Brain reserve is associated with cognition in AD and MCI patients with different vascualr risk factors status

Abstract Background Dementia due to Alzheimer’s disease (AD) is the major type of dementias in the world. In addition to amyloid plaques and neurofibrillary tangles, cerebrovascular disease is another important pathophysiological cause of AD. Cerebrovascular disease is highly associated with vascular risk factors (VRFs). Well‐treated VRFs might decrease the risk and progression of AD. However, findings on the impact of VRFs treatment status on cognitive decline after the diagnosis of AD established are unclear, and there is no direct evidence supporting well‐treated VRFs can slow down the AD progression. Method This study recruited mild cognitive impairment (MCI) and mild AD patients (CDR = 0.5 or 1) with at least one VRF from at Taichung Veteran General Hospital. The treatment status of the VRFs was identified and all participants were evaluated by a standard neuropsychological test battery. We collected the participants’ brain MRI done within one year and performed Apolipoprotein E genotyping. FreeSurfer was used for structural MRI reconstruction and calculated total gray matter volume, hippocampus volume, and AD signature cortical thickness. Cerebrovascular lesions, including perivascular spaces in centrum semiovale, basal ganglia and presence of lobar cerebral microbleeds (LCMBs), and the volume of white matter hyperintensities were estimated by visual rating scales and Lesion Segmentation Tool for Statistical Parametric Mapping. We analyzed the relationships among the treatment status of VRFs, neuropsychological tests, and brain MRI. Result We recruited 61 patients in this study. Four patients refused to keep involving the study, 6 patients were not compatible with the criteria of MCI and AD after neuropsychiatric testing, and 4 patients’ brain MRI images cannot be analyzed after quality checked. The remaining 47 patients (15 MCI patients and 32 AD patients) constituted the final sample for analysis. The patients with well‐controlled VRFs present with similar cognitive function compared to the patients with partially‐controlled VRFs even though the more severe hippocampal atrophy was noted in the patients with well controlled VRFs. The severity of white matter hyperintensities and other cerebrovascular lesions are not correlated with the cognitive function in MCI and AD patients. Conclusion Brain reserve in the AD and MCI patients with well‐controlled VRFs might contribute cognitive function