The 4 A's of Alzheimer's Disease

Amnesia, Aphasia, Apraxia, and Agnosia

The four A's are four words that describe some of the main symptoms of Alzheimer's disease. The A's represent the following:

Petri dish with brain scan showing dementia
Andrew Brookes / Getty Images


Amnesia refers to memory loss and is often the most easily visible and common sign of Alzheimer's disease. Memory loss in Alzheimer's disease typically begins with short-term memory and progresses to a decline in long-term memory.

There are different types of amnesia, including:

  • Retrograde amnesia is memory loss that is limited to the period before a head injury occurred or before a disease such as Alzheimer's developed. Retrograde amnesia hinders the ability to retrieve the memories that were already stored in the brain.
  • Anterograde amnesia is memory loss that is present for events that occur or information that is presented after a brain injury or a disease develops. The ability to make new memories is impaired in anterograde amnesia.


Aphasia is a term used to describe impaired communication. Aphasia may be classified as expressive aphasia, where someone is unable to find the right words or may say them incorrectly, or receptive aphasia, where the ability to understand, receive and interpret language is impaired.

Aphasia is commonly thought of as the impairment of speech and language, but it also can include the ability to read and write.

Alzheimer's disease affects both expressive and receptive aphasia. In the early stages of Alzheimer's, there might be some mild difficulty with finding the right word. As Alzheimer's progresses into the later stages, speech may become nonsensical and impossible to understand, and it may be difficult to determine how much of what you say is being comprehended.

Thus, your non-verbal communication—which is an important aspect of interacting with each other when cognition is intact—becomes that much more important when interacting with someone who is living with dementia. This can include basic tactics such as remembering to smile to reassure your loved one that you are there to help her, as well as more advanced non-verbal approaches such as demonstrating a task you want to have her complete, instead of just verbally telling her.


Apraxia is a deficit in voluntary motor skills. While Alzheimer's is known primarily for affecting cognitive functioning, it also affects the body's physical ability to function. As Alzheimer's progresses, the ability to perform certain activities of daily living such as bathing and getting dressed might decline. Activities such as walking and eating become more difficult in the late stages of Alzheimer's disease.

Due to these changes, people living with Alzheimer's also are at a high risk of falling, and when they do fall, they are at a higher risk of fracturing their hip. Remaining as active as possible, for as long as possible, may help delay some of the physical changes in apraxia that develop in Alzheimer's.


Agnosia is the impairment of the ability to receive or correctly understand information from the senses of hearing, smell, taste, touch, and vision. For example, people with Alzheimer's disease often are less able to identify smells or understand the feeling of a full bladder. They also might not be able to recognize loved ones as the disease progresses. Difficulty recognizing or interpreting visual shapes is frequently present in Alzheimer's disease.

Agnosia may also be auditory, where the sense of hearing is intact but the ability to interpret what the sound means is impaired.

The presence of agnosia is often part of a cognitive assessment. For example, one task on the mini mental state exam (MMSE) requires the test-taker to copy an intersecting pentagon figure. Difficulty in this task reduces the total points the person achieves on this test and can be a sign of cognitive impairment.


Alzheimer's disease has many symptoms which can be loosely grouped into the four categories of amnesia, aphasia, apraxia, and agnosia. If you recognize these symptoms in someone you love, make sure to contact a healthcare provider for a full evaluation.

While the impairments may be due to Alzheimer's disease, there are also other conditions that may cause these symptoms, some of which may be reversible if identified and treated. Thus, early identification and assessment are necessary and beneficial.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
  • Alzheimer's Foundation of America. About Alzheimer's.

  • Alzheimer's Foundation of America. National Memory Screening.

  • Alzheimer Europe. Main characteristics: August 2009. Alzheimer's disease.

  • Kahandawaarachchi, A., Perera, K., and Gunasinghe, L. (2017). Diagnosing Alzheimer’s Disease. International Journal of Computer Applications, 161(4), pp.21-25.

  • US Department of Health and Human Services. National Institute on Aging. About Alzheimer's Disease: Symptoms.

  • US Department of Health and Human Services. October 2008. National Institute on Deafness and Other Communication Disorders. Aphasia.

By Esther Heerema, MSW
Esther Heerema, MSW, shares practical tips gained from working with hundreds of people whose lives are touched by Alzheimer's disease and other kinds of dementia.