Evaluation of the relationship of morphological changes in brain structures with brain functions in alzheimer's patients: a radiological anatomy study

Aim: The aim of this study is to retrospectively investigate the relationship between volumetric measurements of brain regions associated with cognitive functions (white matter, gray matter, hippocampus, temporal lobe, entorhinal area, parahippocampal gyrus, and insula) in Alzheimer's disease (AD) patients, as derived from MR images, and their correlation with gender, advancing age, Mini-Mental State Examination (MMSE) scores, and Clinical Dementia Rating (CDR) results. By comparing the findings of the patient group with those of a control group, the study aims to determine the potential biomarker strength of morphological changes observed in Alzheimer's patients. Materials and Methods: This study utilized brain images obtained from 136 subjects, including 64 diagnosed with Alzheimer's disease and 72 healthy controls, aged between 60 and 96, from the OASIS database. The volumetric measurements of brain structures were performed using the vol2Brain version of the volBrain online application. Volumes of the white matter, gray matter, hippocampus, temporal lobe, entorhinal area, parahippocampal gyrus, and insula were analyzed alongside MMSE scores and CDR grades of the subjects. Data analysis was conducted using the SPSS 25.0 software package. Results: The mean volumes of the assessed brain regions in Alzheimer's patients were found to be significantly lower compared to those in healthy individuals (p<0.05). Gender-based differences in the mean volumes of the evaluated brain regions in Alzheimer's patients were statistically significant (p<0.05). A progressive decrease in the mean volumes of the evaluated brain regions over the years in Alzheimer's patients was statistically significant (p<0.05). A positive correlation was identified between brain volume means and MMSE scores, while a negative correlation was observed with CDR grades in individuals with Alzheimer's disease. Conclusion: The mean brain volumes of individuals with Alzheimer's disease are lower than those of healthy peers, with significant gender-related differences and a greater age-associated decline compared to healthy individuals. The MMSE score in Alzheimer's patients declines more significantly with age than in healthy individuals. Volumetric biomarkers could offer advantages as a non-invasive method, achieving accuracy levels comparable to PET and CSF biomarkers. Therefore, assessing brain volumes in conjunction with clinical tests and relating these volumes to functional regions may aid clinical staging.