The effects of medication on default mode network (DMN) connectivity in attention deficit/hyperactivity disorder (ADHD): Bibliographic review

Abstract

IntroductionADHD is a neurodevelopmental disorder comprising brain structural and functional alterations, especially in default mode network (DMN), as MRI studies have recently shown. However, it is not clear in which extent medication for ADHD may influence the activity of these networks.ObjectivesThe main purpose is to look up published evidence about the effects of ADHD medication on the connectivity of DMN in patients as measured with functional-MRI.MethodsA review was conducted with Pubmed, using search terms ‘default mode network’+ ‘ADHD’ + ‘medication’/‘methylphenidate’/‘atomoxetine’/‘stimulant’/‘lisdexanfetamine’. Original research studies in English using f-MRI to assess DMN connectivity in ADHD patients were included in a more comprehensive review.ResultsThe searches found 124 articles, 8 meeting the review criteria. A total size of 146 ADHD patients was comprised (mean size: 18.25 patients). Three studies used specific resting-state f-MRI. Seven were drug trials, 3 of them short-term, randomized and controlled ones. Six included methylphenidate, 2 atomoxetine, 1 lisdexanfetamine and 3 amphetamines. Two also assessed drugs clinical effects. Evidence seems heterogeneous, but mostly consistent with normalizing drug effects on DMN in patients (in some studies also compared with healthy controls), associated with a measured clinical improvement in one study with amphetamines and one with atomoxetine. One trial found little differences on DMN activity.ConclusionsPsychostimulant drugs and atomoxetine are clinically effective medications; DMN connectivity may partially explain their action mechanisms and constitute a potential response predictor. Further f-MRI studies might more deeply assess the imaging-clinical relationships for each drug.Disclosure of interestThe authors have not supplied their declaration of competing interest.