Experts have documented common patterns of symptom progression that occur in many individuals with Alzheimer’s disease and developed several methods of “staging” based on these patterns.
Staging systems provide useful frames of reference for understanding how the disease may unfold and for making future plans. But it is important to note that not everyone will experience the same symptoms or progress at the same rate. People with Alzheimer’s die an average of four to six years after diagnosis, but the duration of the disease can vary from three to 20 years.
While each individual is different, the progression of his or her disease can be roughly divided into three stages — mild, moderate and severe.
Mild Alzheimer's disease (2 – 4 years)
People in the early stage of Alzheimer's may experience memory loss, lapses of judgment and subtle changes in personality. They often have decreased attention span and less motivation to complete tasks. In addition, they may resist change and new challenges, and get lost even in familiar places.
While everyone occasionally forgets words or names during conversations, this problem occurs with increasing frequency in people with mild Alzheimer's. They may substitute or make up words that sound like or mean something like the forgotten word. They sometimes even avoid talking to keep from making mistakes and appear subdued or withdrawn — especially in socially or mentally challenging situations.
They may also put things in very odd places. For example, a wallet may end up in the freezer, or clothes may go into the dishwasher. They may ask repetitive questions or hoard things of no value. When frustrated or tired, they may become uncharacteristically angry.
Moderate Alzheimer's disease (2 – 10 years)
In the middle stage of Alzheimer's, people can't organize thoughts or follow logical explanations. They lose the ability to follow written instructions and often need help choosing proper clothing for the season or occasion. Eventually, they'll require help getting dressed because their confusion may cause them to put their pajamas on over their daytime clothes or their shoes on the wrong feet. They may also have episodes of urinary or fecal incontinence.
It's usually during this stage that people start having problems recognizing family members and friends. They may mix up identities — thinking a son is a brother or that a spouse is a stranger. They may become confused about where they are and what day, season or year it is. They become unable to recall their address or phone number.
Because they lack judgment and tend to wander, people with moderate Alzheimer's disease aren't safe on their own. They may exhibit restless, repetitive movements in late afternoon, or continually repeat certain stories, words or motions, such as tearing tissues.
Problems with communication worsen during the moderate stage of Alzheimer's. This can lead to a variety of challenging behaviors, including:
- Paranoia that sometimes provokes accusations of infidelity or stealing
- Agitation, frustration or anger that can lead to cursing, kicking, hitting, biting, screaming or grabbing
Severe Alzheimer's disease (1 – 3+ years)
People in the last stage of Alzheimer's require help with all their daily needs. They lose the ability to walk without assistance and then the ability to sit up without support. They are usually incontinent and may no longer speak coherently. They rarely recognize family members. Swallowing difficulties can cause choking, and they may refuse to eat.
How long?
The rate of progression varies widely among individuals. For some, severe dementia occurs within five years of diagnosis. For others, it can take more than a decade. On average, people with Alzheimer's live for eight to 10 years after diagnosis. Some live as long as 20 years. Most people with Alzheimer's don't die of the disease itself, but of pneumonia, a urinary tract infection or complications from a fall.
While the three-stages-classification is commonly accepted by experts, it has the certain limitation, which requires more detailed analysis within the same stages of the disease development process for more precise and focused treatment offerings.
This framework, based on a system developed by Barry Reisberg, M.D., Clinical Director of the New York University School of Medicine’s Silberstein Aging and Dementia Research Center
Unimpaired individuals experience no memory problems and none are evident to a health care professional during a medical interview.
Stage 2: Very mild cognitive decline (may be normal age-related changes or earliest signs of Alzheimer's disease)
Individuals may feel as if they have memory loss and lapses, especially in forgetting familiar words or names or the location of keys, eyeglasses or other everyday objects. But these problems are not evident during a medical examination or apparent to friends, family or co-workers.
Stage 3: Mild cognitive decline
Early-stage Alzheimer's can be diagnosed in some, but not all, individuals with these symptoms
Early-stage Alzheimer's can be diagnosed in some, but not all, individuals with these symptoms
Friends, family or co-workers begin to notice deficiencies. Problems with memory or concentration may be measurable in clinical testing or discernible during a detailed medical interview. Common difficulties include:
- Word- or name-finding problems noticeable to family or close associates
- Decreased ability to remember names when introduced to new people
- Performance issues in social or work settings noticeable to family, friends or co-workers
- Reading a passage and retaining little material
- Losing or misplacing a valuable object
- Decline in ability to plan or organize
Stage 4: Moderate cognitive decline
(Mild or early-stage Alzheimer's disease)
(Mild or early-stage Alzheimer's disease)
At this stage, a careful medical interview detects clear-cut deficiencies in the following areas:
- Decreased knowledge of recent occasions or current events
- Impaired ability to perform challenging mental arithmetic-for example, to count backward from 75 by 7s
- Decreased capacity to perform complex tasks, such as planning dinner for guests, paying bills and managing finances
- Reduced memory of personal history
- The affected individual may seem subdued and withdrawn, especially in socially or mentally challenging situations
Stage 5: Moderately severe cognitive decline
(Moderate or mid-stage Alzheimer's disease)
Major gaps in memory and deficits in cognitive function emerge. Some assistance with day-to-day activities becomes essential. At this stage, individuals may:
- Be unable during a medical interview to recall such important details as their current address, their telephone number or the name of the college or high school from which they graduated
- Become confused about where they are or about the date, day of the week or season
- Have trouble with less challenging mental arithmetic; for example, counting backward from 40 by 4s or from 20 by 2s
- Need help choosing proper clothing for the season or the occasion
- Usually retain substantial knowledge about themselves and know their own name and the names of their spouse or children
- Usually require no assistance with eating or using the toilet
Stage 6: Severe cognitive decline
(Moderately severe or mid-stage Alzheimer's disease)
(Moderately severe or mid-stage Alzheimer's disease)
Memory difficulties continue to worsen, significant personality changes may emerge and affected individuals need extensive help with customary daily activities. At this stage, individuals may:
- Lose most awareness of recent experiences and events as well as of their surroundings
- Recollect their personal history imperfectly, although they generally recall their own name
- Occasionally forget the name of their spouse or primary caregiver but generally can distinguish familiar from unfamiliar faces
- Need help getting dressed properly; without supervision, may make such errors as putting pajamas over daytime clothes or shoes on wrong feet
- Experience disruption of their normal sleep/waking cycle
- Need help with handling details of toileting (flushing toilet, wiping and disposing of tissue properly)
- Have increasing episodes of urinary or fecal incontinence
- Experience significant personality changes and behavioral symptoms, including suspiciousness and delusions (for example, believing that their caregiver is an impostor); hallucinations (seeing or hearing things that are not really there); or compulsive, repetitive behaviors such as hand-wringing or tissue shredding
- Tend to wander and become lost
Stage 7: Very severe cognitive decline
(Severe or late-stage Alzheimer's disease)
This is the final stage of the disease when individuals lose the ability to respond to their environment, the ability to speak and, ultimately, the ability to control movement.
- Frequently individuals lose their capacity for recognizable speech, although words or phrases may occasionally be uttered
- Individuals need help with eating and toileting and there is general incontinence of urine
- Individuals lose the ability to walk without assistance, then the ability to sit without support, the ability to smile, and the ability to hold their head up. Reflexes become abnormal and muscles grow rigid. Swallowing is impaired.
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