(HealthDay News) -- Many patients with a newly identified subtype of Alzheimer's disease are misdiagnosed and don't receive proper treatment, researchers report. They analyzed the brains of more than 1,800 Alzheimer's patients and found that 11 percent of them had this subtype, called "hippocampal sparing Alzheimer's disease."
About 5.2 million Americans have Alzheimer's, which means that nearly 600,000 of them could have this variant of the disease, according to the research team at the Mayo Clinic in Florida.
The findings were scheduled for presentation Thursday at the annual meeting of the American Academy of Neurology, in Philadelphia.
People with hippocampal sparing Alzheimer's tend to be men and they are afflicted at a much younger age than other Alzheimer's patients, the study found. The symptoms of this subtype are often quite different from the most common form of the disease, which affects the hippocampus, the brain's memory center.
Symptoms of hippocampal sparing Alzheimer's include behavioral problems such as frequent and sometimes angry outbursts, vision problems, and the sense that their limbs do not belong to them and are controlled by an unidentifiable "alien" force, the Mayo researchers said.
These patients also experience a much quicker decline than those with the most common form of Alzheimer's, the study found.
"Many of these patients, however, have memories that are near normal, so clinicians often misdiagnose them with a variety of conditions that do not match the underlying neuropathology," study author Melissa Murray, an assistant professor of neuroscience, said in a Mayo news release.
"What is tragic is that these patients are commonly misdiagnosed and we have new evidence that suggests drugs now on the market for AD could work best in these hippocampal sparing patients -- possibly better than they work in the common form of the disease," she added.
Because this study was presented at a medical meeting, it should be viewed as preliminary until published in a peer-reviewed journal