An open-label study of the tolerability of mixed amphetamine salts in adults with attention-deficit/hyperactivity disorder and treated primary essential hypertension

The orphan receptor GPR88 controls impulsivity and is a risk factor for Attention-Deficit/Hyperactivity Disorder

The neural orphan G protein coupled receptor GPR88 is predominant in the striatum and cortex of both rodents and humans, and considered a potential target for brain disorders. Previous studies have shown multiple behavioral phenotypes in Gpr88 knockout mice, and human genetic studies have reported association with psychosis. Here we tested the possibility that GPR88 contributes to Attention Deficit Hyperactivity Disorder (ADHD). In the mouse, we tested Gpr88 knockout mice in three behavioral paradigms, best translatable between rodents and humans, and found higher motor impulsivity and reduced attention together with the reported hyperactivity. Atomoxetine, a typical ADHD drug, reduced impulsivity in mutant mice. Conditional Gpr88 knockout mice in either D1R-type or D2R-type medium spiny neurons revealed distinct implications of the two receptor populations in waiting and stopping impulsivity. Thus, animal data demonstrate that deficient GPR88 activity causally promotes ADHD-like behaviors, and identify circuit mechanisms underlying GPR88-regulated impulsivity. In humans, we performed a family-based genetic study including 567 nuclear families with DSM-IV diagnosis of ADHD. There was a minor association for SNP rs2036212 with diagnosis, treatment response and cognition. A stronger association was found for SNP rs2809817 upon patient stratification, suggesting that the T allele is a risk factor when prenatal stress is involved. Human data therefore identify GPR88 variants associated with the disease, and highlight a potential role of life trajectories to modulate GPR88 function. Overall, animal and human data concur to suggest that GPR88 signaling should be considered a key factor for diagnostic and treatment of ADHD.

Cardiovascular Considerations for Stimulant Class Medications

The cardiovascular (CV) impact of stimulants has been examined for decades, with investigations ranging from small sample targeted studies of heart rate (HR) and blood pressure (BP), to large scale epidemiologic investigations. The preponderance of evidence is reassuring, albeit generally based on healthy samples using variable methodology, excluding those at theoretic high risk (eg, comorbid cardiac illness). Screening for theoretically vulnerable patients are recommended, as well as monitoring for CV symptoms and BP/HR, with shared inquiry/further evaluation if concerned. Future investigations to support the identification of risk are needed, while attention to stimulant-associated CV risk is an opportunity for clinicians to engage in general CV risk identification and intervention.

Cardiovascular Effects of Drugs Used to Treat Attention-Deficit/Hyperactivity Disorder: Part 1: Epidemiology, Pharmacology, and Impact on Hemodynamics and Ventricular Repolarization

Attention-deficit/hyperactivity disorder (ADHD) is a clinical syndrome characterized by persistent inattention, impulsivity, and hyperactivity. It is most commonly encountered in children and adolescents but may persist into adulthood. A variety of psychostimulant and nonpsychostimulant medications have proven to be successful in reducing inattention, impulsivity, and hyperactivity in those with ADHD. Psychostimulants used to treat ADHD include methylphenidate and related drugs and various amphetamine preparations. Non-psychostimulant medications used to treat ADHD include atomoxetine and two alpha-2 adrenergic agonists: guanfacine extended-release and clonidine extended-release. The psychostimulants and atomoxetine have been shown, on average, to increase heart rate by 3-10 beats/min, systolic blood pressure by 3-8 mm Hg, and diastolic blood pressure by 2-14 mm Hg. These drugs may also delay ventricular repolarization. The alpha-2 adrenergic agonists may reduce heart rate and blood pressure. For these reasons, there is concern about the safety of psychostimulant and nonpsychostimulant medications in patients with ADHD. In part 1 of this review, we discuss the epidemiology and natural history of ADHD, describe the pharmacology of drugs used to treat ADHD, and discuss in detail studies assessing the effects of ADHD drugs on blood pressure, heart or pulse rate, and electrocardiographic indices of ventricular repolarization.

