Pharmacological interventions for adolescents and adults with ADHD: stimulant and nonstimulant medications and misuse of prescription stimulants

Trends in Use of Telemedicine for Stimulant Initiation Among Children and Adults

OBJECTIVE

The authors sought to examine trends in stimulant initiation and follow-up care for attention-deficit hyperactivity disorder (ADHD) via telemedicine.

METHODS

This retrospective longitudinal study used national, deidentified commercial health insurance outpatient claims among children (ages 2-17 years; N=535,629) and adults (ages 18-64 years; N=2,116,160) from January 2019 through April 2022. Regression analyses were used to examine risk for stimulant initiation, whether initiation occurred via telemedicine or in-person care, and receipt of a follow-up visit.

RESULTS

The mean monthly adjusted number of stimulant initiations per 100,000 enrollees was similar for children before and during the COVID-19 pandemic (prepandemic, 57 initiations; during pandemic, 56 initiations) but increased for adults (prepandemic, 27 initiations; during pandemic, 33 initiations). Initiations via telemedicine peaked at 53%-57% in April 2020 and dropped to about 14% among children and 28% among adults in April 2022. Telemedicine initiations were significantly more common among psychiatrists than among other prescribers (OR=3.70, 95% CI=3.38-4.06 [children]; OR=3.02, 95% CI=2.87-3.17 [adults]) and less common for rural residents (OR=0.57, 95% CI=0.40-0.82 [children]; OR=0.75, 95% CI=0.61-0.92 [adults]). Follow-up care was significantly more common among individuals whose care was initiated via telemedicine than among those receiving in-person care (OR=1.09, 95% CI=1.00-1.19 [children]; OR=1.61, 95% CI=1.53-1.69 [adults]).

CONCLUSIONS

Many stimulant treatments were initiated via telemedicine. Proposed rules to prohibit controlled substance prescribing without an in-person evaluation would require significant changes in current practice, potentially limiting access to stimulant medications for ADHD.

Adverse Childhood Experiences and Prescription Stimulant Use in Adults: A Systematic Review

Nonmedical prescription stimulant use (NPSU) is an ongoing public health crisis in the United States. There exists, however, a dearth of research investigating specific childhood risk factors that may contribute to this illicit use. Adverse childhood experiences (ACEs) may be a significant risk factor to address in the prevention and treatment of NPSU, as research has provided evidence for increased substance use, potentially including prescription stimulant misuse, among individuals who have experienced trauma. A systematic review of the literature was conducted to gather and synthesize research articles specifically examining the relationship between nonmedical prescription stimulant use in adults and the experience of adverse childhood experiences (ACEs). Four studies met all inclusion criteria and were included in the review. The results demonstrated that the nonmedical use of prescription stimulants in adults is significantly associated with ACEs, with a higher numerical count of ACEs associated with a greater likelihood of nonmedical prescription stimulant use. Gaps in the literature were identified, specifically noting a lack of information available regarding the relationship between ACEs and NPSU within gender- and racially diverse populations. The findings have implications for informing interventions related to ACEs and the misuse of prescription stimulant medication in adults.

Prescription Stimulant Misuse Among Nursing Students: A Systematic Review

ABSTRACT

Nonmedical prescription stimulants are used to reduce symptoms of inattention, impulsivity, and hyperactivity in children and adults with attention-deficit hyperactivity/disorder. They are Schedule II controlled substances because of their high potential for dependence, and individuals who misuse them without a valid prescription are subject to criminal charges. Stimulant medications are also associated with common side effects (e.g., insomnia) as well as more serious but less common side effects (e.g., arrhythmias). Despite the potential health and legal consequences, misuse of prescription stimulants has become a public health crisis on college campuses in the United States. Neurocognitive enhancement is the primary reason that college students report misusing prescription stimulants, despite no enhancement of cognitive functioning when taken by healthy adults. Nursing students may be at risk for misuse because of their high levels of academic and clinical demands and because many start misusing in nursing school. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, the databases PubMed, Science Direct, EBSCOhost, and Academic OneFile were systematically searched to investigate the (a) percentage of prescription stimulant misuse studies that have included nursing students, (b) prevalence of prescription stimulant misuse among nursing students, (c) motivations for prescription stimulant misuse among nursing students, and (d) demographic factors associated with increased use among nursing students. Results revealed that of the 197 studies conducted within the past decade (2010-2021), only 1.02% (two) included nursing students. Future studies must investigate the prevalence and nature of prescription stimulant misuse among nursing students.

Analysis of Daily Sleep Diary Measures From Multilayer Extended-Release Methylphenidate (PRC-063) Studies in Children and Adults With ADHD

OBJECTIVE

To compare the effect of a once-daily extended-release methylphenidate formulation (PRC-063) versus placebo on sleep, measured via daily electronic diary in two clinical trials in pediatric (6-12 years) and adult (≥18 years) patients with attention deficit hyperactivity disorder (ADHD).

METHOD

A diary was completed by adult patients or parents/caregivers of pediatric patients during two randomized, double-blind, placebo-controlled laboratory classroom studies. Following dose optimization of PRC-063, patients were randomized to 1 week of double-blind treatment with PRC-063 or placebo before attending a full-day laboratory classroom session.

RESULTS

In the studies, 148 pediatric patients and 239 adult patients were randomized to either PRC-063 or placebo. When compared with the diaries of placebo patients, the sleep diaries in both pediatric and adult patients showed no statistical difference in total sleep time, efficiency, or latency.

CONCLUSION

PRC-063 did not impact subjective measures of sleep versus placebo in pediatric and adult patients with ADHD.

ADHD and Substance Use Disorders in Young People: Considerations for Evaluation, Diagnosis, and Pharmacotherapy

Co-occurring ADHD and substance use disorder (SUD) is a common clinical presentation associated with significant impairment requiring careful evaluation, diagnosis, and treatment. Treatment with medication, along with cognitive behavioral therapy, is generally regarded as effective in addressing symptoms and impairments associated with both disorders. Options for pharmacotherapy include stimulant and nonstimulant therapies administered with careful monitoring of dosage and compliance to optimize efficacy. In high-risk groups such as college students and/or those with SUD, prescribers should address risks of stimulant misuse and diversion through patient and family education, medication monitoring, and other risk-reducing practices.

Outcomes and Predictors of Stimulant Misuse in College Students with and Without ADHD

In recent years, rates of prescription stimulant misuse have increased among young adults ages 18 to 25 along with increases in dispensing rates of these medications. Preliminary studies suggest that college students with Attention-Deficit Hyperactivity Disorder (ADHD) may be more likely to misuse their stimulant medication than their non-ADHD peers. Research is needed to further explore possible rates, correlates, and outcomes of prescription stimulant misuse among college students with and without ADHD. Data regarding study strategies, psychological functioning, stimulant misuse, and GPA were collected from students from universities within the US (N = 144), showing significantly higher rates of misuse among college students with ADHD. With depression and anxiety entered into the predictive model, inattentive symptoms were the only significant predictor of misuse in the full sample. The present findings have implications for academic interventions aimed at supporting the success of college students with and without ADHD and inform academic outcomes of prescription stimulant misuse.

