Between 1 and 3% of youths have OCD. Among children with OCD, up to 5% may meet the criteria for PANS/PANDAS. While as many as 17% of children with autism also have OCD, it is very rare that their OCD is linked to PANDAS. Even so, the situation can arise. When it does, it can be difficult to separate the symptoms of autism from signs of PANS/PANDAs since many of the symptoms and comorbidities overlap.
While PANS is a group of symptoms without an undetermined cause, PANDAS does have a clear trigger. In most cases, the onset of PANDAS is triggered by exposure to Group A Streptococci, commonly known as strep throat or a strep infection. Other microbes, including Lyme and Mycoplasma, may also be related to PANDAS. When a child with genetic susceptibility (2-5% of the population) is exposed to these microbes, it causes a misdirected immune response, which leads to brain inflammation. This can manifest as PANDAS.