Blood pressure in children with attention deficit/hyperactivity disorder

Objectives

Children with attention deficit/hyperactivity disorder (ADHD) are frequently treated with psycho-stimulant agents causing a modest but significant increase in blood pressure and heart rate. The objective of this study was to define blood pressure characteristics in children with ADHD treated with a variety of medications in a community setup.

Methods

Children registered at a large paediatric clinic in Calgary, AB with documented histories of ADHD were randomly contacted. Consenting participants had standardized office BP measurements, ambulatory blood pressure monitoring (ABPM) studies and were asked to complete the sleep disturbance scale for children (SDSC) questionnaire. Findings were compared with data from the Canadian Health Measures Survey (CMHS).

Results

Fifty-five children (47 males) aged 7 to 17 years (average 11.6 ± 2.5 years) with an average BMI z-score of -0.37 ± 1.22 completed the study. All children were medicated, the majority (82%), with various types of stimulant agents. Elevated office BP values were more prevalent than in the CMHS; >90th percentile in 5 (9.1%) and >95th percentile in 3 (5.5%). ABPM confirmed 'white coat hypertension' in 3 (5.5%), masked hypertension in 2 (3.6%) and nondipping in 28 (51%). The SDSC score suggested that 43 (78%) children had disturbed sleep. Logistic regression modelling indicated that nondipping correlated with disturbed sleep.

Conclusion

The 'white coat' phenomenon may be responsible for increased prevalence of elevated rest/office BP values in children with ADHD. Prevalent sleep 'non-dipping' in this population is associated with sleep disturbances but clinical significance of this finding requires further investigation.

Attention-deficit/hyperactivity disorder treatment: what are the long-term cardiovascular risks?

INTRODUCTION

This drug safety review provides an update on the long-term cardiovascular risks of therapeutic stimulant class medication for children and adults with attention-deficit/hyperactivity disorder (ADHD).

AREAS COVERED

Relevant literature on the long-term (defined as ≥ 12 months) cardiovascular effects of stimulant class medications for ADHD was sought using PubMed searches for clinical literature, epidemiological reports, as well as reviews of post-marketing data and clinical guidelines/consensus statements. Comparison was made to the non-stimulant atomoxetine.

EXPERT OPINION

Long-term cardiovascular risks of stimulants for healthy children and adults with ADHD are limited to minor mean elevations in blood pressure (≤ 7 mmHg) and heart rate (≤ 10 bpm). In a sizeable minority of individuals these elevations are greater and/or reach a clinical threshold. Subjective complaints may also be anticipated during long-term treatment, yet without an increase in serious cardiac outcomes above background rates per age. Future research is needed on possible latent or cumulative cardiovascular risks in healthy individuals, as well as the longer-term cardiovascular safety in vulnerable populations.

Subtypes of attention deficit-hyperactivity disorder (ADHD) and cannabis use

The current study examined the association between subtypes of attention-deficit/hyperactivity disorder (ADHD) and cannabis use within a sample of 2811 current users. Data were collected in 2012 from a national U.S. survey of cannabis users. A series of logistic regression equations and chi-squares were assessed for proportional differences between users. When asked about the ADHD symptoms they have experienced when not using cannabis, a higher proportion of daily users met symptom criteria for an ADHD diagnoses of the subtypes that include hyperactive-impulsive symptoms than the inattentive subtype. For nondaily users, the proportions of users meeting symptom criteria did not differ by subtype. These results have implications for identifying which individuals with ADHD might be more likely to self-medicate using cannabis. Furthermore, these findings indirectly support research linking relevant cannabinoid receptors to regulatory control.

Targeting the dopamine system in the treatment of attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable condition that affects a significant number of children and adults worldwide. During the past 30 years, the diagnosis and treatment of ADHD has relied on clinical assessment and empirical experience with stimulant medications. More recently, advances in family genetic studies, molecular genetic studies, preclinical research, radiographic imaging techniques and neuropsychological evaluation have significantly enhanced our understanding of the neurobiology of ADHD. This review highlights the current central role of dopamine in the pathophysiology and treatment of ADHD and implications for future advances in diagnosis and treatment.

A cardiopulmonary study of lisdexamfetamine in adults with attention-deficit/hyperactivity disorder

OBJECTIVES

Due to concerns about the safety of stimulants for ADHD, novel assessments of the cardiopulmonary impact of these agents are needed.

