The variable number of tandem repeats polymorphism of the dopamine transporter gene is not associated with significant change in dopamine transporter phenotype in humans.
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A 40 base polymorphism of a variable number of tandem repeats (VNTR) has been described in the 3' untranslated region of the gene (SLC6A3) coding for the dopamine transporter (DAT). Despite being located in the untranslated region of the gene, this polymorphism has been associated with clinical phenotypes associated with dysregulation of dopamine transmission, such as attention deficit hyperactivity disorder and cocaine-induced paranoia. To examine the neurochemical phenotype associated with this polymorphism, we compared amphetamine-induced dopamine release (measured as displacement of the radiotracer [123I]IBZM) and DAT expression (measured with [123I]beta-CIT) in the striatum with Single Photon Computerized Emission Tomography (SPECT). Our sample included 59 subjects, 31 healthy controls and 29 patients with schizophrenia. No significant association was found between VNTR polymorphism and amphetamine-induced dopamine release or DAT density in the total sample, nor when each diagnostic group was considered separately. Thus, we did not replicate the findings of two previous studies, which had suggested that the 9 repeat allele was associated with either an increased or decreased DAT expression, albeit in different patient populations. (+info)
Methylphenidate increased regional cerebral blood flow in subjects with attention deficit/hyperactivity disorder.
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The regional cerebral blood flow (rCBF) responses to methylphenidate (MPH) treatment were examined in children with attention deficit/hyperactivity disorder (ADHD). Thirty-two male children, diagnosed with ADHD by the DSM-IV diagnostic criteria, other behavioral assessment scales and neuropsychological battery, were studied using 99mTc-HMPAO-single photon emission computed tomography (SPECT). Subjects were studied before and after MPH treatment. First, using an image subtraction method, we obtained a NDR parametric image of each patient and found increased cerebral blood flow in the frontal lobes, caudate nuclei and thalamic areas after treatment. When the changes in SPECT and clinical response were compared, the matching rate, sensitivity and specificity between them were found to be 77.1, 80.0 and 79.2%, respectively. Second, three transaxial brain slices delineating anatomically defined regions of interest (ROI) at 20, 40, and 60mm above the orbitomeatal line (OML) were used, with the average number of counts for each region of interest normalized to the area of the cerebellar maximal uptake. The left and right prefrontal areas, and caudate and thalamic areas showed significant increases in rCBF after MPH treatment. These findings suggested MPH could affect the function of the fronto-striato-thalamic circuit, which is known as the pathophysiologic site of ADHD and could be used to correct the underlying brain dysfunction of ADHD. (+info)
An auditable protocol for treating attention deficit/hyperactivity disorder.
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We present an auditable protocol for attention deficit/hyperactivity disorder (ADHD) or hyperkinetic disorder. The protocol is derived from standard recommendations and evidence, and is intended for outpatient medical clinic practice in secondary care. Suggested side effect rating scales are included. (+info)
Temporal discounting: basic research and the analysis of socially important behavior.
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Recent basic research on human temporal discounting is reviewed to illustrate procedures, summarize key findings, and draw parallels with both nonhuman animal research and conceptual writings on self-control. Lessons derived from this research are then applied to the challenge of analyzing socially important behaviors such as drug abuse, eating and exercise, and impulsiveness associated with attention deficit hyperactivity disorder. Attending to the broader temporal context in which behavior occurs may aid in the analysis of socially important behavior. Applying this perspective to the study of behavior in natural environments also highlights the importance of combining methodological flexibility with conceptual rigor to promote the extension of applied behavior analysis to a broader array of socially important behaviors. (+info)
Attention-deficit hyperactivity disorder and the adrenergic receptors alpha 1C and alpha 2C.
