Causes and Risk Factors of Alzheimer's Disease
Causes
Not Fully Understood
Modern medicine has yet to discover the true cause for Alzheimer's disease. We know what happens in the brain during the disease progression, described below, that causes the symptoms. But, what causes that is not fully known. Researches believe is is a combination of genetics, lifestyle, and environmental causes. At the most basic level, we know that the proteins in the brain stop functioning correctly. This damages neurons and their connections to each other, and eventually kills neurons completely. The neuron damage together with the build up of proteins in the brain leads to the decreased action of a neurotransmitter named acetylcholine, which plays a key role in memory and body movement.
Plaques
A beta amyloid is used to describe a protein that is a part of a larger protein. When a bunch of beta amyloid proteins cluster together they have a toxic effect on neurons, disrupt neuronal communication by getting in between neurons stopping communication, and/or can cause an immune response which causes inflammation in the brain. The clusters can also form larger deposits called amyloid plaques.
Tangles
Tau proteins, which live inside the neuron, change shape and get into neurofibrillary tangles that disrupt the transport of nutrients and other materials during the progression of Alzheimers.
Plaques and Tangles cause the symptoms of Alzheimer's because not only do they damage neurons and disrupt or stop neuronal communication, they also shrink the brain, starting with the areas responsible for memory. Doctors believe the protein build up happens years before you start to see symptoms.
Risk Factors
Age
The likelihood of developing the disease increases as you grow older. Age is the biggest risk factor.
Genetics
Having the gene for Alzheimer's, apolipoprotein E gene (APOE), can increase your risk of developing Alzheimer's. But, it is not a definite indicator as to whether you will develop the disease or not.
Down syndrome
An estimated 50% of people living with down syndrome will develop Alzheimers. This is because having three copies of chromosome twenty-one also means you have three copies of the gene that creates beta amyloids, which causes plaques in the brain, a.k.a Alzheimer's.
Sex
Statistically, women are more likely to develop Alzheimer's as two thirds of people with Alzheimer's are women. More on why this is described in the possible causes section.
Mild cognitive impairment
People who have a mild cognitive impairment are more likely to develop Alzheimer's. This is because their decline in memory or thinking skills is greater than normal.
Head trauma
A traumatic brain injury increases your likelihood of developing Alzheimer's.
Air pollution
Because air pollution particles can decrease the healthiness of the nervous system, there is a connection between air pollution exposure and having a greater risk for dementia.
Lifestyle and Heart Health
The brain and the health of one’s heart have a strong connection due to the fact that the brain is nourished by the blood vessels that the heart is responsible to pump blood to. So, if you are obese, have high cholesterol, hypertension, smoke, or don’t exercise often, this will decrease the health of your heart and in turn increase your risk for dementia.
Possible Causes
Fat Proteins
Dr. John Mamo found that toxic fat proteins, lipoproteins, can bundle together and enter the bloodstream. This damages capillaries then leaks into the brain which causes inflammation and neuron death.
Porphyromonas Gingivalis
Porphyromonas Gingivalis is the primary bacteria involved in gum disease. It is possible that this bacteria can invade and inflame brain regions affected by Alzheimer's and cause neuronal damage and amyloid plaques.
The Glymphatic System
The Glymphatic system is a recently discovered macroscopic waste clearance system in the brain, almost like an immune system for the brain. It uses perivascular channels formed by astroglial cells to eliminate proteins and metabolites from the CNS. It then connects down to a lymphatic network to fully clear the waste. The system may also function to help distribute glucose, lipids, amino acids, and some neurotransmitters, and does its work mostly during sleep. It could be connected to Alzheimer's because Alzheimer's is characterized by the accumulation of proteins, and if the Glymphatic system functions to get rid of proteins, there could be a connection here. New research is focused on finding ways to keep your Glymphatic system healthy to prevent Alzheimers.
The Neuro-Endocrine system and Menopause
The neuro-endocrine system describes how the ovaries and brain communicate with one another. The key factor of this is that estrogen is responsible for energy production, including making neurons to burn glucose to make energy. So if estrogen is low in your brain your neurons are aging faster and slowing down which can cause amyloid plaques. And with the onset the onset of menopause at the average age of 51, a women’s brain begins to produces less estrogen, which in turn can lead to developing Alzheimer's. This is why women with three or more children have a twelve percent lower risk of dementia, women who have longer pregnancies lower their risk for demetia, and women who have their period later in life and therefore menopause later are less likely to develop Alzheimer's.