When the body attacks the brain: Immune system often to blame for encephalitis, study finds

February 12, 2018 by Susan Barber Lindquist, Mayo Clinic
Credit: Mayo Clinic

Encephalitis caused by the immune system attacking the brain is similar in frequency to encephalitis from infections, Mayo Clinic researchers report in Annals of Neurology.

Encephalitis is a term used to describe brain inflammation. Its symptoms include fever, confusion, memory loss, psychosis and seizures. It progresses quickly over days to weeks and can be life-threatening. Traditionally, it has been thought that infections account for most cases of encephalitis, but this study shows autoimmune encephalitis is an equally common cause.

"The results of our study suggest that doctors evaluating patients with encephalitis should search for autoimmune causes in addition to infectious causes, given both have a similar frequency," says Eoin Flanagan, M.B., B.Ch., senior author of the population-based study and an autoimmune neurology specialist at Mayo Clinic.

Feb. 22 is World Encephalitis Day—a day to raise awareness of the illness.

Infection remains an important concern when evaluating patients with encephalitis, notes Michel Toledano, M.D., one of the study's co-investigators and a neuro-infectious diseases specialist. "But the results of our study indicate that doctors also should explore autoimmune causes to ensure that the appropriate treatment is given, which is essential to prevent long-lasting damage," Dr. Toledano says.

To identify cases of encephalitis, the study used data from the Rochester Epidemiology Project, a medical records database of all medical providers in Olmsted County, Minnesota. The researchers found about 14 per 100,000 people had autoimmune encephalitis in their lifetime, compared to 12 per 100,000 who had infectious encephalitis. One study limitation is that the diagnostic criteria for autoimmune and infectious causes of encephalitis differed, which could affect the comparison.

"Previously, we did not know how common autoimmune encephalitis was, as no prior studies evaluated this," Dr. Flanagan says. "This study allows us to estimate that approximately 1 million people worldwide had autoimmune encephalitis in their lifetime. We also estimate that, currently, about 90,000 people around the world develop autoimmune encephalitis each year."

In this study, the researchers used 2016 for autoimmune encephalitis. Using the Mayo Clinic Neuroimmunology Laboratory, which performs comprehensive neural autoantibody testing on blood and spinal fluid, the researchers were able to identify neural antibody markers that indicate a likely autoimmune cause.

"Our study showed that clinicians are now detecting more cases of autoimmune encephalitis than they were in the past because of the discovery of these new neural autoantibody markers. These advances in diagnostic testing are good news for patients, as they have allowed doctors to diagnose and treat autoimmune more effectively." Dr. Flanagan says.

Explore further: Isolated psychiatric episodes rare, but possible, in common form of autoimmune encephalitis

More information: Divyanshu Dubey et al. Autoimmune encephalitis epidemiology and a comparison to infectious encephalitis, Annals of Neurology (2018). DOI: 10.1002/ana.25131

Related Stories

Isolated psychiatric episodes rare, but possible, in common form of autoimmune encephalitis

July 26, 2013
A small percentage of people diagnosed with a mysterious neurological condition may only experience psychiatric changes - such as delusional thinking, hallucinations, and aggressive behavior - according to a new study by ...

Encephalitis kills at least 430 in India

October 15, 2011
At least 430 people, mainly children, have died from an outbreak of encephalitis in a deeply neglected region of the northern Indian state of Uttar Pradesh, officials said on Saturday.

Effects of brain damage from an autoimmune encephalitis similar to those of 'angel dust'

April 26, 2016
A new study in Biological Psychiatry reports structural brain damage from an autoimmune encephalitis that impairs behavior in ways that are somewhat similar to the effects of "angel dust."

Researchers identify conditions most likely to kill encephalitis patients

August 20, 2013
People with severe encephalitis—inflammation of the brain—are much more likely to die if they develop severe swelling in the brain, intractable seizures or low blood platelet counts, regardless of the cause of their illness, ...

Immunotherapy associated with improved seizure outcomes among patients with autoimmune epilepsy

March 26, 2012
Early-initiated immunotherapy appears to be associated with improved seizure outcomes among patients with autoimmune epilepsy, according to a report published Online First by Archives of Neurology.

Encephalitis kills 60 in eastern India in fortnight

July 22, 2014
An outbreak of encephalitis has killed 60 people in two weeks in the eastern Indian state of West Bengal, a top health official has said, calling the situation "alarming'.

Recommended for you

The brain's frontal lobe could be involved in chronic pain, according to research

May 25, 2018
A University of Toronto scientist has discovered the brain's frontal lobe is involved in pain transmission to the spine. If his findings in animals bear out in people, the discovery could lead to a new class of non-addictive ...

Aggression neurons identified

May 25, 2018
High activity in a relatively poorly studied group of brain cells can be linked to aggressive behaviour in mice, a new study from Karolinska Institutet in Sweden shows. Using optogenetic techniques, the researchers were able ...

Doctors fail to flag concussion patients for critical follow-up

May 25, 2018
As evidence builds of more long-term effects linked to concussion, a nationwide study led by scientists at UCSF and the University of Southern California has found that more than half of the patients seen at top-level trauma ...

Bursts of brain activity linked to memory reactivation

May 24, 2018
Leading theories propose that sleep presents an opportune time for important, new memories to become stabilized. And it's long been known which brain waves are produced during sleep. But in a new study, researchers set out ...

Study suggests brainwave link between disparate disorders

May 24, 2018
A brainwave abnormality could be a common link between Parkinson's disease, neuropathic pain, tinnitus and depression—a link that authors of a new study suggest could lead to treatment for all four conditions.

Researchers define molecular basis to explain link between a pregnant mother's nutrition and infant growth

May 24, 2018
For years, pregnant mothers have questioned their nutritional habits: "Will eating more cause my baby to be overweight?" Or, "I'm eating for two, so it won't hurt to have an extra serving, right?"

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.