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Obsessive Compulsive Disorders are characterized by repetitive behaviors such as sorting. (Photographic Illustration)

Obsessive Compulsive Disorders are characterized by repetitive behaviors such as sorting. (Photographic Illustration)

10/31/2006

When Strep Goes to Your Head

By Elizabeth Bassett

I sort my M&Ms into patterns by color. And my Skittles. And my jelly beans. If I’m not in any rush when I’m walking home, I’ll avoid stepping on the cracks in the sidewalk.

I don’t have an obsessive compulsive disorder.  In my case, it’s mostly just boredom.  These quirks don’t disrupt my daily life, but for people who actually have OCD, which is characterized by repetitive behaviors such as hand-washing or sorting and recurrent thoughts that can cause anxiety, it can be debilitating. And it turns out that the development of obsessive compulsive disorders could be triggered by something commonplace: a childhood strep infection.

This is further proof that the origins of disease are complicated and infections can alter the body in very subtle ways, altering even the brain. When a throat infection can contribute to the start of a mental illness, physicians and patients must reassess the implications of illness.

Before you start wondering if you have OCD because your closet organized is by color and you had strep as a kid, realize that developing OCD associated with strep is extremely rare. Only about 1 percent of children develop OCD, which may continue into adulthood, and not all of these children developed their disease after an infection. While researchers aren’t sure of the frequency of strep-triggering OCD, it’s usually an untreated infection that is associated with OCD.

Researchers relied on children already suffering from an OCD disorder associated with strep to help strengthen the correlation between the two illnesses. Dr. Susan Swedo at the National Institute of Mental Health and two collaborators drew blood from children diagnosed with PANDAS, or pediatric autoimmune neuropsychiatric disorders associated with streptococci. PANDAS is a type of obsessive compulsive and tic disorder. Whereas OCD traditionally develops gradually over time, PANDAS leaves a normal child with full-blown tics and compulsions in 24 hours.

They introduced the drawn blood to cultures of nerve cells. The researchers found that antibodies to strep in the blood of these PANDAS patients caused the nerve cells to produce more of an enzyme that disrupts communication between the cells. This enzyme plays a role in the making and releasing of neurotransmitters, which affects the severity of OCD. When nerve cell cultures are exposed to blood without these antibodies, the enzyme levels are much lower or nonexistent.

The rapid mental changes in PANDAS patients signaled to researchers that something odd was going on. By taking complete patient histories, doctors were finding many of these children had strep infections up to six months before the PANDAS onset, but until now they were only able to make an association between the infection and the disease.

Like most cases of OCD, PANDAS can get better and worse in episodes. If a child with PANDAS has more strep infections, the episodes can start sooner after the infection and the symptoms can be worse.

“If we see kids with PANDAS, we can see whether they have strep antibodies,” said Swedo. “Similarly, if a PANDAS kid’s symptoms start getting worse, we can tell the parents to get a throat culture, because it could be strep again.”

The general public and many scientists used to be skeptical that infections could cause neurological changes, said Swedo, but now more people are recognizing it’s a very real connection. She said research is already underway to replicate the results of her study.

“Once a person introduced me at a lecture by talking about this ‘new’ concept I was studying,” said Swedo. “But this isn’t new. You’ve got to remember the grand-daddy of all mind-changing infections, syphilis. This is actually pretty old-fashioned in some ways.”

Dr. Robert Yolken said that realizing infections can trigger diseases is a hard concept for the general public and scientists to grasp. Yolken, an infectious diseases specialist at Johns Hopkins Children’s Center, is investigating possible infectious triggers of schizophrenia.

“You have this infection where the vast majority of people who get it don’t even realize they have it, and then there’s some people who get it and they develop a disease,” Yolken said.

But Swedo said she’s hopeful that someday people can get a genetic profile done which will show all the antibodies present in their body. That way, if you know which antibodies you have, you know which infections your body has encountered and so which infections may trigger disease.

“Disease origins are a lot more complicated than we thought,” said Yolken. “Just how the genes don’t entirely determine whether someone will get a disease or not, an infection won’t entirely determine if you will develop a disease.”


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