Seizures, Epilepsy and Dementia: What Families Should Know

People with Alzheimer's and other dementias have seizures more often than other people their age, and epilepsy that starts later in life is linked to a higher dementia risk. Here's what seizures can look like, why the link matters, and when to call a doctor.

By Jim Pavlish, Editor · Last updated: October 27, 2026 · Editorial policy

Most people picture a seizure as a person falling and shaking. But many seizures look nothing like that, and in older adults they're easy to mistake for a "bad memory day," a fainting spell or simply getting older. Researchers have also found a two-way link between seizures and dementia that families and doctors are paying more attention to.

This page is general information, not medical advice. If someone is having a seizure that lasts more than five minutes, has trouble breathing afterward, is injured, or has never had a seizure before, call 911.

What a seizure is

A seizure is a sudden burst of abnormal electrical activity in the brain. Epilepsy is the diagnosis doctors use when someone has had two or more seizures that weren't caused by something temporary, such as very low blood sugar or alcohol withdrawal, or one seizure with a high chance of more, according to the National Institute of Neurological Disorders and Stroke.

How the two conditions are linked

Dementia can lead to seizures. People with Alzheimer's disease have seizures more often than people of the same age without it. The brain changes of Alzheimer's, including amyloid and tau buildup, seem to make brain networks more "excitable." Seizures are also seen in Vascular Dementia, after strokes, and in some rarer types such as Creutzfeldt-Jakob Disease.

Some seizures are silent. A small 2016 study at the University of California, San Francisco, recorded brain activity overnight in 33 people with Alzheimer's who had never had a known seizure. About 42% showed seizure-like electrical activity that nobody had noticed, compared with about 11% of people without memory problems. Over the next few years, the group with that hidden activity declined faster on memory tests. The study was small, but it raised the question of whether treating that activity could help, which is now being studied.

Seizures that start later in life can be an early sign. A large US study of more than 9,000 older adults found that people whose seizures began at age 67 or older were about three times as likely to develop dementia later, after accounting for other risk factors. Half of those who developed dementia did so within about three and a half years. Earlier research from the same UCSF team found that people with Alzheimer's who also had epilepsy tended to notice memory problems several years earlier than those without it.

A new study on younger adults. In October 2026, a study in the journal Neurology used national health records from France and Sweden and found that people with epilepsy had about six times the risk of developing dementia before age 65 (Young-Onset Dementia). The authors stressed that this shows a link, not proof that one causes the other, and that the actual risk for any one person is still low.

What seizures can look like in older adults

Not every seizure is a convulsion. In people with memory problems, more than half of seizures may be "nonconvulsive." Signs can include:

• Staring blankly and not responding for a few seconds to a few minutes
• Lip smacking, chewing movements, picking at clothes or fumbling with the hands
• Sudden confusion or not knowing where they are, then a gradual return to normal
• A strange smell, taste or feeling of déjà vu before an episode
• Brief jerking of an arm, leg or the face
• Unexplained falls, tongue biting or losing bladder control
• Being unusually tired, sleepy or muddled for hours afterward

Because these episodes come and go, they can look like delirium, a small stroke, low blood pressure or a sudden worsening of dementia. A doctor's evaluation is the only way to tell.

What to do if you notice something

Keep notes. Write down the date and time, what the person was doing, what you saw, how long it lasted and how they acted afterward. If it's safe, a short phone video can be very helpful to a doctor.

Tell the doctor soon. Report any new spells of staring, unresponsiveness or confusion that come and go. Doctors may order an EEG (a test that records the brain's electrical activity through small sensors on the scalp), sometimes for a longer period or overnight, because a short test can miss intermittent activity. They'll also check for other causes such as infections, medication side effects, low sodium or low blood sugar.

Ask about medicines. Some medicines can lower the seizure threshold. If seizure medicine is prescribed, ask how it may affect memory, balance and alertness, since some older seizure drugs can cause sleepiness or unsteadiness. Never start, stop or change a seizure medicine without the prescriber.

If you have epilepsy yourself. The researchers behind the 2026 study suggested that people with epilepsy may benefit from paying close attention to things that protect the brain, such as controlling high blood pressure, staying active and treating hearing loss. If you notice memory changes, mention them; they're worth checking rather than assuming they're "just the medicine."

Seizure first aid basics

• Stay calm, time the seizure and stay with the person.
• Move hard or sharp objects away and cushion their head.
• Once the jerking stops, gently roll them onto their side.
• Don't put anything in their mouth and don't hold them down.
• Call 911 if it lasts more than five minutes, another seizure follows, they're injured, have trouble breathing, or don't wake up.

The bottom line

Seizures are more common in people with dementia than many families realize, and they don't always look like seizures. New seizures that begin later in life are worth a careful memory check, too. If you see spells of staring, confusion or odd movements that come and go, write down what you saw and tell the doctor. For broader context, see Signs Dementia Is Getting Worse (and When to Call the Doctor) and Reversible Causes of Memory Problems.

Sources

1. Neurology / Epilepsy Action: Epilepsy linked to 6-times increased risk of young-onset dementia (Oct 2026)
2. Annals of Neurology (Vossel et al., 2016): Incidence and Impact of Subclinical Epileptiform Activity in Alzheimer's Disease
3. Neurology (Johnson et al., 2020): Dementia in late-onset epilepsy
4. JAMA Neurology (Vossel et al., 2013): Seizures and Epileptiform Activity in the Early Stages of Alzheimer Disease
5. National Institute of Neurological Disorders and Stroke: Epilepsy and Seizures

Not medical advice. This article is general information, not a diagnosis or treatment plan for any individual. Talk with a doctor about your situation.

Related articles

• Alzheimer's Disease
• Young-Onset Dementia
• Delirium vs. Dementia
• Reversible Causes of Memory Problems
• Getting a Diagnosis
• Signs Dementia Is Getting Worse (and When to Call the Doctor)