The Role of Iron and Zinc in the Treatment of ADHD among Children and Adolescents: A Systematic Review of Randomized Clinical Trials

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder common from childhood to adulthood, affecting 5% to 12% among the general population in developed countries. Potential etiological factors have been identified, including genetic causes, environmental elements and epigenetic components. Nutrition is currently considered an influencing factor, and several studies have explored the contribution of restriction and dietary supplements in ADHD treatments. Iron is an essential cofactor required for a number of functions, such as transport of oxygen, immune function, cellular respiration, neurotransmitter metabolism (dopamine production), and DNA synthesis. Zinc is also an essential trace element, required for cellular functions related to the metabolism of neurotransmitters, melatonin, and prostaglandins. Epidemiological studies have found that iron and zinc deficiencies are common nutritional deficits worldwide, with important roles on neurologic functions (poor memory, inattentiveness, and impulsiveness), finicky appetite, and mood changes (sadness and irritability). Altered levels of iron and zinc have been related with the aggravation and progression of ADHD. Objective: This is a systematic review focused on the contribution of iron and zinc in the progression of ADHD among children and adolescents, and how therapies including these elements are tolerated along with its effectiveness (according to PRISMA guidelines). Method: The scientific literature was screened for randomized controlled trials published between January 2000 to July 2021. The databases consulted were Medline, PsycINFO, Web of Science, and Google Scholar. Two independent reviewers screened studies, extracted data, and assessed quality and risk of bias (CONSORT, NICE, and Cochrane checklists used). Conclusion: Nine studies met the eligibility criteria and were selected. Evidence was obtained regarding the contribution of iron-zinc supplementation in the treatment of ADHD among young individuals. The discussion was focused on how the deficits of these elements contribute to affectation on multiple ADHD correlates, and potential mechanisms explaining the mediational pathways. Evidence also suggested that treating ADHD with diet interventions might be particularly useful for specific subgroups of children and adolescents, but further investigations of the effects of these diet interventions are needed.

A Phase 3, Placebo-Controlled Trial of Once-Daily Viloxazine Extended-Release Capsules in Adolescents With Attention-Deficit/Hyperactivity Disorder

PURPOSE

This phase 3 clinical trial evaluated the efficacy and safety of viloxazine extended-release capsules (VLX-ER) as a monotherapy for attention-deficit/hyperactivity disorder (ADHD) in adolescents (12-17 years).

METHODS

Eligible subjects (n = 310) were randomized to receive once-daily 200 and 400 mg VLX-ER, or placebo for 6 weeks. The primary efficacy end point was change from baseline (CFB) at the end of study (EOS) in ADHD Rating Scale-5 Total score. Key secondary end points were Clinical Global Impression-Improvement score at EOS, CFB at EOS in Conners 3-Parent Short Form Composite T-score, and CFB at EOS in Weiss Functional Impairment Rating Scale-Parent Total average score.

RESULTS

In the 200-mg/d and 400-mg/d VLX-ER treatment groups, a significant improvement was found in the CFB at EOS in ADHD Rating Scale-5 Total (P = 0.0232, P = 0.0091) and Inattention (P = 0.0424, P = 0.0390) and Hyperactivity/Impulsivity (P = 0.0069, P = 0.0005) subscale scores versus placebo. The Clinical Global Impression-Improvement score was significantly improved at EOS in the 200-mg/d and 400-mg/d VLX-ER groups versus placebo (P = 0.0042, P = 0.0003). The Conners 3-Parent Short Form composite T-score and Weiss Functional Impairment Rating Scale-Parent Total average score exhibited improvement in both VLX-ER groups; however, the difference versus placebo was not statistically significant. The most common treatment-related adverse events were somnolence, headache, decreased appetite, nausea, and fatigue. The adverse event-related discontinuation rates were <5% in all groups.

CONCLUSIONS

Viloxazine extended-release demonstrated statistically significant and clinically meaningful improvement in ADHD symptoms in adolescents and was generally well tolerated.

Prevalence and determinants of attention deficit/hyperactivity disorder (ADHD) medication use during pregnancy: Results from the Quebec Pregnancy/Children Cohort

AIMS

The use of attention deficit/hyperactivity disorder (ADHD) medications has grown over the past decade among pregnant women, but these treatments are not without risk. Updated prevalence of ADHD medication use and whether prescribed dosages follow guidelines are needed. The aim of this study is to describe the prevalence of ADHD medication use among pregnant women-dosages and switches-and identify determinants of ADHD medication use.

METHOD

A population-based longitudinal cohort study within the Quebec Pregnancy/Children Cohort (QPC). Women aged 15-45 years old covered by the RAMQ prescription drug plan for at least 12 months before and during pregnancy from 1998 to 2015. ADHD medication exposure was assessed before and during pregnancy. We estimated odds ratios (ORs) for determinants of ADHD medication use during pregnancy with generalized estimating equations.

RESULTS

Among 428,505 included pregnant women, 1,130 (0.26%) used ADHD medication. A 14-fold increase in the prevalence of ADHD medication use in pregnant women was observed, from 1998 (0.08%) to 2015 (1.2%). Methylphenidate was the most prevalent medication at 70.1%. ADHD medication fillings were at optimal dosage 91.8% of the time based on guidelines and 18.1% of women switched to another ADHD medication class during gestation. Main determinants of ADHD medication use during pregnancy were psychiatric disorders (aOR 2.19; 95% confidence interval [CI] 1.57, 2.96), mood and anxiety disorders (aOR 1.74; 95% CI 1.32, 2.24), and calendar year.

CONCLUSIONS

The number of pregnancies exposed to ADHD medications has increased similarly to the increase reported in other countries between 1998 and 2015. In addition to the current literature, the use of ADHD medications during pregnancy is consistent with Canadian guidelines recommendations on dosage.