METHODS

An open design of lisdexamfetamine (LDX) in 15 adults with DSM-IV ADHD. Following a psychiatric evaluation and medical history, subjects underwent echocardiography (TTE) and cardiopulmonary exercise testing (CPET). LDX was titrated to 70 mg daily over 6 weeks, followed by monthly visits to 6 months. Change in TTE and CPET measures were examined following up to 6 months of LDX.

RESULTS

At endpoint, there were no significant alterations in indices of cardiac systolic performance, or in metabolic and ventilatory variables at maximum exertion (P values >0.05). We found significant mean changes in resting LV systolic dimension and Doppler diastolic indices. Change in heart rate recovery at 1 min met statistical significance (P = 0.05).

CONCLUSIONS

We did not detect clinically meaningful changes in cardiac structure and function or in metabolic and ventilatory variables at maximum exertion in ADHD adults receiving open LDX. The clinical significance of changes in resting LV dimension and indices of diastolic function are not in the direction of cardiomyopathy. Future large sample controlled study can examine these findings, as well as stimulants' impact on heart rate recovery.

A long-term open-label safety and effectiveness trial of lisdexamfetamine dimesylate in adolescents with attention-deficit/hyperactivity disorder

OBJECTIVE

Information on psychostimulant treatment in long-term studies for attention-deficit/hyperactivity disorder (ADHD) in adolescents is limited. This study aimed to assess the safety and effectiveness of lisdexamfetamine dimesylate (LDX) over 52 weeks in adolescents with ADHD.

METHODS

This open-label multicenter study enrolled eligible participants after their participation in a randomized, double-blind, placebo-controlled 4 week trial in adolescents with ADHD. Following a 4 week dose-optimization phase, participants were maintained on treatment for up to ∼48 weeks on an optimal dose. Safety assessments included treatment-emergent adverse events (TEAEs), vital signs, laboratory findings, and electrocardiograms. Effectiveness measures included the ADHD Rating Scale IV (ADHD-RS-IV; primary) and Clinical Global Impressions-Improvement (CGI-I). The Youth Quality of Life-Research Version (YQOL-R) was also included in this study; raw scores are transformed to a 0-100 point scale.

RESULTS

Of 269 enrolled (from the antecedent study), 265 (98.5%) were in the safety population and effectiveness population. Common TEAEs (≥5%) with LDX included upper respiratory tract infection (21.9%), decreased appetite (21.1%), headache (20.8%), decreased weight (16.2%), irritability (12.5%), insomnia (12.1%), nasopharyngitis (7.2%), influenza (6.8%), dizziness (5.3%), and dry mouth (5.3%). At end point, for all LDX doses in the overall safety population, mean (SD) increase from baseline in systolic blood pressure was 2.3 (10.53) mm Hg, diastolic blood pressure was 2.5 (8.37) mm Hg, and pulse rate was 6.3 (12.74) bpm. No clinically meaningful electrocardiogram or vital sign changes were observed. At end point with LDX treatment, the ADHD-RS-IV mean (SD) total score change from antecedent study baseline was -26.2 (9.75) (p<0.001); 87.2% of participants were improved (CGI-I=1 or 2). Baseline (antecedent study) mean (SD) YQOL-R perceptual total score was 79.8 (11.28) and increased by 3.9 (9.73) at end point (p<0.001).

CONCLUSIONS

LDX demonstrated a long-term safety profile similar to that of other long-acting psychostimulants and was effective, as indicated by improvements in ADHD symptoms and participant-perceived YQOL, in adolescents with ADHD.

CLINICAL TRIAL REGISTRATION

NCT00764868, http://www.clinicaltrials.gov/ct2/show/NCT00764868?term=SPD489-306&rank=1.