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The adrenergic system has been hypothesized to be involved in the etiology of attention-deficit hyperactivity disorder (ADHD) based on pharmacological interventions and animal models. Noradrenergic neurons are implicated in the modulation of vigilance, improvement of visual attention, initiation of adaptive response, learning and memory. In this study we tested the genes for two adrenergic receptors, alpha 1C (ADRA1C) located on chromosome 8p11.2, and alpha 2C (ADRA2C) located on chromosome 4p16, as genetic susceptibility factors in ADHD. For the adrenergic receptor alpha 1C we used a C to T polymorphism that results in a change of Cys to Arg at codon 492 for the linkage study. For the adrenergic receptor alpha 2C gene we examined a dinucleotide repeat polymorphism located approximately 6 kb from the gene. We examined these polymorphisms in a sample of 103 families ascertained through an ADHD proband. Using the transmission disequilibrium test, we did not observe biased transmission of any of the alleles of these polymorphisms. We conclude that the alleles at the polymorphisms tested in these two genes are not linked to the ADHD phenotype in this sample of families. (+info)
The child with ADHD: using the AAP Clinical Practice Guideline. American Academy of Pediatrics.
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The American Academy of Pediatrics developed an evidence-based clinical practice guideline that provides recommendations for the assessment and diagnosis of school-aged children with attention-deficit/hyperactivity disorder (ADHD). This guideline, the first of two guidelines to provide recommendations on this condition, is intended for use by primary care clinicians. The second set of guidelines will address the treatment of children with ADHD. The guideline contains six recommendations for the diagnosis of ADHD: (1) in a child six to 12 years of age who presents with inattention, hyperactivity, impulsivity, academic underachievement or behavior problems, primary care clinicians should initiate an evaluation for ADHD; (2) the diagnosis of ADHD requires that a child meet the criteria for ADHD in the Diagnostic and Statistical Manual of Mental Disorders; (3) the assessment of ADHD requires evidence directly obtained from parents or caregivers regarding the core symptoms of ADHD in various settings, the age of onset, duration of symptoms and degree of functional impairment; (4) the assessment of ADHD also requires evidence directly obtained from a teacher (or other school professional) regarding the core symptoms of ADHD, duration of symptoms, degree of functional impairment and associated conditions; (5) evaluation of the child with ADHD should include assessment for coexisting conditions; and (6) other diagnostic tests are not routinely indicated to establish the diagnosis of ADHD but may be used for the assessment of coexisting conditions. (+info)
Impulsive choice induced in rats by lesions of the nucleus accumbens core.
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Impulsive choice is exemplified by choosing a small or poor reward that is available immediately, in preference to a larger but delayed reward. Impulsive choice contributes to drug addiction, attention-deficit/hyperactivity disorder, mania, and personality disorders, but its neuroanatomical basis is unclear. Here, we show that selective lesions of the nucleus accumbens core induce persistent impulsive choice in rats. In contrast, damage to two of its afferents, the anterior cingulate cortex and medial prefrontal cortex, had no effect on this capacity. Thus, dysfunction of the nucleus accumbens core may be a key element in the neuropathology of impulsivity. (+info)
Effect of the herbal extract combination Panax quinquefolium and Ginkgo biloba on attention-deficit hyperactivity disorder: a pilot study.
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OBJECTIVE: A combination herbal product containing American ginseng extract, Panax quinquefolium, (200 mg) and Ginkgo biloba extract (50 mg) (AD-FX; CV Technologies, Edmonton, Alta.) was tested for its ability to improve the symptoms of attention-deficit hyperactivity disorder (ADHD). DESIGN: Open study. PATIENTS: 36 children ranging in age from 3 to 17 years who fit the diagnostic criteria for ADHD. INTERVENTIONS: AD-FX capsules were taken twice a day on an empty stomach for 4 weeks. Patients were instructed not to change any other medications during the study. OUTCOME MEASURES: At the beginning of the study, after 2 weeks, and then at the end of the 4-week trial, parents completed the Conners' Parent Rating Scale--revised, long version, a questionnaire that assesses a broad range of problem behaviours (and was used as an indication of ADHD symptom severity). RESULTS: After 2 weeks of treatment, the proportion of the subjects exhibiting improvement (i.e., decrease in T-score of at least 5 points) ranged from 31% for the anxious-shy attribute to 67% for the psychosomatic attribute. After 4 weeks of treatment, the proportion of subjects exhibiting improvement ranged from 44% for the social problems attribute to 74% for the Conners' ADHD index and the DSM-IV hyperactive-impulsive attribute. Five (14%) of 36 subjects reported adverse events, only 2 of which were considered related to the study medication. CONCLUSIONS: These preliminary results suggest AD-FX treatment may improve symptoms of ADHD and should encourage further research on the use of ginseng and Ginkgo biloba extracts to treat ADHD symptoms. (+info)