Alzheimer's disease is a progressive and fatal brain disease that was first discovered in 1906 by German psychiatrist Alois Alzheimer, who reported on a woman who increasingly and inexplicably lost her memories and became unreasonably suspicious of her husband. While the disease was eventually named after Alzheimer, its underlying causes remain a mystery.
Medical science has been able to pin down what's behind the symptoms of Alzheimer's disease. From inspection of the brain tissue of people who have died from Alzheimer's, researchers have found two common characteristics that most patients have: plaques and tangles.
Plaques are the remnants of an unprocessed protein called beta-amyloid that's normally removed from the brain as waste. Beta-amyloid is the result of the breakdown of the amyloid precursor protein, which researchers believe might be used to form the synapses that allow chemical communication between neurons in the brain. When these protein deposits build up, they form the plaque that characterizes Alzheimer's.
The tangles found in the brains of Alzheimer's patients are made up of another protein called tau. This protein fosters the creation of microtubules in nerve cells when they divide and form new ones. The microtubules provide structure for the new cell and when the cellular generation has taken place, the remnant tau, like the beta-amyloid, should generally be removed from inside the neurons as waste.
The development of these plaques and tangles are a normal part of aging. In the brains of Alzheimer's patients, however, this accumulation is much heavier than normal. They appear first in the areas dedicated to things like memory and learning. As the plaques and tangles accumulate around neurotransmitter receptor sites, researchers believe they interfere with proper communication within neural networks, essentially gumming up the brain's works. This leads to the symptoms associated with dementia, like forgetting where you live or failing to recognize your family members. It also destroys brain cells, leading to death.
So far, there's no cure for Alzheimer's. While medical science has concluded that the plaques and tangles found abundantly in the brains of Alzheimer's patients cause the degenerative disease, they remain puzzled why they accumulate more in some people's brains than others.
Some recent research linking Alzheimer's and HSV1 may explain one of the underlying causes of the disease.