"We are encouraged to start looking at these issues younger, rather than later," said Hines.
But ADHD is not a one-size-fits-all diagnosis, which has made it challenging to diagnosis and properly manage the disorder in some, said Dr. David Rosenberg, professor of psychiatry at Wayne State University in Detroit, Mich., who was not involved with the study.
Because ADHD has many symptoms and subtypes, a correct diagnosis is key to being prescribed a treatment that works, he said.
"When the diagnosis is made correctly earlier treatment markedly improves response and functioning," said Rosenberg. "The best predictor of good response and fewer side effects is making an accurate diagnosis."
"This is easier said than done," he added.
Zoega agreed, saying future research should look into categorizing different symptoms and create more exact subtypes for an ADHD diagnosis.