technetium-tc-99m-bicisate and Attention-Deficit-Disorder-with-Hyperactivity

Attention deficit/hyperactivity disorder (ADHD) is one of the most frequent behavioral problems in school-age children. Although the etiology remains unclear, the involvement of the dopaminergic system has been suggested by genetic studies that report an overexpression of the dopamine transporter (DAT) gene. In spite of these abnormalities being directly related to the decrease of dopamine (DA) in the striatum (STR), abnormalities in brain perfusion have also been observed in cortical-subcortical structures. Functional neuroimaging studies have suggested that the DA concentration may cause changes in the cerebral blood flow (CBF). The objective of our study was to evaluate the relationship between DAT density in STR and cortical-subcortical impairment in CBF. Based on the hypothesis that there is a correlation between DA availability and brain perfusion, we postulated that individuals with ADHD, with a higher DAT density in the basal ganglia, will have lower perfusion in the fronto-striatal-cerebellar networks. We used Tc-99m TRODAT-1 SPECT to measure DAT density and Tc-99m ECD SPECT to assess brain perfusion. Ten adolescents diagnosed with ADHD by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria were investigated. Analysis with Statistical Parametric Mapping 5 corrected for multiple comparisons, using small volume correction, showed a significant negative correlation between the DAT density in the STR and CBF in the cingulate gyrus, frontal lobe, temporal lobe, and cerebellum (pFDR <0.01). Our findings suggest that higher DAT density in the STR was associated with a decrease in the regional CBF in the cortical and subcortical attention network.

Topics: Adolescent; Attention Deficit Disorder with Hyperactivity; Basal Ganglia; Cerebrovascular Circulation; Cysteine; Dopamine; Dopamine Plasma Membrane Transport Proteins; Humans; Male; Neostriatum; Organotechnetium Compounds; Tomography, Emission-Computed, Single-Photon; Tropanes; Young Adult

Methylphenidate (MPH) is the most commonly prescribed treatment for attention-deficit/hyperactivity disorder (ADHD). The therapeutic mechanisms of MPH are not, however, fully understood. We studied the effects of MPH on brain activity in male children and adolescents with ADHD, using the blood flow radiotracer technetium-99m ethyl cysteinate dimer ((99m)Tc-ECD) and single-photon emission tomography (SPET). The study was randomized, double blind, and placebo controlled (MPH group, n=19; placebo group, n=17), Radiotracer was administered during the performance of the Continuous Performance Test and before and after 4 days of MPH treatment. Statistical parametric mapping (SPM99) analysis showed a significant reduction in regional cerebral blood flow in the left parietal region in the MPH group compared with the placebo group (P<0.05, corrected for multiple comparisons). Our findings suggest that the posterior attentional system, which includes the parietal cortex, may have a role in the mediation of the therapeutic effects of MPH in ADHD.

Topics: Attention Deficit Disorder with Hyperactivity; Blood Flow Velocity; Cerebrovascular Circulation; Child; Cysteine; Double-Blind Method; Humans; Male; Methylphenidate; Organotechnetium Compounds; Parietal Lobe; Placebos; Radionuclide Imaging; Radiopharmaceuticals

Comorbid developmental coordination disorder (DCD) in the patients with attention-deficit hyperactivity disorder (ADHD) often complicated the treatment strategy. Methylphenidate (MPH) improves the coordination problem in patients with ADHD.. The study intended to investigate the pathophysiology and the mechanisms of MPH in comorbid DCD of the adolescents with ADHD.. Brain images using technetium-99m ethyl cysteinate dimmer ((99m)Tc-ECD) single photon emission computed tomography (SPECT) were done in 10 drug-naïve adolescents with ADHD without DCD and 5 adolescents with ADHD comorbid DCD. The baseline rCBF and changes of rCBF after 10 mg MPH challenge between two groups were compared using statistical parametric mapping (SPM99) analysis.. Lower rCBF of bilateral frontal lobe, inferior parental lobe, and increased rCBF of right posterior cingulate gyrus, anterior lobe of cerebellum were found in ADHD comorbid DCD group compared to ADHD without DCD group. Decreased rCBF in the right occipital, inferior temporal lobe was found in ADHD comorbid DCD group after MPH while ADHD alone group revealed increased rCBF in bilateral occipital lobe.. The results help us understand the pathophysiology of DCD in ADHD adolescents. The different rCBF response to MPH provides a clue for future intervention of DCD in ADHD adolescents.

Topics: Adolescent; Attention Deficit Disorder with Hyperactivity; Brain; Brain Mapping; Central Nervous System Stimulants; Cerebrovascular Circulation; Cysteine; Diagnostic and Statistical Manual of Mental Disorders; Female; Functional Laterality; Humans; Male; Methylphenidate; Motor Skills; Motor Skills Disorders; Neuropsychological Tests; Organotechnetium Compounds; Radiopharmaceuticals; Tomography, Emission-Computed, Single-Photon

Topics: Attention Deficit Disorder with Hyperactivity; Child; Cysteine; Fibrous Dysplasia of Bone; Humans; Male; Organotechnetium Compounds; Sphenoid Bone; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

The prefrontal cortex is asymmetric in both structure and function. In normal subjects, the right prefrontal cortex is activated more than the left during response inhibition. Patients with attention deficit hyperactivity disorder (ADHD) have impaired response inhibition and altered structural interhemispheric asymmetry. This study was conducted to examine the functional interhemispheric asymmetry during response inhibition in children with ADHD. Subjects were divided into three groups according to the level of motor hyperactivity. Blood flow tracer (99m)Tc-ethyl cysteinate dimer was injected while subjects were performing a response inhibition task (RIT), followed by single photon emission computerized tomography (SPECT). After three-dimensional reconstruction, filtering and smoothing, individual scans were morphed to a template. Three average group images were created from individual scans. Each average group image was subtracted voxel-by-voxel from its mirror image to compare the regional cerebral blood flow (rCBF) in the right and left cerebral hemispheres, yielding images of significant interhemispheric rCBF asymmetry. The severe hyperactivity group exhibited most prefrontal left>right rCBF asymmetry and left>right occipitoparietal asymmetry. Reversal of functional prefrontal asymmetry in boys with severe motor hyperactivity supports the hypothesis of right prefrontal cortex dysfunction in ADHD.

Topics: Attention; Attention Deficit Disorder with Hyperactivity; Brain; Cerebrovascular Circulation; Child; Cysteine; Functional Laterality; Humans; Image Processing, Computer-Assisted; Male; Organotechnetium Compounds; Radionuclide Imaging; Radiopharmaceuticals; Reference Values; Regional Blood Flow; Severity of Illness Index; Wechsler Scales