Welcome to HCM
ADHD is a childhood psychiatric disorder, it is characterized by impaired attention, hyperactivity and impulsivity. Usually the cause is idiopathic. If it occurred after head trauma
it is just a chance factor. As his CT, MR scans are normal so most likely the cause of ADHD is not head trauma. Medicines for ADHD includes Stimulant medicines like amphetamines
etc. He is taking Focalin
which is methylphenedate and is right medicine for ADHD. It will take time to show proper improvement. Don't take undue stress he will show improvement with medicines.
Dr. Seikhoo Bishnoi, MD