An update on neurobiology of attention deficit hyperactivity disorder

Abstract

Poremećaj pažnje sa hiperaktivnošću (eng. attention deficit/hyperactivity disorder ADHD) je multifaktorski poremećaj čija učestalost iznosi 5–7% kod dece i oko 2,5% kod odraslih. Smatra se da je moguće postojanje tri slična ali po- sebna tipa poremećaja. Posebno se izdvaja ADHD sa početkom u odraslom dobu. Procenjuje se da su nasledni faktori prisutni kod otprilike 77% slučajeva ADHD-a, pri čemu je identifikovano 18 različitih gena, međutim, spoljašni faktori igraju značajnu ulogu u ekspresiji simptoma. Postoji više modela moždane disfunkcije u ADHD kao što su prefrontalno-egzekutivni model, model pažnje, model nagrade, poremećaj neuronske mreže mirovanja, model kognicije i energije i neurorazvojni model. Biohemijske promene su višestruke i uključuju dopaminergički, adrenergički, serotonergički i holinergički si- stem. Ispitivanja strukture mozga su pokazala smanjenu zapreminu mozga kod dece sa ADHD, a posebno prefrontalne kore, prednje cingularne kore, bazalnih ganglija i malog mozga, a donekle i temporalnog i parijetalnog režnja. Postoje individualne varijacije u međusobnom odnosu kortikalne i supkortikalne disfunkcije što dovodi do heterogenog kliničkog ispoljavanja. S obzirom na nedovoljnu efikasnost i značajne neželjene efekte upotrebe psihostimulan- sa u lečenju ADHD, primena mikronutrijenata je moguća terapija bez značajnih neželjenih pojava i to pre svega cinka, omega-3 masnih kiselina i vitamina D, kao i multivitamina-multiminerala.Attention deficit/hyperactivity disorder (ADHD) is a multifactorial disorder diagnosed in 5-7% children and 2,5% of adults in general population. Three similar but distinct subtypes of ADHD has been identified. A separate form is ADHD with adult onset. Hereditary factors are explaining 77% of cases with at least 18 different susceptibility genes identified, each one with small effect size. However, the inlfuence of several envorinmental factors have been recognized. There are several models of brain dysfunction in ADHD, comprising prefrontal-executive model, attention model, reward model, disruption of neuronal default-mode network, cognition and energy model and neurodevelopmental model. There are multiple biochemical alterations in ADHD, including dopaminergic, adrenergic, serotonergic and cholinergic system. Current research indicate reduced brain volume in children with ADHD, particularly in prefrontal cortex, anterior cingulate cortex, basal ganglia and cerebellum, but also in temporal and parietal lobe to a certain extent. The extent of cortical and subcortical brain involvement varies between individuals which leads to wide variety of clinical presentation. Considering reduced efficacy and significant side effects of psychostimulants in ADHD treatment, the use of micronutrients is a potential therapeutical approach without significant side effects. Most o evidence is available to the use of zinc, omega-3 fat acids and vitamin D, as well as for multivitamins and minerals