Stimulant drugs

Stimulant Drugs and Stimulant Use Disorder

The authors aim to summarize several key points of stimulant drugs and stimulant use disorder, including their indications, short-term and long-term adverse effects, current treatment strategies, and association with opioid medications. The global prevalence of stimulant use has seen annual increase in the last decade. Multiple studies have shown that stimulant use and stimulant use disorder are associated with a range of individual and public health issues. Stimulant misuse has led to a significant increase of overdose deaths in the United States.

Predicting the Response of Children and Adolescents With ADHD to Methylphenidate: A Systematic Review

OBJECTIVE

To report the characteristics associated with response to methylphenidate (MPH) in children and adolescents with ADHD.

METHODS

Studies reporting potentials predictors of response to MPH were searched in Medline and Embase from January 1998 to March 2022. Narrative synthesis was performed.

RESULTS

Fifty-seven reports of 46 studies totaling 6,656 ADHD patients were included. No association appears between response to MPH and age, gender, MPH dosage, ADHD subtype, comorbidities nor socioeconomic status when considering a specific patient. No conclusion could be drawn about body weight, ADHD severity, intelligence quotient, and parental symptoms of depression or ADHD.

CONCLUSIONS

None of these potential predictors have proven their usefulness to predict response to MPH on an individual basis in clinical practice. In research, potential predictors should be measured, their association with response to MPH assessed, in order to control for confounding variables when modeling response to MPH.

Machine learning in attention-deficit/hyperactivity disorder: new approaches toward understanding the neural mechanisms

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent and heterogeneous neurodevelopmental disorder in children and has a high chance of persisting in adulthood. The development of individualized, efficient, and reliable treatment strategies is limited by the lack of understanding of the underlying neural mechanisms. Diverging and inconsistent findings from existing studies suggest that ADHD may be simultaneously associated with multivariate factors across cognitive, genetic, and biological domains. Machine learning algorithms are more capable of detecting complex interactions between multiple variables than conventional statistical methods. Here we present a narrative review of the existing machine learning studies that have contributed to understanding mechanisms underlying ADHD with a focus on behavioral and neurocognitive problems, neurobiological measures including genetic data, structural magnetic resonance imaging (MRI), task-based and resting-state functional MRI (fMRI), electroencephalogram, and functional near-infrared spectroscopy, and prevention and treatment strategies. Implications of machine learning models in ADHD research are discussed. Although increasing evidence suggests that machine learning has potential in studying ADHD, extra precautions are still required when designing machine learning strategies considering the limitations of interpretability and generalization.

Effects of stimulant medication on divergent and convergent thinking tasks related to creativity in adults with attention-deficit hyperactivity disorder

RATIONALE

Common pharmacological treatments for attention-deficit hyperactivity disorder (ADHD) are central nervous system stimulants acting as norepinephrine-dopamine reuptake inhibitors. The noradrenergic and dopaminergic systems have been shown to impact performance on tasks assessing creativity. Some previous studies suggest higher performance on creativity tasks in ADHD. Stimulant medication has been shown to differentially impact creativity in those without ADHD. However, the full range of effects of stimulant medication on creativity in those with ADHD is not known.

OBJECTIVES

This study examined the effects of stimulants on convergent and divergent tasks associated with creativity in adults with ADHD.

METHOD

Seventeen adults diagnosed with ADHD who were prescribed stimulant medication attended two counterbalanced sessions: one after taking their prescribed stimulant dose and one after the dose was withheld. Participants completed convergent problem-solving (anagrams, Compound Remote Associates) and divergent generative (letter/semantic fluency, Torrance Test for Creative Thinking (TTCT)-Verbal) tasks.

RESULTS

There was a significant increase in words generated on the semantic fluency task for the stimulant session. Additionally, significant increases were found in the stimulant session for originality, flexibility, and fluency scores on the TTCT. Stimulant medication did not have an effect on any of the problem-solving tasks.

CONCLUSIONS

Stimulant medication enhanced verbal fluency in adults with ADHD but had no effect on convergent abilities. Furthermore, stimulants enhanced fluency, flexibility, and originality scores on the TTCT. Therefore, stimulants appear to have positive effects on divergent task performance in adults with ADHD, but not convergent tasks. This finding warrants further studies into the specific roles of norepinephrine and dopamine in this effect.

Regional brain volume predicts response to methylphenidate treatment in individuals with ADHD

BACKGROUND

Despite the effectiveness of methylphenidate for treating ADHD, up to 30% of individuals with ADHD show poor responses to methylphenidate. Neuroimaging biomarkers to predict medication responses remain elusive. This study characterized neuroanatomical features that differentiated between clinically good and poor methylphenidate responders with ADHD.

METHODS

Using a naturalistic observation design selected from a larger cohort, we included 79 drug-naive individuals (aged 6-42 years) with ADHD without major psychiatric comorbidity, who had acceptable baseline structural MRI data quality. Based on a retrospective chart review, we defined responders by individuals' responses to at least one-month treatment with methylphenidate. A nonparametric mass-univariate voxel-based morphometric analysis was used to compare regional gray matter volume differences between good and poor responders. A multivariate pattern recognition based on the support vector machine was further implemented to identify neuroanatomical indicators to predict an individual's response.

RESULTS

63 and 16 individuals were classified in the good and poor responder group, respectively. Using the small-volume correction procedure based on the hypothesis-driven striatal and default-mode network masks, poor responders had smaller regional volumes of the left putamen as well as larger precuneus volumes compared to good responders at baseline. The machine learning approach identified that volumetric information among these two regions alongside the left frontoparietal regions, occipital lobes, and posterior/inferior cerebellum could predict clinical responses to methylphenidate in individuals with ADHD.

CONCLUSION

Our results suggest regional striatal and precuneus gray matter volumes play a critical role in mediating treatment responses in individuals with ADHD.

Dyskinesia in Treatment-Naive and Stimulant-Treated Children With ADHD

Objective: Stimulants are safe and effective medications for the treatment of ADHD. There are a number of case studies that report stimulant-induced dyskinesia. The aim of this study was to compare dyskinesia in a treated and a treatment-naive group of children with ADHD, and a healthy control group. Method: Children aged 6 to 18 years were involved in the study (n = 158). Diagnosis of ADHD was measured with the Mini International Neuropsychiatric Interview Kid (MINI Kid). Dyskinesia was assessed with the Abnormal Involuntary Movement Scale (AIMS). Results: Before methylphenidate administration, the treated ADHD group showed significantly higher AIMS total score than the control group (p = .001) and the treatment-naive ADHD group (p < .001). We found the same pattern 1.5 hr after methylphenidate administration. Conclusion: These results call attention that clinicians should take special care for the possible development of dyskinesia during the treatment of their ADHD patients with methylphenidate.

Prediction of sleep side effects following methylphenidate treatment in ADHD youth

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Sleep problems after stimulant use in ADHD were predicted using machine learning.

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Step-wise combination of multi-level features enhanced prediction performance.

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Fronto-striatal connectivity and DAT1, ADRA2A, SLC6A2 SNPs were key features.

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An accuracy of 95.5% was achieved by Logistic Ridge Regression in the training data.

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An accuracy of 86.1% was achieved by J48 in the independent validation analysis.

Objective

Sleep problems is the most common side effect of methylphenidate (MPH) treatment in ADHD youth and carry potential to negatively impact long-term self-regulatory functioning. This study aimed to examine whether applying machine learning approaches to pre-treatment demographic, clinical questionnaire, environmental, neuropsychological, genetic, and neuroimaging features can predict sleep side effects following MPH administration.