Personality to Prescription Drug Misuse in Adolescents: Testing Affect Regulation, Psychological Dysregulation, and Deviance Proneness Pathways

Background: Fifteen to 25-year-olds are the age group most likely to misuse prescription drugs. Few studies have tested theory-driven models of adolescent risk for prescription drug misuse. Moreover, rarely are distinct pathways to different forms of prescription drug misuse considered. Methods: We tested mediational paths from personality to mental health symptoms to prescription drug misuse, informed by etiological models of addiction. We specified pathways from particular personality traits to unique forms of prescription drug misuse via specific mental health symptoms. We used semi-longitudinal data collected across two waves of the Co-Venture Trial. Our sample included students from 31 Canadian high schools tested in Grade 9 (n = 3,024) and again in Grade 10 (n = 2,869; 95% retention). Personality (hopelessness, anxiety sensitivity, impulsivity, sensation seeking) was assessed in Grade 9. Mental health symptoms (depression, anxiety, ADHD, conduct disorder) and prescription drug misuse (opioids, sedatives/tranquilizers, stimulants) were assessed at both time points. Results: Consistent with the negative affect regulation model, hopelessness was specifically associated with opioid misuse via depressive symptoms, and anxiety sensitivity was specifically associated with sedative/tranquilizer misuse via anxiety symptoms. Consistent with positive affect regulation, sensation seeking was directly associated with stimulant misuse. Consistent with the psychological dysregulation model, impulsivity was associated with stimulant misuse via ADHD symptoms. And consistent with the deviance proneness model, impulsivity was also associated with unconstrained (i.e., all three forms of) prescription drug misuse via conduct disorder symptoms. Conclusions: Screening for adolescents high in hopelessness, anxiety sensitivity, sensation seeking, or impulsivity and providing them with personality-matched cognitive-behavioral interventions may be helpful in preventing or mitigating prescription drug misuse. Our results point to the specific mental health symptoms that are important to target in each of these personality-matched interventions.

Accommodation decision-making for postsecondary students with ADHD: Implications for neuropsychologists

Neuropsychologists are often asked to evaluate students for attention-deficit/hyperactivity disorder (ADHD) and to provide documentation to support their requests for academic accommodations in college. Research points to the importance of multi-method, multi-informant data when evaluating ADHD and determining the need for accommodations. However, the Association on Higher Education and Disability (AHEAD) directs disability service providers to give primacy to students' self-reports and their own impressions of students' narratives over objective, third-party data when rendering accommodation decisions. The organization asserts that in many cases information from parents, teachers, and psychologists is not needed to confirm the existence of a disability or students' need for accommodations. In this article, we describe the way disability service providers are directed to evaluate accommodation requests, the limitations of these procedures, and the dangers of well-intentioned, but indiscriminate accommodation-granting. We then provide recommendations for neuropsychologists who conduct ADHD evaluations for college students in light of these professional guidelines.

A Phase 3 Placebo-Controlled Trial of Once-Daily 400-mg and 600-mg SPN-812 (Viloxazine Extended-Release) in Adolescents with ADHD

OBJECTIVES

Three Phase 3 trials have demonstrated the efficacy and safety of SPN-812 in pediatric subjects with ADHD. Here, we report the results of a fourth trial.

METHODS

Eligible adolescent subjects (N = 297) were randomized to SPN-812 (400- or 600-mg/day) or placebo. The primary efficacy endpoint was change from baseline (CFB) at end of study (EOS) in the ADHD Rating Scale-5 (ADHD-RS-5) Total score. Statistical analyses included sequential testing for multiple treatment comparisons. Key secondary endpoints included: Clinical Global Impression-Improvement (CGI-I) score at EOS and CFB at EOS in the Conners 3-Parent Short Form (Conners 3-PS) Composite T-score and Weiss Functional Impairment Rating Scale-Parent (WFIRS-P) Total average score.

RESULTS

The CFB at EOS ADHD-RS-5 Total score (least square [LS] means ± SE) for 400-mg/day, 600-mg/day SPN-812, and placebo was -18.3 ± 1.36, -16.7 ± 1.39, and -13.2 ± 1.38, respectively. The difference vs. placebo was statistically significant only for the 400-mg/day SPN-812 treatment group (600 mg/day: p = 0.0712; 400 mg/day: p = 0.0082). Neither dose could be considered superior to placebo due to the use of statistical method of sequential testing. Significant improvements were observed on a number of secondary endpoints. SPN-812 was well tolerated at both doses, with <5% discontinuation rate due to adverse events.

CONCLUSIONS

Treatment with 400- but not 600-mg/day SPN-812 resulted in statistically significant improvement in the primary endpoint. The negative result seen in the 600-mg/day SPN-812 group was likely due to an unusually high placebo response. Safety data were consistent across all doses in the SPN-812 trials.

Maternal ADHD medication use during pregnancy and the risk of ADHD in children: Importance of genetic predispositions and impact of using a sibling analysis

Attention deficit with hyperactivity disorder (ADHD) medications in pregnancy would be associated with ADHD in children, however, estimates can be confounded by genetic predispositions and environmental factors related to the mother-child pair. We aim to quantify the risk of ADHD in children associated with ADHD medication exposures during pregnancy. A prospective cohort study and sibling analysis conducted within The Quebec Pregnancy/Child Cohort (QPC). All full-term singleton live births covered by the provincial prescription drug insurance in Quebec from 1998 to 2015 were included. ADHD medication exposure during pregnancy was defined according to trimester of use and class-specific medication. ADHD in children was defined as having at least one diagnosis or one prescription filled for an ADHD medication. Cox proportional hazards regression models were used to calculate crude and adjusted hazard ratios (aHR) with 95% confidence intervals (CIs) in the overall cohort, the sub-cohort and the sibling analysis. Of 166,047 full-term singleton live births included, 25,454 (15.3%) had ADHD. In the overall cohort, maternal exposure to ADHD medication during pregnancy was associated with ADHD in children (aHR= 1.96, 95% CI 1.22-3.15). In the ADHD pregnant women sub-cohort (aHR= 1.56; 95% CI 0.93-2.62) and the sibling control analysis (aHR= 1.14; 95% CI 0.62-1.98), ADHD medications during pregnancy was not associated with an increased risk of ADHD in children. Our findings suggest that in utero exposure to ADHD medications was not associated with an increased risk of ADHD in children. This suggests that the association is due to genetic and/or family environmental factors.

Prescription Stimulant Misuse and ADHD Symptomatology Among College Students in Iceland

Objective: Misuse of prescription stimulant medication is a prevalent problem on American college campuses; however, few studies have been conducted beyond the United States. Although Iceland has the highest methylphenidate prescription rates in the world, prevalence of stimulant misuse within the Icelandic college student population remains to be investigated. Method: We examined the prevalence of prescription stimulant misuse among N = 521 college students in Iceland, using an online survey. Results: Overall prevalence of lifetime stimulant misuse was approximately 13%; 11% among participants without a prescription for stimulant medication, and 42% among participants holding a prescription. The primary reported reason for misuse was academic enhancement; risk factors included male sex, anxiety symptoms, and ADHD symptomatology. Conclusion: The present findings have implications for public health policy in Iceland, particularly as it relates to the college population. Prevention and intervention programs that provide college students with safer strategies to manage academic demands are warranted.

