The locus coeruleus is a small, vaguely-blue part of the brainstem that is most notable for releasing the neurotransmitter norepinephrine. It may also be the origin point for Alzheimer’s disease, if new findings from the University of Southern California are to be believed.
The discovery revolves around what is called “tau pathology”, a form of tangled plaque of tau proteins that is considered one of the main precursor signs of Alzheimer’s. Although not everyone with tau will go on to develop dementia, a review of autopsy results shows that initial signs of tau pathology could be found within the coeruleus as early as the mid 20’s.
It is assumed that the locus coeruleus is the initial point for the development of tau pathology because the region is known to be more vulnerable to toxins than other parts of the brain. This is due to the coeruleus having long, unprotected strands of neurons, a location near one of the ventricles of the brain, and a high exposure to the flow of blood. Although Alzheimer’s cannot be transmitted like a blood borne toxin or bacteria, any possible environmental contributors to the disease would be able to affect the coeruleus before other parts of the brain.
These findings offer two main insights. The first is that the attempts to devise methods that can track or predict the development of Alzheimer’s now have a region of the brain to focus on. Ideally, this will result in methods of assessing tau pathology that do not require an autopsy. The second benefit is that the locus coeruleus may also present its own method of preventative medicine.
As mentioned above, the locus coeruleus is known to release norepinephrine. This neurotransmitter has been found to offer protective benefits to other neurons by shielding them from inflammation and “excitotoxicity”—a damaging overabundance of neurotransmitters—both of which are capable of accelerating Alzheimer’s progression. Norepinephrine is released in response to mentally challenging situations, explaining why brains that regularly engage in complex tasks experience slower progression of Alzheimer’s and dementia.
From this comes the idea of a “cognitive reserve”, a form of protection built up by engaging the brain in challenging tasks like playing word puzzles, performing difficult pieces of music, or carrying out intellectually demanding jobs, which can protect against developing tau pathology.
Alzheimer’s disease is a form of progressive dementia that erodes memory, thinking skills, and functioning ability over time. It is estimated that around 5 million people in the U.S. are currently living with Alzheimer’s. There is no specific cause for Alzheimer’s but it is known to have at least a partial genetic component. Although the disease currently lacks a cure, it can be treated to help slow progression while maintaining quality of life for as long as possible.
Sources for Today’s Article:
Beth Newcomb, “Researchers pinpoint brain region as ‘ground zero’ of Alzheimer’s disease,” University of Southern California, February 16, 2016. http://news.usc.edu/91957/researchers-pinpoint-brain-region-as-ground-zero-of-alzheimers-disease/.
“Alzheimer’s Disease Fact Sheet,” National Institute on Aging, last accessed February 17, 2016.