Attention Deficit Hyperactivity Disorder, Ritalin, and the brain 

What constitutes the definition of ADHD? Could it be considered a widespread phenomenon primarily in the Western world? Is there substantial research supporting the notion of structural or regional brain anomalies underlying the disorder's manifestation? Might the issue stem from an overabundance or deficiency of specific neural transmitters? Could it signify a divergence in attention and focus pathways, potentially unsuited for prevailing educational frameworks? How does Ritalin function and where does its action occur? Could adults also contend with this disorder? Is a complete "cure" for this condition conceivable?