Pam
Thank you for your question and welcome to ADHDCentral.com.
I am not a medical professional and would not be able to give you medical advice. However, I can share some of what I have learned from speaking with parents of children with ADHD, having raised a son with ADHD and bipolar and speaking with medical professionals.
You don't mention whether your grandson has been diagnosed with ADHD. You also don't mention whether the parents are involved with your grandson and if so, whether they are also concerned with some of his behaviors.
ADHD has been diagnosed in children as young as 3, however, many doctors are reluctant to diagnose in a child that young because each child develops at a different rate and many of the symptoms of ADHD can be similar to those behaviors seen in children this age.
Preschool children with ADHD can be very hyperactive and may be more aggressive than children without ADHD. According to an article, "What is ADHD?" ["What is ADHD?", 2002, Jim Chandler, M.D., Attention Deficit Disorder Resources], states that preschool children with ADHD::
Have poor social skills
Are more aggressive than peers without ADHD
Disobey twice as often
Display inappropriate behavior 5 times as often
You can read more at: ADHD in Preschool Age Children
I would suggest speaking with the parents and giving specific examples of behaviors you are concerned about.
Please let me know how it is going.
Eileen