Mild behavioral impairment is associated with atrophy in Alzheimer's disease‐related regions in non‐demented older adults

Abstract

AbstractBackgroundMild behavioral impairment (MBI) is a recently developed diagnostic concept describing late‐onset persistent neuropsychiatric symptoms (NPS) in older adults without dementia. Few studies to date investigated associations of MBI with structural brain changes. Our aim was to explore structural correlates of NPS in a non‐demented memory clinic sample using the Mild Behavioral Impairment Checklist (MBI‐C) that has been developed to measure MBI.Method116 non‐demented older adults from the Czech Brain Aging Study presenting with subjective cognitive concerns underwent a neurological, comprehensive neuropsychological examination and brain MRI and were classified as subjective cognitive decline (n=37, MMSE=29.30±0.88) or mild cognitive impairment (n=79, MMSE=26.82±2.51). The Czech version of MBI‐C was administered to participants´ informants. 1.5T MRI with T1‐weighted 3‐dimensional images and FreeSurfer 5.3. algorithm was used to measure a priori selected brain regions: thicknesses of the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), posterior cingulate cortex (PCC) and entorhinal cortex (ERC) and hippocampal volume (HV) adjusted for total intracranial volume. The volumetric measures were averaged between the two hemispheres. The associations of the MBI‐C total score and five domain scores with the aforementioned regions were assessed within the whole sample using covariate‐adjusted Spearman Rank correlations.ResultSignificant associations of MBI‐C total score were found with HV (rho=‐.225, p=.016), ERC (rho=‐.284, p=.002) and OFC (rho=‐.214, p=.023) while controlling for sex, age and education. Both latter associations remained significant after controlling also for MMSE. We found associations of HV with both motivation (rho=‐.248, p=.008) and impulse dyscontrol scores (rho=‐.240, p=.011), ERC with impulse dyscontrol (rho=‐.368, p<.001) and OFC with motivation score (rho=‐.201, p=.033). No other associations were observed.ConclusionNPS (particularly in motivation and impulse dyscontrol domains) detected by the MBI‐C in non‐demented older adults are associated with structural changes in typical Alzheimer´s disease‐related regions. This provides supportive evidence for MBI as an early manifestation of AD.