Investigating the roles of different monoamine transmitters and impulse control using the 5-choice serial reaction time task

Previous studies have shown that drugs which block the reuptake of catecholamine neurotransmitters improve impulse control in diseases such as attention deficit hyperactivity disorder (ADHD). Serotonin-specific reuptake inhibitors (SSRI) lack efficacy in ADHD and have been linked to increased suicide risk. The present study investigated drugs with affinity for one or more of the monoamine reuptake transporters using the 5-choice serial reaction time task, a model of attention and impulsivity in rodents. We also tested the effects of the alpha(2)-adreoceptor antagonist, idazoxan and novel antidepressant, agomelatine, which both increase cortical noradrenaline concentrations through non-reuptake mechanisms. Improvements in impulse control were observed with venlafaxine, a serotonin and noradrenaline re-uptake inhibitor (SNRI) but not bupropion (dopamine and noradrenaline re-uptake inhibitor). Sibutramine (SNRI) reduced premature responses by ~50% at the highest dose tested but this was not significant. All three of the SSRIs tested reduced premature responding in a dose-dependent manner, although also slowed response and collection latencies. Neither idazoxan nor agomelatine significantly reduced premature responding, suggesting a lack of efficacy at the doses tested. None of the drugs tested improved attention in this task but sibutramine (SNRI), fluoxetine (SSRI) and paroxetine (SSRI) all increased omissions at the highest dose tested. These data suggest that the SNRIs and SSRIs reduce premature responding but tend to be less specific than noradrenaline specific reuptake inhibitors in this model. SSRIs did not induce any specific impairment in impulse control in this model.

An update on the pharmacotherapy of attention-deficit/hyperactivity disorder in adults

Adults with attention-deficit/hyperactivity disorder (ADHD) are more frequently presenting for diagnosis and treatment. Medication is considered to be appropriate among available treatments for ADHD; however, the evidence supporting the use of pharmacotherapeutics for adults with ADHD remains less established. In this article, the effectiveness and dosing parameters of the various agents investigated for adult ADHD are reviewed. In adults with ADHD, short-term improvements in symptomatology have been documented through the use of stimulants and antidepressants. Studies suggest that methylphenidate and amphetamine maintained an immediate onset of action, whereas the ADHD response to the nonstimulants appeared to be delayed. At a group level, there appears to be some, albeit not entirely consistent, dose-dependent responses to amphetamine and methylphenidate. Generally speaking, variability in diagnostic criteria, dosing parameters and response rates between the various studies was considerable, and most studies were of a relatively short duration. The aggregate literature shows that the stimulants and catecholaminergic nonstimulants investigated had a clinically significant beneficial effect on treating ADHD in adults.

Safety of stimulant treatment in attention deficit hyperactivity disorder: part II

IMPORTANCE OF THE FIELD

Attention deficit hyperactivity disorder (ADHD) is the most common childhood psychiatric disorder and in at least 50% of cases persists into adulthood. Treatment of ADHD with stimulants is one of the oldest and most effective pharmacological treatments in psychiatry. Yet, there continues to be controversy over the safety of stimulant medications in the treatment of ADHD.

AREAS COVERED IN THIS REVIEW

This paper is a continuation of an earlier paper that reviewed the safety profile of newer stimulant agents, especially in relation to special populations. This part II reviews, through essentially an organ-system approach, the various clinical concerns that have been raised over the safety of stimulant medications. This includes neuropsychiatric, cardiovascular effects on growth and development, and a number of other less common concerns.

WHAT THE READER WILL GAIN

A thorough review of safety concerns in stimulants that emphasizes clinical information, case reports, open series or controlled trials relating to stimulant use in the treatment of ADHD.

TAKE HOME MESSAGE

While many safety concerns have been raised in the use of stimulants, the vast majority of treatment complications are either quickly reversible or easily manageable with appropriate clinical care. The negative consequences of untreated ADHD clearly outweigh the risks of the stimulant medicines when used in an appropriate and careful manner.

Understanding attention-deficit/hyperactivity disorder from childhood to adulthood

Attention deficit/hyperactivity disorder (ADHD) is among the most common neurobehavioral disorders requiring treatment in children and adolescents. The disorder is often chronic, with prominent symptoms and impairment spanning into adulthood. It is often associated with co-occurring disorders, including disruptive, mood, anxiety, and substance abuse disorders. The diagnosis of ADHD is clinically established by review of symptoms and impairment. The biological underpinning of the disorder is supported by genetic, neuroimaging, neurochemistry, and neuropsychological data. All aspects of an individual's life need to be considered in the diagnosis and treatment of ADHD. Multimodal treatment includes educational, family, and individual support. Psychotherapy alone and in combination with medication is helpful for treating patients with ADHD and comorbid disorders. Pharmacotherapy, including stimulants, noradrenergic agents, α-agonists, and antidepressants, plays a fundamental role in the long-term management of ADHD.

