You can’t find your keys, or perhaps you forgot an appointment. For many people in middle age or older, simple acts of forgetfulness like these are scary because they raise the specter of Alzheimer’s disease.

But Alzheimer’s is not the only health problem that can lead to forgetfulness, says the National Institute on Aging. Memory lapses can happen at any age and for a number of reasons. And when the underlying cause is treated, the memory problems often improve as well.

“Patients might experience memory loss and describe their symptoms similarly, but a doctor can tease apart what parts of the brain are affected,” says Seth Gale, MD, a neurologist at Brigham and Women’s Hospital and assistant professor of neurology at Harvard Medical School in Boston.

“When you drill down and find out what’s actually happening with someone’s mental functions, you can reassure them. For example, it’s common for people to still have the capacity to learn and store information, but because of their overloaded mental resources at this time of their life, they have trouble doing it well,” Dr. Gale says.

Talk with your doctor about concerns you may have about your memory, so that the condition responsible for your symptoms can be addressed. Discussing your symptoms and taking various tests, including possibly an MRI, may help your doctor determine what is affecting your memory, Gale says.

In some cases, one or more of the following issues could be playing a role:

1. Stress, Anxiety, and Depression

Significant stress or anxiety can lead to problems with attention and memory, says Constantine Lyketsos, MD, director of the Memory and Alzheimer's Treatment Center at Johns Hopkins Medicine and professor and chair of psychiatry at Johns Hopkins Bayview.

This is particularly common among people who may be juggling home and work responsibilities and are not sleeping well. Usually, easing stress can improve memory, he says.

Untreated chronic stress can lead to depression, which could also affect brain function, including some measures of memory, according to a study published in May 2022 in Frontiers in Psychiatry. However, a mood disorder such as depression may improve with medication and counseling, notes the National Institute on Aging.

2. Sleep Problems

Sleep problems, including insomnia, or the chronic inability to fall or stay asleep, as well as sleep apnea, a disorder that causes breathing to stop briefly and frequently throughout the night, have been linked with memory loss and dementia, according to Harvard Medical School. Lack of sleep causes fatigue, which, in turn, can lead to brain fog and memory problems, it says.

In a study published in May 2022 in the Journal of Sleep Research, people with insomnia and sleep apnea were less likely to perform well on assessments designed to measure memory, compared with people without those conditions.

When not treated, sleep apnea affects spatial navigational memory, found a study published in the Journal of Clinical Sleep Medicine in 2021. This type of memory includes being able to remember directions and where you put things, like your keys, Dr. Lyketsos says.

One explanation is that for people with sleep apnea, oxygen delivery to the brain is interrupted several hundred times during the night, explains Lyketsos. “The brain is stressed by the oxygen disruption, so people wake up,” he says. The injury that sleep apnea causes can show up as a variety of memory loss symptoms, he adds.

3. Medications

Memory loss or forgetfulness could be a sign that your medication needs to be adjusted. Several types of drugs can affect memory, according to the American Association of Retired Persons, including:

Anti-anxiety medications
Antidepressants
Antihistamines
Anti-seizure medications
Blood-pressure medications
Certain painkillers
Cholesterol-lowering medications
Diabetes medications
Drugs to treat Parkinson’s disease
Sleeping pills

The U.S. Food and Drug Administration also cautions that the cholesterol-lowering drugs known as statins could slightly increase the risk of reversible cognitive side effects, including memory loss and confusion.

4. Nutritional Deficiency

A lack of sufficient levels of B12, one of the B vitamins essential for normal nerve function, can lead to confusion and even dementia, according to the Cleveland Clinic.

Each day, adults should get about 2.4 micrograms of B12 in their diet from foods such as dairy products, meat, and fish, or from foods fortified with vitamin B12, such as fortified cereals, according to the National Institutes of Health.

Risk factors for developing a vitamin B12 deficiency include:

Being older than 75
Having a digestive system disorder
Following a strict vegan or vegetarian diet
Taking certain medications, include metformin, proton pump inhibitors or H2 blockers (both are drugs that decrease stomach acid), and birth control pills
Having Sjögren’s syndrome
Drinking large amounts of alcohol

5. Silent Stroke

Obvious changes in the ability to think and move normally can come from a stroke that blocks major blood vessels that feed the brain, Gale says.

Mild memory problems can also develop gradually after “silent strokes” — or those that occur without any noticeable symptoms — which affect smaller blood vessels, the American Heart Association says. These changes in brain function, which can range from mild to severe, are called vascular cognitive impairment.

The brain is especially vulnerable to blocked or reduced blood flow depriving it of oxygen and essential nutrients. People with memory loss are at a greater risk of stroke. And forgetfulness may be an early warning sign of cardiovascular diseases, including stroke, a study published in BMC Public Health in 2021 found.

Less Common Causes of Memory Loss

Other conditions that can lead to problems with memory include:

Infection Memory loss may be attributed to severe infection around the brain, particularly if it’s left untreated, Gale says. For example, some people with long COVID-19 have reported memory loss following infection, according to Lyketsos.
Head Injury Symptoms of a mild brain injury may include confusion and trouble with memory and concentration, according to the U.S. National Institute of Neurological Disorders and Stroke.
Tumors Memory and the ability to process information may be affected by brain tumors, says the National Brain Tumor Society. In addition, the treatments for a brain tumor, such as brain surgery, chemotherapy, or radiation therapy, can all affect your memory.
Alcoholism, Substance Abuse Both alcoholism and drug abuse can affect memory, says Lyketsos. A study published in April 2022 in the Journal of Translational Medicine found that heavy alcohol consumption among adults age 70 and older increased their risk of cognitive impairment, compared with light drinkers and nondrinkers in the same age group.

Additional reporting by Brian P. Dunleavy.

5 Surprising Causes of Memory Loss