Inform the TSA Officer
You may inform the TSA officer that you have a medical condition if assistance or screening modification is needed during the screening process.
Screening
Passengers with non-visible disabilities and medical conditions such as Alzheimer's, autism spectrum disorder, and dementia can be screened without being separated from their traveling companion. If a companion provides assistance during screening, they will need to be rescreened.
Resources:
TravelingWiki.com: Wiki for Autism Resources at U.S. Airports