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What Are PANDAS and PANS?

Sudden-onset OCD and other symptoms triggered by an infection

Writer: Caroline Miller

Clinical Experts: Tom lnsel, MD , Susan Swedo, MD

en Español

Parents use words like “abrupt,” “overnight,” and “out of the blue.” The symptoms, they say, went “from zero to 60.” The child, who had been happy and untroubled, “fell off a cliff.”

Parents can often tell you the exact day a child started his washing hands until they’re raw, opening and closing the door endlessly, asking the same questions over and over. It’s called acute-onset OCD, and the onset can often be linked to a strep or some other kind of infection.

When sudden-onset OCD and other related symptoms are triggered by an infection, it’s thought to be an auto-immune syndrome called PANS or PANDAS. If the infection is strep, which is the most common, it’s called PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections). If it’s something else, such as Lyme disease or flu, it’s called PANS (Pediatric Acute-Onset Neuropsychiatric Syndrome). It’s thought that the symptoms are caused by brain inflammation when the body’s immune system mistakenly attacks healthy brain cells.

The signs of PANS and PANDAS

In most cases of obsessive-compulsive disorder, the symptoms come on gradually. A child begins to experience fears that are disturbing and distracting. He typically hides them as long as he can, managing them with compulsive rituals like counting and touching things repeatedly and washing his hands. Eventually, the obsessions and compulsions take over more and more of his life, until he can’t hide any more.

But with PANS and PANDAS the OCD symptoms appear suddenly and are accompanied by other confusing and disturbing symptoms.

Symptoms of PANS and PANDAS include:

Strep linked to OCD behaviors

This sudden-onset OCD — along with a host of other disorienting symptoms — was first identified in the late 1990s by Susan Swedo, MD, the chief of pediatrics and developmental neuroscience at the National Institute of Mental Health (NIMH). It was named PANDAS—that is, pediatric autoimmune neuropsychiatric disorder associated with streptococcus—because onset seemed to be linked to infection, and strep was the most common of those infections, as well as one that had already been examined extensively. “A disease mechanism is easier to define for a single organism,” Dr. Swedo explains. That said, they knew at the time, Dr. Swedo adds, that some other infections can also be linked to this set of symptoms.

PANDAS is usually diagnosed in children who have what doctors call “occult” strep infections—that is, children who can be “carriers” of the infection to others, but do not show symptoms, and hence don’t get treatment. It happens in about 1 in 1,000 children, and three times as often in boys than girls, explains Dr. Swedo. It’s defined as a pre-pubertal condition, since most kids, by the time they hit adolescence, have developed immunity to strep, so onset isn’t likely to occur after that, though PANDAS symptoms will continue to occur intermittently. Sometimes these symptoms grow worse with each flare-up, or what doctors call “exacerbation.”

Treatment for PANDAS involves targeting the inciting infection with antibiotics; in severe cases treatment options include plasmapheresis (the exchange of blood plasma) or IVIG (intravenous immunoglobin), which gives children antibodies from a myriad of donors.

The theory behind PANDAS

The theory behind PANDAS is that the strep bacteria “hide” from the immune system by mimicking the child’s own cells. “It’s a kind of camouflage to evade detection by the immune system,” Dr. Swedo explains. The immune system eventually recognizes the bacteria, and produces antibodies to fight them, but because of the similarities to human cells, those antibodies in turn sometimes “misrecognize” molecules in a child’s own body and attack them. In the case of rheumatic fever, for instance, they attack the heart. In the case of PANDAS, the theory goes, it’s the brain—specifically the basal ganglia, which is where OCD symptoms are thought to originate.

While there are animal and human studies that demonstrate the link between the infection and the OCD-like symptoms, and human studies that show IVIG and plasmapheresis to be effective in reducing symptoms, not all researchers in the field were initially convinced that the link was adequately demonstrated. And they were especially leery of moving too quickly to accept the link because of the potentially negative effects of putting kids on antibiotics for sign of psychiatric symptoms.


With this controversy as the backdrop, in 2010 Dr Swedo and her colleagues at the NIMH proposed a new, broader category that describes the set of symptoms without a specific link to strep. It’s called PANS (pediatric acute-onset neuropsychiatric syndrome) and it applies to children and adolescents who suddenly develop on-again/off-again OCD symptoms or abnormal eating behaviors, along with other psychiatric symptoms—without any link to a cause.

The effect of this new category was twofold: First, to acknowledge that other infections besides strep—notably Lyme disease, mono, mycoplasma (walking pneumonia) and the flu (such as H1N1)—can be linked to this set of symptoms. Second, to bridge the controversy by separating areas of agreement—what the set of symptoms is—from disagreement over etiology. PANS has been successful in enlarging the definition, Dr. Swedo notes, but not in quieting the controversy.

Battle lines

The battle over PANDAS and PANS was in part a battle over the evidence. Harvey Singer, MD, a professor in the departments of neurology and pediatrics at the Johns Hopkins Hospital Children’s Center, has been a consistent skeptic of PANDAS and now PANS. At the 2010 meeting in which PANS was presented by Dr. Swedo and her colleagues, Dr. Singer rolled out a competing category called CANS (childhood acute neuropsychiatric symptoms) to further downplay the role of strep or other infections in the symptoms. Like PANS, CANS requires only the acute dramatic onset of symptoms; no particular cause is implied.

Singer argued that until there is more research to substantiate a link between strep and other infections and the OCD or tic symptoms, those symptoms should be treated as they normally are, not as infections. “Until we fully understand this thing, our approach should be to treat the symptoms,” he told Infectious Diseases in Children, rather than using plasmapheresis or IVIG, which he considers too dangerous. “There are medicines that work with tics, so treat that. If they have OCD, there are medicines that treat that. If they have anxiety, we have drugs for that.”

Tom Insel, MD, clinical psychiatrist and neuroscientist, puts skepticism about PANDAS in a historical context. “There is a history of reluctance to accept an infectious cause of a psychiatric or behavioral disorder, and the debate over PANDAS has been going on almost two decades,” he wrote in 2012. He describes the new PANS category as a move “toward consensus on some of the larger issues, such as a broader concept of ‘acute and dramatic’ onset of the same profile of psychiatric symptoms identified in PANDAS”—but without positing any cause.

“The onset has not always been linked precisely with a strep infection and the critical increase in antibodies to strep has not been evident consistently,” Dr. Insel notes. “Nevertheless, immune-based treatments have proven successful, leading to the growing acceptance of the concept of PANDAS.”

Nancy Myers, a mother who had to fight her practitioners to get antibiotics to treat her son, is avidly following the debate in the mental health establishment. “I think ultimately we’re going to get the medical community turned around on this” she says. “I’m just hoping it’s going to be fast enough for a lot of people.”

This article was last reviewed or updated on December 5, 2023.