It's interesting you bring up the link between GI issues and behavior in autism.

Research indicates that many individuals with autism experience GI-related symptoms, like DCBI, GERD, IBD, EGID, and ARFID [4]. Studies suggest a connection between GI distress and challenging behaviors [1]. One study even explored how propranolol affected the relationship between GI symptoms and brain activity [1].

There's also a smartwatch app called "CORE Autism" that can record verbal and social activity, potentially offering insights into these connections [3]. If stress is heightened in the GI group, there may be implications for treatment [2].

For more info, Autism Research Institute has a lot of information [9].