Method

The present study included 83 ADHD subjects as a training dataset. The participants were enrolled in an 8-week, open-label trial of MPH. The Barkley Stimulant Side Effects Rating Scale was used to determine the presence/absence of sleep problems at the 2nd week of treatment. Prediction of sleep side effects were performed with step-wise addition of variables measured at baseline: demographics (age, gender, IQ, height/weight) and clinical variables (ADHD Rating Scale-IV (ADHD-RS) and Disruptive Behavior Disorder rating scale) at stage 1, neuropsychological test (continuous performance test (CPT), Stroop color word test) and genetic/environmental variables (dopamine and norepinephrine receptor gene (DAT1, DRD4, ADRA2A, and SLC6A2) polymorphisms, blood lead, and urine cotinine level) at stage 2, and structural connectivities of frontostriatal circuits at stage 3. Three different machine learning algorithms ((Logistic Ridge Regression (LR), support vector machine (SVM), J48) were used for data analysis. Robustness of classifier model was validated in the independent dataset of 36 ADHD subjects.

Results

Classification accuracy of LR was 95.5% (area under receiver operating characteristic curve (AUC) 0.99), followed by SVM (91.0%, AUC 0.85) and J48 (90.0%, AUC 0.87) at stage 3 for predicting sleep problems. The inattention symptoms of ADHD-RS, CPT response time variability, the DAT1, ADRA2A DraI, and SLC6A2 A-3081T polymorphisms, and the structural connectivities between frontal and striatal brain regions were identified as the most differentiating subset of features. Validation analysis achieved accuracy of 86.1% (AUC 0.92) at stage 3 with J48.

Conclusions

Our results provide preliminary support to the combination of multimodal classifier, in particular, neuroimaging features, as an informative method that can assist in predicting MPH side effects in ADHD.

Effects of Interaction Between DRD4 Methylation and Prenatal Maternal Stress on Methylphenidate-Induced Changes in Continuous Performance Test Performance in Youth with Attention-Deficit/Hyperactivity Disorder

OBJECTIVES

Environmental factors may interact with genetic factors via the epigenetic process, and this interaction can contribute to inter-individual variability in the treatment response. The purpose of this study was to investigate the interaction effects between dopamine receptor D4 (DRD4) methylation and prenatal maternal stress on the methylphenidate (MPH) response of youth with attention-deficit/hyperactivity disorder (ADHD).

METHODS

This study was an 8-week open-label trial of MPH that included 74 ADHD youth. We investigated the associations between MPH treatment response, which was defined as a score ≤2 on the Clinical Global Impressions-Improvement (CGI-I) scale, and the methylation of 28 cytosine-guanine dinucleotide (CpG) sites of DRD4. Additionally, the interaction effects between DRD4 methylation and prenatal maternal stress on changes in Continuous Performance Test (CPT) scores after MPH treatment were investigated.

RESULTS

Although there were no significant sites that showed significant association with treatment response, there was a significant interaction effect of the methylation of CpG7 and prenatal maternal stress on changes in omission errors of the CPT following treatment (p = 0.0001).

CONCLUSIONS

The present findings indicate that the interaction between methylation of CpG7 of DRD4 and prenatal maternal stress may be predictive of the treatment response to MPH in youth with ADHD.

Current issues in child and adolescent psychopharmacology. Part 1: Attention-deficit hyperactivity and affective disorders

Drug treatments play an important role in the treatment of child and adolescent psychiatric disorders. However, there is often a long delay before research findings are translated into clinical practice; furthermore, changes in clinical practice outstrip the available evidence. This paper focuses on current issues and research findings on the pharmacological treatment of attention-deficit hyperactivity disorder (ADHD) and affective disorders. Clinical findings from a US study of the treatment of ADHD with extended-release stimulants and non-stimulants, and the development and use of clinical guidelines are discussed. Clinical trials of selective serotonin reuptake inhibitors for early-onset depression, approaches to managing treatment-resistant depression and guidance on the drug treatment of early-onset mania are considered.

Association of the GRIN2B rs2284411 polymorphism with methylphenidate response in attention-deficit/hyperactivity disorder

OBJECTIVE

We investigated the possible association between two NMDA subunit gene polymorphisms (GRIN2B rs2284411 and GRIN2A rs2229193) and treatment response to methylphenidate (MPH) in attention-deficit/hyperactivity disorder (ADHD).

METHODS

A total of 75 ADHD patients aged 6-17 years underwent 6 months of MPH administration. Treatment response was defined by changes in scores of the ADHD-IV Rating Scale (ADHD-RS), clinician-rated Clinical Global Impression-Improvement (CGI-I), and Continuous Performance Test (CPT). The association of the GRIN2B and GRIN2A polymorphisms with treatment response was analyzed using logistic regression analyses.

RESULTS

The GRIN2B rs2284411 C/C genotype showed significantly better treatment response as assessed by ADHD-RS inattention ( p=0.009) and CGI-I scores ( p=0.009), and there was a nominally significant association in regard to ADHD-RS hyperactivity-impulsivity ( p=0.028) and total ( p=0.023) scores, after adjusting for age, sex, IQ, baseline Clinical Global Impression-Severity (CGI-S) score, baseline ADHD-RS total score, and final MPH dose. The GRIN2B C/C genotype also showed greater improvement at the CPT response time variability ( p<0.001). The GRIN2A G/G genotype was associated with a greater improvement in commission errors of the CPT compared to the G/A genotype ( p=0.001).

CONCLUSIONS

The results suggest that the GRIN2B rs2284411 genotype may be an important predictor of MPH response in ADHD.

Stimulant Use Disorders

Compared with other illicit substances, stimulants are not commonly used by adolescents; however, they represent a serious concern regarding substance use among youths. This article uses methamphetamine as a model for stimulant use in adolescents; cocaine and prescription stimulants are also mentioned. Methamphetamine use among adolescents and young adults is a serious health concern with potentially long-term physical, cognitive, and psychiatric consequences. Brain development and the effects of misusing stimulants align such that usage in adolescents can more dangerous than during adulthood. It seems helpful to keep in mind the differences between adolescents and young adults when implementing interventions.

Evolution of the Study of Methylphenidate and Its Actions on the Adult Versus Juvenile Brain

OBJECTIVE

Methylphenidate (MPH) is the most often prescribed medication for treatment of ADHD. However, many of its specific cellular and molecular mechanisms of action, as well as developmental consequences of treatment, are largely unknown. This review provides an overview of current understanding of MPH efficacy, safety, and dosage in adult and pediatric ADHD patients, as well as adult animal studies and pioneering studies in juvenile animals treated with MPH.

METHOD

A thorough review of the current literature on MPH efficacy and safety in children, adults, and animal models was included. Results of studies were compared and contrasted.

RESULTS

While MPH is currently considered safe, there is a lack of knowledge of potential developmental consequences of early treatment, as well as differences in drug actions in the developing versus mature brain system.

CONCLUSION

This review emphasizes the need for further research into the age-dependent activities and potency of MPH, and a need for tighter control and clinical relevance in future studies.

Predicting Methylphenidate Response in ADHD Using Machine Learning Approaches

BACKGROUND

There are no objective, biological markers that can robustly predict methylphenidate response in attention deficit hyperactivity disorder. This study aimed to examine whether applying machine learning approaches to pretreatment demographic, clinical questionnaire, environmental, neuropsychological, neuroimaging, and genetic information can predict therapeutic response following methylphenidate administration.

