What Is ADHD?

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Attention-deficit hyperactivity disorder (ADHD) is a heritable, neurodevelopmental disorder characterised by inattention, impulsivity and hyperactivity (del Campo et al, 2011). The disorder begins in early childhood and persists into adolescence, and for 70% it continues on to adulthood (Sharma & Couture, 2014). Those who suffer ADHD experience challenges, particularly during their development. Impulsivity and inattention often result in lower performance in school, and greater incidents of motor accidents and¬ risky behaviour. Additionally, individuals with ADHD have higher rates of one or more comorbidities including major depression and anxiety disorders (Sharma & Couture). Despite being one of the most researched neuropsychological disorders, the precise cause and pathophysiology of ADHD is still unknown. As technology advances, brain imaging techniques and genetic studies are becoming more sophisticated, and as a result are a leading area in current and future research. Cause There have not been any genes identified that are of major risk of ADHD, however, investigations of de novo “rare copy number variations” (CNVs) as possibly pathogenic (Lionel et al, 2011). This study described a genetic model where a wide range of individual rare mutations might affect a large number of genes that were involved in neurodevelopment which may give a predisposition to ADHD. CNV model might help explain the variability observed in individual cases of ADHD. (Elia et al, 2009) Pathophysiology It is well established that dysfunction in the dopaminergic and norepinephrine systems leads to impaired impulse and attention control, as well as hyperactivity (Trip & Wickens, 2009). Research finds the dopaminergic (DA) receptor density is lower t... ... middle of paper ... ... Wernicke, 2002). This limitation highlights the need for less biased comparison trials of the two drug groups. Prescribing which medications to administer is in itself a challenge for physicians as treatment guidelines are not well established due to the complex and extensive literature available regarding ADHD. Conclusion ADHD is now thought to be caused by a multitude of complex combinations of risk factors and it is improbable a single “ADHD” gene exists however, further investigation into CNVs is promising. The success of stimulants on ADHD symptoms has led to the concept of chemical imbalances of DA and NE in the prefrontal cortex being responsible of the deficits of the disorder. Influence from current research into other brain systems affecting ADHD deficits, such as cholinergic control over dopaminergic systems will lead to new therapy ideas and treatment.
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