Causes of Memory Loss

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Most of us have, either occasionally or more frequently, had the unpleasant experience of forgetting something. These episodes of memory loss can cause irritation and frustration, as well as a fear that we're "losing it" and beginning to develop Alzheimer's disease.

While Alzheimer's and other kinds of dementia are responsible for many cases of memory loss, the good news is that there are other, non-permanent factors that can also cause memory loss. Better yet, some of them are easily reversed.

So, what causes us to forget? What prevents us from mentally storing that piece of information or being able to recall it? Here are some of the many reasons we can't remember.

Emotional Causes of Memory Loss

Because our mind and body are connected and affect each other, our emotions and thoughts can impact our brain. The energy it takes to cope with certain feelings or life stress can get in the way of storing or remembering details and schedules.

Often, these emotional triggers of memory loss can be improved by support, counseling, and lifestyle changes. Even just being aware of—and limiting exposure to—things that increase stress can help.


Too much stress can overload our minds and cause distraction and brain drain.​ Short-term, acute stress can trigger a momentary memory problem, while chronic, long-term exposure to stress may increase your risk of dementia. Stress management is an important strategy for maintaining quality of life and improving the health of your body and your brain.


Depression can blunt the mind and cause such disinterest in your surroundings that memory, concentration, and awareness suffer. Your mind and emotions may be so weighed down that you are just not able to pay much attention to what's happening.

Consequently, recalling something that you weren't paying attention to is difficult. Depression can also cause problems with healthy sleep, which can make it more difficult to remember information. 

Pseudodementia is a term that describes the combination of memory loss and depression. If you think you're experiencing pseudodementia, cognitive testing can be helpful in reassuring you and ruling out true dementia.

Despite feeling "out of it" in daily life, the person with pseudodementia will be able to perform quite well on cognitive tests. Depression is usually highly treatable. Often, a combination of counseling and medication can be very effective.


If you've ever blanked out when taking a test, even though you knew the answers, you can blame anxiety. Some people have anxiety in certain situations, like this test-taking example. Others have a more pervasive generalized anxiety disorder that continually interferes with healthy functioning, including memory. Identifying and treating anxiety can significantly improve quality of life, and possibly memory, as well.


Grieving requires a high amount of physical and emotional energy, and this can reduce our ability to focus on events and people around us. Consequently, our memory can suffer. Grief can be similar to depression, but it's often triggered by a specific situation or acute loss, while depression may seem to be without a specific cause.

Deep grief takes time to process, and it's appropriate and necessary to spend time in your grief. You can expect to feel drained—both physically and mentally—when you're going through grief. Give yourself extra time and grace while you're grieving. Individual counseling and support groups can help you to effectively cope with grief.

​Drugs and Medical Treatments That May Impair Memory

Sometimes memory lapses can be attributed to medications or other substances. These can include prescription drugs, other mind-altering substances, and even surgeries.

Alcohol or Illicit Drugs

Drinking alcohol or using illicit drugs can impair your memory, both in the short term and long term. From blackouts to an increased risk of dementia years later, these substances can significantly harm your memory, among many other things. Too much alcohol can also cause Wernicke-Korsakoff syndrome, which if treated immediately, may be able to be partially reversed in some people.

Prescription Medications​

Just because a medication is legally prescribed by a physician doesn't mean it can't hurt your body or impair your memory. You may be taking the medication exactly as ordered by the doctor, but prescription medicines (especially when taken in combination) can significantly affect your ability to think and remember clearly.

If you go to different doctors for multiple conditions, make sure each one has your complete list of medications. They need to know so they don't order a medication that could interact with the one you're already taking.

Ask your physician if any of your medications can be slowly reduced to eliminate this cause of forgetfulness.


If you're receiving chemotherapy as a treatment for cancer, you might experience "chemo brain," described as brain fog from the medicines targeting your cancer. Knowing that this is a common and often temporary effect from chemotherapy can be reassuring.

Heart Surgery

Some research has indicated that following bypass surgery on the heart, there may be an increased risk of confusion and memory impairment. This may improve as you recover, and typically the need for this type of heart surgery is greater than the possible risk. Be sure to discuss your concerns with your physician.


Some people report memory loss or confusion, typically lasting for a few days, following the use of anesthesia. Research, however, has been unclear in determining if there's a direct correlation between the anesthesia or if other factors may be causing the brain to function less effectively.

Electroconvulsive Therapy

Sometimes referred to as "shock" therapy, ECT can be very helpful for those suffering from severe depression, but it may also cause some memory loss. You should talk with your physician about the risks and benefits of ECT. Because it has been effective for some people, the risk of some memory loss may be worth it for your quality of life.

Physical and Medical Conditions That May Impair Memory

Other conditions aside from dementia or Alzheimer's disease can lead to memory loss or memory problems.

Fatigue and Sleep Deprivation

The benefits of getting a good night's sleep are many: Less weight gain, more energy, and the ability to think more clearly. Being tired because you didn't sleep well last night and being chronically short on sleep both have been shown to affect memory and learning. It's worth trying some easy ways to improve your sleep habits.

Concussions and Head Injuries

Concussions and traumatic head injuries can cause short-term memory impairment, but some research has found that they can also increase the likelihood for the development of dementia over the years.

Be sure to take steps like wearing protective headgear and helmets when playing sports. And, if you do sustain a concussion, it's important to let your head fully heal before returning to regular activities and participating in sports. Discuss any headaches and concentration difficulties after a head injury with your doctor.