METHODS

The present study included 83 attention deficit hyperactivity disorder youth. At baseline, parents completed the ADHD Rating Scale-IV and Disruptive Behavior Disorder rating scale, and participants undertook the continuous performance test, Stroop color word test, and resting-state functional MRI scans. The dopamine transporter gene, dopamine D4 receptor gene, alpha-2A adrenergic receptor gene (ADRA2A) and norepinephrine transporter gene polymorphisms, and blood lead and urine cotinine levels were also measured. The participants were enrolled in an 8-week, open-label trial of methylphenidate. Four different machine learning algorithms were used for data analysis.

RESULTS

Support vector machine classification accuracy was 84.6% (area under receiver operating characteristic curve 0.84) for predicting methylphenidate response. The age, weight, ADRA2A MspI and DraI polymorphisms, lead level, Stroop color word test performance, and oppositional symptoms of Disruptive Behavior Disorder rating scale were identified as the most differentiating subset of features.

CONCLUSIONS

Our results provide preliminary support to the translational development of support vector machine as an informative method that can assist in predicting treatment response in attention deficit hyperactivity disorder, though further work is required to provide enhanced levels of classification performance.

Individualization of treatments with drugs metabolized by CES1: combining genetics and metabolomics

CES1 is involved in the hydrolysis of ester group-containing xenobiotic and endobiotic compounds including several essential and commonly used drugs. The individual variation in the efficacy and tolerability of many drugs metabolized by CES1 is considerable. Hence, there is a large interest in individualizing the treatment with these drugs. The present review addresses the issue of individualized treatment with drugs metabolized by CES1. It describes the composition of the gene encoding CES1, reports variants of this gene with focus upon those with a potential effect on drug metabolism and provides an overview of the protein structure of this enzyme bringing notice to mechanisms involved in the regulation of enzyme activity. Subsequently, the review highlights drugs metabolized by CES1 and argues that individual differences in the pharmacokinetics of these drugs play an important role in determining drug response and tolerability suggesting prospects for individualized drug therapies. Our review also discusses endogenous substrates of CES1 and assesses the potential of using metabolomic profiling of blood to identify proxies for the hepatic activity of CES1 that predict the rate of drug metabolism. Finally, the combination of genetics and metabolomics to obtain an accurate prediction of the individual response to CES1-dependent drugs is discussed.

COMT genotype affects brain white matter pathways in attention-deficit/hyperactivity disorder

Increased dopamine availability may be associated with impaired structural maturation of brain white matter connectivity. This study aimed to derive a comprehensive, whole-brain characterization of large-scale axonal connectivity differences in attention-deficit/hyperactivity disorder (ADHD) associated with catechol-O-methyltransferase gene (COMT) Val158Met polymorphism. Using diffusion tensor imaging, whole-brain tractography, and an imaging connectomics approach, we characterized altered white matter connectivity in youth with ADHD who were COMT Val-homozygous (N = 29) compared with those who were Met-carriers (N = 29). Additionally, we examined whether dopamine transporter gene (DAT1) and dopamine D4 receptor gene (DRD4) polymorphisms were associated with white matter differences. Level of attention was assessed using the continuous performance test before and after an 8-week open-label trial of methylphenidate (MPH). A network of white matter connections linking 18 different brain regions was significantly weakened in youth with ADHD who were COMT Met-carriers compared to those who were Val-homozygous (P < 0.05, family-wise error-corrected). A measure of white matter integrity, fractional anisotropy, was correlated with impaired pretreatment performance in continuous performance test omission errors and response time variability, as well as with improvement in continuous performance test response time variability after MPH treatment. Altered white matter connectivity was exclusively based on COMT genotypes, and was not evident in DAT1 or DRD4. We demonstrated that white matter connectivity in youth with ADHD is associated with COMT Val158Met genotypes. The present findings suggest that different layers of dopamine-related genes and interindividual variability in the genetic polymorphisms should be taken into account when investigating the human connectome.

The use of stimulant medications for non-core aspects of ADHD and in other disorders

Psychostimulants play a central role in the management of ADHD. Here we review the evidence pertaining to the use of methylphenidate, dexamphetamine and related amphetamine salts, the prodrug lisdexamfetamine and modafinil for the management of comorbid ADHD and non-ADHD indications. There is a growing consensus that stimulant medications are helpful at improving the emotional dysregulation and lability, and oppositional and conduct symptoms that are often associated with ADHD. There is some evidence that psychostimulants may improve outcomes in those with treatment resistant depression, reduce negative symptoms and improve cognitive performance in schizophrenia, and that methylphenidate may reduce binge eating in those with bulimia nervosa. In general medicine, whilst the evidence is at times contradictory, psychostimulants have been shown in some studies to be effective treatments for chronic fatigue and narcolepsy, and to improve outcomes post stroke, post head injury, in dementia and various cancers. It seems likely that these effects often result from a combination of, reduction in fatigue, improvements in concentration and cognitive functioning and a lifting of mood which may be a direct or indirect consequence of the medication. Further studies seem warranted and these should focus on efficacy, effectiveness and long term safety. This article is part of the Special Issue entitled 'CNS Stimulants'.

Alterations in pain response are partially reversed by methylphenidate (Ritalin) in adults with attention deficit hyperactivity disorder (ADHD)

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is characterized by dysregulation of sensory processing and neurobiology of dopamine. Although cumulative evidence suggests that dopamine is involved in pain processing, pain perception in ADHD subjects and the effect of dopamine agonists such as methylphenidate (MP, Ritalin) on it have rarely been studied.

AIMS

The aims of this study were to (1) psychophysically assess sensitivity to pain in ADHD subjects as compared to controls and (2) examine the effects of MP on pain response in ADHD subjects.

METHODS

Thirty subjects with ADHD and 30 age- and gender-matched controls participated in a preliminary trial. Pain threshold, intensity, and tolerance in response to cold pain stimulation were measured for both groups (ADHD with no treatment). In addition, the ADHD group was reassessed following a single dose of MP treatment.

RESULTS

The ADHD subjects "without MP" in comparison with controls displayed significantly shorter cold pain threshold (2.8 ± 2.1 vs. 5.8 ± 2.5 seconds, respectively, P < 0.001) and cold tolerance (21.8 ± 22.3 vs. 62.8 ± 59.8 seconds, respectively P < 0.001). No differences in pain intensities between the groups were found. Following MP treatment, both cold threshold and tolerance in the ADHD subjects increased significantly compared to those with no treatment (3.6 ± 2.5 seconds, P = 0.011, and 46.4 ± 53.3 seconds, P < 0.001, respectively).

CONCLUSIONS

These results suggest that adults with ADHD are more sensitive to pain compared with controls and that MP may exert antinociceptive properties in these subjects. Randomized, controlled trials are warranted to verify these findings.

