Some experts believe that changes in activity levels in certain parts of the brain may contribute to ADHD.

These areas are the:

• Pre-frontal cortex: involved in behavior regulation or "executive function." This includes time management, judgment, impulse control, organization, planning, and critical thought.
  
  
• Limbic system: controls emotion, moods, irritability, negativity, and the ability to comprehend emotions.
  
  
• Reticular Activating System: affects attention, arousal and impulse control.

Research has also focused on the important role of genetics in ADHD.