Delusions, memory loss, seizures: How a little-known brain inflammation progresses

And no one can quite explain why.

Across hospitals worldwide, clinicians are increasingly recording a diagnosis many people have never heard of: autoimmune encephalitis. The condition can erase memories, trigger delusional states and cause seizures - yet it is still frequently mistaken for a purely mental health problem. Behind the clinical terminology sits an illness that tears lives apart and pushes families to their limits.

When your own life falls apart inside your head: autoimmune encephalitis

The accounts of those affected read like a psychological thriller - except there is no cinematic happy ending. A 72-year-old retiree cycles along the coast, returns home, and cannot remember the ride. At first it is only a small blackout. Weeks later, the gaps multiply: conversations blur, familiar events seem wiped clean. Hallucinations appear, along with the sensation of disintegrating from the inside. Doctors later refer to his “year of falling apart”.

A young mother in her thirties collapses at home, suffers severe seizures and is admitted to intensive care. Initially, the team looks for a stroke or drug-related causes. Only specialised tests for antibodies in blood and cerebrospinal fluid provide clarity: it is autoimmune encephalitis, triggered by a benign ovarian tumour that has misdirected the immune system.

“Autoimmune encephalitis feels as if the immune system suffers a short circuit - and accidentally attacks the brain.”

This sudden rupture is characteristic. Many patients have been healthy, active and fully engaged in everyday life up to that point. Then, within days or weeks, things tip. It may begin with forgetfulness and irritability, later escalating to aggressive outbursts, delusion-like ideas, disorientation and epileptic seizures.

What is actually happening in the brain

From a medical perspective, the condition primarily affects the interfaces between nerve cells. Specific antibodies latch onto receptors that are crucial for memory, mood and perception. The best known are the so-called NMDA receptors. They help the brain store new information and regulate emotional responses.

When the immune system attacks these structures, multiple functions can unravel at once:

• short-term memory collapses
• attention and concentration drop abruptly
• emotions swing dramatically, from euphoria to panic
• sensory processing becomes chaotic - noise, light and smells overwhelm
• the ability to plan and make decisions shrinks

An Australian research group reports that even simple tasks suddenly become obstacles: drafting an email, keeping an itemised shopping list in mind, or following the thread of a conversation. From the outside, the person may sometimes seem “perfectly normal”. Inside, there is a storm that is difficult to put into words.

“Many people affected report: the face in the mirror is the same - but the person behind it feels unfamiliar.”

The invisible illness that can look like psychosis

The major difficulty is that autoimmune encephalitis often presents like a psychiatric disorder. Hallucinations, odd convictions and abrupt changes in behaviour can resemble psychosis or schizophrenia. In some cases, people receive purely psychiatric diagnoses for years before anyone considers an immunological cause.

Specialist journals include reports of patients who were labelled “schizophrenic” for decades. Only an analysis of cerebrospinal fluid for particular antibodies (for example, against NMDA or AMPA receptors) reveals the true explanation. When immunotherapy is then started, the condition improves significantly. These cases underline how much suffering could be avoided if neurology and psychiatry worked more closely together.

Warning signs that should set alarm bells ringing

Autoimmune encephalitis is rare, but identified cases have risen since testing has improved. Absolute certainty is never possible, yet a cluster of indicators should prompt GPs, neurologists and families to pay close attention:

• sudden memory loss with no clear cause
• rapid personality change over days or a few weeks
• seizures in someone previously healthy
• severe sleep disturbance, agitation, unusual fears
• confused, partly delusional thoughts that were never present before
• a sharp drop in concentration and performance at school or work

The speed of change is critical. Many psychiatric conditions develop slowly. Autoimmune encephalitis often feels like an unexpected crash. Families report that daily life can be transformed completely within two or three weeks.

Diagnosis: a puzzle of labs, imaging and clinical judgement

If these warning signs are taken seriously, an intensive diagnostic search begins. It usually includes:

Test	What it can provide
Brain MRI	signs of inflammation, swelling; helps rule out other causes
Lumbar puncture (cerebrospinal fluid)	antibodies, markers of inflammation; helps distinguish infections
EEG	evidence of epileptic activity and diffuse brain irritation
Blood tests	additional autoantibodies, organ function checks, tumour screening

Together, these findings build an overall picture. Even if no antibodies are detectable, the presentation can be so typical that clinicians still diagnose and treat autoimmune encephalitis.

