<P> Previously it was thought that the elevated number of dopamine transporters in people with ADHD was part of the pathophysiology but it appears that the elevated numbers are due to adaptation to exposure to stimulants . Current models involve the mesocorticolimbic dopamine pathway and the locus coeruleus - noradrenergic system . ADHD psychostimulants possess treatment efficacy because they increase neurotransmitter activity in these systems . There may additionally be abnormalities in serotoninergic, glutamatergic, or cholinergic pathways . </P> <P> The symptoms of ADHD arise from a deficiency in certain executive functions (e.g., attentional control, inhibitory control, and working memory). Executive functions are a set of cognitive processes that are required to successfully select and monitor behaviors that facilitate the attainment of one's chosen goals . The executive function impairments that occur in ADHD individuals result in problems with staying organized, time keeping, excessive procrastination, maintaining concentration, paying attention, ignoring distractions, regulating emotions, and remembering details . People with ADHD appear to have unimpaired long - term memory, and deficits in long - term recall appear to be attributed to impairments in working memory . The criteria for an executive function deficit are met in 30--50% of children and adolescents with ADHD . One study found that 80% of individuals with ADHD were impaired in at least one executive function task, compared to 50% for individuals without ADHD . Due to the rates of brain maturation and the increasing demands for executive control as a person gets older, ADHD impairments may not fully manifest themselves until adolescence or even early adulthood . </P> <P> ADHD has also been associated with motivational deficits in children . Children with ADHD often find it difficult to focus on long - term over short - term rewards, and exhibit impulsive behavior for short - term rewards . </P> <P> ADHD is diagnosed by an assessment of a child's behavioral and mental development, including ruling out the effects of drugs, medications and other medical or psychiatric problems as explanations for the symptoms . It often takes into account feedback from parents and teachers with most diagnoses begun after a teacher raises concerns . It may be viewed as the extreme end of one or more continuous human traits found in all people . Whether someone responds to medications does not confirm or rule out the diagnosis . As imaging studies of the brain do not give consistent results between individuals, they are only used for research purposes and not diagnosis . </P>

The textbook points out that adhd is linked with which of the following