The phenomenon of déjà vu, French for “already seen,” appears in records from as far back as ancient Rome. Charles Dickens even addressed it in his 1850 novel, “David Copperfield,” saying, “We have all some experience of a feeling, that comes over us occasionally, of what we are saying and doing having been said and done before, in a remote time—of our having been surrounded, dim ages ago, by the same faces, objects, and circumstances—of our knowing perfectly what will be said next, as if we suddenly remembered it.”
“It's a feeling of inappropriate familiarity of a present experience with an undefined past,” says Jean Khoury, MD, a neurologist in the Cleveland Clinic's Epilepsy Center. About two-thirds of people have experienced déjà vu, and in the vast majority of cases, it's eerie yet harmless. But déjà vu also has been linked to a common form of epilepsy, and an emerging understanding of its role in seizures may improve diagnoses and even decisions about surgical treatment.
What Causes Déjà Vu?
The déjà vu experience has two main components: a strong feeling that you have experienced something before along with the knowledge that you haven't. While climbing stairs during a vacation, for instance, you may suddenly feel like you have been there previously and even “know” what you'll see on the landing. Yet you know you have never visited that place before.
While strong scientific evidence shows that that feeling of familiarity comes from a specific brain structure, researchers are less certain about how other parts of the brain are involved. “Decades of research in primates and humans tells us that one way in which the perirhinal cortex guides behavior is based on the feeling of oldness—of familiarity,” says Chris Martin, PhD, a cognitive neuroscientist who runs a memory lab at Florida State University in Tallahassee. This structure sits in the medial temporal lobe, deep in the brain, and is close to both the hippocampus, which is involved in memory and cognition, and the amygdala, which is involved in how people experience emotions. When familiarity is triggered, other memory systems come into play. “The brain has many memory systems,” Dr. Martin says.
“Familiarity causes us to search our memories for something more specific,” notes Anne Cleary, PhD, a cognitive psychologist at Colorado State University in Fort Collins. “It's your brain telling you to pay attention to your memory right now.” For example, if you run into someone and feel certain you know them, you might remember in the moment—or later, perhaps that night or in a few days—exactly who that person is. But when memory systems come up empty, déjà vu occurs, Dr. Cleary says: “It's a feeling that the current situation is something you've experienced before, alongside this feeling that that's impossible.”
In her research lab, Dr. Cleary has reproduced déjà vu. Using virtual reality, she introduces spatial layouts to study participants, followed by novel scenes that are distinct but share a similar layout, such as a bowling alley and a subway station. Creating such a scenario “boosts the probability that people will report déjà vu,” she says. “They can't pinpoint which scene is the source of this detected familiarity, but they're more likely to say, ‘Oh, I'm having déjà vu with this scene.’ Their minds pick up on the familiar aspect in an identifiably novel situation. It's a form of pattern recognition.”
In recent studies, Dr. Cleary demonstrated yet another false belief people with déjà vu experience—that they may have the ability to predict the future. She shows a scene to participants, stops it before they reach a turning point, and asks if they have a sense that the scene will turn left or right. “They feel very strongly that they know what the next turn should be,” she says, but their predictions are no better than guesses. “It's an illusory feeling of knowing what will come next.”
When déjà vu is associated with seizures, however, the environment does not stimulate the familiarity region of the temporal lobe. It comes from electrical impulses in the brain—the beginning of the seizure. “It's an internal sensation,” Dr. Khoury says. “You're not reacting to the environment. It's a hallucination [or illusion].”
Key Sign of Epilepsy
Déjà vu has been linked to seizures since the late 19th century. Patients with focal epilepsy, and especially mesial temporal lobe epilepsy, often report experiencing it, Dr. Khoury says. Most epilepsy is focal, starting in an area on one side of the brain, and about 60 percent of people with focal epilepsy have temporal lobe epilepsy, which in most cases involve the inner (mesial) structures. “That's where the familiarity memory system is triggered,” Dr. Martin adds.
Alex Minyakov, 31, of St. Augustine, FL, describes the intense feeling of déjà vu as “like something hits you in the head.” For him, it signals an epileptic seizure is about to begin. “I feel like I've been here before,” he says. “I have a weird smell in my nose, and I feel a little dizzy and kind of lose energy. Afterwards, I'm shaken, scared, kind of freaked out.”
Unlike a fleeting sense that you've already experienced something, seizure-related episodes of déjà vu can last for a minute or two. “You're constantly having the feeling of familiarity that gets stronger and stronger,” Dr. Khoury says. Often, it is associated with other symptoms, especially those affecting the autonomic nervous system, which controls the body's involuntary functions, such as breathing and blood pressure.
“These functions are close to the hippocampus, and they get activated at the same time, so you may feel nauseous, have this rising feeling in your abdomen,” Dr. Khoury adds. Patients may become hot or sweaty, drool excessively, or experience anxiety or other emotions as the amygdala activates. Some might even start having repetitive hand or mouth movements, such as chewing or lip-smacking.
“They may start picking at things around them,” Dr. Khoury says. Many individuals then “lose awareness, so they stop responding even though they're awake. Their eyes are open and seem to [follow objects], but they're just not there. This is the kind of natural progression of a seizure that may start with déjà vu.”
These symptoms differ so much from those of everyday déjà vu that they are red flags, he adds. Since they come and go in a few minutes, however, some people ignore them—until they turn into bigger seizures. And that's a mistake. A neurologist should check out any combination of these experiences, Dr. Khoury says. Recognizing and sharing the signs with a doctor can lead to an earlier diagnosis. “The longer you have seizures that are untreated, the more likely it becomes resistant to medication,” Dr. Khoury says.
Roderick Carlyle Spears, MD, associate professor of migraine research and clinical sciences and of neurology at Warren Alpert Medical School of Brown University, was treating a patient for migraines when she mentioned that she had déjà vu a couple times a week. Knowing that could be a sign of a seizure disorder, which is more common in people with migraines than in the general population, he did further screening that confirmed the dual diagnosis. Dr. Spears wound up treating her with a single antiseizure medication effective for migraines, too.
A patient's experience can even help neurology teams localize the source of a seizure, which is valuable in planning for surgery. For Minyakov, information about his déjà vu was a critical clue for his care team at the Mayo Clinic in Jacksonville, FL, where an MRI identified a small benign tumor affecting his perirhinal cortex that also was close to an olfactory nerve, which helped explain an unusual smell he experienced. “It was also impinging on the amygdala, which explains why he experiences fear in a seizure,” notes Seyed Mirsattari, MD, his neurologist at Mayo Clinic.
After surgery—a left temporal craniotomy and resection of a lesion—Minyakov went home with no neurologic complications and was seizure-free, although it will take a few months to ensure that he remains that way. For now, Minyakov remains on medication but at a much lower dose.
Minyakov had many déjà vu-related seizures before realizing he had epilepsy, and he's not alone in that experience. Dr. Mirsattari says he has had patients who had small déjà vu-type seizures for years but didn't see a doctor until they had a bigger seizure. When he asks if they had that feeling before, some have told him, “I've been having that for years and years, and I thought it was a panic attack.”
Now that he's been treated, Minyakov hopes to put his life back on track. A former manager at a car dealership, he has been unable to work for the last four years and has lived with his parents. “I'm looking to get back to that level again,” he says, adding, “I'm hoping I can move into my own place, get married, and have kids.”
