ADNI does not include what could be the critical population in this theory–younger normal controls. “While the study does include nondemented patients (200 normal individuals and 400 with MCI), these people are all older than 55. It is still speculative to consider when the AD process begins in the brain, but it may be in midlife or even earlier.”
To be truly effective in combating the disease, he suggested, it will be important to study younger groups to detect the beginnings of AD with imaging or biological markers before symptoms appear so that eventually therapies hopefully can be given to prevent the occurrence of dementia.
“It's similar to treating atherosclerosis,” he said. “It's a lot easier to treat cholesterol levels to prevent vascular damage than to wait until a heart attack occurs and try to fix things from that point.”