How to Understand the Stages of Alzheimer’s & Related Dementias

Alzheimer’s disease and other dementias usually slowly get worse over many years.

To describe how far along a person has progressed, doctors and professionals often refer to stages of Alzheimer’s, or of dementia.

This can be confusing to families, however, because if you look online, you might come across a few different methods of staging Alzheimer’s. These include:

  • A three-stage model with mild, moderate, or severe stages of dementia
    • This model sometimes uses the words early-stage, middle-stage, and late-stage.
    • Mild dementia usually corresponds to having difficulty with the Instrumental Activities of Daily Living (IADLs): the “learned in adolescence” skills such as managing finances, driving, grocery shopping and meal preparation, home maintenance, and medications.
    • Moderate dementia usually corresponds to needing increasing assistance with  Activities of Daily Living (ADLs): the “learned in early childhood” skills, such as toileting, getting dressed, walking, and feeding oneself.
    • Severe dementia corresponds to becoming bedbound, losing the ability to speak, not interacting much with people, and little recognition of who people are. The person now requires total assistance with all ADLs and does not seem very aware of his or her surroundings.
    • For more on the symptoms and problems associated with each stage, I recommend the Alzheimer’s Association’s page: Stages of Alzheimer’s.
    • Note: in research, staging people with dementia has often used test scores of the Mini-Mental State Exam (MMSE) and Montreal Cognitive Assessment (MoCA):
      • Mild dementia – MMSE 19 to 26; MoCA 12 to 16
      • Moderate dementia – MMSE 10 to 18; MoCA 4 to 11
      • Severe dementia – MMSE <10; MoCA <4
  • The seven stage Functional Assessment Staging Test (FAST) scale
    • This model considers “normal aging” to be stage 1, mild cognitive impairment to be stage 3, and then covers mild to severe dementia in stages 4-7.
    • FAST sub-divides stage 6 (“moderately severe dementia”) into five sub-stages, reflecting the way people with Alzheimer’s tend to lose their abilities.
    • Stage 7 (“severe dementia”) is sub-divided into six sub-stages, again based on the sequence in which people usually lose their abilities.
  • five stages model of Alzheimer’s disease
    • This model takes into account the fact that microscopic signs of Alzheimer’s disease in the brain often precede obvious symptoms by up to ten years.
    • The stages are preclinical disease, mild cognitive impairment due to Alzheimer’s dementia, and then mild, moderate, and severe dementia due to Alzheimer’s dementia.

Of these three methods, the three-stage model (mild, moderate, severe) is by far the one most commonly used by practicing doctors. It is also often used in clinical research.

The FAST scale is more detailed, so it is sometimes used in research or for administrative purposes. However, the average primary care provider (PCP) is often not familiar with the FAST scale.

I can’t emphasize this enough. If you come to see a primary care doctor and announce that your relative is in “Stage 6d of dementia,” based on the FAST scale, you are likely to get a perplexed look in a response.

Because it’s hard to identify clear boundaries separating one of the three stages of dementia from the next, clinicians often use the terms “mild to moderate dementia” and “moderate to severe dementia.”

Of note, the FDA approval of medications to treat dementia uses these terms. Cholinesterase inhibitors such as donepezil, rivastigmine, and galantamine (brand names Aricept, Exelon, and Razadyne, respectively) are FDA-approved for the treatment of “mild to moderate” dementia.

In contrast, memantine (brand name Namenda) is FDA-approved for the treatment of “moderate to severe” dementia.

(Learn more about medications to treat dementia in these articles: 4 Medications to Treat Alzheimer’s & Other Dementias: How They Work & FAQs and 5 Types of Medication Used to Treat Difficult Dementia Behaviors.)

Very advanced and “terminal” dementia

You may also encounter terms such as “very advanced dementia,” “very late-stage dementia,” “end-stage dementia” or “terminal dementia.”

“Very advanced” and “late-stage” usually mean the person has become bed-bound, cannot speak, and has to be spoon-fed. Eventually, people in this stage will have difficulty swallowing as well.

How long this very advanced stage of dementia lasts really depends on the person, and on their other health conditions. In this stage, the mind seems gone but the body remains able enough to keep living, as long as food and a safe, supportive environment are provided.

Because in otherwise healthy people this stage can last for a few years, I don’t consider very advanced dementia to be synonymous with “end-stage” or “terminal” dementia.

Now, it’s important to remember that  Alzheimer’s and most other dementias are technically terminal diseases, meaning that unless another health problem kills someone first, the dementia does inevitably progress and results in the person’s death.

But, we don’t usually refer to people with dementia as “terminally ill.” That’s because Alzheimer’s and other dementias usually progress very slowly. So it can take ten years or even longer for a person to die of Alzheimer’s.

How to know if it’s end-stage or terminal dementia?

Advanced Alzheimer’s kills people by weakening the immune system and by damaging the body’s ability to manage small crucial movements, like those involved in swallowing. So at a certain point, a person with advanced dementia will begin experiencing recurrent infections, or difficulties swallowing, or both.

Doctors generally refer to someone as “terminally ill” when we have reason to believe they are likely to die within the next 6-12 months of their disease.

Unfortunately, it is quite hard to determine when a person with advanced Alzheimer’s has reached the point of a six-month prognosis (the usual standard for being eligible for hospice care).

When it comes to Alzheimer’s disease, clinical research has found that certain signs indicate that a person with very advanced dementia is more likely to die within the next 12-18 months. These include:

  • Developing pneumonia or other infections
  • Developing fevers
  • Persisting pressure sores (bedsores), despite being regularly turned in bed
  • Developing eating problems
  • Weight loss

If you have a relative with advanced dementia who begins to develop these problems, be sure to talk to the doctors. You’ll want to discuss the goals of medical care, such as whether to focus exclusively on comfort-oriented care, versus considering hospitalizations, antibiotics, and other interventions meant to help a person stay alive.

To learn more about very advanced dementia and when things might be “end-stage,” see this page from the U.K. Alzheimer’s Society.

For a more scholarly — yet informative and practical– take on the subject, see this 2015 article in the New England Journal of Medicine.