Question: Given how things like trauma can alter brain structure and how brains can restructure themselves after damage, is it plausible that ADHD could be due to environmental factors or even be eliminated in a patient purely due to neuroplasticity?
  
  Disclaimer: I say this out of scientific interest, not to suggest that ADHD isn't a real neurological condition or that it can be cured.
Answer: it is most unlikely.  Present research, which is incredibly abundant, shows that variation in humans in their ADHD symptoms is about 70-80% influenced by genetic variation (differences in genes that build and operate the brain).  The remainder is the result of non shared environmental factors, which are things that impacted just that person in their family.  This would include pregnancy complications, maternal infections, material use of alcohol when pregnant, premature delivery warranting the infant to go to an NICU, etc.  After birth, things like lead poisoning, traumatic brain injuries, and any other factor that adversely impacts brain development in the EF prefrontal brain can lead to ADHD.  So its pretty much all biology (neurology and genetics).  Rearing environment has not been found to be a contributor to ADHD.  That said, people with ADHD are more likely to experience traumatic events, including physical, sexual, and emotional trauma, as a consequence of their lack of foresight, risk taking, and other behaviors as well as the peers they select to associated with.  Such things can also arise within families not only from the behavioral difficulties and challenges posed by such children to caregivers, but also by the fact that 25-35% or more of parents have ADHD which can interfere with their own parenting and increase the  likelihood for such traumas and victimization.  Its possible that some kinds of trauma feedback to worsen the ADHD symptoms (traumatic brain injuries for instance) but less clear that emotional trauma can do this.  Regardless, because of their problems with emotional self-regulation, people with ADHD are more prone to develop PTSD if traumatized and find it more difficult to treat such PTSD.  So there is some interaction here between ADHD and traumatizing environments but its  not a simple or single causal direction of emotional trauma causing ADHD.
content: Q: Given how things like trauma can alter brain structure and how brains can restructure themselves after damage, is it plausible that ADHD could be due to environmental factors or even be eliminated in a patient purely due to neuroplasticity?
  
  Disclaimer: I say this out of scientific interest, not to suggest that ADHD isn't a real neurological condition or that it can be cured.
   Ans: it is most unlikely.  Present research, which is incredibly abundant, shows that variation in humans in their ADHD symptoms is about 70-80% influenced by genetic variation (differences in genes that build and operate the brain).  The remainder is the result of non shared environmental factors, which are things that impacted just that person in their family.  This would include pregnancy complications, maternal infections, material use of alcohol when pregnant, premature delivery warranting the infant to go to an NICU, etc.  After birth, things like lead poisoning, traumatic brain injuries, and any other factor that adversely impacts brain development in the EF prefrontal brain can lead to ADHD.  So its pretty much all biology (neurology and genetics).  Rearing environment has not been found to be a contributor to ADHD.  That said, people with ADHD are more likely to experience traumatic events, including physical, sexual, and emotional trauma, as a consequence of their lack of foresight, risk taking, and other behaviors as well as the peers they select to associated with.  Such things can also arise within families not only from the behavioral difficulties and challenges posed by such children to caregivers, but also by the fact that 25-35% or more of parents have ADHD which can interfere with their own parenting and increase the  likelihood for such traumas and victimization.  Its possible that some kinds of trauma feedback to worsen the ADHD symptoms (traumatic brain injuries for instance) but less clear that emotional trauma can do this.  Regardless, because of their problems with emotional self-regulation, people with ADHD are more prone to develop PTSD if traumatized and find it more difficult to treat such PTSD.  So there is some interaction here between ADHD and traumatizing environments but its  not a simple or single causal direction of emotional trauma causing ADHD.