An open study of adjunct OROS-methylphenidate in children who are atomoxetine partial responders: II. Tolerability and pharmacokinetics

OBJECTIVE

The aim of this study was to evaluate the tolerability of adding OROS methylphenidate (MPH) to children who are partial responders to atomoxetine (ATMX) in the treatment of attention-deficit/hyperactivity disorder (ADHD).

METHODS

This was a two-phase, 7-week, open study in children aged 6-17 years. Phase 1 initiated ATMX for a minimum of 4 weeks. Phase 2 entered partial responders to ATMX and added OROS MPH to their regimen. Safety was assessed using blood pressure and heart rate measurements, electrocardiogram readings, AEs, laboratories, and ATMX levels.

RESULTS

Fifty subjects who were partial responders to ATMX received the combination therapy, with 41 subjects completing the entire protocol. As reported elsewhere (Wilens et al., 2009 ), OROS MPH added to partial responders of ATMX was accompanied by a 40% reduction in the ADHD rating scale score and improvements in executive functioning. However, the combination of ATMX plus OROS MPH was associated with greater rates of insomnia, irritability, and loss of appetite compared to ATMX alone. A small significant increase in diastolic blood pressure was observed during adjunctive OROS MPH, with no clinically meaningful changes in electrocardiogram (ECG) parameters during the study. ATMX levels and liver function tests did not significantly change during the combination treatment.

CONCLUSION

Adjunct OROS MPH in ATMX partial responders yielded an additive adverse effect burden in this short-term study. Further controlled research with larger samples of children is warranted.

Attention-deficit-hyperactivity disorder: an update

Attention-deficit-hyperactivity disorder (ADHD) is a common neuropsychiatric disorder that impairs social, academic, and occupational functioning in children, adolescents, and adults. In patients with ADHD, neurobiologic research has shown a lack of connectivity in key brain regions, inhibitory control deficits, delayed brain maturation, and noradrenergic and dopaminergic dysfunction in multiple brain regions. The prevalence of this disorder in the United States is 6-9% in youth (i.e., children and adolescents) and 3-5% in adults. Prevalence rates for youth are similar worldwide. Children with ADHD are at greater risk than children without ADHD for substance abuse and delinquency whether or not they receive drug therapy; however, early treatment with psychoeducation as well as drug therapy and/or behavioral intervention may decrease negative outcomes of ADHD, including the rate of conduct disorder and adult antisocial personality disorder. Drug therapy is effective for all age groups, even preschoolers, and for late-onset ADHD in adults. Stimulants, such as methylphenidate and amphetamine, are the most effective therapy and have a good safety profile; although recent concerns of sudden unexplained death, psychiatric adverse effects, and growth effects have prompted the introduction of other therapies. Atomoxetine, a nonstimulant, has no abuse potential, causes less insomnia than stimulants, and poses minimal risk of growth effects. Other drug options include clonidine and guanfacine, but both can cause bradycardia and sedation. Polyunsaturated fatty acids (fish oil), acetyl-L-carnitine, and iron supplements (for youth with low ferritin levels) show promise in improving ADHD symptoms. As long-term studies show that at least 50% of youth are nonadherent with their drug therapy as prescribed over a 1-year period, long-acting formulations (administered once/day) may improve adherence. Comorbid conditions are common in patients with ADHD, but this patient population can be treated effectively with individualized treatment regimens of stimulants, atomoxetine, or bupropion, along with close monitoring.

Efficacy and safety of dexmethylphenidate extended-release capsules administered once daily to children with attention-deficit/hyperactivity disorder

OBJECTIVE

This 5-week, multicenter, double-blind, placebo-controlled, parallel-group investigation is the first fixed-dose study to evaluate efficacy and tolerability of three doses of (10, 20, or 30 mg, once daily [o.d.]) dexmethylphenidate hydrochloride (HCl) extended-release (d-MPH XR; Focalin XR) across multiple settings to treat pediatric attention-deficit/hyperactivity disorder (ADHD).

