Neuroimaging studies in multiple modalities have implicated the left or right dorsolateral prefrontal cortex (here, middle frontal gyrus) in attentional functions, in
ADHD, and in
dopamine agonist treatment of
ADHD. The far lateral location of this cortex in the brain, however, has made it difficult to study with magnetic resonance spectroscopy (MRS). We used the smaller voxel sizes of the magnetic resonance spectroscopic imaging (MRSI) variant of MRS, acquired at a steep coronal-oblique angle to sample bilateral middle frontal gyrus in 13 children and adolescents with
ADHD and 13 age- and sex-matched healthy controls. Within a subsample of the
ADHD patients, aspects of attention were also assessed with the Trail Making Task. In right middle frontal gyrus only, mean levels of N-acetyl-aspartate + N-acetyl-aspartyl-
glutamate (tNAA), creatine + phosphocreatine (Cr),
choline-compounds (Cho), and myo-
inositol (mI) were significantly lower in the
ADHD than in the control sample. In the
ADHD patients, lower right middle frontal Cr was associated with worse performance on Trails A and B (focused attention, concentration, set-shifting), while the opposite relationship held true for the control group on Trails B. These findings add to evidence implicating right middle frontal cortex in
ADHD. Lower levels of these multiple species may reflect osmotic adjustment to elevated prefrontal cortical perfusion in
ADHD and/or a previously hypothesized defect in astrocytic production of
lactate in
ADHD resulting in decelerated energetic metabolism (Cr), membrane synthesis (Cho, mI), and
acetyl-CoA substrate for NAA synthesis. Lower Cr levels may indicate attentional or executive impairments.