EUNETHYDIS ? Searching for valid aetiological candidates of Attention?Deficit Hyperactivity Disorder or Hyperkinetic Disorder

Abstract

■ Neurobiology of ADHDOne of the main contributions of Eunethydis to the field has been to encourage the development of neurobiological models and mechanisms of HKD/ADHD. The primary model from this work proposes that ADHD/HKD is due to hypofunctioning of dopamine (DA), which produces altered reinforcement processes and deficient extinction [65,66]. A key mechanism involved in reinforcement process is the nucleus accumbens [56]. An alternative "hyper"-"hypo" model of DA has also been proposed [52]. Hypofunctioning of DA is thought to give rise to delay aversion, impulsiveness, deficient response suppression and increased behavioural variability. The dopaminergic hypothesis of ADHD/HKD is crucial to both animal and molecular genetic studies of ADHD and explaining methylphenidate's therapeutic effect.One candidate mechanism is how perinatal anoxia and dopamine relate. Brake, Sullivan, & Gratton [9] found that, while the left prefrontal cortex (PFC) DA response was unaffected by perinatal anoxia, the right PFC response was dramatically suppressed. Moreover, dopamine transporter (DAT) levels were elevated selectively in the right PFC.The Naples group [22] identified an epigenetic mechanism [41] suggesting that tyrosine hydroxylase and dopamine transporter gene expression are significantly and transiently reduced in one rat ADHD model (SHR) midbrain during the first month of postnatal develop-

A Practical Guide to Implementing School-Based Interventions for Adolescents with ADHD

“…Genetics In recent decades, research into potential biological causes of ADHD has increased, but to date no definitive cause has been discovered (Nigg 2013;Sergeant 2004). Still, there is some compelling evidence that ADHD is genetically inheritable, based on family studies, twin studies, and molecular genetic research.…”