Prefrontal blood flow dysregulation in drug naive ADHD children without structural abnormalities

Abstract

Recent studies suggest a role for prefrontal cortex abnormalities in the pathogenesis of attention deficit/hyperactivity disorder (ADHD). We evaluated young drug-naive ADHD outpatients without MRI structural abnormalities to detect prefrontal cortex regional cerebral blood flow (rCBF) functional dysregulation; correlation between age and rCBF; and correlation between symptoms profile and rCBF. Functional brain activities (i.e. rCBF), neuropsychological attention performance and symptom profile were evaluated respectively by single photon emission computerized tomography (SPECT) scan, Stroop Test and the Child Attention Problem Rating Scale. There was a decreased rCBF in the left dorso lateral prefrontal cortex (DLPFC) compared to the right DLPFC of the subjects. In addition, there were positive correlations between age and relative rCBFs of the dorsolateral and orbital prefrontal cortex, and negative correlations between age and absolute rCBFs of the dorsolateral and orbital prefrontal cortex. Finally, higher levels of right relative rCBF and lower levels of left relative rCBF were predictors of higher severity of clinical symptom expression and neuropsychological attention impairment. The results of this study highlight the role of the DLPFC blood flow impairment in the pathogenesis of ADHD even in young subjects without structural abnormalities.

Methylphenidate Down-Regulates the Dopamine Receptor and Transporter System in Children with Attention Deficit Hyperkinetic Disorder (ADHD)

“…Recently Ilgin and co-workers [4] were able to show a decrease of midbrain dopamine receptors in ADHD patients as a result of methylphenidate treatment [6]. We found a dopamine receptor down-regulation of the same magnitude, but this was much smaller than the one we observed for the dopamine transporter.…”

“…Whether asymmetry is physiological in this age group, or is a sign of abnormal function, is still a matter of debate. The studies related to this topic of asymmetry are very inconsistent (Spalletta et al [6]). Moreover, to decide which side is the pathological one is difficult to answer without studying a control sample of normal children.…”

Quantitative regional cerebral blood flow MRI of animal model of attention-deficit/hyperactivity disorder

“…Decreased resting blood flow in the prefrontal cortex in ADHD children relative to controls had been reported as measured by SPECT . The resting CBF abnormalities have also been found to be lateralized with larger reduction in the right compared left prefrontal cortices (Spalletta et al 2001).…”

“…A lower cerebral blood flow (CBF) in the prefrontal cortices and the cerebellum in humans with ADHD has been reported using single photon emission computerized tomography (SPECT) . The resting CBF abnormalities were lateralized with a larger reduction in the right compared to the left prefrontal cortex (Spalletta et al 2001).…”

Gonadal Hormones and Frontocortical Expression of Vascular Endothelial Growth Factor in Male Stroke-Prone, Spontaneously Hypertensive Rats, a Model for Attention-Deficit/Hyperactivity Disorder

“…Because boys are 6 -9 times more prone to be diagnosed with AD/HD (3,4) and because volumetric abnormalities in regional cerebral blood flow (rCBF) in some brain regions, including the frontal cortex and striatum, are common in AD/HD (2,(5)(6)(7)(8)(9)(10)(11), key factors likely to play important roles in AD/HD pathogenesis include gender-and vascular-associated factors.…”