Years ago, scientists established that a small part of the brainstem called the locus coeruleus is one part of the brain that is involved in the development of late onset Alzheimer’s disease. Recently, however, scientists have found that this part of the brain is in fact the location where the disease begins. Researchers at the University of Southern California have identified the locus coeruleus as the first place in the brain that is affected by Alzheimer’s. Because this part of the brain has been pinpointed as the place where the disease starts, scientists are calling the locus coeruleus the “ground zero” of Alzheimer’s disease.
What Does the Locus Coeruleus Do?
The locus coeruleus is the part of the brainstem that releases a neurotransmitter called norepinephrine. Norepinephrine is involved in the body’s own prevention of cognitive decline. It helps the body to regulate heart rate, memory, attention, and cognition. When a person is performing a mentally challenging task, such as solving a problem or reading a research paper, the brain releases norepinephrine. Because norepinephrine helps maintain the body’s memory and cognition abilities, it is also thought that the release of norepinephrine can actually help to prevent Alzheimer’s. In one study, norepinephrine was shown to protect the neurons of mice from the inflammation and stimulation that kills cells and causes Alzheimer’s.
Sleep and the Locus Coeruleus
Researchers have previously linked a lack of deep sleep to making the brain more vulnerable to Alzheimer’s disease. Now, scientists are focusing on specific parts of the brain and how a lack of sleep affects them. Researchers believe that the locus coeruleus may be damaged from lack of sleep. Having a poor sleep-wake cycle may prevent the locus coeruleus from releasing the correct amounts of norepinephrine that it needs in order to keep the brain healthy and free from cognitive decline, thus speeding along Alzheimer’s attack on the brain.
Why the Locus Coeruleus is "Ground Zero"
Because the locus coeruleus is so essential in the body’s own prevention of cognitive decline, this area may be more susceptible to toxins and infections than other parts of the brainstem. The locus coeruleus is the first part of the brain to exhibit what is known as tau pathology, or the spread of the tangles and proteins that are characteristic of Alzheimer’s disease.
As Alzheimer’s starts, the locus coeruleus releases less norepinephrine, and tau protein tangles begin to form. These plaques and tangles collapse over healthy areas of the brain that are needed for transport. Eventually, essential nutrients cannot get to the affected brain cells, and those cells die. The body slowly loses its ability to perform and to control certain functions as the Alzheimer’s plaques and tangles take over the brain.
Our body is equipped with many different ways that it protects itself from any number of things. Norepinephrine is our natural defense against cognitive decline. Scientists hope that being able to pinpoint the first place that is affected by Alzheimer’s disease will help us to eventually prevent Alzheimer’s all together. If we can find a way to keep the locus coeruleus functioning properly, norepinephrine will continue to be released into the brain at the correct times, and the brain will be able to protect itself the way that it was meant to.