Treatment: time is brain

Treatment aims to stop the immune attack and remove possible triggers. Many centres use a stepwise approach:

• high-dose corticosteroids to suppress inflammation quickly
• immunoglobulins by infusion or plasma exchange to dilute or remove harmful antibodies
• long-term immunosuppression using medicines also used for other autoimmune conditions
• targeted searches for tumours, cysts or infections that could be driving the misdirected response

The earlier these steps begin, the better the chances of brain recovery. Many patients gradually return to work and family life. Some, however, remain limited in daily routines: they rely on notes for appointments, tire more quickly and find it harder to buffer stress.

“A disease hardly anyone knows can suddenly determine whether someone can still access their own life story.”

Living with gaps: the long road of rehabilitation

After the acute phase, the real work begins. Anyone who has lost large parts of autobiographical memory has to have their life retold to them. Partners, children and friends show photos and recount holidays, weddings and everyday moments. The brain stores new versions of these memories - often without the emotional depth they once had.

Neuropsychological training programmes help rebuild attention and planning skills. People keep notebooks, use apps for appointments and create routines. Even seemingly mundane methods - fixed steps for getting up or cooking - can restore a sense of safety.

Some establish support groups, keep journals, or write poems or haiku to make the hazy experience more tangible. In this way, a new thread forms, allowing identity to be pieced together again - even if certain chapters of life remain a blank void.

What families and carers should know

For relatives, the illness can feel like a double loss. The person you love is still alive, still speaking and moving - and yet their nature seems altered. Outbursts of anger, suspicion, withdrawal, childlike behaviour: all of this demands patience that can quickly run out in day-to-day caring.

A few practical measures can make things more manageable:

• use clear, short sentences; avoid complex explanations
• reduce stimulation: no television running in the background, keep conversations calm
• establish a stable daily structure with repeating routines
• do not leave critical decisions (finances, contracts) solely to the unwell person
• take your own limits seriously; use respite services and advice

Acceptance matters too: what looks like a personality change is not wilful or a character flaw, but has neurobiological causes. That perspective can take some of the sting out of difficult behaviour.

Why case numbers are rising - and what that means

Autoimmune encephalitis itself does not appear to be increasing explosively. What is changing is awareness. Neurology centres are testing more often for relevant antibodies, and psychiatric teams are more likely to consider immunological causes when young people suddenly enter severe psychotic states.

With every additional case, knowledge grows about typical patterns, risk constellations and therapies. Studies are evaluating new antibody-blocking drugs or combinations with cancer immunotherapies. The aim is treatment strategies with fewer side effects and a lower relapse risk.

For those affected, this offers a genuine opportunity: someone who arrives in A&E today with a sudden, “mysterious” psychosis has far better odds that a clinician will consider possible brain inflammation - and request the right laboratory tests.

When forgetting becomes political

Autoimmune-related brain inflammations also raise wider societal questions. How should school grades be judged if a teenager experiences a cognitive collapse halfway through the academic year? How fair is dismissal when an employee suddenly seems “unreliable”, but in reality has an inflammatory brain disease?

Insurers, public bodies responsible for workplace inclusion and the courts are increasingly having to grapple with diagnoses that are not obvious at first glance. A normal MRI does not mean the brain is functioning normally. This very invisibility makes the condition politically charged: it sits in the tension between performance pressure, inclusion and psychosocial support.

What non-specialists can take from all this

Three ideas follow from current knowledge. First: if someone mentally “drifts” over a short period, it is worth looking beyond purely psychological explanations. Second: the dividing line between mind and body is more porous than many textbooks suggest - biography, immune system and brain interlock.

Third: when you meet people who seem to be “making a fuss”, “letting themselves go”, or suddenly “acting strange”, snap judgements are often wrong. Behind delusions, memory gaps and seizures there may be a quietly advancing inflammation that only becomes visible once life has already come off the rails.