Children's Hospital of Philadelphia is seeking patients to participate in an observational study of medical cannabis.

The study will not provide marijuana products to participants. Researchers want to partner with families whose children have been diagnosed with Autism Spectrum Disorder (ASD) and are already consuming medical cannabis from state-licensed dispensaries. Participation will be confidential, said Dr. Athena Zuppa, director of CHOP's Center for Clinical Pharmacology.

Participating families will be asked to undergo an hour-long interview in person or on the phone; provide information on the child's medical background; answer questions about their child's medical cannabis use and behaviors; and complete optional study materials, Zuppa said in a letter to prospective parents.

>> READ MORE: Medical marijuana news at Philly.com/cannabis.

The hospital is pairing with Zelda Therapeutics, an Australian biopharmaceutical company, for what some advocates have described as the first major effort in the United States to study the effects of medical marijuana on children with autism.

Substantial anecdotal evidence shows that cannabinoids, the active compounds in medical marijuana, can help with some symptoms of autism. Cannabis advocates say cannabinoids help improve social interaction and control repetitive behavior, and don't cause the side effects associated with antipsychotic drugs often given to autistic children.

One of the aims of the study is to determine what parents in the region are giving their autistic children. Cannabidiol, known as CBD, is a substance in marijuana that, unlike THC, does not induce euphoria.

Pennsylvania was the first state to include autism as a qualifying condition for the use of medical marijuana. Though mothers of autistic children led the push for the medical marijuana program in the state, there are few products available in Pennsylvania dispensaries that are predominantly CBD.

CHOP is home to the Center for Autism Research, a collaborative program with the University of Pennsylvania that is trying to determine the origins of autism spectrum disorders and create effective treatments through research.

For more information, call the study coordinator at 877-754-2440 or email carmedcanchop@email.chop.edu .

This story was updated to provide the correct email address for study information.