The development of the disease is divided into three main stages, each presenting a variety of different symptoms. The severity of the symptoms progresses throughout the stages.

Early Alzheimer's

At this stage the most notable problem is memory loss, usually forgetting the most recent memories. This is often accompanied by language problems, such as a reduced vocabulary and difficulty in following conversations. At this stage the patient is still able to communicate with others, but has difficulty engaging in conversations and they can find it challenging to learn new information. Patients frequently misplace objects, leading to anger and frustration. Personality changes, including mood swings, can also be observed.

This stage usually lasts around 2-4 years, with symptoms progressing.

Moderate Alzheimer's

This stage is usually the longest, ranging from 2-10 years. During this time the patient gradually becomes disabled. Patients find they need help with more complex movements, but are still able to conduct simple everyday tasks. Patients begin to develop hallucinations, delusions and often become disorientated. Suffers become disconnected with reality and can begin to confuse past events with the present day.

Depression is associated with this stage of Alzheimer's Disease as the patient begins to be aware of their loss of control and ability. During this stage as the symptoms are progressing, patients become unable to be left alone for long periods of time for safety reasons. Also, patients may become sleep deprived, and become restless and irritable.

Severe Alzheimer's

This stage may last from 1-3 years, with the disease worsening. The patient now needs constant care. At this final stage the patient becomes physically weaker and may be susceptible to other medical illnesses, such as skin infections and respiratory problems.

Memory loss becomes severe and any traces of memory are usually non-existent. Patients lose the ability to speak and often lose control of bodily functions. Patients are usually immobile or have a severe loss of movement with a great chance of falling. Sufferers at this point also have trouble swallowing. Hallucinations become severe, mood swings and behavioural changes become extreme.