What Are the Stages of Alzheimer’s Dementia?

Alzheimer's, Mild Cognitive Impairment, and Alzheimer’s Dementia

Alzheimer’s disease, the most common form of dementia affecting people older than 65, is a progressive disease characterized by worsening symptoms affecting cognitive ability. These symptoms, which tend to include memory loss, inability to problem-solve and lack of judgement, all interfere with a person's ability to function.

Although no two cases of Alzheimer's follow the same path, the progression of the disease is generally understood to fall into three primary stages based on various signs and symptoms.  

Symptoms of stage 3 Alzheimer's Dementia
Verywell / JR Bee  

Stages of Alzheimer's Disease

The first symptoms of Alzheimer’s vary from person to person. For many people, decline in non-memory aspects of cognition, such as word-finding, vision problems and impaired reasoning or judgment may signal the earliest stages of disease. 

The U.S. National Institutes of Health (NIH) breaks down the progression of Alzheimer's disease into three stages based on severity of symptoms:

Stage 1—Mild Alzheimer's: People in this stage begin experiencing greater loss of memory and other difficulties with cognitive function. They may start wandering and getting lost, begin missing bills or asking the same questions repeatedly and generally take longer to complete everyday tasks. Typically, this is the stage where a formal diagnosis is given.  

Some people experience mild cognitive impairment (MCI), which is when people have more memory problems that normal people in their age but do not experience a significant impact on their ability to live their everyday lives.

Stage 2—Moderate Alzheimer's: In this stage, memory loss and confusion worsen and people may start having trouble recognizing their friends and family. They may also start having trouble with multistep activities of daily living (ADLs), such as getting dressed. Additionally, people in the moderate stage of Alzheimer's may start experiencing delusions, hallucinations or paranoia.

Stage 3—Severe Alzheimer’s: In this last stage, disease progression severely impacts brain tissue and cognitive function. People are unable to communicate and are completely dependent on others for their care. Ultimately, the body shuts down.

More on Activities of Daily Living (ADLs)

ADLs are the things people perform every day as part of their daily routines such as eating, dressing, bathing/showering, attending to personal hygiene and grooming such as brushing his/her hair, and toileting.

Not everyone with MCI will go on to develop the third (most severe) stage of Alzheimer’s disease—Alzheimer’s dementia. 

Symptoms of MCI are usually mild, involving problems in cognition. Cognition is defined as the process of thinking—cognitive abilities are the skills required to carry out any task ranging from simple to complex ones. They are the brain-based abilities required to learn, remember, problem-solve and pay attention.

Not all symptoms of MCI interfere with a person’s ability to perform ADLs. These may include forgetting appointments or important events, losing things frequently, or difficulty remembering words.

Symptoms that must be present for a diagnosis of MCI include:

  • Concern about a change in cognition (compared to a previous level of functioning)
  • Impairment of one or more cognitive functions, such as problem-solving or memory (that is greater than expected for a person's age and education level)
  • Ability to perform ADLs (although some tasks may be more difficult than before a diagnosis of MCI)

Stage 3—Alzheimer’s Dementia

Stage 3 is the final and most severe stage of the disease that results from the loss of normal neuron (brain cell) connection, combined with the death of nerve cells from amyloid plaques and other factors. This stage is often referred to as dementia.

It’s important to note that there are several causes of dementia other than Alzheimer’s disease, but AD is the most common cause. 

Stage 3 symptoms may involve:

  • A decline in cognition (including increased severity of memory problems and worsening of thinking skills) 
  • A worsening of visual or spatial problems
  • A worsening (or initiation) of mental and behavioral problems such as anger, aggression, anxiety, and more

The defining factor that determines whether a person is considered at the Alzheimer’s dementia stage of the disease has to do with ADLs. A person whose symptoms are so severe that they interfere with the ability to perform ADLs independently is considered to have Alzheimer’s dementia.

Stage 2 vs. Stage 3

Some of the symptoms of Alzheimer’s dementia (stage 3) and MCI (stage 2) may overlap, but the differentiating factor always comes down to the severity of the symptoms and more specifically, whether the symptoms keep the person from being able to independently perform activities of daily living (ADLs).

Alzheimer’s dementia can be further split into three phases, including mild Alzheimer’s dementia, moderate Alzheimer’s dementia, and severe Alzheimer’s dementia. The following are some symptoms commonly experienced during each phase of Alzheimer’s dementia.

Mild Alzheimer’s Dementia Stage

The symptoms of mild Alzheimer’s dementia must be severe enough to interfere with ADLs to meet a diagnosis. They include memory loss, poor judgment, making bad decisions, a decline in motivation level and spontaneity, and taking longer to perform daily tasks than normal.

Someone with mild Alzheimer's dementia will repeat the same questions or stories over and over, have difficulty balancing the checkbook, managing money, and/or paying bills, get lost in familiar places, wander outside of the home, and lose things and find them in very odd places (such as the cell phone in the refrigerator).

Also notable are the changes in mood and personality, anxiety (increasingly more severe), and even aggression.

Moderate Alzheimer’s Dementia Stage

The hallmark sign of moderate Alzheimer’s dementia is when supervision becomes increasingly more necessary. As with mild Alzheimer’s, these symptoms must interfere with ADLs. They include memory loss and confusion that worsens over time, not being able to learn anything new, worsening language problems (reading, writing, remembering words), and trouble with calculating numbers and logical thinking.

A person in the moderate Alzheimer's dementia stage will also have a worsening ability to focus and declining attention span, have trouble organizing thoughts, and have an inability to cope with stressors or new situations.

In addition, the following symptoms are notable in the moderate Alzheimer's dementia stage:

  • Trouble with tasks that require several steps (such as following a recipe)
  • Trouble recognizing people (including close friends and family members)
  • Symptoms of paranoia (severe fear) delusions (believing things that are untrue) and hallucinations (seeing things that are not there)
  • Angry outbursts
  • Impulsive behavior
  • Inappropriate language
  • Restlessness, anxiety, and agitation
  • Wandering/getting lost in familiar places (such as a person’s own neighborhood)
  • Impulsive behavior such as undressing at inappropriate times or places or using vulgar language
  • Inappropriate outbursts of anger
  • Repetitive movements or muscle twitches

Severe Alzheimer’s Dementia Stage

Symptoms of severe Alzheimer's dementia stage include:

  • Trouble eating and swallowing
  • Weight loss
  • Inability to communicate
  • Skin infections
  • Loss of bladder control (and bowel control)
  • Sleeping constantly/bedridden
  • Inability to walk
  • Seizures

During the severe Alzheimer’s dementia stage, a person is completely dependent on others for care and requires 24/7 supervision.

Perhaps one of the most important aspects of the most recent guidelines for staging of Alzheimer’s disease is that the condition is now differentiated as a spectrum of disease beginning early on in life before symptoms even occur. This means that prevention measures to help stave off symptoms can be started as a part of early treatment. 

How early? Clinical research studies have found that Alzheimer’s disease may start in the brain as early as 20 or even 30 years before the first symptoms of memory loss ever begin. 

The Future

As study results become available and researchers have a better understanding of the disease process, the framework outlining the symptoms and stages of the disease can be easily adjusted, says the NIH. Funding has been provided by the National Institute of Health (NIH) to enable researchers to identify new measures for early diagnosis in the field of preclinical disease. 

Early diagnosis translates into being able to intervene sooner in the hopes of finding effective treatment and prevention measures in the future.  

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  1. U.S. National Institute on Aging. Alzheimer's Disease Fact Sheet. Last reviewed July 8, 2021.

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