When singer/songwriter/actor Demi Lovato was diagnosed with bipolar disorder at age 22, it came as a relief, and allowed her to deal with her condition.

"When I focus on my treatment plan with my team and my support system, I'm able to not only maintain a healthy mind, but ... to maintain my sobriety," she said.

Imagine, however, if you were diagnosed with that mental illness — for which there is no cure — when in fact you had a treatable immune disorder.

Back in 2007, researchers discovered that there was a form of immune encephalitis that affects specific brain receptor functions and triggers symptoms, such as paranoia and hearing voices, that are associated with bipolar disorder and schizophrenia.

Researchers at Houston Methodist Hospital became curious about the potential for misdiagnosis.

"We suspect ... 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 Dr. Joseph Masdeu, the study's principal investigator. "If true, those people have diseases that are completely reversible."

So the researchers are launching a study in which they'll collect cerebral spinal fluid from those diagnosed with the mental illnesses.

If samples contains antibodies known to attack certain brain receptors, researchers will notify the participants so that they can ask their doctor about using existing drugs to suppress production of the attacking antibodies.

Stay tuned for results, and if you or a loved one has been diagnosed with either condition, ask your doc about ruling out anti-NMDA receptor encephalitis as a cause of symptoms.