Alzheimer’s disease (AD) is an irreversible illness of the brain that weakens and kills brain cells, affecting memory, thinking, and other abilities. It is progressive, meaning symptoms get worse as more functions are lost over time. There is no cure, but symptoms can be managed to slow progression and make living with the disease easier.
Despite what some people think, getting Alzheimer’s disease is not a normal part of aging. However, it is true that people are more likely to develop AD as they age. In most cases, individuals are 75 and over at the time of diagnosis.
Alzheimer’s disease is by far the most common form of dementia. In fact, the Alzheimer’s Association has released a 2020 Alzheimer’s Disease Facts and Figures report, and one major finding is that approximately 5.8 million individuals in the United States currently have Alzheimer’s Disease. By 2050, this number is expected to reach approximately 13.8 million Americans. Other important Alzheimer’s disease statistics:
– 80% of people with Alzheimer’s are over 75 years old
– 1-in-10 people over 65 have Alzheimer’s
– ⅔ of Americans with Alzheimer’s are women
– About ½ of people over 85 have Alzheimer’s
Causes, risk factors, and symptoms of dementia due to Alzheimer’s disease (AD) are somewhat different from other forms of dementia. With AD, the disease first attacks the memory center of the brain, causing forgetfulness. As the disease progresses, its symptoms get worse and may include difficulty retaining new information, trouble concentrating, forgetting the names of items and important dates, losing things, poor judgment, withdrawal from social activities, changes in mood / personality, and problems walking.
Alzheimer’s occurs in stages, from the least-severe early stage to a last stage that comes shortly before death. Knowing the stage helps health professionals determine which treatments are best and helps caregivers anticipate symptoms to know what behaviors to expect. Learn more about the stages of Alzheimer’s.
While there are several causes of AD, it can be quite difficult to determine the main reason an individual gets the disease. That said, there are several risk factors for developing Alzheimer’s disease, such as age, family history, diet, and head trauma. For more information about risk factors and causes of AD, click here.
Loss of Independence and Caregiving
All the symptoms of Alzheimer’s disease eventually add up to this unfortunate fact: Alzheimer’s makes it impossible to live independently. This loss of independence typically occurs in the middle stages, when symptoms like wandering (leaving the house and becoming lost and/or confused) make an individual unsafe. There are ways to make a house safer, but eventually your loved one will need to move into assisted living with memory care (where staff is trained to communicate with and help people who have dementia) or live with a caregiver. Caregivers may be full-time nurses hired to live with and supervise your loved one, providing personal and health care as needed, but the Alzheimer’s Association says that 83 percent of caregivers are family members or friends who are not paid.
The symptoms of Alzheimer’s disease are from changes, both structural and cellular, in the brain. A simple analogy helps explain what happens in the brain when Alzheimer’s disease develops. Picture a large city with all its lights on. Each home, street, and shopping center has its own light switch and bulb that lets people go about their daily activities. From an airplane, you can see that together these lights make the entire city glow. Now imagine that a problem occurs with the wiring or circuits within the city’s electrical system. Each home, street, and shopping center gradually loses power. It becomes harder to cook dinner, drive through the city, and do business in stores. The power outage will eventually disable the entire city and its people.
Now imagine that each cell within the brain is a light bulb and the entire brain is the city. Every neuron is a cell in the nervous system. During normal function, neurons and all the parts of the brain work together to carry out tasks such as remembering a relative’s name, washing the dishes, or controlling one’s temper. Alzheimer’s disease gradually “turns off” each neuron in the brain, just like the lights in the city. As the individual neurons stop working, the brain does not function as well and the person has problems thinking, remembering, and carrying on with daily living. However, unlike an electrical circuit that can be repaired, damage in the brain caused by Alzheimer’s disease and dementia is permanent and cannot be repaired.
Alzheimer’s disease strikes certain parts of the brain. The limbic system – primarily the hippocampus – is attacked first; then the cerebral cortex; then the brain stem. Each structure loses its function in turn. The symptoms of Alzheimer’s disease are a direct result of sequential damage to the brain:
1. Limbic system damage impairs a person’s memory and causes mood swings. (The limbic system is located under the cerebral cortex).
2. Cerebral cortex (part of the cerebrum) damage causes trouble controlling emotional outbursts. People at this stage may need help with daily living activities, such as eating, shaving, dressing / undressing, and combing one’s hair.
3. Brain stem damage late in AD impairs organ function, including the function of the heart, lungs, and various other bodily processes.
For more information regarding structural changes to the brain of an individual with dementia, click here.
At the cellular level, Alzheimer’s disease attacks the brain’s neurons, which are cells in the brain that carry out all brain functions. They have spaces between them called synapses. Brain chemicals, called neurotransmitters, are released by neurons and deposited into the synapses. Neurotransmitters are important for communication between neurons. This communication is responsible for producing movement and is a critical part of learning and remembering.
When cellular damage due to AD occurs, neurons cannot communicate, and learning and memory are impaired. The neurons eventually die. Because of all of this damage, the brain gradually shrinks and becomes less functional, leading to symptoms of dementia.
Learn more about cellular brain changes related to Alzheimer’s disease here.
Approaches to diagnosis and treatment of Alzheimer’s disease are similar to other forms of dementia. While there is no cure for AD, multiple treatments can slow the progression of the disease. According to the Alzheimer’s Association, an individual who is diagnosed with AD lives an average of 4 to 8 years after diagnosis. However, individuals can live up to 20 years after being diagnosed with the disease. Therapies and medications can help someone manage symptoms to improve quality of life and live longer. Click on the following links to learn more about Diagnosing Dementia and Treating Dementia.
While an individual with Alzheimer’s disease generally has a shortened life due to the disease, living an average of between 4 and 8 years after diagnosis, it is not the direct cause of death. In the late stage of AD, the damage to the brain is so extensive the inflicted individual often no longer has mobility and must be bed bound. These circumstances can lead to sepsis, blood clots, and infections, which may ultimately cause death. An individual with late-stage AD also has difficulty swallowing, which affects the ability to eat. Rather than swallow food into the food pipe, individuals with Alzheimer’s may swallow food into their windpipe. This can result in an infection called aspiration pneumonia, which is another cause of death of individuals with Alzheimer’s disease.