Alzheimer’s is one of the more widely known diseases, thanks in part to active fundraising campaigns, but also because of how common it is. The Alzheimer’s Association estimates that someone in the US gets diagnosed with Alzheimer’s every 67 seconds and that Alzheimer’s accounts for up to 70% of all dementia cases.
Alzheimer’s is also one of the few diseases that permeates through pop culture via movies and TV shows. All of that is great for spreading awareness, but it doesn’t always paint an accurate picture of Alzheimer’s disease. To fully understand the symptoms of Alzheimer’s, let’s look at how this disease affects the brain.
The human brain is made up of 3 parts: the cerebrum, the cerebellum, and the brain stem. The cerebrum is what’s most commonly pictured as the brain – it’s the bulk of what sits inside the skull. It helps control problem solving, remembering, thinking, feeling, and movement. The cortex of the brain (the wrinkly top layer) helps your body understand different sensations like lights or sounds, generate thoughts, and make and store memories. How does it do this?
Using brain cells known as neurons. The adult brain contains roughly 100 BILLION neurons to send and receive signals from all over the body. Alzheimer’s damages these neurons. It disrupts the way the neurons talk to each other so that they can’t send and receive signals as well. Since these neurons are everywhere in the brain, as Alzheimer’s progresses, the brain slowly shrinks. Most of this shrinkage happens in the area known as the hippocampus, which is responsible for forming new memories – that’s why memory is so severely disrupted.
As the neurons die, protein fragments called “plaques” and “tangles” fill the space. Plaques are made up of a sticky substance called beta-amyloids. These beta-amyloids block neuron-to-neuron communication, and can also activate immune system responses. Tangles make it hard for the brain cells to stay organized to transport important molecules back and forth.
In the earliest stages of Alzheimer’s, before symptoms even show up, these plaques and tangles are already forming in the brain. They start in the areas involved with learning, planning, and memory. As the disease progresses, they spread to the areas responsible for speaking, understanding, and recognition.
Luckily, scientists are finding new ways of using MRI, CT, and PET scans to detect plaques and tangles. By studying the earliest stages of Alzheimer’s development, they can gain new information to better understand the causes of Alzheimer’s and maybe eventually develop treatment for preventing the disease in the first place.