Review article
Neuroanatomical and functional correlates of attention deficit/hyperactivity disorder in the light of two developmental models: deviant brain maturation vs. developmental lag

Attention deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders among children. Worldwide prevalence of ADHD is estimated as about 5% of school-age children.

ADHD is characterized by developmentally inappropriate levels of inattention, hyperactivity and impulsivity. Investigations on the etiology of ADHD highlight its heterogeneity and complexity.

Many studies have examined its neuronal correlates. The most commonly used methods investigating the neurobiological basis of ADHD are EEG and fMRI/sMRI. Results obtained with these methods have indicated altered brain activity and structure in ADHD subjects as compared to healthy children.

Recent research indicates that ADHD is related to some developmental trends, since its symptoms change greatly over time. Nevertheless, there are divergent opinions whether ADHD is related to deviation in brain maturation or to maturation lag. The deviant brain maturation model assumes that the process of maturation is altered and leads to permanent impairment in ADHD subjects’ brain anatomy and functionality. On the other hand, there are studies suggesting that ADHD is related to a lag in brain maturation. They assume that this pathological behavior is related to postponed maturation processes and that these will equalize to the level of healthy subjects when children become adults. This paper reviews the most recent reports concerning ADHD neuroimaging and interprets them in the context of the two above mentioned theories of ADHD.