Why people with Alzheimer’s may lose their way

"To find out the cure for memory impairment in Alzheimer's disease, we need to understand how the network function is impaired," says Kei Igarashi. (Credit: Getty Images)

Disruption of normal brain network function in hippocampus cells may explain loss of spatial memory in people with Alzheimer’s disease, according to a new study.

People with Alzheimer’s disease frequently suffer from spatial memory loss, such as not recognizing where they are, and forgetting where they put their belongings. They often show a wandering symptom, which is also a feature of spatial memory impairment.

Until now, the brain network mechanism that causes spatial memory impairment had been unclear.

The new study in Neuron reveals how the normal brain network function of hippocampus cells which works to discriminate a distinct spatial environment in a process called “remapping,” becomes disrupted in Alzheimer’s disease.

Using Alzheimer’s disease model mice, researchers found that the activity impairment of the entorhinal cortex, a brain region that supplies information to the hippocampus, most likely causes this disruption.

“We recorded the brain cell activity in the hippocampus, which is the memory center of the brain, responsible for spatial memory, among other things,” says Kei Igarashi, an assistant professor in the anatomy & neurobiology department at the University of California, Irvine School of Medicine.

“Our findings could lead to the development of a method to reactivate brain activity of the entorhinal cortex, which may help establish new treatments for preventing the progression of spatial memory impairment in Alzheimer’s disease patients.”

Igarashi has studied brain network mechanisms for Alzheimer’s disease since he started his lab in 2016. “Our memory comes from activities of the brain network. To find out the cure for memory impairment in Alzheimer’s disease, we need to understand how the network function is impaired,” he says.

According to the Alzheimer’s Association, there are an estimated 5.8 million Americans living with Alzheimer’s disease. By 2050, experts expect that number to increase to 13.8 million people.

Spatial memory impairment, such as wandering behavior, is one of the most troublesome symptoms in Alzheimer’s disease, and it occurs in more than 60% of Alzheimer’s patients. Despite recent molecular and cellular findings in Alzheimer’s research, it is still largely unclear how deterioration of brain circuit function causes spatial memory loss.

Heechul Jun, a MD/PhD student in the UCI Medical Scientist Training Program, is the study’s first author. The National Institutes of Health, BrightFocus Foundation, Alzheimer’s Association, Brain Research Foundation, Donors Cure Foundation, Japan Science and Technology Agency, and Whitehall Foundation supported the work.

Source: UC Irvine