Some experts fear PET scans offer few benefits, at substantial costs. “There are lots of incentives, including financial incentives, for doing more testing and interventions,” said Dr. Kenneth Langa, a researcher at the University of Michigan and author of a recent article in JAMA Internal Medicine about diagnosis of early Alzheimer’s disease. “My hope is we’ll think hard about the unintended downsides.”¶¶What downsides? Amyloid plaques occur commonly in older people’s brains, but not everyone with amyloid will develop dementia, which probably involves multiple factors. Nor does a negative PET scan mean someone won’t develop dementia.