Immune Condition May be Mistaken for Schizophrenia, Bipolar Disorder

A large number of people diagnosed with schizophrenia or bipolar disorder may actually have a treatable immune system condition, according to researchers at Houston Methodist Neurological Institute.

The research was inspired by the 2007 discovery of anti-NMDA receptor encephalitis, a disease that causes symptoms similar to schizophrenia or bipolar disorder but can be treated with existing immunotherapy drugs.

“We suspect that a significant number of people believed to have schizophrenia or bipolar disorder actually have an immune system disorder that affects the brain’s receptors,” said Joseph Masdeu, M.D., Ph.D., the study’s principal investigator and a neurologist with the Houston Methodist Neurological Institute.

“If true, those people have diseases that are completely reversible — they just need a proper diagnosis and treatment to help them return to normal lives.”

In a healthy immune system, the body produces antibodies that attack foreign substances, such as bacteria. When this process goes awry, antibodies are produced that attack receptors in the brain, causing the receptor to stop listening to the signals being sent to it. In cases of anti-NMDA receptor encephalitis, antibodies attack the N-methyl-D-aspartate (NMDA) receptors.

Conditions that cause the brain’s receptors to stop working properly are often mistaken for schizophrenia or bipolar disorder, because they lead to a decrease in the activity of NMDA receptors, which help manage thinking processes, decision-making, and how a person perceives the world around them.

Typical schizophrenia and bipolar disorder symptoms seen in anti-NMDA receptor encephalitis and similar conditions include hearing voices and paranoia.

“We know that nearly one percent of the U.S. population — or more than 3.5 million people — have schizophrenia,” Masdeu said. “Another 2.6 percent of American adults have bipolar disorder. What we don’t know is how many of these patients actually have one of these treatable immune system disorders.”

The researchers are going to enroll 150 patients diagnosed with schizophrenia or bipolar disorder and 50 healthy people between the ages of 18 and 35 who are willing to undergo a spinal tap to collect a small amount of their cerebral spinal fluid. This fluid will be screened for the presence of antibodies attacking NMDA and other receptors.

If abnormal antibodies are found, the researchers will notify the patient or caregiver, so that they may consider asking their health care provider about treatment options, such as using existing drugs that could suppress the production of the attacking antibodies.

Masdeu plans to use the study results to develop more sensitive tests to aid in the detection of attacking antibodies.

Source: Houston Methodist