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Memory Loss


Mark Freedman

, MD, MSc, University of Ottawa

Reviewed/Revised Oct 2023
Topic Resources

Memory loss can be a symptom of brain malfunction Overview of Brain Dysfunction Brain damage can cause many types of dysfunction. Such dysfunction ranges from complete loss of consciousness (as occurs in a coma), to disorientation and an inability to pay attention (as occurs... read more . It is one of the most common reasons that people, particularly older adults, visit a doctor. Sometimes family members notice and report the memory loss.

The biggest concern for the person, family members, and doctors is usually whether the memory loss is the first sign of Alzheimer disease Alzheimer Disease Alzheimer disease is a progressive loss of mental function, characterized by degeneration of brain tissue, including loss of nerve cells, the accumulation of an abnormal protein called beta-amyloid... read more , a progressive and incurable form of dementia (a type of brain disorder). People with dementia have lost the ability to think clearly. Usually, if people are aware enough of their memory loss to be concerned about it, they typically do not have early dementia.

Did You Know...

  • People who are aware of their memory loss typically do not have dementia.

Memories may be stored in short-term or long-term memory, depending on what they are and how important they are to the person.

  • Short-term memory holds a small amount of information that a person needs temporarily, such as a list of things to buy at the grocery store.

  • Long-term memory, as the name suggests, stores memories (such as the name of the person's high school) for a long time.

Short-term memory and long-term memory are stored in a different parts of the brain. Long-term memory is stored in many areas of the brain. One part of the brain (the hippocampus) helps sort new information and associate it with similar information already stored in the brain. This process turns short-term memories into long-term memories. The more often short-term memories are recalled or rehearsed, the more likely they are to become long-term memories.

Causes of Memory Loss

Common causes

The most common causes of memory loss are

  • Age-related changes in memory (most common)

  • Mild cognitive impairment

  • Dementia

  • Depression

Age-related changes in memory (called age-associated memory impairment) refer to the normal slight decline in brain function that occurs as people age. Most older adults have some memory problems. Retrieving memories of new things, such as what is a new neighbor's name or how to use a new computer program, takes longer. Older adults also have to rehearse new memories more often for the memories to be stored. People with this type of memory loss occasionally forget things, such as where they left their car keys. But for them, unlike people with dementia, the ability to do daily activities or to think is not impaired. Given enough time, these people usually remember, although sometimes later than is convenient. This type of memory loss is not a sign of dementia or early Alzheimer disease.

Mild cognitive impairment is an imprecise term used to describe impairments in mental function that are not severe enough to affect daily functioning. Memory loss is often the most obvious symptom. Memories are actually lost, not merely slow to retrieve, as occurs in people with age-related changes in memory. People with mild cognitive impairment have trouble remembering recent conversations and may forget important appointments or social events, but they typically remember past events. Attention and the ability to do daily activities are not affected. However, up to half of people with mild cognitive impairment develop dementia within 3 years.

Dementia Dementia Dementia is a slow, progressive decline in mental function including memory, thinking, judgment, and the ability to learn. Typically, symptoms include memory loss, problems using language and... read more is a much more serious decline in mental function. Memory loss, particularly for recently acquired information, is often the first symptom, and it becomes worse with time. People who have dementia may forget entire events, not just the details. They may do the following:

  • Have difficulty remembering how to do things they have done many times before and how to get to places they have often been to

  • No longer do things that require many steps, such as following a recipe

  • Forget to pay bills or keep appointments

  • Forget to turn off a stove, lock the house when they leave, or take care of a child left in their care

In the early stages of dementia, people may be aware of their memory loss. But as dementia progresses, they, unlike people with age-related changes in memory, become unaware of their memory loss and often deny that they have such loss.

Finding the right word, naming objects, understanding language, and doing, planning, and organizing daily activities become more and more difficult. People with dementia eventually become disoriented, not knowing what time or even what year it is or where they are. Their personality may change. They may become more irritable, anxious, paranoid, inflexible, or disruptive.

Some conditions that increase the risk of heart and blood vessel disorders (such as high blood pressure, high levels of cholesterol, and diabetes) seem to increase the risk of dementia.

