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Why the sudden memory loss? Image Credit: Shutterstock

She was missing but police knew where she was. She could not remember her name, her family or her childhood. She knew that she was dying, but only that. Interpol released a missing persons report : 1.7m, 91kg, brown eyes, chip on front tooth, right-handed, Caucasian, appears to be in her 50s, piercing on each ear, shoe size 39. Languages: English, French.

She called herself “Sam” and spoke to the media this month , explaining that she had been found semi-conscious by police outside a church in Carlsbad, California, five months ago. She had stage three ovarian cancer, she said.

A Facebook campaign earned 200,000 shares and ignited worldwide media interest. Then Sam’s scattered recollections started to emerge: “... swimming in a salt water pool in Perth, then icebergs in New South Wales and in Cairns in Queensland and Byron Bay”.

A San Diego TV station reported that her family, who had lost touch with Sam in 2013, identified her after seeing a news report. Her real name was Ashley Menatta: born in Pennsylvania, lived in Arizona and moved to southern California.

Menatta described the subsequent reunion (no family members have appeared in media reports). “It was extremely emotional,” Menatta said. “We were all sobbing. They’re so sorry I had to go through what I did during this time without them.”

She is no longer missing, but the concept of her identity remains challenging. Is she who she thinks she is, or who other people say she is? Special Agent Darrell Foxworth spoke to reporters after Sam became Ashley: “The FBI is not identifying this individual as by the name of Ashley. This is something she is self-identifying herself as based on conversations she had with people that represent themselves as family members.”

In The Bourne Identity, assassin Jason Bourne (Matt Damon) loses his life history in mysterious circumstances. Italian fishermen discover his body floating in the Mediterranean. There are two bullets in his back and a bank code embedded in his hip. He does not know who he is or was, though his combat abilities and foreign language skills are retained. Bourne is eventually diagnosed with psychogenic amnesia.

Away from the big screen, psychogenic amnesia is a condition in which the showreel of personal life malfunctions. Traumatic personal events disappear and fall to the cutting-room floor. Narrative gaps infiltrate your story. White noise drowns out your past. For some, amnesia is specific to a situation: being in car crash or witnessing a murder. In others, it is not a solitary personal experience that drifts away in time but your identity, your self. “Who am I, what have I been doing all my life?”

Jason Bournes in the real world are usually found by police on street corners and led, in an often dishevelled and confused state, to emergency rooms. No name and no memories. Some have travelled hundreds of miles from home as part of their psychogenic fugue (fugue is Latin for flight). It is a departure from a distant physical location, but a remote place of the mind, too.

In the early morning of August 31, 2004, a man was found behind the bins of a Burger King outlet in Richmond Hill, Georgia. He was semi-naked and unresponsive, with evidence of blunt force trauma to the head. Later, he regained consciousness but could remember almost nothing. There were fragmented memories of Denver and Indianapolis.

“Of the 56 years he said he’d lived, he had enough memories to fill a day,” according to a 2010 report. He named himself Benjaman Kyle and became the only American citizen officially listed as missing despite his whereabouts being known. His identity remains a mystery more than a decade later, despite an FBI investigation, DNA analysis, facial recognition technology, linguists, hypnotists and an appearance on the Dr Phil show. Kyle was later diagnosed with schizophrenia. He is not a fraudster, say his doctors. “To him,” said his psychologist, “his lack of memory prior to 2004 is real.”

Loss of personal identity rarely, if ever, happens because of structural brain damage rather than psychological distress. If it does, a severe injury would be expected - devastating encephalitis, or profound dementia with an inability to form new memories (from damage of the medial temporal lobe, the part closer to midline) as well as retain old ones. Even then, we remember our own names long after we have forgotten everyone else’s. Personal identity draws upon different parts of the temporal lobe: further away from the midline and further forward.

Menatta said that antibodies from the her ovarian cancer had caused her amnesia. Certain tumours do set off an immune response that inadvertently targets the nervous system, causing encephalitis. However, there has never been a case of ovarian cancer causing loss of personal identity while preserving the ability to form new memories.

In 2009, Susannah Cahalan was 24 years old and working as a reporter at the New York Post . She was in a new relationship with a musician boyfriend, renting a Manhattan apartment and living her dream. Except soon, she wasn’t.

