Finally, disorder occurs most frequently in cases of very low birth weight infants, premature delivery, or significant damage in the frontal regions of the brain. Origin and causes of ADHD today in day it is clear that genetic inheritance is the main factor that determines the appearance of ADHD in a human being, being responsible for 80% of the probability that this disorder is registered. In fact, already identified several genes that contribute to ADHD, and will possibly be identified more, because as we said before, it’s a complex disorder that is not attributable to a single gene. It is a hereditary influence strong, comparable in intensity and percentage to which exert the genes that control the height (in deliberately simple terms, the likelihood of an individual having certain height depends on 80% of their genetic inheritance). The remaining 20% seems to correspond to factors such as difficulties during pregnancy, exposure to tobacco and alcohol during the prenatal stage, preterm birth and very low weight at birth, and post-natal damage in the prefrontal regions of the brain. At the biological level, ADHD manifests itself as a slight but contrastable difference in normal brain functions. I.e.
it’s a subtle brain dysfunction, which is considered to be originated by a unbalance or imbalance in brain neurotransmitters, primarily dopamine and noradrenaline levels. This imbalance is mainly located in brain areas responsible for self-regulation and self-control of behaviour (the prefrontal lobes and their deep connections, which are basal ganglia) these brain dysfunctions are tested and diagnosed today unequivocally, through medical tests objective such as (English PET) positron emission tomography and magnetic resonance imagingboth functional as volumetric. Main features of ADHD predominant features of this disorder are: reduced capabilities to inhibit or control responses, to control impulses, or to delay obtaining a reward or reinforcement. This manifests itself in the inability of the person with ADHD to think before acting, to wait their turn in games, to resist distractions when they should concentrate, or to work towards goals of greater importance instead of focusing on goals of less substantial and long-term and more immediate. .