APOE and Alzheimer disease: Finally, in the Wolk et al. study, the authors used MRI to measure brain volume and cortical thickness in their mild AD patients and found that APOE4+ AD patients, who performed worse on memory retention, displayed greater hippocampal volume loss than APOE4− AD patients, whereas APOE4− AD patients, who performed worse on working memory, executive function, and lexical access, displayed decreased cortical thickness in their superior parietal lobule, precuneus, and angular gyrus than APOE4+ AD patients.