In the world, there are 24 million people with dementia. By the year 2050, predictions show that number will increase to nearly 100 million. (Reitz and Mayeau, 2014) Alzheimer’s disease is the primary cause of dementia.
Tau, Amyloid-β and Loss of White Matter
In the initial stages of Alzheimer’s disease, we see three things that go wrong.
- Tangles of tau and
- plaques of amyloid-β develop in the brain, as well as
- loss of white matter.
These three are considered the hallmarks of Alzheimer’s disease.
Tau Initiate and Stablize Communication Tracks
Microtubules are communication tracks or pathways in the brain. Tau is a protein which binds to microtubules and aids in formation and stabilization of microtubules. However, when phosphorus binds to tau, tau becomes hyperphosphorilized. With the additional phosphorus, tau is no longer able to function. As a result, microtubules become unstable and fail to form. Tau, having lost its job, accumulates in the cells as neurofibrillary tangles. These sticky tangles interfere with the brain’s function. (Scholl, et al., 2018)
Amyloid-β Helps to Form New Memories
Neurons need amyloid-β to grow and survive. Amyloid-β binds to toxic substances, including advanced glycation end-products (AGES: follow this link to learn more) and forms plaques. (Puzzo and Arancio, 2013)
Microglia Clear Amyloid-β While We Sleep
Microglia, the brain’s cleaning crew, helps to clear amyloid plaques from the brain. This occurs while we sleep.
Too Much Amyloid-β
Amyloid-β becomes toxic when there is too much in the brain. In Alzheimer’s disease, the brain is overwhelmed with amyloid-β sticky plaques.
While we sleep, microglia rid excess amyloid-β in the brain. When there is too much amyloid-β, microglia asks for assistance. It asks the immune system for help. The immune response causes inflammation.
Chronic inflammation Toxic to Neurons
Long term activation of microglia and immune response which causes damage. This results in chronic inflammation, which is toxic to neurons. Additionally, during times of stress, dark microglia develop. Dark microglia engulf dendritic spines, axon terminals, and entire synapses. (Bisht et. al., 2016)
Brain Shrinks
The end result is the loss of neurons, synapses and white matter and brain shrinkage. (Sarlus and Heneka, 2017) The brain requires neurons and synapses to communicate.
Chronic stress triggers depression and accelerates aging. This predisposes us to dementia. Also, long term stress encourages dementia to begin. As well, in those who already have dementia, stress worsens the symptoms.
Prevention is Key
Getting adequate sleep is required for microglia to clear toxins from the brain. Decreasing stress is vital to prevent cognitive decline. Exercise (move more) also assists to rid the brain of toxins, including amyloid-β. Getting adequate sleep, decreasing stress, as well as moving more is vital. In this way, we can avoid and delay dementia.
Coming Next: Decreasing Your Stress
Sustained stress, as well as inadequate sleep and exercise, as well as poor diet, cause dementia to begin earlier. Many of us live with unrelenting stress. In this next post, we will discuss what you can do today to reduce stress in your life.