Executive Functioning Outcomes Over 6 Months of Atomoxetine for Adults With ADHD: Relationship to Maintenance of Response and Relapse Over the Subsequent 6 Months After Treatment

Objective: This study examines the relationship between maintenance of improved executive functioning (EF) in adults with ADHD with long-term symptom improvement with atomoxetine. Method: Data were collected from a yearlong, double-blind, placebo-controlled clinical study on adult patients with ADHD receiving atomoxetine (80-100 mg/day) for 24 weeks. Patients were then randomized to continue atomoxetine or placebo for 6 months. Executive functioning was rated with Behavior Rating Inventory of Executive Function-Adult Version: Self-Report™ (BRIEF-A: Self-Report™), and the T-scores were determined. Results: Postrandomization T-scores for atomoxetine patients were significantly better than those of placebo patients (3 and 6 months postrandomization). Patients with greater improvements in EF were more likely to show worsening of EF and to relapse after atomoxetine discontinuation. The maintenance of improved EF was significantly associated with improved ADHD symptoms (Conners' Adult ADHD Rating Scale-Investigator Rated: Screening Version [CAARS-Inv:SV] with adult prompts). Conclusion: Treatment with atomoxetine improved EF during the treatment phases. Improved EF was maintained up to 6 months after discontinuation of atomoxetine.

Methylphenidate Treatment Initiated During Childhood Is Continued in Adulthood in Half of the Study Population

Objectives: To estimate the number of patients who started methylphenidate during childhood and continued treatment beyond the age of 18 years and to study the determinants that may be associated with continuing treatment. Methods: Patients 17 years of age and younger who have received at least one prescription of methylphenidate were identified in the Integrated Primary Care Information database (1996-2017). Logistic regression analyses were performed to assess the association between potential determinants and continuation with methylphenidate treatment at the age of 18 years. Results: Fifty-three percent of all methylphenidate users (n = 1020) continued their treatment after the age of 18 years. Patients were more likely to continue treatment with methylphenidate if they started treatment at the age of 15-17 years compared with patients of 11 years and younger (adjusted odds ratio [OR]: 5.74, 95% confidence interval [CI]: 1.48-22.31), if they had a medication possession ratio (MPR) between 0.80 and 1.00 compared with a low MPR (adjusted OR: 2.18, 95% CI: 1.23-3.85) and if they lived in an area with a medium level of urbanization (adjusted OR: 1.98, 95% CI: 1.06-3.69). Furthermore, a relatively high number of patients had a MPR >1.0 (24.8%), of whom 91.3% started their treatment when they were between 15 and 17 years of age. Conclusions: Methylphenidate treatment initiated during childhood was continued in half of the study population when reaching the age of 18, where adolescents were more likely to continue treatment than young children. We also found that ∼25% of our study population had a MPR >1, mainly patients 15-17 years of age, which may suggest misuse or abuse of methylphenidate.

Interplay Between Amphetamine and Activity Level in Gene Networks of the Mouse Striatum

The psychostimulant amphetamine can be prescribed to ameliorate the symptoms of narcolepsy, attention-deficit hyperactivity disorder and to facilitate weight loss. This stimulant can also have negative effects including toxicity and addiction risk. The impact of amphetamine on gene networks is partially understood and this study addresses this gap in consideration of the physical activity. The striata of mice exposed to either amphetamine or saline treatment were compared in a mouse line selected for home cage physical overactivity, a phenotype that can be mitigated with amphetamine, and in a contemporary control line using RNA-seq. Genes presenting opposite expression patterns between treatments across lines included a pseudogene of coiled-coil-helix-coiled-coil-helix domain containing 2 gene (Chchd2), ribonuclease P RNA component H1 (Rpph1), short stature homeobox 2 (Shox2), transient receptor potential melastatin 6 (Trpm6), and tumor necrosis factor receptor superfamily, member 9 (Tnfrsf9). Genes presenting consistent treatment patterns across lines, albeit at different levels of significance included cholecystokinin (Cck), vasoactive intestinal polypeptide (Vip), arginine vasopressin (Avp), oxytocin/neurophysin (Oxt), thyrotropin releasing hormone (Trh), neurotensin (Nts), angiotensinogen (Agt), galanin (Gal), prolactin receptor (Prlr), and calcitonin receptor (Calcr). Potassium inwardly rectifying channel, subfamily J, member 6 (Kcnj6), and retinoic acid-related (RAR)-related orphan receptor alpha (Rora) were similarly differentially expressed between treatments across lines. Functional categories enriched among the genes presenting line-dependent amphetamine effect included genes coding for neuropeptides and associated with memory and neuroplasticity and synaptic signaling, energy, and redox processes. A line-dependent association between amphetamine exposure and the synaptic signaling genes neurogranin (Nrgn) and synaptic membrane exocytosis 1(Rims1) was highlighted in the gene networks. Our findings advance the understanding of molecular players and networks affected by amphetamine in support of the development of activity-targeted therapies that may capitalize on the benefits of this psychostimulant.

Lower risk of fractures under methylphenidate treatment for ADHD: A dose-response effect

Methylphenidate (MP), a widely used and abused stimulant medication for ADHD, negatively affects bone mass. However, previous epidemiological studies demonstrated that MP is not associated with increased incidence of fractures in children, and may even have a protective effect due to behavior modification. This study aimed to investigate the association between MP and fracture risk in a retrospective cohort of healthy military recruits, aged 18-25, with at least 1 year of service between 2008 and 2017. Subjects were divided into five groups: subjects without ADHD; untreated subjects with ADHD; and subjects with ADHD and prescriptions of 1-90, 91-180, or 181+ tablets during the study period. The primary outcome was at least one fracture diagnosis during the study. Among 682,110 subjects (409,175 men [60%]), 50,999 (7.5%) had fractures. MP was used by 1,681 (0.4%) men and 2.828 (1%) women. The fracture rates in the no ADHD, untreated ADHD, ADHD 0-90, ADHD 91-180, and ADHD 181+ groups were 10.4%, 16.4%, 8.7%, 4.8% and 5.8% in men, and 3.6%, 7.1%, 4.6%, 4.4% and 3% in women, respectively. Multivariate regression analysis confirmed an inverse dose-response association between MP and fractures in men (p < 0.001). In women, untreated ADHD was associated with a significantly higher fracture risk, compared to healthy controls (OR = 1.82, p < 0.001). The study confirms previous literature and demonstrates an inverse dose-response association between MP and fracture risk in men. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3328-3333, 2018.

