Functional magnetic resonance imaging (fMRI) without an explicit task, i.e.,
resting state fMRI, of individuals with Attention-Deficit/Hyperactivity Disorder (ADHD) is
growing rapidly. Early studies were unaware of the vulnerability of this method to even
minor degrees of head motion, a major concern in the field. Recent efforts are
implementing various strategies to address this source of artifact along with a growing
set of analytical tools. Availability of the ADHD-200 Consortium dataset, a large-scale
multi-site repository, is facilitating increasingly sophisticated approaches. In parallel,
investigators are beginning to explicitly test the replicability of published findings. In
this narrative review, we sketch out broad, overarching hypotheses being entertained while
noting methodological uncertainties. Current hypotheses implicate the interplay of
default, cognitive control (frontoparietal) and attention (dorsal, ventral, salience)
networks in ADHD; functional connectivities of reward-related and amygdala-related
circuits are also supported as substrates for dimensional aspects of ADHD. Before these
can be further specified and definitively tested, we assert the field must take on the
challenge of mapping the “topography” of the analytical space, i.e.,
determining the sensitivities of results to variations in acquisition, analysis,
demographic and phenotypic parameters. Doing so with openly available datasets will
provide the needed foundation for delineating typical and atypical developmental
trajectories of brain structure and function in neurodevelopmental disorders including
ADHD when applied to large-scale multi-site prospective longitudinal studies such as the
forthcoming Adolescent Brain Cognitive Development study.