Could The Thoughts Of Transgender In A Child Be Due To Vyvanse?

My 12 yr old is on Vyvance for ADHD, and is doing wonderful in school. But recently we saw in his diary that he has started having thoughts of wanting to be a girl, and wearing his mom s underwear. He also wrote of having sex with other boys, but he claims he made that up. My question is: Can this medication cause these thoughts?