Abstract
Background: Tics are common in people with autism spectrum disorder (ASD). However, their phenomenology and characteristics have not been studied in detail. Methods: Based on video sequences of 21 adults with ASD without intellectual disability and 16 adults with Gilles de la Tourette syndrome (GTS), tic severity, tic repertoires, and tic awareness were determined. Results: Ten ASD and all GTS participants had tics during video recordings. The ASD group had significantly fewer tics, compared to GTS. Tic distribution and tic repertoires were comparable, but more restricted in ASD. All GTS participants, but only 5 of the 10 ASD participants, were aware of their tics. Conclusions: Tics are common in adults with ASD. They are indistinguishable from tics in GTS and are similarly distributed, but less severe. Tic awareness is limited in ASD.