Neuropsychology of attention deficit hyperactivity disorder: relevant theories and empirical studies
Günay Kiliç, B.
Turk Psikiyatri Dergisi 16(2): 113-123
2005
ISSN/ISBN: 1300-2163 PMID: 15981150 Document Number: 585973
There is a rapidly accumulating body of knowledge related to the neurobiology of Attention Deficit Hyperactivity Disorder (ADHD) stemming from multidisciplinary neuropsychological and neuroimaging studies. This paper is a review of recent knowledge in the context of neuropsychological theory and research in this area. The final section of the article introduces animal models on the subject. It has been emphasized that the controversy regarding the results of neuropsychological studies is semantic rather than substantive. The semantic issue here is believed to be that the term "attention" has to be related to more than one anatomical network among several brain regions. ADHD, which has many cognitive and behavioral dimensions like attention deficit, hyperactivity and impulsivity, has a heterogeneous nature reflecting the neurobiological basis related to parallel information processing models. Based on clinical and neuropsychological data it has been stated that both the orbitofrontal cortex and dorsolateral prefrontal cortex are functionally disturbed in ADHD. However, whether these functional disturbances are related to the prefrontal cortex or other brain regions associated however primarily with this cortex is yet unclear. Dopamine and epinephrine as neurochemical factors and the frontal lobe and basal ganglia as anatomical factors have been found to be especially responsible. Valid endophenotypic features should be determined in order to specify genetic subtypes of neuropsychiatric syndromes. A review of the literature leads us to the conclusion that tests used to assess attentional components like the executive control network and behavioral inhibition could determine valid endophenotypes.