How Short-Term Memory Is Affected by Alzheimer's

Short-term memory (STM) is the period of time during which you can remember information immediately after being exposed to it. For example, after hearing a phone number and repeating it a couple of times, you may be able to remember it long enough to dial it accurately. Five minutes later, however, it’s entirely likely you won't be able to recall that phone number.

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Capacity of Short-Term Memory

It has long been established that short-term memory holds between five to nine items of information, with the average being seven.

This capacity can be extended by using memory strategies, such as chunking information or attaching meaning to it. You can also hold information indefinitely in your short-term by rehearsing it (repeating it over and over), which may result in it eventually being transferred over to your long-term memory.

Clinicians' Definition

Some experts measure short-term memory in hours, days, or weeks. For example, if it’s late afternoon and you can’t recall what you ate for breakfast or you forgot that you went to the doctor four days ago, your physician may call that "short-term memory impairment."

Technically, information from a few hours ago better fits into the term intermediate memory: the time period that bridges the gap of approximately a few minutes and extends into a day or two.

How Is Short-Term Memory Affected by Alzheimer's Disease?

Short-term memory impairment is one of the earlier symptoms of Alzheimer's disease. It can cause people to forget the question they just asked or where they set their glasses down. Repetition of questions and behaviors is often a result of short-term memory impairment in dementia.

Other Causes of Short-Term Memory Impairment

It's normal to be concerned if you experience occasional memory lapses, but you can rest reassured that not all short-term memory problems are a sign of Alzheimer's. In fact, there's a wide variety of reasons you might experience short-term memory impairment, many of which are temporary or easily treatable.

  • Acute grief
  • Chronic depression
  • Stress/feeling overwhelmed
  • Anxiety
  • Fatigue/lack of sleep
  • Normal pressure hydrocephalus
  • Vitamin B12 deficiency
  • Mild cognitive impairment
  • Other kinds of dementia
  • Delirium from an infection or illness
  • Head injuries
  • Conditions in the brain (tumor, infection, blood clots)
  • Certain diseases of the thyroid, kidney, or liver
  • Medications, among them the antidepressant Paxil (paroxetine) and the heartburn drug Tagamet (cimetidine)
  • Drinking too much alcohol


If you notice a persistent problem with your short-term memory or someone else has identified this as a concern, you should seek an evaluation to determine the cause and appropriate treatment. If it's related to a reversible condition, you'll be able to address the cause and improve the symptoms. If it's caused by a dementia like Alzheimer's, early treatment has thus far been the most effective in maintaining cognitive functioning and can help you cope with that new diagnosis.

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9 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.
  1. Vallar G. Short-Term Memory. Reference Module in Neuroscience and Biobehavioral Psychology. Elsevier, 2017, doi:10.1016/B978-0-12-809324-5.03170-9

  2. University of Minnesota Libraries Publishing. 8.1: Memories as Types and Stages. Introduction to Psychology. Oct 26, 2015. doi:10.24926/8668.1201

  3. Kamiński J. Intermediate-term memory as a bridge between working and long-term memory. J Neurosci. 17 May 2017, 37 (20) 5045-5047. doi:10.1523/JNEUROSCI.0604-17.2017

  4. Alzheimer's Association. 10 Early Signs and Symptoms of Alzheimer's Disease.

  5. National Institute on Aging. Do Memory Problem's Always Mean Alzheimer's Disease? Jan 24, 2018.

  6. Hydrocephalus Association. About Normal Pressure Hydrocephalus.

  7. Issac TG, Soundarya S, Christopher R, et al. Vitamin B12 deficiency: an important reversible co-morbidity in neuropsychiatric manifestations. Indian J Psychol Med. 2015 Jan-Mar; 37(1): 26–29.


  8. UpToDate. Delirium Causes. Feb 16, 2021.

  9. Harvard Health. 7 common causes of forgetfulness. Apr 18, 2020.

Additional Reading
  • The Newsletter of the Memory Disorders Project at Rutgers University. Glossary.