Lisdexamfetamine Dimesylate: A Review in Paediatric ADHD

Lisdexamfetamine dimesylate (lisdexamfetamine; Elvanse^®; Tyvense^®), an orally-active dexamfetamine prodrug, is indicated in the EU for the treatment of attention-deficit hyperactivity disorder (ADHD) in children aged ≥ 6 years (including adolescents) when the response to previous methylphenidate (MPH) treatment is clinically inadequate. The original approval of the drug was based on the results of phase III trials in children and adolescents with ADHD who had an inadequate response to previous pharmacotherapy (e.g. MPH) or were treatment naïve. In these studies, short-term treatment with flexibly-dosed lisdexamfetamine demonstrated greater efficacy than atomoxetine, based on a prospective comparison, and osmotic-release oral system (OROS)-MPH, based on a post hoc comparison. Improvements in ADHD symptoms were accompanied by improvements in health-related quality of life and functioning that were maintained as long as treatment with lisdexamfetamine was continued in a long-term extension of one of these trials. In subsequent phase IV head-to-head studies in adolescents with ADHD and an inadequate response to previous pharmacotherapy, lisdexamfetamine demonstrated greater efficacy than OROS-MPH when both medications were force-titrated, but not when they were flexibly-titrated. Lisdexamfetamine was generally well tolerated, with an adverse event profile (e.g. decreased appetite, headache, weight reduction, insomnia and irritability) typical of that reported for other stimulants. Thus, lisdexamfetamine provides an alternative option for the treatment of children and/or adolescents with ADHD who have not responded adequately to previous ADHD pharmacotherapies.

The Relation Between ADHD Medication and Mild Cognitive Impairment, as Assessed by the Montreal Cognitive Assessment (MoCA), in Patients Entering Substance Use Disorder Inpatient Treatment

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) frequently co-occurs with substance use disorders and has some overlapping symptoms with mild cognitive impairment, including executive functions. We wanted to investigate whether patients with ADHD have an excess risk of mild cognitive impairment-like symptoms, as defined by the Montreal Cognitive Assessment (MoCA). Second, we assessed the impact of ADHD medication on the dichotomized MoCA for patients with ADHD.

METHODS

The participants in this study were 129 inpatients at seven treatment clinics in Norway. All were screened with the MoCA. We calculated relative risk estimates (RR) for scoring in the mild cognitive impairment range (< 26) for those having ADHD. Finally, we calculated the RR for the patients within the ADHD group who were taking medication.

RESULTS

Of the 129 participants included in the analyses, 38 (29.5%) scored below the MoCA threshold (< 26), and 24 (18.6%) had ADHD that was diagnosed before or during the inpatient treatment. Of the 105 participants without ADHD, 31 (29.5%) scored below the threshold. Seven (29.2%) of those with ADHD scored below the threshold. The risk of scoring in the mild cognitive impairment range for those with and without ADHD was equal (RR = 0.98). Of the 24 patients with ADHD, 9 (37.5%) were taking medication at the time of testing. One of the patients taking medication scored below the threshold compared to six of those not taking medication. This suggests a 72% lower risk of mild cognitive impairment-like symptoms when taking medication (RR = 0.28); however, the effect was not significant.

CONCLUSIONS

We revealed no excess risk of mild cognitive impairment-like symptoms for the ADHD group. However, within the ADHD group, there was a possible lower risk of mild cognitive impairment-like symptoms for patients taking medication. These results suggest that there may be a confounding overlap of symptoms between ADHD and cognitive function screens that necessitates adequate assessment and treatment of ADHD before screening or measuring cognitive function.

Attention-Deficit/Hyperactivity Disorder and Transitional Aged Youth

PURPOSE OF REVIEW

Extensive research has been conducted on attention-deficit/hyperactivity disorder (ADHD) in children and adults; however, less is known about ADHD during the transition from childhood to adulthood. Transitional aged youth (TAY) with ADHD represents a particularly vulnerable population as their newfound independence and responsibility often coincides with the development of comorbid disorders. The purpose of this review is to provide an update on the evaluation, diagnosis, and treatment of TAY-ADHD.

RECENT FINDINGS

Recent studies discovering ADHD symptoms emerging in TAY call the classification of ADHD as a disorder necessarily developing in childhood into question. TAY-ADHD are also shown to be vulnerable to academic and social impairments, increased risky behavior, and comorbid psychiatric disorders. Due to the risk of stimulant diversion in TAY, providers are advised to take precaution when prescribing medication to this population. Recent studies demonstrating the efficacy of psychotherapy in conjunction with non-stimulant or extended release stimulant medication provide a feasible alternative. This review highlights research on the course and evaluation of ADHD, impairments and comorbidities specific to TAY, and treatments tailored to address the unique challenges associated with TAY-ADHD.

Neurocognitive, Autonomic, and Mood Effects of Adderall: A Pilot Study of Healthy College Students

Prescription stimulant medications are considered a safe and long-term effective treatment for Attention Deficit Hyperactivity Disorder (ADHD). Studies support that stimulants enhance attention, memory, self-regulation and executive function in individuals with ADHD. Recent research, however, has found that many college students without ADHD report misusing prescription stimulants, primarily to enhance their cognitive abilities. This practice raises the question whether stimulants actually enhance cognitive functioning in college students without ADHD. We investigated the effects of mixed-salts amphetamine (i.e., Adderall, 30 mg) on cognitive, autonomic and emotional functioning in a pilot sample of healthy college students without ADHD (n = 13), using a double-blind, placebo-controlled, within-subjects design. The present study was the first to explore cognitive effects in conjunction with mood, autonomic effects, and self-perceptions of cognitive enhancement. Results revealed that Adderall had minimal, but mixed, effects on cognitive processes relevant to neurocognitive enhancement (small effects), and substantial effects on autonomic responses, subjective drug experiences, and positive states of activated emotion (large effects). Overall, the present findings indicate dissociation between the effects of Adderall on activation and neurocognition, and more importantly, contrary to common belief, Adderall had little impact on neurocognitive performance in healthy college students. Given the pilot design of the study and small sample size these findings should be interpreted cautiously. The results have implications for future studies and the education of healthy college students and adults who commonly use Adderall to enhance neurocognition.

Addictive potential of novel treatments for refractory depression and anxiety

Treatment-resistant mood disorders and anxiety disorders require intensive treatment, but treatment options should balance benefits and adverse effects or other potential detrimental effects on patients, including the risk of developing prescription medication addiction. Some of the newer treatment modalities for mood and anxiety disorders may have similar properties to benzodiazepines. The goal of this review was to identify the potential for developing dependence on the novel treatment approaches to treatment-resistant depression and refractory anxiety disorders. PubMed, MEDLINE, PsycINFO, Ovid, Cochrane Library, and Google Scholar were searched. Ketamine is effective in improving symptoms of major depressive disorder, but with no sustained benefits. Long-term use of oral or intranasal ketamine formulations may be associated with the risk of developing dependence. Augmentation of stimulant medication is usually effective for residual symptoms of depression, but the effects are usually short lasting and there is a potential for abuse. Synthetic cannabinoids and medicinal cannabis are increasingly being prescribed for a number of medical conditions, including anxiety disorders, without enough evidence about their efficacy and with the risk of patients developing dependence. In summary, benzodiazepines, ketamine, stimulant medications, and cannabinoids have some common characteristics, including short-lasting benefits and the risk of developing prescription medication addiction with longer use. All of these treatments may raise ethical dilemmas about the appropriateness of prescribing these medications in the long run for patients with depression and anxiety disorders.

