Researchers in California suspect that covid-19 triggered sudden mental illness in at least two of their teenage patients.

Because mental illness is unfortunately common and often linked to a variety of influences, it can be difficult to show cause and effect from any one thing, including a viral infection.

But doctors at the University of California, San Francisco (UCSF) Benioff Children’s Hospital say they’ve come across a few cases in the past year where covid-19 does seem to have been a primary trigger for a patient’s sudden mental illness.

In a new paper published Monday in JAMA Neurology, they describe teen patients who developed newly documented psychiatric symptoms, including extreme mood swings, paranoid delusions, and suicidal ideation, after a confirmed but mild or asymptomatic case of covid-19.

Pleasure noted that immune-related problems after an infection have been documented well before covid-19, often linked to viral infections.

To better understand these cases and definitively establish a link between sudden psychiatric illness and covid-19 would require more research, which the authors say they’re conducting now.