Mild behavioral impairment as an indicator of early dementia neurodegeneration: Evidence from structural neuroimaging

Background Mild behavioral impairment (MBI) refers to the de novo emergence of persistent neuropsychiatric symptoms in older adults and has been associated with cognitive decline incident dementia. The purpose this study was identify structural neural correlates MBI using a hypothesis-driven region-of-interest (ROI) approach. Method cohort consisted 744 participants (60.3% female; mean SD age = 71.0 ± 9.7 years; education: 15.8 5.3 years) without dementia from National Alzheimer’s Coordinating Centre dataset. Structural T1-weighted images for each participant were processed segmented FreeSurfer then normalized by age, sex, intracranial volume, scanner characteristics, image quality generate adjusted measures grey matter volume (GMV) ROI. Our primary ROIs included five regions, representing one Braak stage: entorhinal cortex (stage I), hippocampus II), fusiform gyrus III), inferior temporal IV), frontal pole V). We also three hippocampal subfields (CA1, CA3, CA4) four commonly various psychiatric disorders (amygdala, insula, anterior cingulate, prefrontal cortex) as secondary analysis. All are anatomically highlighted Figure 1. Participants classified MBI+ if they presented derived Neuropsychiatric Inventory Questionnaire two consecutive visits year apart. Logistic regressions adjusting diagnosis (cognitively normal, n 568; mild impairment, 176) used model relationship between ROI GMV (predictor) status (outcome). Result As shown Table 1, lower early stage (entorhinal hippocampus) status. This trend maintained all subfield ROIs. However, mid-late (fusiform gyrus, cortex, pole) GMVs not For disorder ROIs, only amygdala Conclusion findings demonstrate that presence may implicate neurodegeneration regions linked early-stage Furthermore, explicitly identifies neurodegenerative marker sharing few neuroanatomical disorders, despite their clinical manifestations. aging after 90.