The brains of people who have Alzheimer's can't use glucose effectively. That's because a natural enzyme in the body called indoleamine-2,3-dioxygenase 1 (IDO1) becomes overactive and disrupts how the brain uses glucose.
A study published in Science found IDO1 is harmful to cells called astrocytes, which are essential for supporting neurons. When the scientists blocked IDO1 with an inhibitor in mice and human cells, the brain's ability to use glucose improved significantly. This led to better memory and cognitive function in the mice.
From NPR:
One [test] involved placing a mouse in the center of a shiny white disk under a bright light.
"It really wants to get out of there," [Dr. Katrin Andreasson, a professor of neurology and neuroscience at Stanford] says. "But it has to learn where the escape hole is" by following visual cues.
Healthy mice learned how to read those cues after a few days of training, and would escape almost instantly.
"But in the Alzheimer mice, the time to find the escape hole really skyrocketed," Andreasson says.
That changed when the team gave these mice an experimental cancer drug that could block the enzyme much the way genetic engineering had.
The treated mice learned to escape the bright light as quickly as healthy animals. And a look at their brains showed that their astrocytes had woken up and were helping neurons produce the energy needed for memory and thinking.
In the hippocampus, a brain area that's critical for memory and navigation, tests showed that the drug had restored normal glucose metabolism even though the plaques and tangles of Alzheimer's were still present.
The team also tested human astrocytes and neurons derived from Alzheimer's patients. And once again, the drug restored normal function.
Currently, IDO1 inhibitors are being developed for cancer treatment, but this study suggests they could also be useful for treating Alzheimer's. However, more research is needed to see if these drugs are safe and effective for people with Alzheimer's.
Previously:
• Artist's self portraits reflect progression of Alzheimer's disease
• Former prima ballerina with Alzheimer's remembers her Swan Lake moves by listening to its music
