Seth Rogen's Dad Says Weed Cured His ADHD Celebrity According to his father, the 'Knocked Up' actor smoked marijuana in order to be able to relax as he struggled with attention deficit hyperactivity disorder. Apr 23, 2021 AceShowbiz - Marijuana became Seth Rogen's saving grace during his youth because nothing else could help calm him down as he battled attention deficit hyperactivity disorder (ADHD). The " Knocked Up" star is well known as a weed aficionado, and even boasts his own brand of cannabis, and he likens smoking the drug to wearing a pair of shoes. He explained, "It's just a tool we use to make our experience more palatable, and some people need those tools a lot more than others. For me, it's like shoes. For you, it might be like sunglasses. Not everyone's the same."