Trouble paying attention to people. Being constantly on the move. Invading personal space, not reading social cues well and having meltdowns. These can all be signs of both ADHD and autism. And the two conditions can occur together.
The signs of autism, also called autism spectrum disorder or ASD, can range in severity. While ADHD (also known as ADD) isn’t a spectrum disorder, like autism it can produce a range of symptoms. And each symptom can cause a range of difficulty from one child to the next.
Source: Understood.org – The Difference Between ADHD and Autism