Condition: Alzheimer’s Disease
Layman’s Definition: A specific type of progressive memory loss and worsen brain function caused by the gradual loss of nerve cells in the brain that are necessary for storing and retrieving memories, as well as a later loss of nerve cells required for other tasks.
Prevalence: 4.5-5.2 million in US
Typical Age of Symptom Onset: >65, (early onset 45-55); risk increases with age
Primary Symptoms: Progressive problems with memory, concentration, and reasoning ability. Forgetfulness. The mental decline in individuals with Alzheimer’s Disease is significantly worse than the mild age-related increase in forgetfulness and greater difficulty finding words or concentrating on tasks, which are parts of the normal aging process. Although memory generally declines slightly with age, in normal aging it is primarily information of low importance that is lost. People with Alzheimer’s Disease, however, also forget events or people that were highly important to them, things that people who have known the person for years never would have expected them to forget. In people with Alzheimer’s Disease, memories of more recent events are typically lost before childhood memories. This characteristic pattern of last in/first out memory loss differs from other forms of dementia for which the time of storage is not as closely linked to data loss.
Because more recent adult memories tend to be lost before earlier childhood ones, individuals with Alzheimer’s Disease often believe they are much younger than they are and that they are living at an earlier time in their lives. In addition, because emotional connections to people tend to be maintained longer than the ability to recognize who people are, someone with Alzheimer’s Disease may think that their spouse is their brother or sister or that their child is actually their parent.
Secondary Symptoms: Sleep disturbances. Nighttime wandering. As memory problems worsen, individuals with Alzheimer’s Disease may have episodes of intense anxiety, often believing that they have been kidnapped by family members or hospital staff and need to escape (Alzheimer’s Psychosis). Speech and muscle control eventually fail, and the condition is ultimately fatal.
Cause(s)/Risk Factor(s): The cause of Alzheimer’s Disease is not fully understood. The current understanding is that the condition is likely due to a misfolded protein that attaches to other proteins of the same type, causing them to similarly misfold and clump together in plaques that “gunk up the system.” These plaques slowly kill neurons in a part of the brain that plays a key role in storing and retrieving memories. The original information is still stored in the brain, but there is no way of finding or retrieving it later.
Specific genetic mutations have been identified in people with early-onset Alzheimer’s Disease. Most of these involve enzymes that break down the protein that forms amyloid plaques before they get to that stage. The assumption is that for most people the ability to break down this molecule slows with age and that amyloid plaque proteins slowly buildup. In people who develop Alzheimer’s Disease, the plaques build up fast enough to begin killing neurons, while in those who do not develop Alzheimer’s Disease the buildup rate is too slow to cause symptoms during a normal human lifespan.
Conclusive diagnosis of Alzheimer’s Disease can only be made by examining brain tissue after death. Autopsies of individuals with Alzheimer’s Disease show characteristic amyloid plaque structures in a part of the brain associated with learning and memory.
Standard Treatment(s): There is no cure for Alzheimer’s Disease nor any treatment that improves the long-term course of the disease. Drugs have been approved by the Food and Drug Administration that appear to improve memory function in at least some people with Alzheimer’s Disease for a few months. However, there is no current treatment to prevent or reverse the progressive mental decline.
Sleep medication and/or anti-anxiety medications may be prescribed to reduce nighttime wandering or reduce the distress experienced by the individual when they are unable to recognize loved ones or their surroundings. These medications may make it easier for loved ones to continue to care for their loved ones in their own homes. Moderate daily exercise and staying mentally active and socially engaged has been shown to slow the progression of mental decline from all causes.
Because some other forms of dementia respond to treatment, it’s important to rule out other treatable conditions before accepting a diagnosis of Alzheimer’s Disease.
For a more comprehensive discussion of how to evaluate possible causes of memory problems, see: Is it Alzheimer’s disease?
For more information about Alzheimer’s Disease, see: https://www.nia.nih.gov/alzheimers/publication/alzheimers-disease-fact-sheet
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