When Tics, OCD, or Anorexia Develop Following Strep Infection
By: Shin Jie Yong
Tags: Mental Health, Technology, Health, Psychology, Ideas

Infection | Brain

When Tics, OCD, or Anorexia Develop Following Strep Infection

It’s called PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections).

In the late 1900s, physicians reported that children started showing tics following a strep sore throat outbreak. The tics also disappeared when strep is killed by antibiotics.

A 2007 Case Report

An 8-year-old boy with recurrent strep sore throat developed a set of rituals before eating. He nodded, flapped his arms, tapped his mount, opened and closed his fists, etc. before taking a bite. He said the rituals helped him cope with intrusive thoughts that the food is poisoned. He became severely conscious with healthy eating and body fat, avoiding all ‘bad’ foods and eating only 200 calories/day — eventually losing 8kg. After receiving treatment for his recurrent sore throat, all his behavioural anomalies vanished.

The boy had PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections), obsessive-compulsive disorder (OCD), tics and anorexia nervosa.

PANDAS: What you need to know

Diagnosis: It’s diagnosed when a child develops tics or OCD right after a strep infection. Or when symptoms of tics/OCD worsen following a strep infection. The DSM-5 put PANDAS under “Obsessive-Compulsive and Related Disorders Due to Another Medical Condition.” While PANDAS is more closely associated with tic and OCD, it may include anorexia in some cases.

Cause: Nearly all children experienced strep throat infection at least once in life. The average schoolchild gets it 2–3x per year. It’s caused by a contagious bacterium called Streptococcus pyogenes. A strep sore throat infection can clear up on its own or with simple antibiotics. But in a small subset of children, perhaps with genetics and cultural predispositions, it can lead to PANDAS.

Statistics: Due to the lack of diagnostic guidelines, its precise prevalence is still unknown. Scientists, however, estimated that PANDAS contribute to at least 10% of childhood OCD and tic disorders.

Treatment: Usually with antibiotics and cognitive behavioural therapy. Steroids and antidepressants are prescribed if deemed necessary, though antidepressants often cause side effects in children with PANDAS. The best treatment is aggressive antibiotics — with about 50% cure rate according to a 2017 population study.

Prognosis: Long-term outcomes of PANDAS vary between cases due to the variability of PANDAS subtypes and treatment protocols. “Whether children with a PANDAS subtype typically will go on to remission or progress to a more chronic course of illness is not known,” says Tanya Murphy, MD, professor and director at the Rothman Center for Pediatric Neuropsychiatry, Florida.

If Strep infection is recurrent, for example, long-term antibiotics until adulthood is necessary. Even if Strep is eliminated, some may still suffer neuropsychiatric symptoms as the brain (or more specifically, the basal ganglia) is sufficiently compromised. Some children recover naturally too as the immune system matures and can distinguish Strep from the brain.

Basal Ganglia

Tic is viewed as the most common form of movement disorder in children. Tics are sudden and repetitive movement (e.g., shoulder shrugging, blinking, or head jerking) or vocalizations (e.g., sniffing or grunting). Tics can be short-term (11–20% prevalence) or long-tern (0.5–0.7% prevalence). Whereas OCD affects 1–3% in the general population. It’s characterized by persistent unwanted thoughts (obsessions) and/or repetitive behaviours driven by strong urges (compulsions).

What PANDAS, tic and OCD have in common is that the basal ganglia are involved. It’s a set of brain structures deep within the brain that is enriched with dopamine neurons responsible for movement coordination. It also has connections to the outer cortex that controls voluntary movement.

The dopamine-powered basal ganglia — motor cortex circuitry “control and select goal-directed motor, cognitive and motivational behaviour,…inhibitory control and habit formation” psychiatrists wrote.

The Trickster Streptococci

About 40% of children and adolescents with tics/OCD have higher levels of Strep-specific antibodies in their blood. This means that their immune system was actively fighting Strep bacteria.

Intriguingly, their Strep-specific antibodies reacted with brain dopamine receptors in a lab plate. Give Strep-specific antibodies to rodents and the antibodies deposit in the basal ganglia, causing motoric disorders. Immunize mice for Strep infection and the same thing happened.

This shows that antibodies generated by the immune system to neutralize Strep can invade the brain and attack the basal ganglia (where dopamine neurons are abundant). In a sense, the immune system mistook the basal ganglia for Strep bacteria. Or that Strep bacteria trick the immune system into attacking the basal ganglia.

This is a form of autoimmunity — as the ‘A’ implies in PANDAS — when the immune system attacks the host own cells.

What’s the Trick?

Molecular mimicry is currently the best explanation for any autoimmunity initiated by microbial infections. In molecular mimicry, the structure of the pathogen is similar to some tissues of the body. Antibodies that bind to the pathogen might also unintentionally bind to some other tissues by chance.

Chances of molecular mimicry happening are unknown. Scientists think that people with genetics prone to developing autoimmune diseases might be at a higher risk for PANDAS.

“Maybe you have more of a genetic risk for OCD or anorexia, and the infection then unmasks that vulnerability. That’s one possibility,” opines Kyle Williams, the director of the pediatric-neuropsychiatry-and-immunology program at Massachusetts General Hospital for Children.

PANDAS Anorexia

Symptoms of anorexia can be viewed as OCD, such as food and body weight obsessions and compulsive exercise or purging. Anorexia is also a neuropsychiatric disorder with multifactorial causes that include sociocultural, psychological and biological aspects.

In 2000, Mae Sokol, MD and professor of psychiatry at Creighton University in Omaha, reported 4 cases of “infection-triggered anorexia nervosa in children.” These children were also diagnosed with PANDAS and OCD. They successfully regained their weight (and OCD disappeared) after taking antibiotics.

“Maybe we are seeing the same thing in children with PANDAS anorexia and children with PANDAS OCD — only in the PANDAS anorexia, the obsessions are about food and weight, whereas in PANDAS OCD they are about other things,” Prof. Dr. Sokol said.

“Since the basal ganglia are also involved with emotion, we think this area of the brain may be affected slightly differently with each condition,” the psychiatrist professor added. Besides the basal ganglia, researchers have found higher levels of antibodies that target appetite-regulating hormones in the bloodstream of anorexics. They also suggested that molecular mimicry is at play but has not pinpointed a specific microbial agent. More details here:

It seems that Strep could very well be the microbial agent playing molecular mimicry tricks on the immune system to target the basal ganglia (and appetite hormones).

To Close

“We say disease is due to biological factors, social factors, and psychological factors all interacting together,” remarks Jim Morris, a professor at Lancaster University, UK, in response to PANDAS. “Well, it works with psychiatric disease as well.”

Researchers have focused on genetics and other medical comorbidities for decades. But now the microbial angle has started to gain recognition as part of the biological aspect in psychiatric diseases. Though scientists still have a long way to go, as evidenced by the lack of clinical studies, diagnostic and treatment guidelines, statistical prevalence, etc.

“When a child suddenly develops food rituals, becomes unusually picky about food and loses weight, you might not think of a bacterial, viral, or other types of infection,” says the psychotherapist Sharon K. Farber, PhD, at New York University.

This article was inspired by Caelyn H.