RESULTS

ADHD pediatric outpatients (n = 253) diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, 4(th) edition, criteria were randomized (1:1:1:1) to receive d-MPH XR (10, 20, or 30 mg o.d.) or placebo. Treatment with d-MPH XR significantly (p < 0.001) reduced the mean score (change from baseline) on Conners'-ADHD/DSM-IV Scales (CADS) as assessed by the teacher CADS-T (dose [mean];10 mg [18], 20 mg [16.9], 30 mg [20.7]) and parents, CADS-P (dose [mean];10 mg [15.8]; 20 mg [17.8]; 30 mg [20.5]) compared to placebo (mean CADS-T [5.7]; CADS-P [4.6]). A significant (p < 0.001) proportion of patients in the three d-MPH XR treatment groups showed improvement on the clinician-rated, Clinical Global Impressions-Improvement (CGI-I) scales (10 mg [73.8%]; 20 mg [71.2%]; 30 mg [77.2 %]) and severity ratings (CGI-S) compared to the placebo group (CGI-I, 22.2%). Adverse events were mild to moderate in severity and similar to previous observations for this class of neurostimulants.

CONCLUSION

All three doses of d-MPH XR (10, 20, or 30 mg o.d), were significantly more effective than placebo in improving ADHD symptoms as confirmed by the teacher, parent and clinician. Additionally, d-MPH XR was well tolerated and demonstrated a consistent safety profile.

Prospective, naturalistic, pilot study of open-label atomoxetine treatment in preschool children with attention-deficit/hyperactivity disorder

OBJECTIVE

The aim of this study was to report preliminary data regarding effectiveness and tolerability of atomoxetine in 3- to 5-year-old preschool children with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Nine boys and 3 girls (mean age = 5.0 +/- 0.72 years) diagnosed with ADHD were treated with atomoxetine in an open-label pilot study. Atomoxetine was gradually titrated to a maximum dose of 1.8 mg/kg per day.

RESULTS

There was a significant effect of time from baseline to end point on the parent-rated hyperactivity/impulsivity Swanson Nolan and Pelham (SNAP-IV-HI) subscale ratings (F[9, 11] = 6.32, p < 0.0001). The mean difference between the baseline and end-point parent SNAP-IV-HI scores was 10.2 +/- 7.3 (p = 0.0005). The rate of positive response (defined as at least a 30% reduction in the end-point parent SNAP-IV-HI scores and a Clinical Global Impressions-Improvement [CGI-I] rating of Much Improved or Very Much Improved) was 75%. The Children's Global Assessment Scale scores improved significantly over time [F(9, 11) = 6.24 p < 0.001]. The mean end-point daily dose of atomoxetine was 1.59 +/- 0.3 mg/kg. A high proportion (66.7%) of the preschoolers experienced side effects with atomoxetine. Side effects of defiance, tantrums, aggression, and irritability were most disconcerting to parents, and gastrointestinal complaints were the most commonly reported adverse effects. One child was terminated from the study due to "chest ache." There were no changes in weight, height, or cardiovascular measures.

CONCLUSION

This open-label pilot study provides preliminary evidence of effectiveness and tolerability of atomoxetine for treating ADHD in preschool children, although double-blind, randomized, placebo-controlled studies are needed to confirm this.

[Alternative agents used in ADHD]

Attention-deficit/hyperactivity disorder (ADHD) is, with a prevalence of 2% to 6%, one of the most common neurobehavioral disorder affecting children and adolescents, persisting into adulthood. Comorbidity and psychosocial circumstances enter into the choice of intervention strategies. Several agents have been demonstrated effective in treating individuals with ADHD. Direct or indirect attenuation of dopamine and norepinephrine neurotransmission appears closely related to both the stimulant and nonstimulant medications efficacious in ADHD. However, important differences concerning efficacy and side effects exist both between and with the specific classes of agents like neuroleptics, antidepressants, antiepileptics, alpha-agonists, beta-blockers, buspiron, l-dopa, melatonin, pycnogenol, zinc, magnesium, polyunsaturated fatty acids, and homeopathy. Elucidating the various mechanisms of action of ADHD medications may lead to better choices in matching potential responses to the characteristics of individuals. We review the purported mechanism of action and available evidence for selected complementary and alternative medicine therapies for ADHD in childhood and adolescence.

