The findings come from the Metabolic Cerebral Imaging in Incipient Dementia study, an ongoing national clinical trial sponsored by the Centers for Medicare and Medicaid Services (CMS).
|Arrows point to the brain areas that undergo progressive decline in metabolism.
First Row: Normal cognition.
Second Row: Age-associated memory impairment, defined as memory within normal limits for age, but noticeably worse for that patient than when he or she was younger.
Third Row: Mild cognitive impairment, defined as below normal limits compared with healthy people of the same age and education level.
Fourth Row: Alzheimer’s disease, shown here for a metabolically advanced stage of dementing disease — in cases where each of these levels of symptoms is due to the Alzheimer’s pathologic process occurring in the patient’s brain.
The interim data show that patients whose doctors gleaned information from a brain PET scan performed with the tracer FDG — which measures energy being used throughout regions of the brain — did better over two years of follow-up than those whose doctors were randomized to not have access to the scan information. “During the subsequent two years after their PET scans, these patients had superior executive function, better memory abilities and greater preservation of overall cognitive function,” says Daniel Silverman, MD, (RES ’94, FEL ’96) PhD, professor of molecular and medical pharmacology and the study’s principal investigator. The research, Dr. Silverman says, provides “the first direct evidence that patients whose early Alzheimer’s disease is revealed by FDG–PET will do better than patients with the same condition but with their brain-metabolism pattern remaining unknown to their doctors and themselves.”
Prior to these study findings, there was no rigorously controlled scientific evidence on the long-term clinical benefit associated with obtaining PET scans, or any other kind of neuroimaging, in the evaluation of cognitively declining patients. This multicenter, prospective, randomized and blinded study demonstrates significant clinical benefits, which may also save healthcare dollars.
“Patients who don’t have Alzheimer’s disease may be prescribed drugs that won’t help them or may even make them worse,” Dr. Silverman says. “And each year of taking these medications costs hundreds of dollars more than the reimbursement for a PET scan would cost.” Conversely, he says, undiagnosed Alzheimer’s patients won’t get the drugs that this study shows would help them, when given early, to maintain their cognitive abilities. These patients may ultimately need nursing-home care, at an average cost of about $7,000 a month, six-to-nine months earlier than patients with the same brain pattern who were diagnosed and treated sooner as a result of the early availability of the PET-scan information.
The interim results are based on an examination of 63 patients who underwent FDG-PET and neuropsychological testing at baseline. The testing and collection of medication-prescription data were repeated every six months for two years. The doctors in the arm of the study who were able to immediately view the PET scans treated their patients differently than doctors who didn’t get scan results until the end of the two-year study. About 40 percent of the patients whose doctors were informed of the presence of the Alzheimer’s brain-metabolism pattern were given drugs specifically indicated for dementia within the first six months of the study.