There is growing evidence that a common childhood throat infection increases the risk of neurological disorders such as Tourette's syndrome.
The researchers looked at children with neurological disorders
Scientists found children with such disorders were twice as likely to have had recent streptococcal infections than their healthy peers.
Researchers at Seattle's Center for Health Studies suggest the body's response to the infection may be key.
But they tell the journal Pediatrics that it is just one potential trigger.
OCD is more commonly associated with adults, but the researchers say it affects around 1 to 2% of school-age children - and transient tics can affect 10 to 25% of primary school age children.
Tourette's - a neurological disorder characterized by tics, involuntary vocalization, and, in some cases, the compulsive utterance of obscenities - affects around one in every 100 children to some degree.
Scientists had suspected there may be a link between the streptococcal infection and neurological disorders.
It has been suggested that the body's natural response to infection, where particular antibodies are produced and directed to parts of the brain, might be linked in some way to these disorders.
However, it is not clear why most of the millions of children who have bacterial throat infections each year do not develop such disorders.
The team from the Group Health Center for Health Studies in Seattle aimed to assess the strength of the link between strep infections and the incidence of neurological disorders.
They looked at 200 children aged four to 13 diagnosed with a neurological disorder between 1992 and 1999, and compared them with healthy children in the same age group.
Children with Tourette's, OCD or a tic disorder were more than twice as likely to have had at least one streptococcal infection in the three months before symptoms of their disease emerged.
And incidence of the disorders was more than three times as common among patients who had had two or more streptococcal infections in the year before the onset of their disease.
Dr Robert Davis, who led the study, said: "There are likely a number of different causes for these conditions, which often show up first in childhood or adolescence.
"Following a number of different leads from past research, we've found more tantalising clues about possible connections between childhood infections and certain disorders.
"However, our findings certainly don't suggest that there is any immediate need for a change in medical - or parental - practice."
He stressed that much more research was needed before advice could be given to parents and doctors in a bid to reduce the occurrence of childhood neurological disorders.
But he added: "Right now, this is all still in the research stage.
"We still don't know if treatment with common antibiotics helps prevent these neurological conditions that might follow strep throat, or reduce their severity, or shorten their duration if they do occur."
The researchers say a person's genes may play a critical role, with infection acting as a trigger.
The UK's Obsessive Compulsive Disorder Centre says streptococcal infection is one of several suggested causes for the condition, because of the potential damage caused by antibodies to neurotransmitters in the brain.
It adds: "Investigations into the impact of throat infection on the malfunctioning area of the brain identified with OCD are looking promising but are, as yet, inconclusive."