Seven stages of Alzheimer's disease have been described 

Stage 1: no cognitive impairments

Stage 2: slight decrease in functional memory skills. Memory tests may or may not reveal a mild impairment. The patient may occasionally forget the name of a friend or well-known person. The patient may or may not be aware of slight changes in memory skills. Employment is not negatively affected.

Stage 3: mild cognitive deficits. The patient may begin to lose items, become lost in unfamiliar locations, demonstrate increased anxiety, have difficulty recalling verbal information, and exhibit decreased ability to attend to tasks. The patient generally denies symptoms.

Stage 4: continued decline of cognitive skills. The patient demonstrates decreased recall of general knowledge. The patient is oriented to place and is able to recognize familiar friends and family members. Pathfinding for well-known places is intact. The patient is unable to complete complex tasks, and attention is noticeably impaired. The patient may continue to deny symptoms.

Stage 5: moderately severe cognitive impairments. The patient is generally able to recall the names of immediate family members and complete personal care with occasional cues. Because of the patient's poor judgment, it is unsafe to leave the person alone. The patient is unable to answer biographical and temporal orientation questions accurately (for example: How many children do you have? Where do your children live? What is your address? What is today's date? What time is it?).

Stage 6: severe cognitive impairments. The patient may show some knowledge of surroundings. The patient is able to recall own name. The person may be able to complete simple routine tasks such as cleaning the table. The patient may be unable to recall the names of spouse and children, recall recent experiences, or maintain a train of thought. Assistance for daily living activities is needed. The patient may exhibit delusional and/or violent behaviors and may become easily agitated.

Stage 7: severe cognitive deficits. This stage is classified as late dementia. The patient may be totally nonverbal, phonating only occasionally. Loss of all basic functions (including urinary continence, self-feeding, and walking) characterizes this final stage.

There is no standard length of time that the patient with Alzheimer's disease remains in a particular stage. Some patients progress rapidly from one stage to the next; others remain in the early stages for decades before deteriorating to later stages.