Stage 1:

No impairment (normal function)

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 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

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)

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• The affected individual may seem subdued and withdrawn, especially in socially or mentally challenging situations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)

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.