My younger brother is an upcoming freshman, but he was tagged as a fourth grader by his teacher because he acts like one - running here and there, cannot sit still in class (even at home), and cant focus at any task. In fact my mom is the one who's doing all his projects and other homework. May I know if he has any chance of having ADHD or any mental disorders?

Thank you for taking the time out to ask a question about your brother.  It certainly shows the care and concern you have for him and he is fortunate to have someone like you in his life.

As far as the question you ask, you certainly raise some concerns indicating ADHD may be an issue here... specifically your mentioning he cannot sit still in class and at home and his inability to focus. 

And while I think it is very important your brother follow up with his physician, it is also difficult for me to respond to whether any co-morbidities (or as you state, “mental disorders”) exist without knowing more information.  But at the same time, it is so very important to determine if any exist because it can impact treatment decisions for someone with ADHD.

So what I would like to do is share some general characteristics of ADHD and its subtypes so you have a sense of what may be going on with your brother.  Firstly, while your brother is now older (14 years of age), typically the symptoms appears before 7 years of age.  The impact can be felt at school, home and in relationships with peers.   Although numbers vary, studies suggest 5%-10% of all school-aged children may be affected. 

The 3 subtypes as classified by the Diagnostic and Statistical manual of Mental Disorders, Fourth Edition (DSM-IV), are relatively straightforward:

• Inattentive only (ADHD-IA): typically this involves the problem with focusing.  The hyperactivity is usually not seen here.  This is the most common form among girls.  
  
• Hyperactive/Impulsive (ADHD-H/I): behavior is typically hyperactive and impulsive.  Only 10% of children with ADHD have this type.
  
• Combined Inattentive/Hyperactive/Impulsive: just as it sounds... showing all 3 ADHD symptoms.  This is the most common type of ADHD with the range being anywhere from 50%-60%.  

The best advice I can give you and your brother is to have him evaluated further by his physician. 

Dr. Jeremy