How autoimmune encephalitis disrupts thinking, memory and everyday life

Have you ever found yourself searching for a word you should know, forgetting what you were just doing, or feeling mentally foggy for no obvious reason?

These everyday lapses are common and are most often a normal part of life, or a sign we might be tired or stressed. But for some people, they could be early signs of a rare condition called autoimmune encephalitis. This is when the body’s own immune system mistakenly attacks the brain and causes inflammation and swelling.

It can happen suddenly and at any age. Sometimes it follows a viral infection, but in many cases, the exact cause is unknown.

Autoimmune encephalitis is rare, affecting up to roughly 14 people in 100,000 each year. However, as awareness and testing improve, doctors are realising it’s more common than once thought.

So, what are the signs of autoimmune encephalitis, and how is it treated?

What does it do to the brain?

Autoimmune encephalitis causes inflammation that disrupts normal brain function, affecting how people think, remember and process information.

The inflammation often begins in the limbic system – the part of the brain that regulates emotions and forms memories. From there, inflammation can spread along connected brain networks, disrupting attention, language and planning.

Symptoms can range from striking changes – such as seizures, personality changes and hallucinations – to subtler difficulties, including confusion, forgetfulness, trouble focusing and feeling mentally slower.

These changes may come and go, or seem like stress or fatigue. Over time, they can make everyday life significantly more difficult.

As symptoms are not always visible, they are easily overlooked, resulting in delays or misdiagnosis.

MRI scans may reveal signs of swelling or inflammation, but many people have normal results in the disease’s early stages.

PET scans, which are able to measure changes in brain activity or microscopic inflammation, can sometimes detect these changes sooner.

The toll on everyday life and relationships

A 2023 Australian study of 50 people with autoimmune encephalitis found those with the disease often struggle with:

This can make daily tasks such as following a conversation, writing an email or managing a schedule feel exhausting. Some people say they feel like a completely different person after becoming ill – more anxious, less confident and mentally foggy.

Nearly a third of people with this condition don’t return to work or study because of ongoing difficulties with thinking and emotions. Others may return, but need modified duties or extra time to complete tasks.

Cognitive problems can also affect relationships. Family and friends may not always understand what’s changed, especially if the person “looks fine”.

This disconnect can lead to frustration and isolation. Caregivers often carry the emotional load while trying to navigate a condition that’s still not widely understood.

It’s often misdiagnosed

One of the biggest challenges with autoimmune encephalitis is how often it’s misdiagnosed.

Its cognitive symptoms are commonly mistaken for depression, anxiety, chronic fatigue or early dementia.

There isn’t one single test that confirms autoimmune encephalitis. Many people will have multiple appointments and tests before doctors can determine exactly what’s happening. These might include:

• blood and spinal fluid tests to look for signs of inflammation or specific antibodies that target the brain

• MRI and PET brain scans to detect inflammation or changes in brain activity

• an electroencephalogram (EEG) to identify abnormal electrical activity or seizure patterns

• cognitive tests to assess thinking, attention, memory and problem-solving.

In some cases, the diagnosis is made based on symptoms and supportive findings even before antibody results are available – which can take time.

How is it treated?

Delays in diagnosis can cause further brain injury, as inflammation keeps progressing. So early treatment is key to reduce inflammation, reverse symptoms and help prevent long-term effects.

Treatment often combines:

Researchers are also developing better ways to assess and track symptoms, including self-report questionnaires and formal cognitive testing. These are essential for personalising treatment and measuring progress.

Recovery looks different for everyone

Many people can make a full recovery – especially when treatment starts early – but not everyone does. Some people with autoimmune encephalitis may recover quickly, while others take months or years to feel like themselves again.

Support makes a huge difference. People are more likely to recover well and rebuild confidence and independence when they have flexible school or work arrangements, access to therapy, and a support system that understands what they’re going through.

Living with a condition that affects your thinking can create a great sense of frustration. Because it’s not always visible to others, it can lead to isolation or self-doubt.

So mental health care is also vital. Counselling or peer support groups can provide much-needed emotional support and practical tips.

The takeaway

Autoimmune encephalitis is rare and its symptoms can overlap with many other, far more common conditions.

If you’re worried about yourself or a loved one, it’s best to speak first with your GP. They can arrange blood tests and refer you to a neurologist for further assessment if needed.