You might be surprised to learn that there’s no single definition of the “stages of Alzheimer’s.” Several different staging approaches are variously used; all reflect the fact that Alzheimer’s is a degenerative disease (it gets gradually worse) that progresses along a spectrum.
Depending who you talk to, you might encounter any of the following three most common ways of staging Alzheimer’s dementia. The first one is the most useful to caregivers, I think, because of its practicality and ease of understanding. It’s also fairly applicable to any type of progressive dementia.
1. Mild-Moderate-Severe dementia staging
Probably the most widely used staging system due to its simplicity, this approach refers to three main phases: mild (early), moderate (middle) and severe (advanced or late). Because they chart degeneration, they’re sometimes further subdivided (early mild, mid-mild, late mild, early moderate, and so on).
A key insight: Skills and abilities are lost in the reverse order of which they’re learned. So more advanced skills gained during adolescence, like paying bills, disappear well before basic skills mastered in infancy, like self-feeding.
The person can still manage basic self-care and communicate well, but memory changes are interfering with independent activities of daily living (IADLs), higher-order thinking skills, such as driving, shopping, preparing meals, and managing money or medications.
Think of mild-stage dementia as: Losing the skills that had been gained in the teenage years.
Someone with mild-stage Alzheimer’s may:
Repeat questions and comments
Show poor judgment or an inability to plan or make decisions
Get lost on familiar routes (walking or driving)
Seem preoccupied or irritable, or show other personality changes
Have trouble with basic finances, transportation, and medications.
The person begins to have trouble with the so-called “activities of daily living” (ADLs), which are such basic skills as getting dressed, grooming, self-feeding, walking, and toileting.
Think of moderate-stage dementia as: Losing the skills that were gained during childhood.
Someone with moderate-stage Alzheimer’s may:
Remember the distant past better than more recent events
Need help choosing clothes or dressing, brushing teeth, or bathing.
Fidget restlessly, pace, wander away from home, shadow a caregiver
Have delusions (fixed false beliefs), make false accusations
Experience evening agitation known as sundowning
The person becomes unable to perform the activities of daily living without significant help. Basic life skills (speaking, sitting up, continence) are also affected.
Think of severe-stage dementia as: Losing essential skills that were gained during the first year or so of life.
Someone with severe-stage Alzheimer’s may:
Seem to lose all memory and live in a constant present
Not talk intelligibly
Not recognize even close family
Have urinary and fecal incontinence
Lose the ability to walk
Because people with Alzheimer’s tend to have bad days and good days, it can sometimes be hard to tell where in the progression they are. If you look at the big picture, though, there is ongoing decline.
Another “stage” to know: End-stage Alzheimer’s, also called “terminal dementia.” This refers to the final days, weeks, to months of life. It’s not identical to severe stage (for one thing it’s almost always shorter) though they overlap. Because Alzheimer’s is a terminal disease, the person will die from it in the absence of another health problem causing death first.
2. Diagnostic guidelines for Alzheimer’s dementia and MCI
In 2011, classifying guidelines for clinicians were updated for the first time since 1984 following a two-year congress of leading researchers, sponsored by the National Institute on Aging and the Alzheimer’s Association. The stages in these guidelines are as follows:
Preclinical Alzheimer’s, also called pre-symptomatic: First defined in 2011, it’s when changes are seen in biomarkers—for example, the nerve cells and blood—now that such biomarkers can be seen through brain imaging and other tests even when the person doesn’t show behavioral or cognitive symptoms. This stage is currently of greatest value to researchers.
Mild cognitive impairment (MCI) due to Alzheimer’s: Mild changes in memory and thinking ability are noticeable to the person and to family and friends but don’t interfere with the ability to carry out daily activities. Most, but not all, cases of MCI eventually develop into Alzheimer’s.
Dementia due to Alzheimer’s: This is the stage most people think of as “Alzheimer’s.” Memory, thinking, and behavioral symptoms increasingly impair the person’s ability to function in everyday life.
3. Seven stages of Alzheimer’s (FAST Scale)
Developed by geriatrician Barry Reisberg, this “global deterioration scale” (also called the FAST Functional Assessment Staging Tool) is a seven-stage assessment that’s often used by researchers to evaluate patients. It’s used less frequently by primary care doctors but you may see it referenced in guides and online chat groups. The later stages include sub-stages that mark the loss of specific skills.
Stage 1: No impairment; a normal person.
Stage 2: Very mild cognitive decline (forgetfulness) that may or may not be normal aging.
Stage 3: Mild cognitive decline: Memory problems obvious to others, trouble with complex tasks. Akin to mild cognitive impairment.
Stage 4: Moderate cognitive decline: Increased trouble with IADLs, or instrumental activities of daily living (cooking, bill paying, cleaning, traveling). Mild-stage Alzheimer’s.
Stage 5: Moderately severe cognitive decline: Can’t manage living independently without lots of help; needs help selecting clothes. Moderate-stage Alzheimer’s.
Stage 6: Severe cognitive decline: Moderately severe mid-stage Alzheimer’s. 6a: Needs help dressing. 6b: Needs help bathing. 6c: Needs help with toileting. 6d: Increasing urinary incontinence. 6e: Increasing fecal incontinence.
Stage 7: Very severe cognitive decline: Severe or late-stage Alzheimer’s. 7a: Speaks only a few words. 7b: May say just one word a day. 7c: Can’t walk. 7d: Can’t sit up without assistance. 7e: Can’t smile.
Paula Spencer Scott is the author of Surviving Alzheimer's: Practical Tips and Soul-Saving Wisdom for Caregivers. This information is excerpted from the book's new second edition, which covers common challenges and solutions at every stage of dementia.