Technetium-99m HMPAO brain SPECT in children with attention deficit hyperactivity disorder

Abstract

Attention deficit hyperactivity disorder (ADHD) is a developmental, neurobehavioral syndrome with an onset in childhood. The aim of this study was to investigate the existence of regional perfusion changes in ADHD by means of Tc-99m HMPAO brain SPECT. Thirteen children with a diagnosis of ADHD and 7 healthy, age-matched controls were included in this study. Hypoperfusion was observed on the right temporal cortex in 9, and on the left temporal cortex in 3 children. The distribution of the lesions showed right lateral temporal cortex involvement in 3, right medial temporal cortex in 9 and left medial temporal cortex in 8 children. Asymmetric perfusion was seen on the caudate nucleus in 4, on the thalamus in 3 and on the frontal cortex in 6 children. There was a significant difference between children with ADHD and controls in right medial temporal cortex: cerebellum and right lateral temporal cortex: cerebellum ratios. Hypoperfusion in the right medial temporal cortex was significantly and inversely correlated with Du Paul teachers' questionnaire rating scale (r = -0.71, p = 0.006). It has been postulated that difficulty in self regulating response to stimuli in ADHD is mediated by underfunctioning of the orbital frontal cortex and subsequent connection to the limbic system. Decreased temporal cortex perfusion may dysfunction of the limbic system or the orbito-frontal-limbic axis.

Brain perfusion and dopaminergic genes in boys with attention‐deficit/hyperactivity disorder

“…However, some issues should be highlighted: a) The SPM-99 is a conservative way of analyzing brain imaging, allowing adjustments for multiple comparisons; b) In a previous study (with a different sample) assessing dopaminergic genes and ADHD symptomatology, the only significant association found was exactly between the interaction of these two alleles and hyperactive/impulsive symptoms [Roman et al, 2001); c) Although imaging studies have predominantly suggested alterations in frontal and striatal areas in ADHD, recent studies suggested the involvement of temporal areas [Kaya et al, 2002;Kim et al, 2002;Sowell et al, 2003]. …”

“…Although the majority of ADHD brain imaging studies has suggested structural or perfusional alterations in frontal and striatal areas, modifications of perfusion in other areas, such as the right temporal area, have also been reported in ADHD adults [Kaya et al, 2002]. Recently, structural modifications of the cerebellum and anterior temporal cortices have been consistently associated to ADHD [Castellanos et al, 2002;Sowell et al, 2003].…”

Attention-deficit/hyperactivity disorder is characterized by a delay in cortical maturation

“…Structural change in the temporal lobes is a common finding in studies of ADHD, from the level of the entire lobe (11) through more focal gray matter density and cortical thickness anomalies (31,32) and may have metabolic (9,33), functional (10,(34)(35)(36), and electrophysiological correlates (37,38). A unifying feature of the frontal and temporal regions with greatest maturational delay is the involvement of heteromodal cortex (39).…”

Supportive neurodevelopmental evidence for ADHD as a developmental disorder

“…They would learn to ignore their mothers as far as possible, avoiding eye contact, in fear of the parasympathetic state the mother can induce by scolding or humiliating the child. This would lead to impaired development of the orbitofrontal cortex and deficiencies in self-regulation, as have been demonstrated in children with ADHD [16], [17], [18] and [19]. Furthermore, abnormalities in dopamine transmission and adrenaline excretion have been shown in children with ADHD, and are related to inattention [20] and [21].…”