Skip to main content



Rogue immune system could be mistaken for psychosis

SINGAPORE — In Nov 2011 when she was a final-year business undergraduate, the seizures came fast and furious for Ms Deborah Yap. It was the start of a nightmare, during which her family members thought she had gone “mental”.

Autoimmune encephalitis survivor Deborah Yap, 28, with her parents Agnes Goh, 59, and Patrick Yap, 64. Photo: NNI

Autoimmune encephalitis survivor Deborah Yap, 28, with her parents Agnes Goh, 59, and Patrick Yap, 64. Photo: NNI

Follow us on Instagram and Tiktok, and join our Telegram channel for the latest updates.

SINGAPORE — In Nov 2011 when she was a final-year business undergraduate, the seizures came fast and furious for Ms Deborah Yap. It was the start of a nightmare, during which her family members thought she had gone “mental”.

Hospitalised after suffering multiple seizures in a day, Ms Yap, 28, started seeing and hearing things that were not real. She could not recognise her parents and grew convinced she had a brother when, in reality, she has a younger sister. She also thought “some guy” no one else could see was waiting for her.

By mid-Jan 2012, she could no longer write, walk or eat on her own. Forming sentences became a struggle for the bright and articulate young woman. Her parents feared they might have lost the elder daughter as they knew her to be.

“If you looked at her, you’d think it’s a mental issue. Some of our relatives even thought it could be due to a possession (by a spirit),” said Ms Yap’s mother Agnes Goh, 59.

As it turned out, Ms Yap was not mentally ill. After extensive tests, her doctors at the National Neuroscience Institute (NNI) discovered her hallucinations and symptoms were due to an autoimmune disease known as anti-NMDA receptor encephalitis.

The disease occurs when antibodies from the immune system mistakenly attack nerve cells in the brain, wreaking havoc on various cognitive functions including behaviour, personality and mood.

Encephalitis, or brain inflammation, is most often due to a viral infection or develops as a result of bacteria, fungi or parasites. Doctors have recently identified that it could also occur when the immune system goes rogue, as in the case of autoimmune encephalitis.


At the NNI, doctors see two to three cases of autoimmune encephalitis each month.

Dr Charles Siow, a neurologist at Mount Elizabeth Novena Hospital, sees two to three such cases each year. Symptoms of the disease are commonly mistaken for schizophrenia or other psychiatric problems, he said.

“This would mean that some cases (of autoimmune encephalitis) could go undetected or mistaken for a psychiatric condition,” said Dr Siow.

The symptoms vary with each individual. Some patients display symptoms similar to that of psychosis or schizophrenia, said Associate Professor Kevin Tan, senior consultant at NNI’s Department of Neurology.

Besides abnormal behavior, patients may experience confusion, memory impairment, seizures or abnormal movements, he added.

Dr Belinda Lennox from the University of Oxford has published studies suggesting a small proportion of schizophrenia-like psychosis may be due to the autoimmune disease.

In one of her studies, published in The Lancet Psychiatry in December 2016, Dr Lennox and her team found that 9 per cent of 228 patients who experienced their first psychotic episode had antibodies against a range of brain cell receptors.

This may have important implications for treatment because “affected patients might respond to immunotherapy rather than antipsychotics or psychological interventions”, the study authors wrote.

Sharing her story ahead of World Encephalitis Day on February 22, Ms Yap said she has little recollection of what happened during the time, but was told that her symptoms were considered “mild” compared to what some patients go through.

“Strangely, I can recall a lot of the fantasies and hallucinations that I had during the episode, but I can’t really remember what had happened in reality. There was once, the doctor asked me where my parents were and I replied “pineapple tarts”,” said Ms Yap, who blogs about her experiences and is a member of the Autoimmune Illness Support Group - Singapore Facebook support group.

While the incident seems comical in retrospect, it was a time of fear and uncertainty for her parents. Her father Patrick Yap, 64, said the diagnosis came as “some relief” to them as it meant that she could be treated accordingly.

Ms Yap said she is fortunate to have been properly diagnosed. “I got to know another girl living in another country where her doctors were unaware of the condition and misdiagnosed her with bipolar disorder. She only got treated after waiting for a very long time,” she said.



At present, there are no clear answers as to why some people get it, said Assoc Prof Tan.

Dr Siow said it usually occurs in younger adults and teenagers. “They have a more active immune system, hence the tendency of autoimmune conditions occurring is higher. The immune systems of older adults are not so active,’ he said.

Most patients are young females with a certain type of ovarian tumour, Dr Siow added. Studies from the University of Pennsylvania found more than half of women under 18 years old who had anti-NMDA receptor encephalitis also had ovarian tumours known as teratomas.

Patients will not recover on their own if the condition is left untreated, said Dr Siow.

“It can get worse, and patients might have seizures and become unresponsive. Untreated, it can result in rapid development of brain swelling (which can manifest as agitation) and this can lead to death,” he said.

To diagnose autoimmune encephalitis, doctors need to carry out tests including MRI brain scans, blood tests and cerebrospinal fluid tests, said Assoc Prof Tan.

The mainstay of treatment focuses on controlling the immune system with medications such as steroids and intravenous immunoglobulin (a type of therapy commonly used to treat conditions related to the immune system), he said.

“Subsequently, there is a need for immunosuppressive drugs for a period of time, usually between a few months to a few years, to keep the immune system under control,” said Assoc Prof Tan.

The good news is, with the right diagnosis and treatment, the chances of a full recovery without lingering effects are “very high”, said Dr Siow.

But not all patients recover, and the recovery time varies -- from days to years, said Assoc Prof Tan.

Ms Yap’s nightmare did not end with her first ordeal, which resulted in a one-and-a-half-month hospital stay. After recovering in 2012, she resumed her studies but suffered a relapse a year later.

“It’s not proven if it’s stress-related but we noticed that both times, the seizures started during the examination period,” she said.

The frequency of her seizures was far worse the second time round, occurring every minute at its peak. Ms Yap underwent treatment again, which helped control the seizures and got her back on her feet.

She was on immunotherapy and other medications for over two years to keep her condition – now in remission – under control.

Ms Yap’s relapse spurred her and her family to make drastic changes. Fearing another relapse, her father quit his job as an IT executive to keep an eye on her, and she gave up her degree studies to take up baking, as she considered the latter to be less stressful.

While baking is her passion, Ms Yap, now a pastry cook, said she sometimes feels a tinge of regret for not being able to complete her university studies. “This is especially when I see my peers, who have graduated, earning a lot more,” she said wistfully.

Ms Yap may consider eventually going back to the corporate world but for now, she is grateful to be alive and medicine-free. As for her parents, they are simply glad to have their daughter back.

Read more of the latest in



Stay in the know. Anytime. Anywhere.

Subscribe to get daily news updates, insights and must reads delivered straight to your inbox.

By clicking subscribe, I agree for my personal data to be used to send me TODAY newsletters, promotional offers and for research and analysis.