Although every person with Alzheimer's experiences the disease differently, it is possible to divide its typical progression into a series of stages.
However, it is essential to make sure that a person with dementia has a good quality of life with the condition and that their needs are met, rather than focusing on what stage they might have reached.
Alzheimer's mainly affects older people and it usually progresses over a number of years.
Looking at Alzheimer's disease in stages can provide a clearer idea of the possible changes that could affect someone following their diagnosis.
The stages can only be a rough guide, and experts have proposed many different "staging" systems over the years.
Some people think of the disease as having seven stages, while others refer to just three. The symptoms that occur and when they appear will vary from person to person.
In this article, we discuss Alzheimer's disease in five stages:
- Stage 1: preclinical Alzheimer's disease
- Stage 2: mild cognitive impairment due to Alzheimer's disease
- Stage 3: mild dementia due to Alzheimer's disease
- Stage 4: moderate dementia due to Alzheimer's disease
- Stage 5: severe dementia due to Alzheimer's disease
Dementia describes a set of symptoms that affect memory, thinking, problem-solving, or language. In someone with dementia, these symptoms are severe enough to affect daily life.
Stage 1: Preclinical Alzheimer's disease
The functional changes that occur due to Alzheimer's may begin years or even decades before diagnosis.
This long phase is known as the preclinical stage of Alzheimer's disease. During this stage, the individual will not have any noticeable clinical symptoms.
Although there are no noticeable symptoms in the preclinical stage, imaging technologies can spot deposits of a protein called amyloid beta.
In people with Alzheimer's disease, this protein clumps together and forms plaques. These protein clumps may block cell-to-cell signaling and activate immune system cells that trigger inflammation and destroy disabled cells.
Other biological markers, or biomarkers, can show if a person has a higher likelihood of developing Alzheimer's symptoms. Genetic tests can also detect a higher risk.
Imaging technology that can locate amyloid beta clumps, biomarker detection, and genetic testing could all be important in the future as scientists develop new Alzheimer's treatments.
Researchers are studying this preclinical stage to work out which factors can predict the risk of progression from normal cognition to stage 2 of Alzheimer's disease.
Researchers are also hoping that their studies will help people with Alzheimer's access treatment at an earlier stage.
Disease-modifying therapies may be most effective in the early stages of Alzheimer's, and they could slow disease progression.
Stage 2: Mild cognitive impairment
Both older age and Alzheimer's disease can lead to forgetfulness, but not everyone develops dementia as they get older.
Mild cognitive impairment (MCI) is a more significant cognitive decline than that which occurs as a normal part of aging, but it occurs before the more severe decline of dementia. Between 15 and 20 percent of people aged 65 years or older have MCI.
It is important to note that not everyone with MCI will develop dementia. According to the Mayo Clinic, around 10–15 percent of those with MCI will develop dementia each year.
A person with MCI may notice subtle changes in their thinking and their ability to remember things. They may have memory lapses when they try to recollect recent conversations, events, or appointments.
However, changes to memory and thinking are not severe enough at this stage to cause problems with day-to-day life or usual activities.
It is normal for people to become more forgetful as they age or to take longer to think of a word or remember a name.
However, if a person is experiencing significant issues with these tasks, this could be a sign of MCI.
Symptoms of MCI include:
- forgetting things more often
- forgetting appointments, conversations, or recent events
- an inability to make decisions or feeling overwhelmed when doing so
- becoming increasingly unable to judge the passing of time or the sequence of steps to complete a task
- being more impulsive or showing increasingly poor judgment
- changes becoming noticeable to friends and family
As of yet, no drugs or therapies have regulatory approval to treat MCI. However, studies are underway to identify treatments that may help improve symptoms or prevent or delay their progression to dementia.
Stage 3: Mild dementia
The mild dementia stage is the point at which doctors typically diagnose Alzheimer's disease.
As well as becoming noticeable to friends and family, problems with memory and thinking may also begin to affect daily life.
