Autoimmune encephalitis can cause psychosis, challenging psychiatry's diagnostic boundaries

September 26, 2026 at 05:00 PM1 min

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Autoimmune encephalitis, a rare brain inflammation, can trigger hallucinations and psychosis that resolve with immune-suppressing treatment. Some psychiatrists are screening broader patient groups for antibodies linked to the condition. The effort is reshaping the boundary between psychiatry and neurology.

Key Facts

Peter Jones, an academic psychiatrist at the University of Cambridge, treated a patient whose vivid animal hallucinations resolved after plasma exchange, a therapy for immune system disorders.
Autoimmune encephalitis is typically identified through blood or spinal fluid tests for specific antibodies, along with MRI signs of inflammation, rapidly worsening psychosis, and neurological symptoms such as seizures.
Around 3 percent of people will experience a psychotic episode in their lifetime, and brain inflammation from autoimmune encephalitis has been recognized for the past couple of decades.
Michael Zandi, a neurologist at University College London, says the artificial divide between psychiatry and neurology is starting to break down.

Diagnostic Challenge

Jones' patient lacked obvious neurological symptoms such as seizures, so the autoimmune cause would likely have been missed without his suspicion. Some experts suspect psychiatry is overlooking a small number of patients with autoimmune encephalitis and are working to find more of them. They are considering screening a broader array of psychiatric patients and seeking new antibodies that may be involved in the condition.

Clinical Implications

When patients with autoimmune encephalitis are treated with drugs that tamp down the immune system, psychotic symptoms often disappear. Many worry that overdiagnosis could plant false hopes and divert patients from psychiatric treatments the vast majority will actually need. Psychosis can be caused by a mix of mental and biological factors, from psychological trauma to drug abuse to physical diseases or infections such as syphilis.