What influences clinicians' decisions about ADHD medication? Initial data from the Influences on Prescribing for ADHD Questionnaire (IPAQ)

Despite evidence for its efficacy and effectiveness, the use of medication for the treatment of ADHD remains controversial. Little is known about the factors that influence clinicians' decisions to use medication for ADHD. Here, we present initial data on the attitudes of prescribing clinicians from the Influences on Prescribing for ADHD Questionnaire (IPAQ)-a new clinician-completed, 40-item scale. The eight IPAQ subscales cover attitudes towards (1) treatment outcome optimisation, (2) the use of rule based over more informal approaches, (3) side effects, (4) symptoms control as the primary goal of treatment, (5) the influence of external pressure on medication-related decisions, (6) the value of taking the child's views into account, (7) long-term medication use and (8) the value of psychosocial approaches for the treatment of ADHD. Sixty-eight clinicians from Belgium and the UK took part. All subscales had acceptable levels of internal reliability (Chronbach's alpha = 0.62-0.78). Overall, clinicians reported taking a rule-based approach to prescribing with a focus on treatment optimisation, taking the child's view into account and valuing psycho-social approaches. They focused on treating broader patterns of impairment, but were wary of the potential side effects and long-term treatment. Psychiatrists scored high on their focus on symptom control and preference for long-term medication use, while paediatricians reported using more rule-based approaches. We identified four distinctive response profiles: (1) pro-psychosocial; (2) medication focused; (3) unsystematic; and (4) response optimizers. Future larger scale studies are required to replicate these profiles and to explore their relationship with prescribing behaviour and treatment outcomes.

No Association between the Response to Methylphenidate and DRD4 Gene Polymorphism in Korean Attention Deficit Hyperactivity Disorder: A Case Control Study

Objective

Recently the relationship between alleles frequency distribution, drug response and the attention deficit hyperactivity disorder (ADHD), has been actively researched. We investigated the association between the genetic type, alleles and drug response for the dopamine receptor D4 (DRD4) gene in ADHD patients in Korea.

Methods

One hundred fourteen patients diagnosed with ADHD according to the the Diagnostic and Statistical Manual of Mental Disorders version IV (DSM-IV) diagnostic criteria were selected for the study. The clinical features of patients were confirmed by Korean version of Conners' parent rating scale, Attention deficit Diagnostic System, Korean version of Spielberger state-trait anxiety scale. Blood samples were taken from the 198 subjects. DNA was extracted from blood lymphocytes, PCR was performed for DRD4 Polymorphism. Alleles, genotype frequencies, the Clinical Global Impression (CGI) improvement score were compared using the chi-square test. Korean ADHD Rating Scale (K-ARS) and CGI severity scores were compared using the t-test.

Results

In comparing the ADHD with 4/4 repeats group and without the ADHD with 4/4 repeats group, no significant difference was seen between the DRD4 genetic type, alleles distribution, and CGI drug response.

Conclusion

As a result, it is viewed that there is no relationship between ADHD and DRD4, but final decision is indefinite. Follow up studies with larger patient or pure subgroups are expected.

Psychiatric disorders and sleep

There is growing experimental evidence that the relationship between psychiatric disorders and sleep is complex and includes bidirectional causation. This article provides the evidence that supports this point of view, reviewing data on sleep disturbances seen in patients with psychiatric disorders as well as data on the impact of sleep disturbances on psychiatric conditions. Although much has been learned about the psychiatric disorders-sleep relationship, additional research is needed to better understand the relationship. Such work promises to improve comprehension of these phenomena and lead to better treatment for the many patients with sleep disorders and psychiatric disorders.

Dopaminergic and noradrenergic gene polymorphisms and response to methylphenidate in korean children with attention-deficit/hyperactivity disorder: is there an interaction?

OBJECTIVE

We aimed to investigate the independent and interaction effects of dopamine transporter gene (DAT1), dopamine D4 receptor gene (DRD4), alpha-2A adrenergic receptor gene (ADRA2A), and norepinephrine transporter gene (NET1), with regard to treatment response to methylphenidate (MPH) in attention-deficit/hyperactivity disorder (ADHD).

METHODS

The participants of the study were 103 children and adolescents (ages 9.1±2.1 years) diagnosed as having ADHD according to American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) criteria. They were enrolled in an 8-week, open-label trial of MPH. The good responder group was defined as subjects having an ≥50% decrease in the ADHD Rating Scale-IV (ADHD-RS) total score from the baseline, and at the same time a Clinical Global Impressions-Improvement Scale (CGI-I) score of 1 or 2, both at the 8th week of MPH treatment. Multivariate stepwise logistic regression was performed to examine the independent and interaction effects of genotypes on the dichotomized MPH treatment response.

RESULTS

Significant interaction effects on MPH response were detected between the genotypes of the DRD4 variable number of tandem repeat (VNTR) polymorphisms and those of either the ADRA2A DraI or the NET1 -3081(A/T) polymorphisms; significant interaction effects were also detected between the genotypes of the ADRA2A DraI polymorphisms and those of either the NET1 G1287A or the NET1 -3081(A/T) polymorphisms (Nagelkerke R(2)=0.40). No significant independent effect of a genotype was detected according to the stepwise logistic regression results.

CONCLUSION

The results suggest that genes involved in the dopaminergic and noradrenergic systems might interact to form important predictors of short-term response to MPH.

Sex differences in the behavioral response to methylphenidate in three adolescent rat strains (WKY, SHR, SD)

Methylphenidate (MPD) is the most widely used drug in the treatment of attention-deficit hyperactivity disorder (ADHD). ADHD has a high incidence in children and can persist in adolescence and adulthood. The relation between sex and the effects of acute and chronic MPD treatment was examined using adolescent male and female rats from three genetically different strains: spontaneously hyperactive rat (SHR), Wistar-Kyoto (WKY) and Sprague-Dawley (SD). Rats from each strain and sex were randomly divided into a control group that received saline injections and three MPD groups that received either 0.6 or 2.5 or 10mg/kg MPD injections. All rats received saline on experimental day 1 (ED1). On ED2 to ED7 and ED11, the rats were injected either with saline or MPD and received no treatment on ED8-ED10. The open field assay was used to assess the dose-response of acute and chronic MPD administration. Significant sex differences were found. Female SHR and SD rats were significantly more active after MPD injections than their male counterparts, while the female WKY rats were less active than the male WKY rats. Dose dependent behavioral sensitization or tolerance to MPD treatment was not observed for SHR or SD rats, but tolerance to MPD was found in WKY rats for the 10mg/kg MPD dose. The use of dose-response protocol and evaluating different locomotor indices provides the means to identify differences between the sexes and the genetic strain in adolescent rats. In addition these differences suggest that the differences to MPD treatment between the sexes are not due to the reproductive hormones.

Effects of methylphenidate on intelligence and attention components in boys with attention-deficit/hyperactivity disorder

BACKGROUND

Methylphenidate (MPH) is an efficient treatment to reduce behavioral symptoms of attention-deficit/hyperactivity disorder (ADHD); however, its impact on cognitive functioning has not been sufficiently demonstrated so far. This study investigates the hypothesis that MPH improves attention-related cognitive functions.

METHODS

Sixty-seven medication-naive boys aged 6-13, with newly diagnosed ADHD, were tested before treatment with a neuropsychological assessment battery, including the Wechsler Intelligence Scales for Children (WISC-IV) and the Test of Attentional Performance for Children (KITAP). A follow-up assessment was performed after 8-12 weeks, with 37 participants receiving MPH treatment and 30 controls without medication. The effect of MPH on test performance was analyzed by repeated measures analyses of variance.

RESULTS

Both groups improved significantly across a broad range of psychometric measures of cognitive performance. There were no significant interaction effects of group and time on attention-related cognitive functions. Exploratory analyses revealed an effect of MPH on verbal comprehension in the WISC-IV.