Depression Depression Depression is a feeling of sadness and/or a decreased interest or pleasure in activities that becomes a disorder when it is intense enough to interfere with functioning. It may follow a recent... read more can cause a type of memory loss (called pseudodementia) that resembles memory loss due to dementia. Also, dementia commonly causes depression. Thus, determining whether dementia or depression is the cause of memory loss can be difficult. However, people with memory loss due to depression, unlike those with dementia, are aware of their memory loss and complain about it. Also, they rarely forget important current events or personal matters and usually have other symptoms, such as intense sadness, sleeping problems (too little or too much), sluggishness, or loss of appetite.

Stress can interfere with forming a memory and with recalling a memory, partly by preoccupying people and thus preventing them from paying attention to other things. However, in certain circumstances, particularly when stress is mild to moderate and does not last long, it can enhance memory.

Less common causes

Many disorders can cause a deterioration of mental function that resembles dementia.

Some of these disorders may be reversed with treatment. They include the following:

Other disorders are only partially reversible. How much they can be reversed depends on how much tissue has been damaged. They include

In people with these disorders, treatment can sometimes improve memory and mental function. If damage is more extensive, treatment may not improve mental function but can often prevent further deterioration.

In delirium Delirium Delirium is a sudden, fluctuating, and usually reversible disturbance of mental function. It is characterized by an inability to pay attention, disorientation, an inability to think clearly... read more , memory is affected, but memory loss is not the most noticeable symptom. Rather, people with delirium are very confused, disoriented, and incoherent. Severe alcohol withdrawal (delirium tremens), a severe bloodstream infection (sepsis), lack of oxygen (as may result from pneumonia), and many other disorders can cause delirium, as can use of illicit drugs.

Evaluation of Memory Loss

When evaluating memory loss, doctors first determine whether the cause is delirium Delirium Delirium is a sudden, fluctuating, and usually reversible disturbance of mental function. It is characterized by an inability to pay attention, disorientation, an inability to think clearly... read more or another reversible cause. Reversible causes require immediate treatment.

Doctors then focus on determining whether the cause of memory loss is normal age-related changes in the brain, mild cognitive impairment, depression, or early dementia.

Warning signs

In people with memory loss, certain symptoms are cause for concern:

  • Difficulty doing usual daily activities

  • Difficulty paying attention and fluctuations in level of consciousness—symptoms that suggest delirium

  • Symptoms of depression (such as loss of appetite, suicidal thoughts, difficulty sleeping, and slowing of speech and general activity)

When to see a doctor

People with warning signs should see a doctor. They should see a doctor immediately if they

  • Cannot pay attention and seem very confused, unfocused, and disoriented—symptoms that suggest delirium

  • Feel depressed and are thinking of hurting themselves

  • Have other symptoms that suggest a problem with the nervous system, such as headaches, difficulty using or understanding language, sluggishness, vision problems, or dizziness

People who do not have warning signs but are concerned about their memory or have difficulty doing basic daily activities should call their doctor. The doctor can determine how quickly they need to be seen based on other symptoms they have and the severity of the symptoms.

What the doctor does

Doctors ask about the person’s symptoms and medical history Medical History in Neurologic Disorders Before doing a physical examination, doctors interview the person to obtain information about the person's current and past health (medical history). The history is the most important part of... read more . Doctors then do a physical examination. Having a family member present is helpful because people with memory difficulties may not be able to describe their symptoms accurately. What doctors find during the history and physical examination often suggests a cause and the tests that may need to be done (see table ).

Doctors often talk to the person and the person’s family members separately because family members may not feel free to describe the symptoms candidly with the person listening.

Doctors ask specific questions about the memory loss:

  • What types of things the person forgets (for example, whether the person forgets words or names or gets lost)

  • When the memory problems started

  • Whether memory loss is getting worse

  • How the memory loss is affecting the person’s ability to function at work and at home

Doctors also ask whether the person has other symptoms, such as difficulty using or understanding language and changes in their eating and sleeping habits or mood. They ask about all disorders the person has had and all the medications, illicit drugs, over-the counter medications, and nutritional supplements the person is taking to check for possible causes. Doctors also ask the person about any unusual dietary habits. Information about the person’s education, jobs, and social activities can help doctors better assess the person's previous mental function and gauge the severity of the problem. Doctors ask whether any family members have had dementia or early mild cognitive impairment.