Low Vitamin B12

Vitamin B12 is a very important vitamin. In more extreme cases, deficits in vitamin B12 have caused symptoms that have been mistaken for dementia. Upon receiving adequate vitamin B12, those symptoms may improve and even resolve in some people.

Thyroid Problems

Both hypothyroidism and hyperthyroidism can cause cognitive problems such as memory loss and mental fog. If you're noticing brain sluggishness or that it's more difficult to remember things, mention this to your doctor. It may be appropriate to test your thyroid functioning, especially if you're experiencing other symptoms of thyroid issues. Treating thyroid problems could improve your memory and concentration.

Kidney Disorders​

When your kidneys aren't working well, such as in chronic or acute kidney failure (also called renal failure), the accumulation of waste products, such as the breakdown of proteins, can affect brain function. In addition, studies published in 2017 have shown that those with albuminuria (the presence of albumin protein in the urine) are more likely to display impaired memory and cognition.

Liver Disorders

​Liver diseases, such as hepatitis, can cause toxins to be released into your bloodstream, which can then affect brain functioning. Hepatic encephalopathy is a related brain disorder that can develop from serious liver problems. If you have liver problems and notice some difficulty with memory and thinking, be sure to report this to your physician for prompt diagnosis and treatment.


This acute infection of brain tissue may trigger symptoms of dementia, such as confusion and memory problems, along with a fever, headaches and even seizures. If you suspect encephalitis, seek emergency medical treatment.

Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH) typically has symptoms in these three areas: cognitive problems, incontinence, and a decline in balance and walking. Prompt evaluation and treatment by a physician have the potential to reverse the problems with memory and thinking in NPH, as well as help with regaining the ability to be continent and to walk well.


Sometimes, the changes in the body's chemicals and hormones, combined with the emotional and physical changes in pregnancy, can contribute to forgetfulness and poor concentration. Fortunately, this is a temporary condition that resolves in due time.


Similar to pregnancy, the hormonal changes in menopause can bring chaos to thought processes and disturb sleep, which also impacts your cognitive processes. Some physicians prescribe hormonal supplements or other treatments to relieve the temporary symptoms of menopause.


Infections, such as pneumonia or urinary tract infections, can cause forgetfulness, especially in older adults and others with chronic health conditions. For some people, delirium—a sudden change in mental ability—is one of the only outward signs of an infection, so be sure to report these symptoms to the physician right away. Prompt treatment can often help restore memory to its normal functioning.


Strokes can significantly affect brain functioning. Sometimes, the memory loss related to a stroke is permanent, but other times the cognitive functioning improves as the brain recovers.

Transient Ischemic Attacks

A TIA, also known as a "little stroke" (although that isn't completely accurate medically), is a brief blockage in the brain that can cause lapses in memory, along with other stroke-like symptoms. Symptoms usually resolve on their own, but treatment is important to prevent future strokes.

Brain Tumors

Brain tumors can cause headaches and physical problems, but they can also affect our memory and personality at times. Depending on the severity and type of tumor, treatment can often relieve these symptoms.

Sleep Apnea

Sleep apnea, where you actually stop breathing for a few seconds while you're sleeping, has been connected to a higher risk of dementia. A study published in 2018 also tied sleep apnea to memory problems, which is not surprising given that sleep deprivation can cause forgetfulness and diminished brain functioning. 


As people age into older adulthood, cognitive processing generally slows down, and memory ability may slightly decline. For example, a healthy older person will still be able to memorize information, but it probably won't be as easy as when they were a child or young adult.

Knowing the difference between normal aging and true memory concerns can help you determine if you should visit the doctor or stop worrying about it.

Cognitive Causes of Memory Loss

Sometimes, problems with how the brain functions can lead to memory loss. These may be due to aging.


​Thinking about too many things at once? Attempts to multi-task in order to be efficient can sometimes decrease efficiency because of the need to repeat a task that was poorly completed or forgotten. Your brain has a limit on what it can effectively process simultaneously and remember.

Natural Memory Ability

Some people naturally just don't have a great memory. Maybe you've seen the difference between one person who needs to spend three hours to effectively learn and remember material, and another who has it mastered and can quickly recall it after taking only 20 minutes to page through it.

Mild Cognitive Impairment

Mild cognitive impairment (MCI) consists of a decline in mental abilities that develops gradually but generally doesn't change the person's ability to function fairly well on a daily basis. One symptom of MCI is forgetfulness.

Sometimes, MCI responds to medications that are designed to treat Alzheimer's. Some cases of MCI hold steady or even resolve completely, while others progress into Alzheimer's disease or other types of dementia.

Is It Alzheimer's or Another Kind of Dementia?

Alzheimer's disease is the most common cause of dementia and causes significant memory loss, in addition to multiple other symptoms. If you think your memory loss could be caused by Alzheimer's, review the symptoms and make an appointment with your physician for an assessment. Although Alzheimer's typically affects those over the age of 65, early-onset Alzheimer's can occur in those as young as 40.

Memory loss can also be caused by other kinds of dementia, such as vascular dementiaLewy body dementiafrontotemporal dementia, and several others. Problems with memory should be discussed with your doctor so that any reversible cause can be found and treated, or so that treatment for Alzheimer's or dementia can begin as soon as possible if this is the cause.

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Additional Reading

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.