Atomoxetine reverses attentional deficits produced by noradrenergic deafferentation of medial prefrontal cortex

BACKGROUND

The majority of studies assessing executive function in attention deficit disorder (ADD) have shown deficits in attentional set shifting using either the Wisconsin card sorting task or the intra-dimensional/extra-dimensional set-shifting task (ID/ED). Damage to the prefrontal cortex in humans, primates, and rodents impairs extra-dimensional (ED) shifts. Noradrenergic depletion of the medial prefrontal cortex in rats is sufficient to impair attentional set shifting. Atomoxetine, a selective norepinephrine (NE) re-uptake inhibitor, is hypothesized to produce beneficial effects in patient with ADD by augmenting NE release in prefrontal cortex.

MATERIALS AND METHODS

We assessed the effects of systemic administration of atomoxetine (0.0, 0.1, 0.3, and 0.9 mg/kg/ml) in normal and noradrenergically lesioned (NE-LX) rats on attentional-set shifts. We replicated findings showing NE-LX rats are selectively impaired on the ED shifts but not reversals or other discriminations.

RESULTS

Atomoxetine remediated the attentional set-shifting impairments in NE-LX rats but impaired ED performance of non-lesioned rats.

DISCUSSION

Though atomoxetine is neurochemically selective, it is not wholly specific at doses >0.3 mg/kg. All doses of the drug were similar in their efficacy in reversing the ED deficit, but the effectiveness of the 0.1 mg/kg dose supports the hypothesis that increases in prefrontal NE alone are sufficient to improve attention in NE-LX rats. Moreover, the detrimental effects of the drug in non-lesioned rats support the hypothesis that optimal levels of NE in prefrontal cortex are critical to attentional set shifting with both supra- and sub-optimal levels producing attentional impairments.

No evidence for genetic association between DARPP-32 (PP1R1B) polymorphisms and attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) has a strong genetic basis, and evidence from human and animal studies suggests that a dopamine system dysfunction plays a role in the disorder pathophysiology. Several genes involved in dopamine neurotransmission have shown replicated genetic association with ADHD. These include the dopamine receptors D4 (DRD4), D5 (DRD5), and the dopamine transporter (DAT1) genes. Recently, evidence has also accumulated in favor of the dopamine receptor D1 gene (DRD1). The dopamine- and cAMP-regulated phosphoprotein of relative molecular mass of 32 kDa (DARPP-32) is a key component of dopamine signaling, acting as a converging point for several neurotransmitter systems influencing dopaminergic neurons and regulating a wide variety of downstream effectors. Here, we tested the DARPP-32 gene, PPP1R1B, for association with ADHD using four polymorphic markers selected across the gene in a sample of 255 ADHD families. We did not detect evidence of association of individual marker alleles and haplotype analysis did not reveal significant association in this sample of families. Moreover, we found no relationship between the same alleles or haplotypes and symptom scores of inattention or hyperactivity/impulsivity in these families using a quantitative approach. In conclusion, albeit a key regulatory role in dopamine signaling, our data do not support a major contribution of the DARPP-32 gene in ADHD.

Treatment of adults with attention-deficit/hyperactivity disorder

This review focuses on the treatment of attention deficit hyperactivity disorder (ADHD) in adults. It briefly addresses prevalence, diagnostic and differential diagnostic issues specific to adults. Stimulant medication, non-stimulant medication, and psychosocial treatments are thoroughly reviewed. For each class of medication possible mechanism of action, efficacy and side effects are summarized. Special attention is given to the pharmacological treatment for patients with adult ADHD and various comorbidities. In summary, stimulant medications are most effective and combined medication and psychosocial treatment is the most beneficial treatment option for most adult patients with ADHD.