The Effect of Previous Methylphenidate Use on Incidence of Stress Fractures in Military Recruits: A Retrospective Cohort

BACKGROUND

Previous research has detected an increased risk of stress fractures among subjects who reported previous use of methylphenidate. Conversely, stimulant medication use has been associated with traumatic fracture risk reduction, possibly because of the improved control of the underlying symptoms of attention deficit hyperactivity disorder (ADHD). The goal of this study was to investigate the effect of previous methylphenidate use on the incidence of traumatic and stress fractures among combat soldiers with previously treated and untreated ADHD.

METHODS

The retrospective cohort included 100,000 combat soldiers recruited to the Israeli Defense Forces from 2005 through 2015. Diagnosis of ADHD and previous exposure to methylphenidate were determined on the basis of self-reported recruitment questionnaires and medical records. Accordingly, the cohort was divided into 3 groups: subjects with ADHD who were previously treated with methylphenidate (n = 689), untreated subjects with ADHD reporting no medication use (n = 762), and controls having no ADHD diagnosis (n = 98,549). Logistic regressions were fitted to determine the odds ratios (ORs) of study subjects for stress and non-stress (traumatic) fractures. Multivariate analysis incorporated baseline characteristics, including age, sex, weight, duration of service, and diagnosis of anemia, at some point during the service.

RESULTS

After adjustment for sex, anemia, weight, age, and duration of service, the risk of traumatic fractures was increased in both subjects with treated ADHD (OR, 1.03 [95% confidence interval (CI), 1.00 to 1.05]) and subjects with untreated ADHD (OR, 1.04 [95% CI, 1.02 to 1.07]) compared with controls. Subjects in the treated ADHD group were at a higher risk of stress fractures (OR, 1.04 [95% CI, 1.02 to 1.07]). Interestingly, a diagnosis of anemia was an independent predictor of stress fractures (OR, 1.05 [95% CI, 1.04 to 1.06]).

CONCLUSIONS

Methylphenidate use is associated with an increased risk of stress fractures but a decreased risk of traumatic fractures in individuals diagnosed with ADHD. These and previous findings may serve as sufficient basis for screening for other risk factors and perhaps taking prevention measures in all those using stimulant medications, especially those planning to engage in strenuous physical activity.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Experiences of an internet-based support and coaching model for adolescents and young adults with ADHD and autism spectrum disorder -a qualitative study

BACKGROUND

There is a great demand for non-medical treatment and support targeting the needs of adolescents and young adults with autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). There is also a lack of qualitative studies providing in-depth insight into these individuals' own experiences within this area. The current study aimed to explore how adolescents and young adults with ADHD, ASD or both experienced taking part in an internet-based support and coaching intervention.

METHODS

Sixteen participants with ASD, ADHD or both who had participated in an 8-week internet-based support and coaching model, were interviewed using semi-structured interviews. Data was analyzed using qualitative content analysis.

RESULTS

Analysis yielded three themes; Deciding to participate, Taking part in the coaching process and The significance of format. Various motives for joining were expressed by participants, such as viewing the technology as familiar and appealing and expecting it to be better suited to their situation. There was also a previously unfulfilled need for support among participants. In deciding to take part in the intervention the coaches' competence and knowledge were considered essential, often in the light of previously negative experiences. Taking part in the coaching process meant feeling reassured by having someone to turn to in view of shared obstacles to seeking and receiving help. The support was used for talking through and receiving advice on matters related to their diagnosis. Findings further revealed appreciation for aspects relating to the format such as communicating through the written word, being in one's own home and an experience of immediacy. Some disadvantages were voiced including incomplete personal interaction and failing technology. There were also suggestions for greater flexibility.

CONCLUSIONS

The in-depth qualitative data obtained from this study suggest that the current model of support and the internet-based format have specific qualities that could play an important role in the support of adolescents and young adults with ADHD and ASD. Although not a replacement for face-to-face interaction, it could be a promising complement or alternative to other support and treatment options.

TRIAL REGISTRATION

"Internet-based Support for Young People with ADHD and Autism - a Controlled Study" retrospectively registered in www.clinicaltrials.gov ( ClinicalTrials.gov Identifier: NCT02300597 ) at 2014-11-10.

Desirability, availability, credit assignment, category learning, and attention: Cognitive-emotional and working memory dynamics of orbitofrontal, ventrolateral, and dorsolateral prefrontal cortices

BACKGROUND

The prefrontal cortices play an essential role in cognitive-emotional and working memory processes through interactions with multiple brain regions.

METHODS

This article further develops a unified neural architecture that explains many recent and classical data about prefrontal function and makes testable predictions.

RESULTS

Prefrontal properties of desirability, availability, credit assignment, category learning, and feature-based attention are explained. These properties arise through interactions of orbitofrontal, ventrolateral prefrontal, and dorsolateral prefrontal cortices with the inferotemporal cortex, perirhinal cortex, parahippocampal cortices; ventral bank of the principal sulcus, ventral prearcuate gyrus, frontal eye fields, hippocampus, amygdala, basal ganglia, hypothalamus, and visual cortical areas V1, V2, V3A, V4, middle temporal cortex, medial superior temporal area, lateral intraparietal cortex, and posterior parietal cortex. Model explanations also include how the value of visual objects and events is computed, which objects and events cause desired consequences and which may be ignored as predictively irrelevant, and how to plan and act to realise these consequences, including how to selectively filter expected versus unexpected events, leading to movements towards, and conscious perception of, expected events. Modelled processes include reinforcement learning and incentive motivational learning; object and spatial working memory dynamics; and category learning, including the learning of object categories, value categories, object-value categories, and sequence categories, or list chunks.

CONCLUSION

This article hereby proposes a unified neural theory of prefrontal cortex and its functions.

Processing speed can monitor stimulant-medication effects in adults with attention deficit disorder with hyperactivity

BACKGROUND

Treatment responses to methylphenidate by adults with ADHD are generally monitored against DSM-IV/DSM-V symptomatology, rating scales or interviews during reviews.

AIMS

To evaluate the use of single- and dual-dimension processing-speed and efficiency measures to monitor the effects of pharmacological treatment with methylphenidate after a short period off medication.

