Cerebral glucose metabolism in patients with AD and different APOE genotypes

Objective: To examine the influence of the APOE ε4 allele on cerebral glucose metabolism in a large series of patients with Alzheimer disease (AD). Methods: Eighty-three patients (41 APOE ε4 positive and 42 ε4 negative) were selected from a pre-existing databank of patients with AD (n > 1,000). The patients were carefully matched for age, age at onset, approximate disease duration, educational level, and overall degree of cognitive impairment. Cerebral [¹⁸F]fluorodeoxyglucose PET imaging was performed in all patients by a standardized protocol. Statistical comparison of patient PET data vs a healthy control population was performed as well as an analysis of differences between groups (SPM99; Wellcome Department of Cognitive Imaging, London, UK). Results: A similar pattern of cerebral hypometabolism was detected in the ε4-positive and -negative patient groups vs healthy volunteers in regions typically affected by AD (bilateral temporal, parietal, posterior cingulate, and prefrontal cortical areas). The comparison between ε4-positive and -negative patients additionally revealed stronger abnormalities in ε4 carriers in parietal, temporal, and posterior cingulate cortical regions. Conclusions: A generally similar pattern of cerebral hypometabolism was detected in APOE ε4-positive and -negative patients with Alzheimer disease. However, in direct comparison of the two matched groups, the abnormalities in the ε4-positive group were demonstrated to be more pronounced.