The Little-Known Link Between Dementia and Epilepsy

The strange episodes started several years ago, when Jeff Will was not yet 70.

At the electrical contracting business Mr. Will had run for decades, employees noticed him acting oddly, zoning out in meetings, forgetting what was discussed. They would call his wife, Pam, asking her to come get him.

At home in Erie, Pa., he had spells of confusion, wandering the house, staring vacantly. Once, around 3 a.m., his wife heard rustling and discovered him putting on one of her Christmas sweaters like a pair of pants, returning to bed with “‘Merry Christmas’ upside down on his butt,” she said.

While preparing for their family’s July 4 gathering, he spent hours in their yard stuffing leaves and twigs into his golf bag. Another time, the state police called after Mr. Will, who had driven to the YMCA to play pickleball, blanked out in the parking lot and drove over a curb into a bush.

“About once a month or so, I would wake up and not know exactly where I was, what I was doing,” said Mr. Will, now 73. “It happened more and more often, and I sold my business mainly because of that,” he added.

For nearly three years, he couldn’t get a diagnosis. Early on, his wife took him to a hospital, worried he was having a stroke. She took him to neurologists, neuropsychologists and a psychiatrist. While staying at a home they bought in Florida, he attended a program intended to boost brain health.

On cognitive blockessments, he scored in the average range for his age. Brain scans also appeared typical for a 70-year-old. Some doctors suggested it might be stress.

“We finally got fed up with it and went to the Cleveland Clinic,” Mr. Will said.

There, doctors came to a conclusion that surprised him: His dementia-like symptoms were being triggered by silent epileptic seizures he didn’t know he was experiencing.

Mr. Will’s experience may sound like a medical curiosity, but research is finding that epileptic seizures can drive symptoms resembling dementia. And vice versa.

“There’s about a two- to threefold increased risk of developing dementia if you have epilepsy,” said Dr. Alice Lam, an blockociate professor of neurology at Harvard Medical School. And “if you have dementia, you have, on average, a two- to threefold increased risk of developing seizures.”

Links between epilepsy and dementia — conditions that affect millions and are more prevalent in older age — are increasingly crucial to recognize as people live longer, experts say.

“It’s a super important, super common thing around the world, and yet it really, really does not get attention,” said Dr. Arjune Sen, a professor of global epilepsy at the University of Oxford.

Cognitive symptoms fueled by epilepsy often differ from symptoms of Alzheimer’s or other dementias. They may occur during a seizure that is often so subtle it is unnoticeable, or they may occur afterward, in what is called the postictal phase, said Anny Reyes, a neuropsychologist at the Cleveland Clinic.

Spells of confusion may resolve after hours or days, said Dr. Lam, adding that people may be unresponsive to questions or conversation, “like the lights are on but no one’s home.”

Dr. Sen said another hallmark is “accelerated long-term forgetting” — for example, forgetting details of a movie days after seeing it and forgetting almost the entire movie weeks later.

Mr. Will’s episodes of confusion were so startling that his wife began jotting them down.

He would forget how to get home from work or mistake the TV remote for his phone. Once, his wife discovered him “talking to a scammer” and realized he had inadvertently begun giving over access to their checking account, she wrote in her log. “I convinced him that it was a scam and to hang up,” she noted, and the couple straightened things out at their bank. But she began carefully monitoring his phone and computer use.

Mr. Will said he would be unaware of the experiences as they happened, but later sometimes had a feeling something was wrong. He couldn’t remember some special events. When he saw a photo of his wedding, he recognized the church, but “I don’t remember being inside that,” he said. “I don’t remember who my best man was.”

One day, Mrs. Will wrote: “He looked up ‘memory loss’ on the computer and said he thought he should see a doctor about it. I told him that he had been seeing doctors and having tests for months.”

Sometimes, such episodes may be solely caused by epileptic brain activity and resolve with anti-seizure medication, said Dr. Lennart Mucke, director of the Gladstone Institute of Neurological Disease. It’s unclear how often that happens. In other cases, it could be “a harbinger of Alzheimer’s disease,” he said.

In the other direction, people with dementia may develop seizures that might exacerbate their cognitive decline.

A Two-Way Relationship

About 7 million people in the United States have dementia, much of it caused by Alzheimer’s. Another 10 million Americans 65 and older are estimated to have mild cognitive impairment, often a precursor to dementia.

Several experts said that at least 10 percent of people with dementia or mild cognitive impairment are likely to develop seizures or subtler electrical disturbances, although estimates vary.

Often, the seizures are invisible and may occur during sleep.

