9 Surprising Memory Loss Causes Later in Life

These lesser-known factors may affect your risk of dementia.

Genetics and aging are major risk factors for memory loss and dementia—loss of cognitive functions such as thinking, remembering, and reasoning, per the National Institute on Aging (NIA). About a third of people ages 85 or older may experience dementia, so it's important to understand the early signs and risks for the condition.

The main cause of dementia is a brain disorder called Alzheimer's disease, per the NIA. But other conditions can also cause issues with memory and reasoning.

Researchers don't fully understand what causes cognitive issues, but they've identified some factors associated with dementia. Some, such as depression, may be both a risk and an early warning sign—something to watch for, especially as you age.

Poor Sleep

Poor sleep can affect a person's brain in many ways. It may lead to brain inflammation and other processes that contribute to Alzheimer's disease. And Alzheimer's in turn can lead to even worse sleep, per a July 2020 report published in the journal Lancet Commissions.

Different sleep issues can increase the risk of dementia and Alzheimer's, including insomnia, sleep apnea, sleeping less than 5 hours or more than 10 hours a night, and poor sleep quality in general, per an August 2018 paper published in the journal Sleep Medicine Reviews. Sleep apnea is a disorder that causes a person to occasionally stop breathing during sleep.


Social isolation may contribute to the decline of certain cognitive functions, including memory. On the other hand, social contact may be protective against dementia, per the July 2020 report. Engaging in activities with other people and having larger social networks later in life is associated with better cognitive functioning, per an August 2019 review published in the Journal of Alzheimer's Disease.

It's also possible that isolation is not a cause of dementia, but rather its early symptom. People who experience memory loss may no longer be able to participate in their hobbies or keep up with their favorite sports team, leading to withdrawal from social interaction, per a March 2021 review published in the journal Alzheimer's & Dementia.

Head Injuries

Head injuries, also called traumatic brain injuries (TBIs), can increase your risk of dementia, per the March 2021 review. TBIs occur from a blow or jolt to the head, or penetration of the skull by an object. A mild TBI is also known as a concussion.

The risk of dementia is higher in people who have experienced multiple TBIs or a severe TBI, per an April 2018 study published in the journal Lancet Psychiatry. The mechanism for that was unclear and possibly dependent on the severity of the injury, per a September 2018 study published in JAMA Neurology.

Air Pollution

Exposure to air pollutants has been linked to an increased risk of dementia, per an August 2019 review published in the Journal of Alzheimer's Disease. Specifically, high levels of PM2.5 and NO2/NOx in the air can lead to inflammation in the brain.

PM2.5 stands for tiny particulate matter (particle pollution) that can come from sources such as power plants, construction sites, and fires, per the United States Environmental Protection Agency (EPA). NO2/NOx are harmful gases emitted from burning fuel in cars and power plants, per the EPA.

Breathing air with a lot of NO2 can lead to respiratory issues such as asthma, per the EPA. And PM2.5 air pollution has been linked to a variety of health issues in addition to dementia, such as heart disease, kidney disease, high blood pressure, and type 2 diabetes, per a November 2019 study published in the journal JAMA Network Open.

Heavy Alcohol Use and Smoking

Heavy alcohol use can cause changes in brain structures, possibly leading to cognitive issues. Specifically, drinking more than 21 units of alcohol (about two bottles of wine) weekly can lead to an increased risk, per the July 2020 report. There's no evidence that light or moderate drinking can hurt your cognitive functioning later in life.

A January 2019 review published in the journal Alzheimer's Research & Therapy suggested that reducing alcohol use could be a dementia prevention strategy, but more research was needed. Try to limit your drinking to about 14 units per week—about 6 pints of average-strength beer—spread out over multiple days.

Smoking is also associated with dementia. But quitting smoking may reduce that risk, per a September 2018 study published in the journal Annals of Clinical and Translational Neurology.

Hearing Loss

Hearing loss is associated with a higher risk of Alzheimer's, per an August 2019 review published in the International Tinnitus Journal. Using hearing aids can help, according to the July 2020 report.

The exact reason for this connection is unknown, but there are several theories. One is that hearing loss can lead to increased social isolation—another risk factor for dementia. The other is that losing hearing makes the brain work harder to make up for the impairment, leading to fewer resources for other cognitive functions. Finally, it's possible that hearing loss and dementia develop through similar brain mechanisms.

Heart Disease

Brain and heart health are closely connected. The brain uses 20% of the body's oxygen and energy supplies, per the March 2021 report. Heart disease and its risk factors—such as smoking and diabetes—are associated with dementia as well.

Physical activity and a heart-healthy diet—with fruits, vegetables, whole grains, fish, nuts, and legumes—can protect against heart disease, which can, in turn, reduce the risk of cognitive decline, per the March 2021 report. But note that there isn't a diet that can directly lower your risk of dementia, per a March 2019 study published in the journal JAMA.

High Blood Pressure

Blood pressure readings come with two numbers: systolic and diastolic blood pressure. Systolic pressure is measured when your heart beats, and diastolic is measured between beats, per the Centers for Disease Control and Prevention (CDC).

Healthy systolic blood pressure is below 120 mmHg. Your risk of dementia increases when this number is 130 mmHg or higher in midlife (at 50 years old), per a June 2018 paper published in the European Heart Journal.

Getting treatment for high blood pressure (hypertension) and keeping it in check in your midlife can help, per the July 2020 report. And high blood pressure that develops later in life may actually have a protective effect, per a July 2017 review published in the journal Neurotoxicology.

Physical Inactivity

Being physically active can reduce your risk of dementia, per the July 2017 review. But researchers don't know how much or what type of exercise is best. Aerobic exercise, aka cardio, had a small but beneficial effect in some studies, per the July 2020 report.

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