Symptoms of mild dementia due to Alzheimer's disease include:
- difficulty remembering newly learned information
- asking the same question repeatedly
- having trouble solving problems and completing tasks
- reduced motivation to complete tasks
- experiencing a lapse in judgment
- becoming withdrawn or uncharacteristically irritable or angry
- having difficulty finding the correct words to describe an object or idea
- getting lost or misplacing items
Stage 4: Moderate dementia
When a person has moderate dementia due to Alzheimer's disease, they become increasingly confused and forgetful. They may need help with daily tasks and with looking after themselves.
Symptoms of moderate dementia due to Alzheimer's disease include:
- losing track of the location and forgetting the way, even in familiar places
- wandering in search of surroundings that feel more familiar
- failing to recall the day of the week or the season
- confusing family members and close friends or mistaking strangers for family
- forgetting personal information, such as address, phone number, and education history
- repeating favorite memories or making up stories to fill memory gaps
- needing help deciding what to wear for the weather or season
- needing assistance with bathing and grooming
- occasionally losing control of the bladder or bowel
- becoming unduly suspicious of friends and family
- seeing or hearing things that are not there
- becoming restless or agitated
- having physical outbursts, which may be aggressive
Stage 5: Severe dementia
In time, a person with Alzheimer's will need more care and help to carry out daily tasks.
During this stage, mental functioning continues to decline, while movement and physical capabilities can worsen significantly.
Symptoms of severe dementia due to Alzheimer's disease include:
- an inability to speak and communicate coherently
- needing complete assistance with personal care, eating, dressing, and using the bathroom
- an inability to sit or hold the head up or to walk without help
- rigid muscles and abnormal reflexes
- loss of the ability to swallow
- the inability to control bladder and bowel movements
A person with severe Alzheimer's disease has a high chance of dying from pneumonia. Pneumonia is a common cause of death in people with Alzheimer's because the loss of ability to swallow means that food and beverages can enter the lungs and cause infection.
Not everyone experiences the stages of Alzheimer's in the same way, and the rate and extent of the progression depend on the individual.
A person may not have all the symptoms above, and specific symptoms, such as aggressiveness, may come for a short while and then disappear. The stages can also overlap.
Medications can slow progression for a while, and they may help with memory symptoms and other cognitive changes.
Factors that can affect disease progression include:
Age: People with symptoms of Alzheimer's that develop before the age of 65 years may have faster progression.
Genetic factors: A person's genes may affect the rate of disease progression.
Keeping active, being involved in activities, and getting regular exercise may help the individual maintain their abilities for longer.
Other lifestyle changes that may help slow disease progression include:
- maintaining a healthy diet
- staying mentally and physically active
- getting enough sleep
- taking all prescribed medications correctly
- quitting smoking
- limiting or avoiding alcohol consumption
- having regular health checkups
If a person with Alzheimer's disease experiences a sudden change in their abilities or behavior, they could have another health problem or an infection. It is vital to seek advice from a doctor as soon as possible.
It is important to remember that, although changes happen, the individual is still the same person.
Alzheimer's disease is currently the sixth leading cause of death in the U.S. Around one in every three people aged 65 years and older will die from Alzheimer's or another type of dementia. It kills more people than breast cancer and prostate cancer together.
Life expectancy for individuals with Alzheimer's disease varies depending on many factors.
The average life expectancy for a person with Alzheimer's is 3–11 years after diagnosis, but people can live with Alzheimer's for 20 years or more.
If a person's symptoms appear before the age of about 75 years, they are likely to live for another 7–10 years after diagnosis. However, if symptoms appear when a person is aged 90 years or older, they are likely to live for around another 3 years.
Among the top 10 leading causes of death in the U.S., Alzheimer's is the only disease that treatment cannot slow down or cure and that lifestyle or other changes cannot help prevent.
Alzheimer's disease is a type of dementia and a neurocognitive disorder that happens when physical changes take place in the brain.
It is not a sign of aging, but it becomes more likely to happen as people get older. Not everyone will develop dementia with age.
It is important to remember that a person with Alzheimer's is still the same person, even if their behavior changes. A sense of frustration is common as people struggle to do the things that they used to do or to remember things that they feel they should know.
The more informed family members and loved ones are about Alzheimer's and how it affects an individual, the better they will be able to provide help and support.
There is currently no way to prevent or cure Alzheimer's, but ongoing research is looking at ways to detect the disease earlier and to try to stop or reverse its progression.