BARCELONA – Consider the possibility of an autoantibody-related etiology in all cases of first-onset psychosis, Josep Dalmau, MD, PhD, urged at the annual congress of the European College of Neuropsychopharmacology.
“There are patients in our clinics all of us – neurologists and psychiatrists – are missing. These patients are believed to have psychiatric presentations, but they do not. They are autoimmune,” said, professor of neurology at the University of Barcelona.
Dr. Dalmau urged psychiatrists to become familiar with the red flags suggestive of synaptic autoimmunity as the underlying cause of first-episode, out-of-the-blue psychosis.
“If you have a patient with a classical presentation of schizophrenia or bipolar disorder, you probably won’t find antibodies,” according to the neurologist.
It’s important to have a high index of suspicion, because anti–NMDA receptor encephalitis is treatable with immunotherapy. And firm evidence shows that earlier recognition and treatment lead to improved outcomes. Also, the disorder is refractory to antipsychotics; indeed,
Manifestations of anti–NMDA receptor encephalitis follow a characteristic pattern, beginning with a prodromal flulike phase lasting several days to a week. This is followed by acute-onset bizarre behavioral changes, irritability, and psychosis with delusions and/or hallucinations, often progressing to catatonia. After 1-4 weeks of this, florid neurologic symptoms usually appear, including seizures, abnormal movements, autonomic dysregulation, and hypoventilation requiring prolonged ICU support for weeks to months. This is followed by a prolonged recovery phase lasting 5-24 months, and a period marked by deficits in executive function and working memory, impulsivity, and disinhibition. Impressively, the patient has no memory of the illness.
In one large series of patients with confirmed anti–NMDA receptor encephalitis reported by Dr. Dalmau and coinvestigators, psychiatric symptoms occurred in isolation without subsequent neurologic involvement in just 4% of cases ().
Dr. Dalmau was senior author of an international cohort study including 577 patients with anti-NMDA receptor encephalitis with serial follow-up for 24 months. The study provided an unprecedented picture of the epidemiology and clinical features of the disorder.
“It’s a disease predominantly of women and young people,” he observed.
Indeed, the median age of the study population was 21 years, and 37% of subjects were less than 18 years of age. Roughly 80% of patients were female and most of them had a benign ovarian teratoma, which played a key role in their neuropsychiatric disease (). These benign tumors express the NMDA receptor in ectopic nerve tissue, triggering a systemic immune response.
One or more relapses – again treatable via immunotherapy – occurred in 12% of patients during 24 months of follow-up.
When a red flag suggestive of synaptic autoimmunity is present, it’s important to obtain a cerebrospinal fluid (CSF) sample for analysis, along with an EEG and/or brain MRI.
“I don’t know if you as psychiatrists are set up to do spinal taps in all persons with first presentation of psychosis, but this would be my suggestion. It’s extremely useful in this situation,” Dr. Dalmau said.
The vast majority of patients with anti–NMDA receptor encephalitis have CSF pleocytosis with a mild lymphocytic predominance. The MRI is abnormal in about 35% of cases. EEG abnormalities are common but nonspecific. The diagnosis is confirmed by identification of anti–NMDA receptor antibodies in the CSF.
First-line therapy is corticosteroids, intravenous immunoglobulin, and/or plasma exchange to remove the pathogenic antibodies, along with resection of the tumor if present. These treatments are effective in almost half of affected patients. When they’re not, the second-line options are rituximab (Rituxan) and cyclophosphamide, alone or combined.
Antibodies to the NMDA receptor are far and away the most common cause of synaptic autoimmunity-induced psychosis, but other targets of autoimmunity have been documented as well, including the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor,, and neurexin-3-alpha.
Dr. Dalmau and various collaborators continue to advance the understanding of this novel category of neuropsychiatric disease. They have developed a simple 5-point score, known as the NEOS score, that predicts 1-year functional status in patients with anti–NMDA receptor encephalitis (Neurology. 2018 Dec 21.). He and his colleagues have also recently shown in a prospective study that herpes simplex encephalitis can result in an autoimmune encephalitis, with NMDA receptor antibodies present in most cases ( ).
Dr. Dalmau’s research is supported by the U.S. National Institute of Neurological Disorders and Stroke, the Spanish Ministry of Health, and Spanish research foundations. He reported receiving royalties from the use of several neuronal antibody tests.