METHODS

A Quick Test of Cognitive Speed (AQT) monitored the effects of immediate-release methylphenidate in 40 previously diagnosed and medicated adults with ADHD. Processing speed was evaluated with prior prescription medication, without medication after a 2-day period off ADHD medication, and with low-dose (10/20 mg) and high-dose (20/40 mg) methylphenidate hydrochloride (Medikinet IR).

RESULTS

Thirty-three participants responded to the experimental treatments. One-way ANOVA with post-hoc analysis (Scheffe) indicated significant main effects for single dimension colour and form and dual-dimension colour-form naming. Post-hoc analysis indicated statistical differences between the no- and high-dose medication conditions for colour and form, measures of perceptual speed. For colour-form naming, a measure of cognitive speed, there was a significant difference between no- and low-dose medication and between no- and high-dose medications, but not between low- and high-dose medications.

CONCLUSIONS

Results indicated that the AQT tests effectively monitored incremental effects of the methylphenidate dose on processing speed after a 2-day period off medication. Thus, perceptual (colour and form) and cognitive speed (two-dimensional colour-form naming) and processing efficiency (lowered shift costs) increased measurably with high-dose medication. These preliminary findings warrant validation with added measures of associated behavioural and cognitive changes.

Methylphenidate Enhances Early-Stage Sensory Processing and Rodent Performance of a Visual Signal Detection Task

Methylphenidate (MPH) is used clinically to treat attention-deficit/hyperactivity disorder (ADHD) and off-label as a performance-enhancing agent in healthy individuals. MPH enhances catecholamine transmission via blockade of norepinephrine (NE) and dopamine (DA) reuptake transporters. However, it is not clear how this action affects neural circuits performing cognitive and sensorimotor functions driving performance enhancement. The dorsal lateral geniculate nucleus (dLGN) is the primary thalamic relay for visual information from the retina to the cortex and is densely innervated by NE-containing fibers from the locus coeruleus (LC), a pathway known to modulate state-dependent sensory processing. Here, MPH was evaluated for its potential to alter stimulus-driven sensory responses and behavioral outcomes during performance of a visual signal detection task. MPH enhanced activity within individual neurons, ensembles of neurons, and visually-evoked potentials (VEPs) in response to task light cues, while increasing coherence within theta and beta oscillatory frequency bands. MPH also improved reaction times to make correct responses, indicating more efficient behavioral performance. Improvements in reaction speed were highly correlated with faster VEP latencies. Finally, immunostaining revealed that catecholamine innervation of the dLGN is solely noradrenergic. This work suggests that MPH, acting via noradrenergic mechanisms, can substantially affect early-stage sensory signal processing and subsequent behavioral outcomes.

Physiological substrates of executive functioning: a systematic review of the literature

Executive function (EF) is a multifaceted construct that has been defined as a set of higher-order cognitive processes that allow for flexibility, self-regulation, strategic planning, and goal-directed behaviors. EFs have been studied in numerous clinical disorders using a variety of neuropsychological tasks and, more recently, neuroimaging techniques. The underlying physiological substrates of EF were historically attributed to the frontal lobes; however, recent studies suggest more widespread involvement of additional brain regions. The purpose of the present study was to conduct a systematic review (using PRISMA 2009 guidelines) of neuroimaging studies employing functional magnetic resonance imaging and diffusion tensor imaging methods investigating the physiological substrates of EFs in attention-deficit/hyperactivity disorder compared to other clinical groups and non-clinical participants. Research articles were retrieved using PsycINFO, PsycARTICLES, MEDLINE, and ScienceDirect, beginning February 2015 through May 2016. A total of 42 studies met eligibility. Of those 42 studies, 22 studies included clinical participants and 20 studies included non-clinical participants. Results revealed increased activation of the frontal brain region in the majority of non-clinical studies and approximately 50% of the clinical studies, albeit with some inconsistencies across subregions, tasks, and age groups. Implications, methodological limitations, and suggestions for future research are discussed.

Neuropsychological functioning in college students with and without ADHD

OBJECTIVE

Increasing numbers of students with attention-deficit/hyperactivity disorder (ADHD) are attending college; however, little empirical information is available concerning the functional impairment experienced by these students. Although preliminary studies suggest that college students with ADHD are more likely to experience a variety of psychosocial and academic difficulties compared to their peers without the disorder, findings regarding neuropsychological functioning have been inconsistent with some studies reporting that college students with ADHD perform more poorly on various cognitive and neuropsychological tasks while others report no differences compared to their peers without ADHD.

METHOD

The purposes of the present study, the Trajectories Related to ADHD in College project, a longitudinal study following the 4-year outcomes of college students with and without ADHD, were to (a) examine the performance of 436 first-year college students with and without ADHD (51.6% female) on measures of executive function (EF) and intelligence and (b) investigate the association of self-reported use of stimulant medication and neuropsychological performance in students with ADHD. Participant data from their first year of involvement in the study were analyzed.

RESULTS

Participants with ADHD performed more poorly on task-based and self-report EF measures relative to the comparison group. In contrast, no significant group differences were found with respect to intellectual performance. Within the ADHD group, use of prescription stimulant medication was associated with improved performance on some, but not all, neuropsychological tasks. Additional analyses also revealed significant group differences in EF based on clinical diagnostic status.

CONCLUSION

College students with ADHD demonstrated poorer EF than their peers without ADHD and psychostimulant medication was associated with improved EF performance. No group differences were found with respect to intellectual functioning, Lastly, having one or more comorbid psychiatric diagnoses in addition to ADHD was associated with poorer EF outcomes. (PsycINFO Database Record

Pharmacological and non-pharmacological treatment of adults with ADHD: a meta-review

Attention-deficit/hyperactivity disorder (ADHD) is characterised by a persistent and impairing pattern of inattention and/or hyperactivity/impulsivity and it is one of the most common neuropsychiatric conditions. Evidence about interventions of adults with ADHD is growing rapidly and clinicians need a reliable summary of all the best available information in order to better inform their daily practice. We searched MEDLINE, PubMed, PsycINFO and Cochrane databases until 31 May 2016 for systematic reviews about pharmacological and non-pharmacological treatments in adults with ADHD and carried out a meta-review to address clinically relevant questions. We identified a total of 40 papers. Psychostimulants-such as methylphenidate, dexamphetamine, mixed amphetamine salts and lisdexamfetamine-and non-psychostimulants-such as atomoxetine-were the most studied agents. Overall, pharmacological treatments were significantly more efficacious than placebo (standardised mean difference (SMD) 0.45, 95% CI 0.37 to 0.52), albeit less well accepted (OR 1.18, 95% CI 1.02 to 1.36) and tolerated (OR 2.29, 95% CI 1.97 to 2.66). The effects of pharmacological treatment for individuals with co-occurring ADHD and substance use disorder are still uncertain. The evidence for the efficacy and effectiveness of non-pharmacological treatments of ADHD in adults, as well as the combination of pharmacological and non-pharmacological strategies, is only preliminary. In conclusion, while available evidence addressed mainly the efficacy and tolerability of psychostimulants and non-psychostimulants for ADHD core symptoms in the short term, we still need further empirical support for the non-pharmacological and multimodal treatments. A comprehensive evidence-informed hierarchy of ADHD drugs based on their efficacy and tolerability is not yet available but it should be the next research priority in the field.

