Attention-Deficit/Hyperactivity Disorder Symptoms Coincide with Altered Striatal Connectivity

Background Corticostriatal network dysfunction in attention-deficit/hyperactivity disorder (ADHD) is generally investigated by comparing functional connectivity of the main striatal subregions (i.e., putamen, caudate, and nucleus accumbens) between an ADHD group and a control group. However, dimensional analyses based on continuous symptom measures might help to parse the high phenotypic heterogeneity in ADHD. Here, we focus on functional segregation of regions in the striatum and investigate corticostriatal networks using both categorical and dimensional measures of ADHD. Methods We computed whole-brain functional connectivity for six striatal subregions that resulted from a novel functional parcellation technique. We compared functional connectivity maps between adolescents with ADHD (n = 169) and healthy controls (n = 122), and investigated dimensional ADHD-related measures by relating striatal connectivity to ADHD symptom scores (N = 444). Finally, we examined whether altered connectivity of striatal subregions was related to motor and cognitive performance. Results We observed no case-control differences in functional connectivity patterns of the six striatal networks. In contrast, inattention and hyperactivity/impulsivity symptom scores were associated with increases in functional connectivity in the networks of posterior putamen and ventral caudate. Increased connectivity of posterior putamen with motor cortex and cerebellum was associated with decreased motor performance. Conclusions Our findings support hypotheses of corticostriatal network dysfunction in ADHD by demonstrating that dimensional symptom measures are associated with changes in functional connectivity. These changes were not detected by categorical ADHD versus control group analyses, which highlights the important contribution of dimensional analyses to investigating the neurobiology of ADHD.