Researchers have identified "ground zero" for Alzheimer’s in the brain: the place the disease appears to strike first and a region they say may be more important to keep sharp than previously thought.

The locus coeruleus, a small part of the brainstem, is the first region of the brain to exhibit tau pathology— a well-known marker for Alzheimer’s. Lead study author Mara Mather, a gerontology and psychology professor at the University of Southern California, said while not all people will develop Alzheimer’s, most people have some signs of tau pathology in this brain region by early adulthood.

In their study, published in the February edition of Trends in Cognitive Science, Maher and her team argue the locus coeruleus may be more vulnerable to infections and toxins compared to other brain regions due to its interconnectedness. The brain region releases norepinephrine, the neurotransmitter that helps regulate heart rate, attention, memory and cognition. Its neurons distribute branch-like axons all throughout the organ and help monitor blood vessel activity.

That release of norepinephrine may play a role in Alzheimer’s prevention, according to the release. Previous animal studies have suggested the neurotransmitter may help shield neurons from elements that kill cells and expedite the disease— like excessive stimulation from other neurotransmitters and inflammation.

Mental stimulation, by way of challenging the brain with a word puzzle, performing music, or solving a problem at work can all release norepinephrine, according to the release.

"Education and engaging careers produce late-life 'cognitive reserve,' or effective brain performance, despite encroaching pathology," Mather said in the release. "Activation of the locus coeruleus-norepinephrine system by novelty and mental challenge throughout one's life may contribute to cognitive reserve."