Attention deficit hyperactivity disorder (ADHD) a prevalent worldwide disorder has
been associated to anatomical and circuits changes involving mainly pre-frontal and
parietal cortex, cerebellum and basal ganglia. Executive functions as working memory,
inhibition capacity and mental flexibility are important functions related to those
brain areas[1].
Nevertheless, studies looking for treatment effect on those functions have retrieved
conflicting results. In this issue of The Arquivos de Neuropsiquiatria, Bolfert et
al.[2], assess the executive functions of 23 children with ADHD, before and after 3 months
of methylphenidate treatment, comparing them to 30 healthy age and gender matched
control school children.
Different activation paths have been observed on functional tests in ADHD subjects
compared to healthy controls[3]. Furthermore, although some functions may be improved on drug therapy, they do not
occur through the same circuits as in normal subjects[4]. Different drugs as well as motivation and reinforcement improve executive functions,
and, although sharing some final effects, in different specific ways, some directed
to working memory, while others to inhibition or mental flexibility[5],[6],[7].
The catecholamine reuptake inhibitor methylphenidate seems to upregulate the left
inferior frontal cortex and enhances fronto-temporo-striatal activation[7]. The study by Bolfert et al highlights the effects after 3 months methylphenidate
treatment on digit span backwards and arithmetic, the Taril Making Test part B and
on the Stroop Color Test, executive function tests, adding new information on this
matter.
