Alzheimer’s is a progressive disease that damages neurons (nerve cells) in the brain, affecting a person’s ability to remember, reason, judge, use language, and otherwise meet the demands of daily life.
While there are treatments that can help sharpen the mind for a short while and make behavioral symptoms more manageable, there is currently no cure.
In a typical case, Alzheimer’s first destroys neurons and their connections in parts of the brain that retain memories, including the entorhinal cortex and hippocampus.
Later the disease causes damage to regions in the cerebral cortex that control language, reasoning, and social behavior. Eventually many other parts of the brain are affected. (1)
Ultimately the disease is fatal. On average people with Alzheimer’s live for four to eight years after diagnosis, although some can live as long as 20 years depending on other factors. (2)
More than one-half of all Alzheimer’s-related deaths are caused by respiratory system diseases, such as pneumonia, an infection that can develop when swallowing issues result in food and liquid entering the lungs. (3)
Every person with Alzheimer’s will experience the disease in a different way. Some retain their cognitive abilities for longer than expected, while others move more quickly through the various stages.
Among the factors that influence the speed of progression are age, overall health, emotional resilience, medication regimen, and network of support.
Outlining the stages of Alzheimer’s is helpful in understanding the overall arc of the disease and planning for changes to come. Still, it’s important to remember that:
- Some symptoms can appear earlier or later than is typical, in a different order, or not at all.
- Some stages can overlap.
- Some symptoms, such as irritability, may appear and then disappear while others, such as memory loss, continually worsen. (4)
Alzheimer Disease Begins Long Before the First Symptoms
Alzheimer’s disease can begin a decade or more before the first symptoms. Despite a lack of outward evidence, changes are happening in the brain.
Researchers have identified a condition called mild cognitive impairment (MCI) that in some — but by no means all — individuals may be the earliest indication of Alzheimer’s or another type of dementia.
MCI involves lapses in memory, language, thinking, and judgment that are noticeable to the person and his family and close friends yet are not serious enough to interfere with everyday life.
According the Alzheimer’s Association, approximately one-third of those with MCI develop dementia due to Alzheimer’s within five years. (3)
Unfortunately, people with MCI who experience symptoms of memory loss or impairment are less likely to recognize their own difficulties than someone with MCI who does not experience such symptoms, which can lead to delays in diagnosis.
One of the highest priorities of Alzheimer’s research is understanding what happens inside the brain long before the first symptom. The hope is that these insights will lead to more effective treatments that slow or even prevent damage.
After the onset of symptoms, the disease progresses through three main stages: mild (early-stage), moderate (middle-stage), and severe (late-stage).
The First Stage: Mild Alzheimer’s Dementia
A person experiencing the earliest symptoms of Alzheimer’s disease may still be able to work, drive, take part in social activities, and otherwise live independently.
But they may begin to experience problems with memory or concentration. They may have trouble retaining new information — remembering the name of someone they’ve just met, for instance, or recalling material they’ve just read.
Unfortunately, this symptom is often dismissed as a normal part of aging or the result of stress, delaying diagnosis and treatment.
Other common symptoms of mild Alzheimer’s include:
- Misplacing items
- Language problems, such as having trouble coming up with the right words
- Trouble planning, organizing, or solving problems
- Losing a sense of time
- Vision-related problems, such as with depth perception and color contrast
- Increasingly poor judgment leading to bad decisions
- Mood and personality changes, such as becoming confused, anxious, irritable, or depressed
- Difficulty completing familiar home, work, or leisure tasks, such as managing a budget
- Withdrawal from work or social engagements
The Second Stage: Moderate Alzheimer’s Dementia
In most cases of moderate Alzheimer’s dementia, the disease has spread to areas of the brain that control language, reasoning, sensory processing, and conscious thought, causing previous symptoms to become more pronounced.
Damage to the brain can make it difficult for people to say what they’re thinking or complete basic tasks, such as paying bills.
But they may still remember important details about their personal history.
This is typically the longest stage, potentially lasting for many years. (2)
Symptoms of this period may include:
- Increased memory loss and confusion, including forgetting names or personally significant events
- Trouble recognizing family and friends
- Inability to learn new things or cope with new situations
- Hallucinations, delusions, and paranoia
- Loss of impulse control, such as undressing at inappropriate times or using vulgar language
- Repetitive statements or movements, such as hand-wringing or tissue-shredding
- Trouble carrying out activities that require multiple steps, such as getting dressed
- Difficulty reading, writing, or working with numbers
- Behavioral problems, such as moodiness or inappropriate anger outbursts
- Restlessness, agitation, anxiety, tearfulness, and increased risk of wandering, especially in the late afternoon or evening (a condition called sundowning) (5)
The Third Stage: Severe Alzheimer’s Dementia
People with severe Alzheimer’s dementia are completely dependent on others for around-the-clock care.
They become increasingly unable to respond to their environment, communicate, and perform basic daily activities, such as dressing, eating, or bathing. They become bedridden or chair-bound. Eventually, they become unable to control movement.
This stage may last from several weeks to several years. (2)
Other symptoms of advanced Alzheimer’s may include:
- Weight loss
- Increased risk of infections, including skin infections and pneumonia
- Failure to recognize family and friends
- Increased sleeping
- Groaning, grunting, and moaning
- Difficulty swallowing
- Loss of bowel and bladder control
Even at this advanced stage, patients may experience flashes of lucidity (being aware of their situation) and some of their abilities may come back for a short while.
A person with severe Alzheimer’s may be capable of experiencing a sense of happiness or safety in the presence of loved ones even when he doesn’t seem to recognize them. (4)