Gray matter volume abnormalities in ADHD: voxel-based meta-analysis exploring the effects of age and stimulant medication.
Level 3 - non-randomized controlled study
Meta-analysis of observational case-control neuroimaging studies
PubMed 21865529 · doi:10.1176/appi.ajp.2011.11020281
What was done
The authors conducted a meta-analysis of voxel-based morphometry studies comparing children and adults with ADHD to healthy comparison subjects using PubMed, ScienceDirect, Web of Knowledge, and Scopus (2001–2011). Coordinates of significant gray matter volume differences between groups were extracted. Metaregression analyses were used to assess the potential effects of age and the percentage of patients taking stimulant medication on regional gray matter volumes.
What was found
Fourteen data sets were included, comprising 378 patients with ADHD and 344 healthy comparison subjects. ADHD patients showed global reductions in gray matter volumes, robustly localized to the right lentiform nucleus and extending into the caudate nucleus. In metaregression, increasing age and higher percentage of patients taking stimulant medication were independently associated with more normal values in this region. Patients also showed slightly greater gray matter volumes in the left posterior cingulate cortex. No numerical effect sizes, test statistics, or confidence intervals were reported in the abstract.
Why it matters
This study pinpoints the basal ganglia (lentiform and caudate nuclei) as the primary site of structural gray matter alterations in ADHD across pediatric and adult cohorts. It also provides preliminary evidence that developmental maturation and stimulant treatment may be associated with structural normalization.
Limits
The underlying studies were cross-sectional case-control designs, preventing causal inferences regarding developmental trajectories or medication effects. Metaregression used study-level aggregated data rather than individual patient-level data. The abstract does not provide exact effect estimates, confidence intervals, or details on medication duration and dosage.
Cited by
- supports Neuroimaging and neuroscience research indicate that ADHD is associated with dysfunction in the basal ganglia.