Transient Global Amnesia Is an Experience You’ll Never Forget
John Birmingham, a magazine editor, was startled to find his wife, Lola — dressed for work and for a birthday gathering afterward, in a jacket with a large fabric flower — perched on the edge of their bed, peering at her outfit in bewilderment.
“Why am I dressed this way?” she kept asking.
“You’re scheduled to go to a party after work,” he answered.
“But … what do I do?”
That’s when John got scared. His wife owned a small company that made one-of-a-kind hats with handcrafted materials; she was passionately dedicated to her work.
“She kept asking me where I was, where I had been. Then she said, ‘And what do you do?’ Very chilling. I thought: OK, take her to the hospital.”
At Mount Sinai Beth Israel Hospital, doctors peppered Lola with cognitive tests: Did she know her name? The year? The current president?
“Hillary Clinton?” she guessed. The doctor smiled. “Not yet.”
Finally, a neurologist delivered the diagnosis: transient global amnesia (TGA), an episode of sudden and short-lived forgetting that is most common in people between 50 and 70. It affects between three and eight of every 100,000 people each year.
The chief symptom of TGA is anterograde amnesia, or not being able to form and hold new memories. “[TGA patients] can only hold the world in their brain for 5 minutes or so,” explains Nancy Sicotte, MD, chair of the Department of Neurology at Cedars-Sinai in Los Angeles. “They’re very confused. The hallmark is repeatedly asking, ‘Where am I? What’s happening? What’s going on?’” Some people with TGA lose back-dated memories as well, though they retain knowledge of their own identities and are able to walk, speak, and do other tasks. “They may not recognize somebody they’ve been married to for only 2 or 3 years,” Sicotte says.
The episodes typically last between 4 and 6 hours, though they may endure as long as 24 hours. They get better on their own, with older memories returning first. Only the actual period of the TGA remains a cipher.
Lola, 74, recalls getting dressed that spring morning in 2015. “The next thing I know, I was waking up in the ER with no clue what was going on. It felt very much like a dream. I remember seeing a clock. I thought: Is it night? Is it day? And where am I?”
While an episode of TGA is deeply unsettling to patients — and to their loved ones, who may fear a stroke or a brain tumor as the cause — neurologists consider it a “benevolent syndrome” with no long-term effects.
About 80% of patients never have a recurrence, says Steven L. Lewis, MD, chief of neurology at Lehigh Valley Health Network and editor of Continuum: Lifelong Learning in Neurology. The remaining 20% may have another attack or two throughout their lives. A 2020 study published in JAMA Neurology showed that TGA patients with a higher personal and family history of migraine were more likely to have it happen again.
Neurologists don’t yet know exactly how TGA happens, but research points to brief venous hypertension in the brain. This temporarily deprives the brain’s two memory-forming hippocampi of oxygen. “What we don’t understand is exactly what is happening on a physiological level,” says Sicotte. “There’s a decrease in blood flow, but why?”
Doctors do know that TGA episodes usually have a trigger: a sudden plunge into hot or cold water; extreme physical exertion; a severe emotional jolt; sexual intercourse.
That’s what happened to Joan Lang, 65, one afternoon 9 years ago. She and her husband were cuddled in post-coital bliss at their home in Portland, ME, when she suddenly asked when they should plan to put their boat in the water for the season.
They’d sold the boat, to a guy named Forest, the previous summer.
“I had no memory of that,” Joan says. She barely recalls the car ride to Mercy Hospital, where, according to her husband, she asked over and over, “What happened to me?”
Admitted to the hospital overnight, “I had one of the strangest nights I’ve ever had, completely untethered to my life. I slept, had dreams, woke up, wasn’t sure where I was. I remember being given a cheese sandwich. The night was crazy, this miasma of stuff. I didn’t feel like I had gotten back into my body until the next day.”
Doctors emphasize that while TGA is not a symptom or a risk factor for stroke or other neurological disturbance, people who have any type of amnesia should be evaluated in a hospital.
Sicotte describes TGA as an existential phenomenon as much as a physiological one. The hippocampi, humming along like tiny tape recorders deep in the twin temporal lobes of our brains, without our conscious will, supply the data that lets us know who we are, and where we are, from moment to moment.
In an episode of TGA, “the machinery our brain uses to make new memories and also access old memories is offline,” Sicotte explains. “It’s like a switch goes off. Maybe it’s a protective mechanism.”
TGA is a source of fascination for neurologists, a syndrome that reminds both medical trainees and laypeople how much we still have to learn about the way memories form, encode, vanish, and come back.
While the experience is disturbing for many patients, for some the aftereffect is positive.
Lola thinks of her TGA as a moment when her brain and body hit the “pause” button at a time of overwhelming stress. On top of managing her usual torrent of work — a staff of 20 and constant decisions — she was planning a trip to Peru.
The incident left her with a sense of deep relaxation and blissful well-being, she says. “My whole day is answering questions, dealing with problems, coping with emergency issues. At some point, the brain needs space. I look at the incident as recalibrating.”