CONCLUSION

The study results do not support that MPH improves attention-related cognitive functions of boys with ADHD. The potential effect of MPH on verbal abilities deserves further research.

Methylphenidate treatment and dyskinesia in children with attention-deficit/hyperactivity disorder

OBJECTIVES

Case reports suggest a relationship between methylphenidate treatment and dyskinesia in attention-deficit/hyperactivity disorder (ADHD). The aim of the current study was (a) to investigate abnormal involuntary movements of children with ADHD before and after the administration of methylphenidate and (b) to investigate the effect of a provocative assessment method used to make latent dyskinesia visible, which is included in the Abnormal Involuntary Movement Scale (AIMS).

METHODS

Participants, aged 6-18, were recruited from a Child and Adolescent Psychiatric Hospital and Outpatient Clinic (Vadaskert Foundation), Budapest, Hungary. Using a structured diagnostic interview (Mini International Neuropsychiatric Interview Kid), 37 children were included in the ADHD group and 34 children in the control group. The AIMS was used to observe and score dyskinesia.

RESULTS

There was a significant difference between the baseline total AIMS score in the ADHD and the control groups, with the ADHD subjects evidencing substantially higher severity than controls. Provocation, as applied with the administration of the AIMS, significantly increased the AIMS total score in both groups. The administration of methylphenidate had no effect on the total score of the AIMS. In the ADHD group, we observed a significant negative relationship between the patients' age and the overall severity on the AIMS. In contrast, in the control group we detected a significant positive relationship between the patients' age and the overall severity on the AIMS before and no relationship after provocation.

CONCLUSIONS

Methylphenidate-treated children with ADHD had more dyskinesia than children in the control group. Dyskinesia did not worsen after a single dose of methylphenidate. Higher dyskinesia scores in the methylphenidate-treated younger age group warrant caution in the methylphenidate treatment of ADHD; however, further studies are needed to clarify the possible causal relationship between dyskinesia and methylphenidate treatment and/or age and/or the disease itself.

Central stimulants in the treatment of attention-deficit hyperactivity disorder (ADHD) in children and adolescents. A naturalistic study of the prescription in Sweden, 1977-2007

BACKGROUND

An increased prescription of central stimulants (CS) for treatment of attention-deficit hyperactivity disorder (ADHD) in children and adolescents has been reported in Sweden.

AIMS

To follow-up the treatment with CS as concerns total as well as regional differences in prescription rate. Efficacy and side-effects reported and gender differences in prescription over time also have been summarized.

METHODS

Data from the Swedish Medical Products Agency (MPA) of individual licences, annual reports about patients on individual or clinic licences from the MPA and sales statistics from the National Pharmacy (Apoteket AB) have been used.

RESULTS

The number of new licences and prescriptions increased dramatically from 1992 to 2007 and a change of preparations was seen. Great differences (fivefold) between the 21 counties of Sweden were noticed. In the follow-up reports to the MPA, a good/moderate treatment effect was reported in 92% and adverse effects were reported in 4% leading to discontinuation of medication in 46% of them. Abuse/misuse of the preparation was suspected in 0.2% of the reports. A tendency of a reduction of the proportion of boys to girls treated through individual licences has been seen.

CONCLUSIONS

The study, although observational, supports good efficacy, limited adverse effects and a low degree of misuse in clinical use of CS for children and adolescents with ADHD.

College students with attention-deficit/hyperactivity disorder

As more students with attention-deficit/hyperactivity disorder attend college, studies are emerging that reveal problems in psychosocial and academic functioning. Substance use may magnify deficits in self-regulation. Recommendations are made for comprehensive assessment; however, the usual diagnostic categories may not be developmentally relevant. Students who are identified benefit from medication and nonmedication interventions, strategy support, and accommodations.

DIFFERENTIAL LOCOMOTOR RESPONSES IN MALE RATS FROM THREE STRAINS TO ACUTE METHYLPHENIDATE

Genetic variability is an important consideration in the study of the effect of drugs on humans and animals. Specifically, the effect of drugs on behavior varies from one rat strain to another. Methylphenidate (MPI), commonly known as Ritalin, is a psychostimulant with a pharmacological profile similar to amphetamine and cocaine, and is widely used in the treatment of attention deficit/hyperactivity disorder (ADHD). The purpose of this study was to examine the acute dose-response characteristics of MPD on three different male rat strains: spontaneously hypertensive/hyperactive rats (SHR), Wistar-Kyoto (WKY) rats, and Sprague-Dawley (SD) rats. Results showed clear differences in the pattern of behavioral response to the various MPD doses among the three rat strains. The 0.6 mg/kg MPD dose had no effect on any of the strains. At the dose of 2.5 mg/kg MPD, WKY rats reached peak locomotor activity within the initial 10 min, whereas SHR and SD rats reached peak activity in approximately 30 min. Furthermore, the effects on locomotor activity of SHR were longer in duration and higher in locomotor activity, whereas the effects on SD rats were shorter in duration and amplitude. Following the 10.0 mg/kg MPD, WKY, and SD mats reached their peak locomotor activity within 80 min post-injection, whereas SHR reached their peak locomotor activity within the initial 10 min post-injection. In addition, the SHR strain exhibited increased behavioral sensitivity to MPD as expressed by the latency, duration, and amplitude of their response. In conclusion, the dose-response experiment on the acute effects of MPD demonstrated that there are genetic differences in the responses to MPD.

MAOA is associated with methylphenidate improvement of oppositional symptoms in boys with attention deficit hyperactivity disorder

The monoamine oxidase A (MAOA) gene has been extensively related to aggressive, impulsive and violent behaviours. Previous studies have documented the improvement of oppositional symptoms in attention deficit hyperactivity disorder (ADHD) patients with methylphenidate (MPH). However, the effect of the MAOA gene in response to MPH has not been investigated. A sample of 85 boys from an ADHD outpatient service was genotyped for the MAOA-uVNTR polymorphism. The outcome measure was the parent-rated oppositional subscale of the Swanson, Nolan and Pelham Scale - version IV. The scale was applied by child psychiatrists blinded to genotype at baseline and in the first and third months of treatment. A significant interaction between the presence of MAOA high-activity genotype and treatment with MPH over time on oppositional scores was detected during the 3 months' treatment (n=85, F2,136=4.83, p=0.009). These results suggest an effect of the MAOA-uVNTR high-activity genotype on the improvement of oppositional symptoms with MPH treatment.

Attention Deficit Hyperactivity Disorder in Children: Comparative Efficacy of Traditional Chinese Medicine and Methylphenidate

Traditional Chinese medicine (TCM) is frequently used to treat attention deficit hyperactivity disorders (ADHD) in children in China. However, until now there has been no strong evidence to prove that TCM has better efficacy than western medicine. In this systematic study of 34 studies published in the Chinese literature, the effectiveness of TCM in treating ADHD in children was examined and compared with methylphenidate (MPH), which is widely used to treat ADHD. It was found that TCM may have equal or better effectiveness than MPH. However, the lack of high-quality clinical trials to support this conclusion means that it is not currently possible to recommend any particular kind of TCM preparation for treating ADHD in children.