  • Orientation to time, place, and person: State the current date and place and who they are.

  • Attention: Repeat a short list of words.

  • Concentration: Spell "world" backwards or repeat their phone number forward, then backward.

  • Short-term memory: Recall the short list of words after several minutes.

  • Long-term memory: Answer questions about the distant past.

  • Use of language: Name common objects and body parts, and read, write, and repeat certain phrases.

  • Ability to understand spatial relationships: Copy simple and complex structures (for example, using building blocks) and draw an object such as clock, cube, or house.

This testing also assesses abstract thinking, comprehension, the ability to follow commands and solve math problems, awareness of the illness, and mood.



Doctors can usually determine whether the cause is age-related changes, mild cognitive impairment, or early dementia based on the type of memory loss and the symptoms that accompany it.

However, when the diagnosis is unclear, neuropsychologic testing can provide more information. This testing is similar to mental status testing except it is much more detailed. Complete testing may take hours. These tests must be given by a trained, licensed psychologist or psychiatrist with expertise in memory loss. These tests may not be as useful in people over 65.

If doctors suspect dementia or find any abnormalities during the neurologic examination, they usually do magnetic resonance imaging (MRI) or, if MRI is unavailable, computed tomography (CT) to check for abnormalities such as a brain tumor, normal-pressure hydrocephalus, damage due to a head injury, and stroke.

Doctors may also do blood tests to measure levels of vitamin B12 and thyroid hormones to determine whether vitamin B12 deficiency or a thyroid disorder could be causing memory loss. These disorders are reversible causes of memory loss.

If a brain infection is suspected, doctors usually do a spinal tap Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Imaging tests commonly used to diagnose nervous system (neurologic) disorders... read more Spinal Tap (lumbar puncture) to obtain samples of the fluid around the brain (cerebrospinal fluid) for analysis.

Treatment of Memory Loss

Treating any disorders contributing to memory loss may help restore memory. For example, vitamin B12 deficiency is treated with vitamin B12 supplements, and an underactive thyroid gland is treated with thyroid hormone supplements. For depression, treatment involves medications, psychotherapy, or both. Doctors choose antidepressants that do not worsen memory loss, such as selective serotonin reuptake inhibitors Selective serotonin reuptake inhibitors (SSRIs) Several types of medications can be used to treat depression: Selective serotonin reuptake inhibitors (SSRIs) Norepinephrine-dopamine reuptake inhibitors, serotonin modulators, and serotonin-norepinephrine... read more (SSRIs). For normal-pressure hydrocephalus, a shunt can be surgically placed to drain the excess fluid around the brain. If a person is taking medications that affect brain function, doctors may stop the medication, decrease the dose, or try substituting another medication.

If the only cause is age-related changes in memory, doctors reassure people that the problem is not serious, that these changes do not mean that mental function will decline substantially, and that there are ways to compensate for losses and possibly to improve mental function (see Essentials for Older People Essentials for Older People Memory loss can be a symptom of brain malfunction. It is one of the most common reasons that people, particularly older adults, visit a doctor. Sometimes family members notice and report the... read more ).

General measures

Some generally healthful measures are often recommended for people who are worried about memory loss:

  • Exercising regularly

  • Eating a healthy diet with lots of fruits and vegetables

  • Getting enough sleep

  • Not smoking

  • Minimizing use of alcohol or other substances (such as marijuana)

  • Participating in social and intellectually stimulating activities

  • Getting regular check-ups

  • Avoiding high levels of stress

  • Protecting the head from injury

These measures, along with controlling blood pressure, cholesterol levels, and blood sugar levels, also tend to reduce the risk of heart and blood vessel disorders. Some evidence suggests that they may reduce the risk of dementia, but this effect has not been proved.

