Apparently as many as one in four children develop some kind of tic disorder that can range from a compulsive ordering of objects to obsessive hand-washing to the uncontrolled lashing out of Tourette's syndrome.
Although in most cases, the tic disappears after a period of time, Tourette's and obsessive-compulsive disorders may be lifelong afflictions, that can only be controlled with powerful drugs.
Dr. Robert Davis of the Center for Health Studies in Seattle, one of the authors of the study, says that although genetics possibly play a major role in these conditions, strep throat might be one of the triggers.
In the study children aged 4 to 13 with tics who were patients of Davis' Seattle-based Group Health Cooperative between 1992 and 1999 were identified , and were matched with children without tics.
On the basis of their medical histories, it was seen that children with tics were twice as likely as tic-free children to have had a streptococcal infection, primarily strep throat, within the previous three months, and for those who had multiple infections, the risk of developing a tic tripled.
It is believed by many scientists that the body's response to infection, and to the antibiotics prescribed to fight it, is to produce antibodies that attack not only the infection but may also damage brain cells that control movement and behavior.
Davis says that strep infections share certain proteins that stimulate a set of antibodies that cross-react with the brain, and the result is an autoimmune response, where the body's own immune system attacks healthy cells as in multiple sclerosis or lupus.
To date science has failed to find cures for autoimmune diseases.
Davis says that strep infections are quite common, but it is too early to know whether choosing one treatment option or none at all would help stave off tics.
The study was published in Pediatrics, the monthly journal of the American Academy of Pediatrics.
In studies of cell cultures and of mice engineered to have HD, the researchers found that the p53 increase causes malfunctions in mitochondria. What's more, they found that this p53 increase induced by the abnormal HD protein greatly increases cell death.
The researchers also found effects of the abnormality in p53 in whole animals. They found that deleting p53 suppresses damage to neurons in the eye of fruit flies engineered to have the abnormal HD protein. And in mice with the abnormal protein, knocking out p53 corrects behavioral abnormalities that the mice otherwise display. These behaviors include abnormal reflexes such as an inhibited startle response to loud noise, which is also present in human HD patients.
"In summary, our study establishes a specific role for p53 in HD," concluded Sawa and colleagues. "As p53 is a nuclear transcription factor that regulates various mitochondrial genes and insofar as mitochondrial dysfunction appears important in HD, our findings provide a molecular mechanism linking disturbances of nuclei and mitochondria in HD."
neuron/