Predicting positive and negative treatment responses to stimulants with brain SPECT imaging

The goal of this study was to test whether clinician-rated regional cerebral blood flow (rCBF) as rendered by SPECT imaging is a meaningful predictor of patient response to CNS stimulants. Chart reviews were used to identify patients who reported prior significant positive and negative responses to CNS stimulants. Each patient in the study had received resting and concentration SPECT scans using Tc99m exametazime. Differences in cerebral blood flow for frontal regions of interest were assessed in three conditions (resting, concentration, and their difference, or "delta") using ANCOVAs and age-matched ANOVAs. Prefrontal pole deltas were found to be highly sensitive and specific predictors of response to CNS stimulants, with pole activation predicting adverse responses and pole deactivation predicting good responses. Positive and negative predictive values were greater than .75 for both poles. We conclude that SPECT renderings of rCBF, particularly in the prefrontal cortex, are a potentially powerful clinical tool for anticipating response to stimulant medications, both positive and adverse.

Quantitative electroencephalography and attention-deficit/hyperactivity disorder: implications for clinical practice

Although behavioral symptoms of inattention, impulsivity, and hyperactivity serve as a foundation for the accurate diagnosis of attention-deficit/hyperactivity disorder (ADHD), the low interrater reliability and specificity of behavioral rating scales and the absence of comprehensive screening for medical conditions that mimic ADHD have created a barrier to the effective treatment of ADHD. Recently published studies using quantitative electroencephalographic techniques have identified abnormal patterns of cortical activation through power spectral analysis, in event-related cortical potentials, and in slow cortical potentials that may serve as a basis for overcoming these barriers. This paper reviews the initial evidence indicating that power spectral analysis and event-related cortical potentials may be useful in differentiating ADHD from other psychiatric disorders, helping in medication selection, evaluating medication response, and improving the rate of treatment initiation and maintenance. Studies examining electroencephalogram biofeedback (neurotherapy) are reviewed using published efficacy guidelines.

Practitioner review: How can epidemiology help us plan and deliver effective child and adolescent mental health services?

This review focuses on ways in which epidemiological research can inform mental health service development and clinical practice. Data from epidemiological studies can provide cross-sectional and secular estimates of the prevalence of psychopathology to support rational service development. Epidemiological surveys have difficulties in finding large enough samples of children with rare disorders, although these disorders are often severely debilitating and require extensive service input. Systematic surveillance provides a rigorous method for studying rare disorders and events. Only a minority of children with impairing psychopathology reach mental health services, although a larger proportion have mental health related contacts with other services. The gap in provision is such that an expansion of mental health services is unlikely to reach all children who could benefit, suggesting that mental health professionals need to develop innovative strategies to increase the number of children seen and the effectiveness of interventions that they receive. Training and supervision of non-mental-health professionals working with children in the identification and management of mental health problems is also extremely important. Most studies suggest that the children with the severest problems are getting to specialist mental health services, and service contact is more likely if important adults can perceive the child's difficulty or find it to be burdensome. The latter suggests that education of key adults would improve detection if services had the capacity to cope. Studies consistently suggest that the region in which the child lives affects the likelihood of service contact, but studies of other characteristics predicting service contact are so contradictory that studies should only be (cautiously) applied to similar populations to assess which types of children may currently be falling through gaps in service provision. Academics are beginning to explore the use of structured measures developed for epidemiological studies in clinical assessment and outcome monitoring.

Effects of methylphenidate on the catecholaminergic system in attention-deficit/hyperactivity disorder

Stimulants are part of the standard-of-care treatment for attention-deficit/hyperactivity disorder (ADHD). Methylphenidate, with a history of use spanning approximately 5 decades, is a first-line stimulant treatment for ADHD. Methylphenidate chiefly affects the prefrontal cortex and striatum, the mechanism of action being modulation of catecholaminergic tone. Methylphenidate treatment produces an increase in dopamine (DA) signaling through multiple actions, including blockade of the DA reuptake transporter and amplification of DA response duration, disinhibition of DA D2 autoreceptors and amplification of DA tone, and activation of D1 receptors on the postsynaptic neuron. The actions of methylphenidate may also be mediated by stimulation of the noradrenergic alpha2 receptor and DA D1 receptor in the cortex. The role of other neurotransmitters such as histamine, acetylcholine, serotonin, and alpha-agonists in modulating catecholamine pathophysiology in ADHD and ADHD treatment needs to be elucidated. Overall, the changes in catecholaminergic tone clinically manifest as improvements in attention deficit, distractibility, and motor hyperactivity in patients with ADHD.

Effects of psycho-educational training and stimulant medication on visual perceptual skills in children with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is treated with stimulants and psycho-educational remedial programs despite limited literature support for the latter. This study aimed to examine changes in a "Test of Visual Perceptual Skills" (TVPS) that has not been previously reported in children with ADHD enrolled in such a program.

METHODS

Sixteen children, 7-11 years old, with ADHD were involved in occupational therapy and special education geared towards attention training. Six months later methylphenidate 1 mg/kg/day was prescribed. It was not taken by eight children because of family choice. The TVPS was given twice, upon diagnosis, and 8 months post-intervention. The groups were compared by a repeated measures analysis of variance (ANOVA) with medication as a between groups factor and test-retest scores as within factor.

RESULTS

All children demonstrated increases in total scores in the second measurement. Medicated children scored higher but ANOVA showed a nonsignificant F for the two groups, medicated and unmedicated (F = 0.0031, p = 0.9563), indicating a nondifferential effect of the two levels of treatment. It revealed a significant F for the pre- and post-treatment total TVPS scores (F = 30.91, p < 0.0001) indicating a significant difference between pre- and post-treatment tests. The interaction between pre-post treatment and level of treatment (medicated-unmedicated) was nonsignificant (F = 2.20, p = 0.1604).

CONCLUSION

TVPS scores improved in all children following intervention. Medicated children did better, but differences were nonsignificant.

Psychosocial treatments for children with attention deficit/hyperactivity disorder

This article reviews studies examining the efficacy of behavioral interventions for the treatment of attention-deficit/hyperactivity disorder (ADHD). A specific emphasis is placed on evidence-based interventions that include parent training, classroom, academic, and peer interventions. Results indicate that school-aged children respond to behavioral interventions when they are appropriately implemented both at home and in the classroom setting. Combined treatments (behavioral management and stimulant medication) represent the gold standard in ADHD treatment and are often recommended as the first-line treatment option due to the many problems faced by children with ADHD. Diversity issues, although an important consideration in the treatment of ADHD, continue to remain an understudied area. Recommendations for future research are made pertaining to treatment sequencing with regard to behavior management as well as for subgroups of ADHD children who may respond best to specific treatments.

Reduction of impulsivity with amphetamine in an appetitive fixed consecutive number schedule with cue for optimal performance in rats

RATIONALE

Impulsivity is a key feature of many psychopathologies such as mania, personality disorders or attention deficit-hyperactivity disorder (ADHD). Most experimental paradigms assessing impulsive behaviour also require non-specific capacities such as time estimation. This may interact with the measures and mask the beneficial effects of psychostimulants-the most commonly used treatment for ADHD-on impulsivity, given that these drugs speed up the internal clock.

OBJECTIVES

The present experiment investigated the effects of suppressing behaviours non-specific to impulsivity in a fixed consecutive number (FCN) schedule and examined whether amphetamine, previously shown to increase impulsive responses in this task, could have beneficial effects when impulsive responses are promoted.

