Question: Asked another question, but remembered another really important one.
  
  Is there any observable difference between a brain that has ADHD "naturally" versus one that "develops" it? That is, if someone receives an injury to the frontal lobe, can changes in behavior be differentiated from someone who has had it their entire life? Is there any difference on a mechanical, chemical, or other such level?
  
  I ask because my father had a traumatic brain injury and I suspect my mother is part of the genetic link to my ADHD. Both of my parents had traumatic childhoods, but I don't believe my mother has ever been diagnosed with an injury. I was born after my dad's injury, so I didn't observe the changes others had. I also had a traumatic childhood, so my particular combination of nature and nurture made it hard to realize there was more than just PTSD causing problems.
Answer: Briefly, as I noted above, most ADHD arises from genetic sources, though they can certainly interact with biological hazards and other injurious events to the brain such as head trauma.  The clinical presentation may be the same, but often the acquired form of ADHD is worse, doesn't respond so well to ADHD medications (50% improve vs. 75-90%), may experience more medication side effects (the drugs don't seem to work as well when damage is present vs. genetic maldevelopment), and of course the onset of the ADHD may be different (any time in life the injury occurs) compared to the developmental-familial form of the disorder.  And, yes, they would be different in their neuroanatomy as injuries produce more detectable damage int he brain than would a genetically caused malformation of brain circuitry.
content: Q: Asked another question, but remembered another really important one.
  
  Is there any observable difference between a brain that has ADHD "naturally" versus one that "develops" it? That is, if someone receives an injury to the frontal lobe, can changes in behavior be differentiated from someone who has had it their entire life? Is there any difference on a mechanical, chemical, or other such level?
  
  I ask because my father had a traumatic brain injury and I suspect my mother is part of the genetic link to my ADHD. Both of my parents had traumatic childhoods, but I don't believe my mother has ever been diagnosed with an injury. I was born after my dad's injury, so I didn't observe the changes others had. I also had a traumatic childhood, so my particular combination of nature and nurture made it hard to realize there was more than just PTSD causing problems.
   Ans: Briefly, as I noted above, most ADHD arises from genetic sources, though they can certainly interact with biological hazards and other injurious events to the brain such as head trauma.  The clinical presentation may be the same, but often the acquired form of ADHD is worse, doesn't respond so well to ADHD medications (50% improve vs. 75-90%), may experience more medication side effects (the drugs don't seem to work as well when damage is present vs. genetic maldevelopment), and of course the onset of the ADHD may be different (any time in life the injury occurs) compared to the developmental-familial form of the disorder.  And, yes, they would be different in their neuroanatomy as injuries produce more detectable damage int he brain than would a genetically caused malformation of brain circuitry.