Abstract 152: Exploring Age‐related Changes in Brain Metabolism among Individuals with Cardiovascular Risk Factors: An FDG‐PET Analysis

Abstract

Introduction Patients with cognitive impairment often have a history of cardiovascular disease (CVD) or multiple cardiovascular risk factors (CRFs) such as hypertension, obesity, and hypercholesterolemia. The literature reports that CVD with CRFs may increase the risk of developing vascular dementia and Alzheimer’s Disease. 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) allows for the in vivo study of cerebral glucose metabolism, and can detect metabolic alterations in several neurological diseases. As we age, the brain undergoes both structural and functional changes; the regional distribution of these alterations mirrors cognitive decline. This study aims to assess the effect of aging on regional glucose uptake in subjects with known cardiovascular risk factors. Methods In total, 40 subjects (mean age 55.9 ± 11.89 years, 50% males) with known cardiovascular risk factors underwent FDG‐PET scanning, and 70 whole brain structures were analyzed in each subject. Participants were recruited from a group of patients with chest pain syndromes who were referred for coronary CT angiography. All subjects underwent whole‐body FDG‐PET/CT imaging 180 minutes after the administration of 4.0 MBq/kg dose of FDG. The quantitative regional analysis of PET images was performed using MIMneuro version 7.1.5 (MIM Software, Inc., Cleveland, Ohio). MIMneuro provides region‐based analysis, with z‐scores generated by comparing the patient to the selected age‐matched set of normal controls. Pearson’s R was calculated and evaluated for significance in all variables. The threshold for significance was set at P < 0.05. Results Various significant associations between age and FDG uptake across all 70 brain regions of interest were observed. In particular, age was found to have an inverse correlation with regional metabolism in the middle temporal gyrus (r= ‐0.364, p=0.021), superior frontal gyrus (r= ‐0.433, p=0.005), superior parietal lobule (r= ‐0.354, p=0.025), supplementary motor area (r= ‐0.436, p=0.005), and temporal operculum (r= ‐0.370, p=0.019). Conclusion The results demonstrate a significant inverse correlation between age and FDG uptake in five regions among individuals with cardiovascular risk factors. This information may be useful in the determination of whether such scans might be useful in the evaluation of patients with a history of CVD/CRF or with mild cognitive impairment (MCI). Previous literature has reported that increased medial temporal gyrus atrophy is a predictor of dementia in subjects with MCI, and alterations within this lobe mark the beginning of the disease process. Our strongest inverse correlation, the superior frontal gyrus, has been shown to be related to working memory; hypometabolism in this region has previously correlated with severity of cognitive impairments in attention, executive function, and language. Further research is needed to determine the potential for using FDG‐PET imaging as a tool for early detection and intervention for cognitive decline. If patients with CVD or CRFs can be properly diagnosed, if there exists a metabolic signature of regional functional change, intervention may prove highly beneficial for cognitive function, quality of life, and overall well‐being.