MATERIALS AND METHODS

Food-deprived rats were trained to press one lever of a two-lever operant chamber eight times before pressing the other lever to obtain food. Premature ending of responses resulted in absence of food delivery and reset the counter. A cue light indicating the required number of presses was present (FCN8(cue)) and removed after training (FCN8). Rats were then trained under an FCN16(cue) schedule to be challenged with d-amphetamine (0.125, 0.25 and 0.5 mg/kg).

RESULTS

The cue improved performances, and similar scores were obtained under FCN16(cue) compared to FCN8. Premature responses under these two conditions were unrelated. Amphetamine reduced impulsive responses in FCN16(cue) at the lower dose.

CONCLUSIONS

Suppression of capacities non-specific to impulsivity in the FCN schedule, associated with conditions that permit the expression of inhibitory deficits, allows the beneficial effects of psychostimulants observed clinically to be evidenced experimentally.

Methylphenidate-induced orofacial and extremity dyskinesia

In this paper, we report the case of a 6(1/2)-year-old male patient diagnosed with attention-deficit/hyperactivity disorder (ADHD) who developed orofacial and extremity dyskinesias immediately after methylphenidate treatment. The episode lasted 5 hours, peaking in intensity 2 hours after the medication was administered before gradually subsiding. Five hours after the methylphenidate was administered, the child became extremely irritated and aggressive, which lasted approximately 2 hours. The patient's general intelligence (IQ) was measured to be below the normal range. The potential relationship between methylphenidate intake and the development of dyskinesia calls into question different mechanisms involving drug-receptor interaction or individual drug sensitivity related to a lower IQ. Our case report has practical implications for physicians by raising their awareness of dyskinesia as a potential side effect of methylphenidate treatment.

Evidence-based guidelines for management of attention-deficit/hyperactivity disorder in adolescents in transition to adult services and in adults: recommendations from the British Association for Psychopharmacology

Attention-deficit/hyperactivity disorder (ADHD) is an established diagnosis in children, associated with a large body of evidence on the benefits of treatment. Adolescents with ADHD are now leaving children's services often with no readily identifiable adult service to support them, which presents problems as local pharmacy regulations often preclude the prescription of stimulant drugs by general practitioners (GPs). In addition, adults with ADHD symptoms are now starting to present to primary care and psychiatry services requesting assessment and treatment. For these reasons, the British Association for Psychopharmacology (BAP) thought it timely to hold a consensus conference to review the body of evidence on childhood ADHD and the growing literature on ADHD in older age groups. Much of this initial guidance on managing ADHD in adolescents in transition and in adults is based on expert opinion derived from childhood evidence. We hope that, by the time these guidelines are updated, much evidence will be available to address the many directions for future research that are detailed here.

Osmotic, controlled-release methylphenidate for the treatment of ADHD

Methylphenidate (MPH) is the most commonly used and best-studied stimulant medication for attention-deficit hyperactivity disorder. However, its short duration of action usually results in a requirement to administer multiple daily doses in order to achieve optimal clinical benefit. Although a wax-matrix-based SR formulation of MPH has been available since the 1990s, it was not well accepted into clinical practice. The variable absorption profile and lack of an immediate-release component results in a slower onset of action compared with immediate-release MPH. Hence, there was a need to develop alternative longer-lasting preparations of MPH that were as efficacious as IR MPH, but which also addressed the problems inherent in multiple daily dosing. An osmotic, controlled-release (OROS) formulation of MPH HCl has been developed over the past 10 years for once-daily administration. OROS MPH has been widely accepted by clinicians and is now the most widely prescribed MPH product in North America. Clinical trials have shown OROS MPH to have a continued action over a 12-h period, to be superior to placebo and to be as effective as immediate-release MPH dosed three times daily, in reducing symptoms of attention-deficit hyperactivity disorder, with similar incidence of side effects. There have been a smaller number of trials comparing OROS MPH with non-stimulant treatments, such as atomoxetine.

Attention deficit hyperactivity disorder, tics and Tourette's syndrome: the relationship and treatment implications. A commentary

Tourette's Syndrome (TS) is now recognised to be a common childhood onset neurodevelopmental disorder. Attention deficit hyperactivity disorder (ADHD) is also a common childhood disorder. There are many cases in which the two disorders are comorbid. The reasons for this are unclear, but the comorbidity does not necessarily point to one genetic cause. Sleep is also often disturbed in individuals with TS and ADHD. The treatment implications of ADHD in the setting of tics or TS are important. Clonidine is suggested as a first line treatment. It was once thought that stimulants were contraindicated in the treatment of ADHD in the setting of TS, whereas it is suggested that they may be safe, but should be used judiciously. In addition, it was once thought that the combination of stimulants and clonidine was contraindicated, but from a large study the combination does appear to be safe. A relatively new medication for ADHD is atomoxetine, and although not documented widely in the setting of tics and TS, it may prove useful in this setting; further research is required. This commentary briefly discusses the comorbidity between TS and ADHD and offers treatment suggestions.

Dose-response characteristics of methylphenidate on locomotor behavior and on sensory evoked potentials recorded from the VTA, NAc, and PFC in freely behaving rats

BACKGROUND

Methylphenidate (MPD) is a psychostimulant commonly prescribed for attention deficit/hyperactivity disorder. The mode of action of the brain circuitry responsible for initiating the animals' behavior in response to psychostimulants is not well understood. There is some evidence that psychostimulants activate the ventral tegmental area (VTA), nucleus accumbens (NAc), and prefrontal cortex (PFC).

METHODS

The present study was designed to investigate the acute dose-response of MPD (0.6, 2.5, and 10.0 mg/kg) on locomotor behavior and sensory evoked potentials recorded from the VTA, NAc, and PFC in freely behaving rats previously implanted with permanent electrodes. For locomotor behavior, adult male Wistar-Kyoto (WKY; n = 39) rats were given saline on experimental day 1 and either saline or an acute injection of MPD (0.6, 2.5, or 10.0 mg/kg, i.p.) on experimental day 2. Locomotor activity was recorded for 2-h post injection on both days using an automated, computerized activity monitoring system. Electrophysiological recordings were also performed in the adult male WKY rats (n = 10). Five to seven days after the rats had recovered from the implantation of electrodes, each rat was placed in a sound-insulated, electrophysiological test chamber where its sensory evoked field potentials were recorded before and after saline and 0.6, 2.5, and 10.0 mg/kg MPD injection. Time interval between injections was 90 min.

RESULTS

Results showed an increase in locomotion with dose-response characteristics, while a dose-response decrease in amplitude of the components of sensory evoked field responses of the VTA, NAc, and PFC neurons. For example, the P3 component of the sensory evoked field response of the VTA decreased by 19.8% +/- 7.4% from baseline after treatment of 0.6 mg/kg MPD, 37.8% +/- 5.9% after 2.5 mg/kg MPD, and 56.5% +/- 3.9% after 10 mg/kg MPD. Greater attenuation from baseline was observed in the NAc and PFC. Differences in the intensity of MPD-induced attenuation were also found among these brain areas.

CONCLUSION

These results suggest that an acute treatment of MPD produces electrophysiologically detectable alterations at the neuronal level, as well as observable, behavioral responses. The present study is the first to investigate the acute dose-response effects of MPD on behavior in terms of locomotor activity and in the brain involving the sensory inputs of VTA, NAc, and PFC neurons in intact, non-anesthetized, freely behaving rats previously implanted with permanent electrodes.

[Treatment effects of parent management training for ADHD]

OBJECTIVES

The study investigated the efficacy of a programme of parent management training in groups for the parents of ADHD children that is based on a cognitive behavioural concept.

