Neuroscientists have identified a subtype of Alzheimer's disease (AD) that is largely unrecognized and rarely treated properly.
The variant is dubbed the hippocampal sparing AD and made up about 11 percent of 1,821 AD-confirmed brains seen in the study, a Mayo Clinic news release reported. This finding suggests the variant is relatively common in Alzheimer's patients.
Hippocampal sparing AD comes with different symptoms than the most common variant, which does affect the hippocampus.
Hippocampal sparing AD patients are usually men, and are often affected at a younger age than what would be seen with other forms of AD.
The condition is characterized by "frequent and sometimes profane angry outbursts, feelings that their limbs do not belong to them and are controlled by an "alien" unidentifiable force, or visual disturbances in the absence of eye problems," the news release reported.
These patients also decline at a much faster rate than patients with more common forms of AD.
"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," says the study's lead author, Melissa Murray, Ph.D., an assistant professor of neuroscience at Mayo Clinic in Florida.
Many of the patients are diagnosed with frontotemporal dementia, which causes behavioral and social changes.
"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," Doctor Murray said.
The researchers hope the new study will help medical workers understand that memory loss is not necessary in an Alzheimer's diagnosis.
"Our studies support the notion that dementia related to AD does not necessarily equate to a loss of memory, and points to the need for more research in amyloid and tau imaging biomarkers to help clinicians accurately diagnose AD - regardless of subtype," Doctor Murray says.
