Alzheimer's Disease
Alzheimer's disease is a progressive neurodegenerative disease that affects the memory and other cognitive functions. Currently ranked as the sixth leading cause of death in the United States overall, it is the third leading cause of death among the elderly. This difficult disease affects roughly 5.7 million Americans, and that number is expected to climb to 14 million by the year 2050.
Though some changes in memory and cognition are a natural consequence of aging, Alzheimer's disease is not a normal part of aging. In its early stages, symptoms typically include mild confusion and changes in memory. Over time, these symptoms worsen and physiological changes in the brain cause the patient to lose their memory and most of their mental function.
Over the course of the disease, the most common symptoms of Alzheimer's include the following:
- Having trouble remembering names or dates
- Repeating statements or asking the same questions
- Forgetting appointments or events
- Getting lost in familiar places
- Having trouble finding the right words
- Difficulty managing daily tasks at home or at work
- Trouble making decisions or judgments
- Difficulty planning multi-step activities
- Depression, apathy, or social withdrawal
- Mood swings and/or angry outbursts
- Irritability, agitation, or aggressiveness
- Changes in sleeping habits
- Loss of inhibitions
- Inability to perform daily tasks or basic hygiene
- Sundowning
These symptoms typically start out very mild but progress and become compounded over time. As the most common form of dementia, Alzheimer's disease follows a predictable pattern when it comes to the progression of symptoms. There are three stages of Alzheimer's:
- Early Stage (Mild Alzheimer's) – In the early stages of Alzheimer's, the patient may show few noticeable symptoms and may still be able to function independently. As the disease progresses, however, the patient may have trouble recalling names, performing daily tasks, and finding the right words for each situation.
- Middle Stage (Moderate Alzheimer's) – The middle stage of Alzheimer's can last for many years, during which time the patient may become increasingly more confused and agitated. The patient may become forgetful, moody, and confused, may need help with daily tasks and personal hygiene, and might start to develop personality or behavioral changes.
- Late Stage (Severe Alzheimer's) – In the final stage of Alzheimer's, the patient loses the ability to interact with their environment. In this stage, patients are typically unable to carry on a conversation or control their own bodily movement.
In most cases, patients with Alzheimer's disease live between 4 and 8 years after the diagnosis has been made, though some live as long as 20 years. While this disease most commonly affects adults over the age of 65, over 200,000 Americans under the age of 65 develop early-onset Alzheimer's each year.
Alzheimer's disease is not a normal consequence of aging but the result of physiological changes in the brain. Scientists are still struggling to fully understand these changes, but they have largely been attributed to the development of abnormal protein deposits that damage nerve cells. Though these changes are microscopic, they begin long before the first outward signs of Alzheimer's and they become compounded as the disease progresses.
The human brain has roughly 100 billion nerve cells, or neurons, in a giant network of connections. Within this network are a number of specialized nerve cells – each group is involved in certain functions, such as learning and memory. When the nerve cells responsible for memory and cognition sustain damage, it leads to the early symptoms of Alzheimer's.
Though they can only be identified through autopsy, a human brain affected by Alzheimer's shows abnormal deposits of proteins throughout the brain. Scientists believe that these deposits are somehow responsible for damaging and killing off nerve cells. Deposits of beta-amyloid protein that build up in the spaces between neurons are called plaques, and tangles are twisted tau fibers that accumulate inside the nerve cells themselves.
Scientists have yet to pinpoint the exact role plaques and tangles play in Alzheimer's disease, but it is clear they develop most heavily in areas of the brain responsible for memory before spreading to other regions. Because these deposits physically damage and eventually kill the affected nerve cells, the effects of Alzheimer's disease are irreversible.