METHODS

The parents of 16 ADHD children participated in group training over a ten-week period. Children were medicated with methylphenidate and received consultations. 17 other ADHD children (control group) benefited only from medication with methylphenidate plus consultation; however, their parents did not participate in any group training. In both groups, assessment was done by means of parent questionnaires: in the experimental group to assess the core symptoms of ADHD, homework problems and global problems that occur in families with ADHD; in the control group to assess only the core symptoms of ADHD.

RESULTS

The training significantly reduced core symptoms of ADHD, homework problems and global problematic situations in the experimental group. In comparison to the control group, the core symptoms of ADHD decreased more strongly in the experimental group. This effect failed to reach the significance level of p < 0.05 (Mann-Whitney U-test). However, the verification with the linear model showed a significant difference between the two groups on the factor "hyperactivity index".

CONCLUSIONS

Parent management training in groups was a useful adjunct in the treatment of ADHD children.

Methylphenidate-evoked changes in striatal dopamine correlate with inattention and impulsivity in adolescents with attention deficit hyperactivity disorder

Abnormal central dopamine (DA) neurotransmission has been implicated in the impulsivity, inattention, and hyperactivity of attention deficit hyperactivity disorder (ADHD). We hypothesized that a pharmacological challenge with methylphenidate (MP) at a therapeutic dose increases extracellular DA concentrations in proportion to the severity of these specific ADHD symptoms. To test this hypothesis, we measured by PET the effect of acute challenge with MP on the availability of striatal binding sites for [11C]raclopride (pB), an index of altered interstitial DA concentration, in nine unmedicated adolescents (1 female, 8 males; age 13.7 +/- 1.8 years) with a current diagnosis of ADHD. We estimated the pB of [11C]raclopride for brain dopamine D2/3 receptors first in a baseline resting condition, and again after an acute challenge with MP (0.3 mg/kg, p.o.), and calculated the percentage change in (%DeltapB) in left and right striatum. On another day, measurements of impulsivity and inattention were performed using a computerized continuous performance test. There was a significant correlation between the magnitude of %DeltapB in the right striatum and the severity of inattention and impulsivity. MP-evoked %DeltapB correlated with standard scores for impulse control (r = 0.68; P = 0.02), attention (r = 0.81; P = 0.005), information processing (r = 0.66; P = 0.02), and consistency of attention, or variability (r = 0.60; P = 0.04). In conclusion, the results link inattention and impulsivity with sensitivity of brain DA receptor availability to an MP challenge, corroborating the hypothesis that MP serves to potentiate decreased DA neurotransmission in ADHD.

Effects of transcutaneous electrical nerve stimulation (TENS) on cognition, behavior, and the rest-activity rhythm in children with attention deficit hyperactivity disorder, combined type

OBJECTIVE

The aim of this study was to examine the effects of transcutaneous electrical nerve stimulation (TENS) on cognition, behavior, and the rest-activity rhythm in children with attention deficit hyperactivity disorder, combined type (ADHD-CT).

METHODS

Twenty-two children diagnosed with ADHD-CT received TENS treatment during 6 weeks, 2 times 30 min a day. Neuropsychological tests were administered to assess cognition, parent/teacher behavioral rating scales were used to measure behavior, and actigraphy was used to assess the rest-activity rhythm.

RESULTS

TENS appeared to have a moderate beneficial influence on cognitive functions that load particularly on executive function. There was also improvement in behavior as measured by parent/teacher behavioral rating scales. Moreover, motor restlessness during sleep and motor activity during the day decreased by TENS.

CONCLUSIONS

The effects of TENS in children with ADHD are modest but encouraging and warrant further research.

Service Contacts Among the Children Participating in the British Child and Adolescent Mental Health Surveys

METHOD

  A third of the children from the 1999 British Child and Adolescent Mental Health Survey were followed up over 3 years. Parents provided summary information on service contacts for emotional, behavioural and concentration difficulties, with more detailed information being obtained by telephone interview for selected subgroups.

RESULTS

  Having a psychiatric disorder predicted substantially increased contact with social services, special educational needs resources, the youth justice system and mental health services (district CAMHS and tier four, but not tier two). Of those children with psychiatric disorders, 58% had been in contact with at least one of these services for help with emotional, behavioural or concentration difficulties, including 23% who had been in contact with mental health services.

CONCLUSIONS

  British children attend a wide variety of services for help with emotional, behavioural and concentration difficulties. The proportion seeing specialist mental health services is higher than that generally reported in the research literature.

Non-stimulant medications in the treatment of ADHD

BACKGROUND

Stimulants are the first-line medication in the psychopharmacological treatment of attention-deficit hyperactivity disorder (ADHD). However, 10 to 30% of all children and adults with ADHD either do not respond to or do not tolerate treatment with stimulants.

OBJECTIVE

To describe alternative treatment approaches with various non-stimulant agents, especially atomoxetine.

METHOD

General review of empirically based literature concerning efficacy and safety of the substances.

RESULTS

A large and still increasing body of data supports the usefulness of atomoxetine, a once daily dosing, and new selective noradrenalin reuptake inhibitor, with few side effects. Atomoxetine has been licensed in the US for use in ADHD across the lifespan, and is currently under consideration in Europe. Other non-stimulant substances, such as tricyclic antidepressants (TCAs) and alpha-2-adrenergic agonists, which are used to treat ADHD, are also reviewed. TCAs have been well studied and shown to be efficacious in the treatment of ADHD, but are limited by side effects. The number of studies documenting the efficacy of alpha-2-adrenergic agonists is still limited. Some experimental studies support a potential role of cholinergic drugs such as acetylcholinesterase inhibitors (tacrine, donepezil) as well as novel nicotinic analogues (ABT-418).

CONCLUSION

Non-stimulant agents have been shown to be effective in treatment of ADHD. Especially, atomoxetine seems promising and newline drugs are in development.

Methylphenidate for pervasive developmental disorders: safety and efficacy of acute single dose test and ongoing therapy: an open-pilot study

OBJECTIVE

The aim of this study was to investigate the effects of ongoing methylphenidate (MPH) on ADHD-related and autistic symptoms in Pervasive Developmental Disorders (PDD) in children who did not present any adverse effects to an initial acute dose administered at the clinic.

METHODS

Participants included 13 subjects (12 males, with a mean age of 7.9 years) with PDD and moderate to severe hyperactivity/impulsivity. The severity of the symptoms assessment was based on Clinical Global Impression (CGI), Childhood Autism, Child Psychiatric and Conners Parent and Teacher Rating Scales (CPRS). Scores at baseline, and after 1 and 3 months of treatment, were compared to intent-to-treat analyses.

RESULTS

One (1) hour after a single MPH dose (0.4 mg/kg), 5 subjects exhibited increased hyperactivity, stereotypes, dysphoria, or motor tics and were rated as minimally or much worse on the CGI Global Improvement Scale. They received no further treatment with MPH. Four (4) of the remaining subjects were rated as improved, and four as unchanged; they proceeded to a 12-week open trial of MPH. Two children remained unchanged: they discontinued treatment after 1 week on maximally tolerated doses. However, in group analyses, behavioral measures of hyperactivity and impulsivity improved significantly, while autism core symptom measures were unaffected. No significant adverse effects were observed in any of the 8 subjects.

CONCLUSIONS

Administering a single MPH test dose may be useful in identifying children with PDD who may benefit from prolonged therapy.