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Childhood disorder prompts study of infection link to mental illness

Cases of children suddenly exhibiting obsessive-compulsive disorder after strep has led to studies that reinforce the belief that some mental illnesses can be triggered by an immune response.

December 05, 2011|By Shari Roan, Los Angeles Times

Another paper, published online in August in the Journal of Pediatrics, found that, compared with children with typical OCD, children diagnosed with PANDAS were more likely to have biological evidence of a recent strep infection, a sudden onset of psychiatric symptoms and an easing of those symptoms while taking antibiotics.

PANDAS may be caused by a mechanism similar to that of rheumatic fever, an autoimmune disorder triggered by strep infection, says Dr. Susan Swedo, a leading researcher on the condition based at the National Institute of Mental Health in Bethesda, Md., which sponsored a symposium on the disorder last year.

When an infection occurs, the body produces antibodies to fight the bacteria and clear them from the body. But in the case of rheumatic fever, the antibody response malfunctions and the immune system attacks the heart valves, joints or parts of the brain. This autoimmune response in the brain is called Sydenham's chorea or St. Vitus' dance, a condition that features rapid jerking movements and tics.

In PANDAS, a vulnerable part of the brain may be the target of the wayward immune response. In a 2003 study in Nature Medicine, immunologist Madeleine Cunningham of the University of Oklahoma College of Medicine reported that antibodies generated by a strep infection can bind to neurons and prompt the release of unusual amounts of dopamine and other brain chemicals. Abnormal amounts of dopamine are thought to cause tics and OCD symptoms.

But almost every child is infected with strep at some point, and most don't develop OCD symptoms. Some researchers say that children who develop PANDAS may have a genetic vulnerability that puts them at risk. For instance, kids with PANDAS are more likely than healthy children to have a family history of rheumatic fever, which suggests an inherited vulnerability to strep infections that go awry, says Dr. Mady Hornig, who studies interactions between the brain and immune system at Columbia University in New York.

Uncertainty and skepticism

The link between strep and OCD is hard to make "because it's hit and run," Hornig says. Children with PANDAS symptoms typically have recovered from their strep infection by the time they see a psychiatrist or neurologist, she says. An anti-streptococcal antibody test can show whether the child has had a strep infection within the last few months. But some children without OCD symptoms also have high antibodies to strep, and some children with PANDAS have no evidence of strep infection.

There are also case reports in the medical literature that infections besides strep, such as mononucleosis and a type of pneumonia caused by mycoplasma, may give rise to PANDAS, Jenike says.

All of this uncertainty makes many doctors skeptical.

One of them is Dr. Harvey Singer, director of pediatric neurology at the Johns Hopkins Hospital Children's Center in Baltimore, who has studied the illness. Children diagnosed with PANDAS actually may have obsessive-compulsive disorder that flares up when they are stressed by an event or illness, he says.

And some researchers have tried and failed to find a link between infection and OCD. A study published this year in the Journal of the American Academy of Child and Adolescent Psychiatry compared children with PANDAS to other children with OCD or Tourette's syndrome and found no link between worsening symptoms and strep infections in either group.

Still, some doctors are using antibiotics to try to rid the body of any lingering strep infection as a way to treat PANDAS or prevent OCD symptoms from returning if the child is exposed to strep again. Authorities at NIMH have criticized this practice because it may contribute to antibiotic resistance.

A more invasive treatment — called intravenous immunoglobin (IVIG) or plasmapheresis — is aimed at shutting down the strep antibody response by giving children infusions of donor plasma to prompt normal immune-system functioning.

A 1999 Lancet study showed that children with strep and OCD were helped by the therapy. But a 2000 study in the Journal of the American Academy of Child and Adolescent Psychiatry found that it did not improve symptoms and caused side effects, such as nausea and headaches. The National Institutes of Health is currently enrolling children with PANDAS in a new study to evaluate the treatment.

These approaches may be controversial in the medical community, but many patients are eager to try them. Diana Pohlman of Palo Alto credits both with pulling her 11-year-old out of a four-month-long bout of OCD that began within weeks of what seemed like a routine case of strep.

Pohlman remembers the day her then-second grader came home from school and began running frantically through the house switching off the lights because, he said, "we'll get radiation." The TV had to be turned off too, he insisted, because "there's poison in there."

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