MONTREAL – Streptococcal pharyngitis may be a very occasional trigger for anorexia nervosa and other neuropsychiatric conditions and should be investigated in patients with sudden onset of psychiatric symptoms, Mae S. Sokol, M.D., said at an international conference sponsored by the Academy for Eating Disorders.
Identification of this cause of anorexia nervosa would not change treatment of the condition (although this possibility is being investigated), but it would alert patients and physicians to the need for more aggressive prevention and treatment of future strep infections, said Dr. Sokol of Creighton University in Omaha, Neb.
She said group A beta hemolytic streptococci (GABHS) have been linked with several illnesses known collectively as PANDAS (pediatric autoimmune neuropsychiatric disorder associated with streptococcus). The PANDAS classification also includes obsessive-compulsive disorder (OCD) and tic disorders such as Tourette's syndrome.
It is well recognized that rheumatic fever and Sydenham's chorea are streptococcus-triggered autoimmune attacks on cardiac cells and cerebral neurons, respectively. It also is believed that PANDAS might be caused by similar attacks on basal ganglia cells, noted Dr. Sokol, who is also director of the eating disorders program at Children's Hospital in Omaha.
“We hypothesize that the immune system may look at the basal ganglia cells in the brain and mistakenly attack those cells, which may cause patients to have abnormal thoughts about food and weight,” she said in an interview at the conference.
Why this damage to basal ganglia cells manifests sometimes as anorexia and other times as OCD, Tourette's, or infantile autism is not known, she 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. Another theory is that 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. What's common in all these patients is a sense of perfectionism after they become ill,” Dr. Sokol explained.
She presented her study of 21 children and adolescents with possible PANDAS anorexia. The subjects met some or all of the following criteria:
▸ Presence of anorexia meeting DSM-IV criteria.
▸ Prepubertal onset of anorexia. This was present in 10 of the 21 participants. Participants ranged in age from 10.5 to 18 years at enrollment, with symptom onset at 9.7–16 years.
▸ Acute onset/exacerbation of their anorexia symptoms. This occurred in 19 of the 21 participants.
▸ Association with GABHS infection: anorexia onset or exacerbation within 1 day to 6 months of strep infection. This occurred in all participants.
▸ Increased psychiatric symptoms, not exclusively during the strep illness. Present in all participants.
▸ Concomitant neurologic abnormalities, such as choreiform movements, motor hyperactivity, or adventitious movements. This occurred in only two participants but has been reported more frequently in PANDAS OCD.
Dr. Sokol said physicians who suspect PANDAS anorexia should try to confirm laboratory strep tests, although at this stage treatment recommendations would be no different for this group.
However, identification of an infection-triggered anorexia could alert physicians and patients to the need for more aggressive prevention strategies such as the use of prophylactic antibiotics (which is still under investigation) and to the importance of influenza vaccination, which can decrease vulnerability to strep, she said.