The changes were subtle at first. She uncharacteristically missed some deadlines, then became fixated that there were bedbugs in her apartment. Within days, Cahalan was drowning in an ocean of paranoid delusions and hallucinations. Her boyfriend was cheating on her (he wasn’t). Her father was trying to kill her stepmother (he wasn’t). Then she had a seizure. And another.

Soon she lay in a New York intensive care unit, drooling, grunting, lashing out and grimacing. Her blood pressure soared and plummeted. Her memory ebbed away. “Her brain is on fire,” her family was told by a neurologist. “Her brain is under attack by her own body.”

Her body was churning out rogue antibodies that spiralled towards the brain. Hers was the 217th reported case worldwide of a type of brain inflammation called anti-NMDA receptor encephalitis. Cahalan was given the right treatment to reset her immune system and made a long journey to full recovery.

Ever the journalist, she wrote a book about the experience, a forensic investigation into those lost months. She recalled searching her boyfriend’s apartment for signs of infidelity. And waking up strapped to a hospital bed. But the rest was recreated through interviewing family and friends, speaking to doctors, ploughing through medical files, trying to make sense of her disjointed diary entries and watching videos of her own psychosis. So removed was she from her memories that she initially wrote part of the book in the third person.

She tells me that much of the memory vault from that time is close to empty. “I will never get it back. It’s just a darkness, a place of despair.” But her most striking memories are of her hallucinations and delusions. A floating eyeball. A Buddha statue that smiled at her and stalled her attempt to jump out a window.

In one instance, as she was being interviewed by a psychiatric nurse, Cahalan realised that she had the power to age others. The nurse’s face became wrinkled, catapulted into senescence by Calahan’s superpowers. She then “aged” her boyfriend, Stephen, watching his hair turn grey, his face transform into his father’s.

The recollection of these hallucinations remain stronger than anything else, leading her to ask: “Why are these the things I remember whereas reality was gone?” She has found solace in the words of a psychiatrist, who said her selective remembering made sense. “He said I remembered hallucinations because they are high on emotional content, imprinted in the brain, and they’re made from the self.”

In 1889, British neurologist John Hughlings Jackson described the case of a doctor with epilepsy, Dr Z. One day, Dr Z reviewed a child brought in by his mother with respiratory symptoms. Dr Z remembers feeling somewhat unwell himself for a moment. He described taking out his stethoscope, but “turning away a little to avoid conversation”. His next recollection was of “sitting at a writing table in the same room and speaking to another person.” Where were the boy and his mother?

An hour later, he found notes about the boy that he did not recall making. He discovered that he had examined the patient, documented his findings (“pneumonia of the left base”) and formulated a treatment plan. He remembered nothing of this.

In transient epileptic amnesia (TEA), seizures fire from the temporal lobe. Amnesia is frequently the only manifestation - difficulty learning new things and recalling past events. The person experiencing this amnesic seizure looks “normal”. They can converse, multitask, perceive. Occasionally there is slight confusion or speech repetition, but there are reports of patients driving normally, playing a winning round of golf or, in the case of Dr Z, correctly diagnosing pneumonia.

John Hodges, a professor of cognitive neurology, has studied TEA for more than three decades. I asked him how patients can continue while in the grip of a seizure that lasts up to an hour. “These automatic tasks,” Hodges replies, “depend on procedural memory, a function overseen by parts of the brain other than the temporal lobe, such as the basal ganglia and cerebellum.” He tells me about a lawyer who defended a case but had no memory of it afterwards. The lawyer, Hodges believes, had an attack of TEA after the case, but lost his memory for the event that had preceded it.

Any of us could be Ashley Menatta, Susannah Cahalan or Benjaman Kyle. Our memories are not immutable; they evolve over time. Memories are embedded, consolidated, refreshed and mislaid. They are precise or unreliable, enriched or fragmented, exposed or repressed, honest or deceptive.

Given the fragility of recollection, we can only hope that we are more than our memories. The neuropsychologist Alexander Luria once said: “A man does not consist of memory alone. He has feeling, will, sensibility, moral being ... It is here ... you may touch him, and see a profound change.”

 

Jules Montague is a consultant neurologist at the Royal Free London NHS Foundation Trust, and an honorary consultant neurologist at the National Hospital for Neurology and Neurosurgery, Queen Square. Guardian News & Media Ltd, 2015