with the right inferior parietal lobule (RIPL) (p < 0.01). The FC of RAI in both LMTG and RIPL sees a significant decrease in MCI smokers (p< 0.01). Furthermore, the FC between RAI and RIPL was associated with processing speed (r = -0.35, p = 0.003) and execution (r = -0.45, p< 0.001)in smokers. Conclusion Smoking affects insular FC differently between MCI and CN, and could decrease the insula FC in MCI patients. Our study provides evidence of neural mechanisms between smoking and AD.