Some experts recommend the following:

  • Learning new things (such as a new language or a new musical instrument)

  • Doing mental exercises (such as memorizing lists, doing word puzzles, or playing chess, bridge, or other games that use strategy)

  • Reading

  • Working on the computer

  • Doing crafts (such as knitting and quilting)

  • Using cues to help with remembering and organizing things

These activities may help maintain or improve mental function, possibly because they strengthen connections between nerves. Having stronger nerve connections helps people postpone the decline in mental function that results from changes in the brain and then helps them compensate for that decline.


Aducanumab is used to treat Alzheimer disease. However, many experts disagree about which people should use the medication or even whether the medication should be used at all. Lecanemab and donanemab are newer medications that may be used to treat Alzheimer disease.

Mild cognitive impairment may be treated with donepezil. This medication may temporarily improve memory, but the benefit appears to be slight. No other medication has been shown to help.

Safety and supportive measures

No treatment can restore mental function or completely stop the progression of dementia. Thus, treatment of dementia Treatment Dementia is a slow, progressive decline in mental function including memory, thinking, judgment, and the ability to learn. Typically, symptoms include memory loss, problems using language and... read more focuses on keeping the person safe and providing support as the person declines.

If memory loss is relatively severe or family members are concerned about the person's safety, the person's home can be evaluated by occupational or physical therapists. They can recommend ways to prevent falls and other accidents and may suggest protective measures, such as hiding knives, unplugging the stove, and taking the car keys away.

A supportive environment has the following characteristics:

  • Orientation is frequently reinforced (for example, by large calendars and clocks).

  • The atmosphere is bright and cheerful.

  • A regular routine is followed.

  • Some stimulation (for example, from a television or radio) and enjoyable activities are available.

Eventually, the person may need a housekeeper or home health aide or may need to move to a one-story home, an assisted-living facility, or a skilled nursing facility.

Essentials for Older People: Memory Loss

As people age, most start having some memory problems. Usually, memory loss is caused by normal age-related changes in the brain and does not lead to dementia. Understanding such changes can reduce anxiety and thus help older people adjust and compensate.

Estimates of how many people have mild cognitive impairment vary, but it is common. Some studies report that 7% of people have it at age 70 and 25% of people have it after age 80.

Dementia occurs in

  • About 1% of people aged 60 to 64

  • 3% of people aged 65 to 74

  • Almost 15% of people aged 75 to 79

  • About 25% of people aged 80 to 84

  • 30 to 50% of people over 85

  • 60 to 80% of older nursing home residents


Strategies that can help people cope with a declining memory include

  • Making lists

  • Keeping a detailed calendar

  • Establishing routines

  • Making associations or relating new information to information already known, such as associating a new person’s name with the name of a movie star

  • Repeating information, such as repeating a new person’s name several times

  • Focusing on (paying attention to) one thing at a time

  • Improving organizational skills, such as keeping frequently used items such as car keys in the same place

Making sure that they can hear and see well can help people stay engaged with others and participate in social activities. Such participation helps people maintain confidence in themselves and often improves mental function.

Key Points

  • Memory loss and fear of dementia are common sources of worry among older adults.

  • Usually, memory loss results from normal age-related changes in the brain, which slow mental functions slightly but do not significantly impair them.

  • Memory loss due to dementia usually interferes with the ability to do daily activities and becomes progressively worse.

  • People who are aware of memory loss may not have dementia.

  • Doctors can usually identify the cause based on results of the examination, imaging tests (such as MRI or CT), and other tests, including formal tests of mental function.

  • Having a healthy lifestyle, staying mentally active, and participating in social activities may help maintain mental function or postpone its decline.

  • Using lists and other memory aids, focusing on one thing at a time, and getting organized can help older adults compensate for age-related changes in memory.

  • Medications called cholinesterase inhibitors (such as donepezil) and may help with memory, particularly if people have Alzheimer disease or dementia with Lewy bodies, and lecanemab and donanemab may help.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  • Alzheimer's Association: This web site has information about dementia in general and Alzheimer disease (such as statistics, causes, risk factors, early symptoms and signs, options for care, and daily care of someone with Alzheimer disease). It also includes tips to improve brain health and links to support groups and local resources.

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