What Are the Stages of Alzheimer’s Dementia?

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

In This Article

The stages of Alzheimer’s disease (AD) may vary depending on the source a person is getting the information from. Many medical experts disagree on exactly how many stages of AD there are and exactly how those stages are defined. However, today most will agree that Alzheimer’s disease is a disorder involving a continuum of symptoms that can be defined using various stages. This was not always the case. At one time, the only stage that was considered Alzheimer’s disease was the final, most severe stage.

In fact, it was as recent as 1984 that Alzheimer’s disease was described as having only one stage—Alzheimer’s dementia. The most glaring disadvantage of waiting to diagnose AD until the latest, most severe phase of the disorder is that once a person reaches this advanced stage, most interventions have been shown to be ineffective in fighting the disease. Therefore, in 2011, the National Institute on Aging updated and refined its definition of the various signs and symptoms of Alzheimer’s disease, grouping them to three primary and three secondary stages. 

Stages of Alzheimer's Disease

In some instances (such as before conducting medical research studies) an additional stage of Alzheimer’s disease is used, called “stage 0.” This is a stage in which a person does not have Alzheimer’s disease, it has not yet started in the brain, no symptoms occur, and no one knows whether a person will be diagnosed with Alzheimer’s in the future. But, the three primary stages defined by the National Institute on Aging does not include stage 0. They are comprised of the following:

Stage 1—Preclinical stage: the earliest stage of Alzheimer’s disease in which symptoms have not begun, but changes have started to occur in the brain. These changes include the buildup of amyloid plaques—an abnormal sticky substance that accumulates in the brain and prevents normal neuron (nerve cell) transmission—and other changes in the brain cells.    

Stage 2—Mild cognitive impairment (MCI): the next most severe stage of Alzheimer’s disease, which involves memory problems and/or other types of thinking problems that are worse than a person’s normal age-related cognitive decline. It’s important to note that at this stage of AD, a person’s symptoms are not severe enough to interfere with what is called activities of daily living (ADLs). 

Stage 3—Alzheimer’s dementia: the symptoms of Alzheimer’s (memory loss, cognitive impairment, and more) are severe enough to interfere with ADLs.

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 judgement, making bad decisions (that are uncharacteristic for the person with AD), 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 the 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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