Treatment of adults with attention-deficit/hyperactivity disorder

This review focuses on the treatment of attention deficit hyperactivity disorder (ADHD) in adults. It briefly addresses prevalence, diagnostic and differential diagnostic issues specific to adults. Stimulant medication, non-stimulant medication, and psychosocial treatments are thoroughly reviewed. For each class of medication possible mechanism of action, efficacy and side effects are summarized. Special attention is given to the pharmacological treatment for patients with adult ADHD and various comorbidities. In summary, stimulant medications are most effective and combined medication and psychosocial treatment is the most beneficial treatment option for most adult patients with ADHD.

Current issues and trends in the diagnosis and treatment of adults with ADHD

Attention-deficit/hyperactivity disorder (ADHD) has been commonly thought of as a childhood disorder that diminished over time. It is one of the most common developmental disorders and it is estimated that ADHD affects 5-10% of children. Two-thirds of children with ADHD will continue to have symptoms of ADHD that persist throughout adolescence. Longitudinal studies have demonstrated that symptoms of ADHD can also remain in adulthood, affecting 4.4% of the adult population. However, diagnosing adults with ADHD can prove difficult because they often find that their symptoms are egosyntonic. In addition, the development of comorbid conditions, such as anxiety, depression, personality disorders or substance abuse, can often overshadow underlying ADHD symptoms. Nonetheless, treatments such as stimulant and nonstimulant medication (e.g., atomoxetine), and cognitive-behavior therapy have been effective in treating adults with ADHD. This article reviews the prevalence of adults with ADHD, followed by a discussion of the neurobiological and genetic underpinnings of the disorder. Issues regarding the diagnosis and treatment of ADHD are also addressed.

Emerging drugs for attention-deficit/hyperactivity disorder

Symptoms of attention-deficit/hyperactivity disorder (ADHD) are heterogeneous and often accompanied by comorbid psychiatric disorders. Although symptoms tend to lessen with age, many patients continue to be affected by the disorder into adulthood. Although many medications are available to treat ADHD, it is unlikely that a single medication will ever be developed to work for all patients. Recent advances, such as long-acting, extended-release formulations and transdermal delivery systems, have lengthened the duration of effectiveness, which has increased compliance and eliminated the need for additional medication dosing during the school or work day. Additional safe, well-tolerated, long-acting medications with further reduced potential for diversion and abuse are needed. Catecholamine pathways and their effect on executive functions and ADHD symptom control have been productive areas of research. Potential therapies such as adrenergic receptor agonists, glutamatergic agents, GABA receptor antagonists and nicotine receptor agonists are being explored as future pharmacotherapies for ADHD.

Stimulant therapy in the management of ADHD: mixed amphetamine salts (extended release)

The efficacy of amphetamines in the management of attention-deficit/hyperactivity disorder (ADHD) is well established. However, their value in improving the symptoms of ADHD has been compromised by concerns about compliance, abuse potential and adverse events. An extended-release formulation of mixed amphetamine salts (MAS XR) provided the first long-acting amphetamine formulation, and thus, filled an important gap in available treatments for ADHD. MAS XR has been shown to improve ADHD symptoms in children, adolescents and adults in both short- and long-term studies. The drug is generally well tolerated in clinical trials. Although its safety profile in patients with concomitant cardiovascular conditions in a real-world setting has yet to be fully evaluated, a tolerability study of mixed amphetamine salts in adults with ADHD who were being treated for primary essential hypertension showed that these patients can be safely treated with MAS XR.

Attention Deficit/Hyperactivity Disorder in Adults

Attention deficit/hyperactivity disorder (ADHD), characterized by inattention, hyperactivity/impulsivity, or a combination of these, is being increasingly recognized in adults. Adult ADHD prevalence rates range from 1% to 4%. The pathophysiology of adult ADHD is likely multifactorial, including genetic, environmental, and neurobiological influences. Though ADHD diagnostic criteria per the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) were developed based on child samples, the symptoms are believed to be similar in adults, with some developmental differences in symptom presentation. This article identifies common presenting complaints of adults who have ADHD and provides information useful for differential diagnosis of these patients. Specific strategies for pharmacological and nonpharmacological intervention are also presented.