“When people hear seizures, they sort of imagine somebody twitching all over,” said Dr. Mucke. That can characterize a grand mal seizure, he said, “but epilepsy can be so much more nuanced and subtle,” presenting, for example, as “absence seizures,” characterized by “staring into space and being entirely disconnected from their environment.”

About 3 million adults and over 450,000 children in the United States have active epilepsy, meaning they take anti-seizure medicine or have had seizures in the past year.

While people often blockociate epilepsy with childhood, it is at least as common in adults aged 65 and older, said Dr. Vineet Punia, an epileptologist at the Cleveland Clinic. Often, the underlying cause is unclear and there is no identifiable trigger such as a stroke, he said.

Among older adults with unexplained epilepsy, around 20 to 25 percent are likely to develop dementia within five years, Dr. Punia said. Others will develop mild cognitive impairment, he said, while some already have cognitive issues when they begin having epileptic seizures.

There are several aspects to the biological relationship between epilepsy and dementia. Sometimes, epileptic electrical disturbances have effects “like jamming the radio signals for memory formation,” said Dr. Lam, a leader of a study tracking cognitive impairment in people with late-in-life epilepsy.

One way this might occur, Dr. Sen said, is that the “hyper-excitability” of epileptic activity may trigger molecules that fuel neuron loss, fraying some brain signaling pathways and creating a “cycle of electrical activity, nerve cell loss, neurodegeneration.”

The brain’s attempts to rewire to counteract that hyper-excitability may reduce its agility and “constrain some of the processes that we need to think properly,” Dr. Mucke said.

Also, in both epilepsy and dementia, brain cells called interneurons that operate “like the conductor of an orchestra” become impaired, he said. And both conditions can affect the same memory-related brain areas, especially the temporal lobe and the hippocampus, he said.

Two proteins central to Alzheimer’s, amyloid and tau, “tend to increase the risk of seizures,” Dr. Reyes said.

Other dementias, including vascular, frontotemporal and Lewy body, may increase the risk of epileptic activity too, Dr. Punia said.

What’s more, some health conditions that increase epilepsy risk in adults, including hypertension, diabetes and high cholesterol, also increase dementia risk. And some epilepsy medications may themselves hasten cognitive decline, Dr. Reyes said. For that reason, she said, when doctors prescribe anti-seizure medications to treat cognitive episodes caused by epilepsy, they should avoid drugs that worsen cognition.

Treatment decisions for Alzheimer’s may also be more complicated if patients have seizures. It is unclear whether such patients are candidates for the recently approved Alzheimer’s treatments, Dr. Mucke said, because clinical trials of those drugs excluded people with epilepsy over concerns about additional safety risks.

Experts said many doctors fail to consider the possibility of epileptic activity in cognitively impaired patients, partly because epileptologists and dementia experts have typically focused on their specialties. Also, because these seizures are usually subtle, general neurologists might not think to send patients for electroencephalogram, or EEG, testing to check for abnormal electrical activity.

“In a perfect world, every patient with a dementia diagnosis would get an EEG study,” said Dr. Reyes, who leads a new Cleveland Clinic program on epilepsy and dementia.

Solving the Mystery

When Mr. Will arrived at the Cleveland Clinic, about two hours from his home, in March 2025, doctors, helped by his wife’s log, immediately flagged the likelihood of epilepsy, said Dr. Carolyn Tsai, one of the epileptologists who treated him.

To check, the clinic evaluated him for five days. Its epilepsy unit blockesses patients by placing EEG electrodes on their heads and tracking their brains’ electrical activity around the clock. Overhead video cameras in the patients’ rooms capture seizure-related movements. In another room, clinic staff monitor screens showing EEG readouts and video feeds for patients in Cleveland and satellite locations in Ohio, Florida and the United Arab Emirates.

During his stay, Mr. Will experienced at least two seizures overnight, Dr. Tsai said. “It looks like he just woke up but stares straight ahead,” she said. His mouth made chewing movements, and his left hand formed a shape like a duck, common symptoms of temporal lobe seizures, she said. When the medical team “came and tried to talk to him during it, he wouldn’t respond,” she said.

The clinic prescribed Keppra, a common epilepsy drug. Dr. Tsai said the seizures have stopped since he began taking it.

The cognitive episodes have stopped, too, the Wills said one recent afternoon at their dining table, as sunlight streamed in from the yard where Mr. Will had once, in confusion, used his golf bag as a trash can.

“I still have that memory loss from that time period, but I don’t have dementia,” he said. “I can relearn things,” he added, noting that when he was having the episodes, he would get lost on the way to a family member’s house. “Now,” he said, “I remember how to get there again.”