While Alzheimer's has different progression rates and different emergence of the typical symptoms experts agree that there are common patterns of progression. It is important to understand that not every person with Alzheimer's will go through the general stages at the same rate.
The following stages are based on the work of Dr. Barry Reisberg who is the Clinical Director of the Silberstein Aging and Dementia Research Centre at the New York University School of Medicine.
Stage 1: Very mild cognitive decline. This can be deceptive and the symptoms can be normal age-related memory loss, or the very early signs of encroaching Alzheimer's Disease.
There is the awareness of memory lapses. This can be losing glasses, keys and so on or tip-of-the-tongue moments where the word or name you were just going to use suddenly vanishes. A medical examination will not find physical evidence or something wrong - generally other people will not notice the memory lapses.
Stage 2: Mild cognitive decline.
The memory lapses are noticed by other people. Concentration becomes more difficult. It is more difficult to retain the names of newly-met people, it is harder to retain the memory of newly-read or heard information, and performance issues in the workplace may be noticed. It becomes harder to remember the location of objects, and planning or organising is impaired.
At this stage a cognitive psychometric test may pick up the mild declines in many people.
Stage 3: Moderate cognitive decline - sometimes termed mild or early-stage Alzheimer's disease.
Recent occasions or current events are difficult to recall. Working memory is affected: mental arithmetic is increasingly difficult and the person will find it difficult to complete the common cognitive item 'counting backwards by 7s'.
Complicated tasks requiring planning and organisation become unmanageable. Details of one's own personal history can become sketchy. The person may become withdrawn and feel embarrassed in social or mentally challenging situations - there is awareness of the problems experienced.
Stage 4: Moderately severe cognitive decline - termed moderate or mid-stage Alzheimer's disease.
Memory difficulties are now obvious and help with the activities of daily living (ADLs) is needed. Tasks such as choosing appropriate clothing may be challenging at this stage. However, usually using the toilet and eating can be managed unassisted.
Autobiographical memory is now very impaired with possibly forgetting own address and/or telephone number and important own-history events, although one's own name is remembered and friends and family members are recognised. There may be confusion about location, time, date, and so on.
Stage 5: Severe cognitive decline - termed moderately severe Alzheimer's disease.
Awareness of recent experiences and events are lost. Person may be unsure of their surroundings or where they are. There will be little ability to 'picture' what once-familiar places or buildings look like.
Personal history may become confused, fragmented and inaccurate. Names of friends or even family may be forgotten though very close people will be recognised as familiar. Dressing requires help as the sequence of putting on clothing may be forgotten.
The sleep/wake pattern is likely to be disrupted and wandering may occur.
Toileting will require help with sequencing such as wiping and flushing, and increasing episodes of urinary or fecal incontinence are likely to occur.
Personality changes and behavioural changes such as becoming suspicious of people or believing belongings have been stolen, repetitive behaviours such as shredding tissues, and hallucinations will be experienced.
Stage 6: Very severe cognitive decline - termed severe or late-stage Alzheimer's disease.
This is the final stage of Alzheimer's. Individuals lose the ability to respond to their environment, to friends and family, the ability to speak, and finally, the ability to control movement.
There is a loss of the ability to walk without assistance and during the final stage the abiity to sit unsupported, to smile, or to hold up the head is affected. Muscle rigidity occurs and reflexes become abnormal. Swallowing is impaired.
There are increasing difficulties with toileting and eating and these cannot be managed without full assistance.
The Alzheimer's Reading Room have produced a wonderful little video showing how Alzheimer's disease spreads through the brain. This may be viewed at: http://aboutalz.org