Alzheimer’s disease accounts for the cause of dementia in about half of people with dementia. Alzheimer’s disease is a disease that progresses over time. Experts use “stages” to explain how a patient’s normal abilities change as Alzheimer’s disease progresses.
However, keep in mind that stages are a general criterion, and the symptoms vary. The symptoms experienced and the rate at which they progress varies from person to person. The 7 stages of Alzheimer’s disease will be discussed in this article. 
Stage 1: No Real Cognitive Impairment (i.e., Normal Function)
In this stage, there is no cognitive impairment. People with no cognitive impairment have not experienced memory loss and have no problems communicating with medical professionals. At this stage, even you are unlikely to notice Alzheimer’s disease unless you have a specialized test such as a PET scan.
However, the changes in the brain started from that stage. 
Stage 2: Presence of Very Mild Cognitive Decline (the Earliest Signs of Alzheimer’s Disease)
In this stage, the person begins to notice something is wrong. It is a time of transition from “mild cognitive impairment (MCI),” which is the pre-stage of dementia, to mild dementia.
There are little changes such as the individual forget where they put things they use every day, and also words and names they are used to. The person begins to notice the change; however, these changes are not obvious in health examinations, nor are they obvious to family, friends, or colleagues.
At this stage, work and life will not be affected.