A major new study has found that changes in mental health and behavior, including depression, anxiety and emotional instability, are common in people who survive encephalitis, an inflammation of the brain that can be caused by infections or autoimmune diseases.
The study, led by a team of scientists and clinicians from the Institute of Psychiatry, Psychology and Neuroscience (IoPPN) at King’s College London, the University of Oxford and the University of Liverpool, is the most comprehensive analysis of its kind. The study, published in Brain Communications, was funded by the National Institute for Health Research (NIHR).
Encephalitis affects up to 6,000 people in the UK each year and can be life-threatening. Although treatment has improved survival, many survivors have long-term complications. Until now, the focus has been on physical and neurological recovery, with little known about how the disease affects mental health over time.
Dr Cameron Watson, lead author of the study and MRC Clinical Research Teaching Fellow at IoPPN, said: “Encephalitis doesn’t end when patients are discharged from hospital. Many people experience mental health problems, such as depression, anxiety and personality changes. However, the true extent of these problems is not clear, so we wanted to gather all available evidence to understand how common these mental illnesses are among encephalitis survivors.”
The research team analyzed data from 101 studies involving more than 4,700 encephalitis survivors around the world. This includes cases of both infectious causes (such as herpes simplex virus and Japanese encephalitis) and autoimmune causes (where the immune system mistakenly attacks the brain). Using advanced statistical techniques, they combined the findings to calculate average rates for various symptoms and investigated how these varied by cause, age, and other factors.
The main findings are:
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Approximately one in five people experienced anxiety, disinhibition, and emotional instability, even months or years after becoming ill.
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Importantly, few studies have provided patients with consistent mental health follow-up, and methods of measuring outcomes vary widely, indicating the need for a standardized approach.
Researchers say the results highlight the importance of regular mental health screening and support for people recovering from encephalitis.
These findings should change the way we track people recovering from encephalitis. Psychiatric complications are common and can cause disability. We have highly effective treatments for many of these. Mental health assessment should be a routine part of post-encephalitis care and should never be put on the back burner. Patients do not have to suffer in silence. ”
Dr Thomas Pollak, IoPPN Senior Clinical Lecturer and Consultant Psychiatric Neurologist
Dr Jack Fanshawe, Academic Clinical Research Fellow at the University of Oxford and co-lead author of the study, said: “This study gives us a first real sense of the long-term impact of encephalitis on mental health. But in many ways it raises further questions. We still don’t know what treatments will work, who is most at risk and how to tailor support and clinical pathways to those whose personality and behavior are affected.”
Dr Eva Easton, co-author and CEO of Encephalitis International, said: “We often hear in our community that mood changes, anxiety and personality changes can be just as distressing, if not more so, than physical symptoms. This study shows that brain inflammation can be “This confirms what survivors have been saying for years: that it can have a deep and lasting impact on the mental health of people living with it. It’s important that we now mobilize this evidence and start building services that respond to the holistic needs of people experiencing this outcome.” Often a devastating neurological condition. ”
Stuart, an Encephalitis International Volunteer who has personally been affected by autoimmune encephalitis, said: “This study is a great show of support for members of the encephalitis community. I’m now in my third year of recovery, and I struggle every day to understand that the emotional events that occur are not part of my perceived personality, because that’s who I am.”
The authors call for prospective, long-term studies that track mental health outcomes using consistent and validated tools. They also call for the integration of neuropsychiatric expertise into standard care and the inclusion of patients with lived experiences in research designs.
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Reference magazines:
Watson, C.J. others. (2026) Psychiatric and behavioral sequelae after encephalitis: a systematic review and meta-analysis, Brain communication. DOI: 10.1093/braincomms/fcag175. https://academic.oup.com/braincomms/article/8/3/fcag175/8707381