Prescription stimulant medication misuse: Where are we and where do we go from here?

Prescription stimulants, including methylphenidate (e.g., Ritalin) and amphetamine compounds (e.g., dextroamphetamine; Adderall), have been approved by the U.S. Food and Drug Administration for the treatment of attention-deficit/hyperactivity disorder (ADHD) and are classified by the United States Drug Enforcement Administration as Schedule II medications because of their high potential for abuse and dependence (Drug Enforcement Administration, U.S. Department of Justice, 2015). Despite the potential health and judicial consequences, misuse of prescription stimulants, typically defined as taking stimulants without a valid prescription, or use of stimulants other than as prescribed, has become a serious problem in the United States and abroad, especially on college campuses. The purpose of the present article is to review historical information concerning prescription stimulants and to summarize the literature with respect to misuse among adults, particularly college students, including risk factors, mediators and moderators, and motivations for prescription stimulant misuse. In addition, evidence is presented concerning the question of whether prescription stimulants truly enhance cognitive functioning in individuals with and without ADHD, and the ethical and professional implications of these findings are explored. Lastly, recommendations for addressing prescription stimulant misuse and suggestions for future research are advanced. (PsycINFO Database Record

Neurocognitive enhancement or impairment? A systematic meta-analysis of prescription stimulant effects on processing speed, decision-making, planning, and cognitive perseveration

Increasing numbers of adults, particularly college students, are misusing prescription stimulants primarily for cognitive/academic enhancement, so it is critical to explore whether empirical findings support neurocognitive benefits of prescription stimulants. Previous meta-analytic studies have supported small benefits from prescription stimulants for the cognitive domains of inhibitory control and memory; however, no meta-analytic studies have examined the effects on processing speed or the potential impairment on other domains of cognition, including planning, decision-making, and cognitive perseveration. Therefore, the present study conducted a meta-analysis of the available literature examining the effects of prescription stimulants on specific measures of processing speed, planning, decision-making, and cognitive perseveration among healthy adult populations. The meta-analysis results indicated a positive influence of prescription stimulant medication on processing speed accuracy, with an overall mean effect size of g = 0.282 (95% CI [0.077, 0.488]; n = 345). Neither improvements nor impairments were revealed for planning time, planning accuracy, advantageous decision-making, or cognitive perseveration; however, findings are limited by the small number of studies examining these outcomes. Findings support that prescription stimulant medication may indeed act as a neurocognitive enhancer for accuracy measures of processing speed without impeding other areas of cognition. Considering that adults are already engaging in illegal use of prescription stimulants for academic enhancement, as well as the potential for stimulant misuse to have serious side effects, the establishment of public policies informed by interdisciplinary research surrounding this issue, whether restrictive or liberal, is of critical importance. (PsycINFO Database Record

Regulation of the Dopamine and Vesicular Monoamine Transporters: Pharmacological Targets and Implications for Disease

Dopamine (DA) plays a well recognized role in a variety of physiologic functions such as movement, cognition, mood, and reward. Consequently, many human disorders are due, in part, to dysfunctional dopaminergic systems, including Parkinson's disease, attention deficit hyperactivity disorder, and substance abuse. Drugs that modify the DA system are clinically effective in treating symptoms of these diseases or are involved in their manifestation, implicating DA in their etiology. DA signaling and distribution are primarily modulated by the DA transporter (DAT) and by vesicular monoamine transporter (VMAT)-2, which transport DA into presynaptic terminals and synaptic vesicles, respectively. These transporters are regulated by complex processes such as phosphorylation, protein-protein interactions, and changes in intracellular localization. This review provides an overview of 1) the current understanding of DAT and VMAT2 neurobiology, including discussion of studies ranging from those conducted in vitro to those involving human subjects; 2) the role of these transporters in disease and how these transporters are affected by disease; and 3) and how selected drugs alter the function and expression of these transporters. Understanding the regulatory processes and the pathologic consequences of DAT and VMAT2 dysfunction underlies the evolution of therapeutic development for the treatment of DA-related disorders.

Lisdexamfetamine: A Review in ADHD in Adults

Lisdexamfetamine dimesylate (lisdexamfetamine) is a long-acting amfetamine prodrug with a convenient once-daily oral regimen that offers the potential for improved adherence and reduced abuse compared with short-acting preparations of amfetamines. Lisdexamfetamine (as Elvanse Adult(®); Tyvense Adult™) has been approved for use in adults with attention-deficit hyperactivity disorder (ADHD) under the EU decentralization procedure, with the first approvals in the UK, Sweden and Denmark. This approval reflects the results of three short-term trials in adults with ADHD in which fixed- or flexible-dose lisdexamfetamine produced significantly greater improvements than placebo in ADHD symptoms, overall functioning, executive functioning (including in patients with significant pre-existing impairment) and quality of life. Of note, a post hoc analysis of one of these studies suggested that the response to lisdexamfetamine was generally similar in treatment-naïve patients and those who had already received-and not responded satisfactorily to-previous ADHD therapies, including methylphenidate (MPH). Two further studies demonstrated the longer-term effectiveness of flexible-dose lisdexamfetamine in reducing ADHD symptoms, albeit maintenance of efficacy required ongoing treatment with the drug. Lisdexamfetamine was generally well tolerated in clinical trials, with an adverse event profile typical of that reported for other long-acting stimulants. Head-to-head comparisons with other long-acting agents, notably MPH and atomoxetine, are lacking. Nonetheless, on the basis of the available data, lisdexamfetamine provides a useful alternative option for the treatment of adults with ADHD, including those who have not responded adequately to previous ADHD therapies, including MPH.

Bipolar disorder and ADHD: comorbidity and diagnostic distinctions

Attention-deficit/hyperactivity disorder (ADHD) and bipolar disorder (BD) are neurodevelopmental disorders with onset in childhood and early adolescence, and common persistence in adulthood. Both disorders are often undiagnosed, misdiagnosed, and sometimes over diagnosed, leading to high rates of morbidity and disability. The differentiation of these conditions is based on their clinical features, comorbidity, psychiatric family history course of illness, and response to treatment. We review recent relevant findings and highlight epidemiological, clinical, family history, course, and treatment-response differences that can aid the differential diagnosis of these conditions in an outpatient pediatric setting.