Development of a novel rodent rapid serial visual presentation task reveals dissociable effects of stimulant versus nonstimulant treatments on attentional processes.

The rapid serial visual presentation (RSVP) task and continuous performance tasks (CPT) are used to assess attentional impairments in patients with psychiatric and neurological conditions. This study developed a novel touchscreen task for rats based on the structure of a human RSVP task and used pharmacological manipulations to investigate their effects on different performance measures. Normal animals were trained to respond to a target image and withhold responding to distractor images presented within a continuous sequence. In a second version of the task, a false-alarm image was included, so performance could be assessed relative to two types of nontarget distractors. The effects of acute administration of stimulant and nonstimulant treatments for ADHD (amphetamine and atomoxetine) were tested in both tasks. Methylphenidate, ketamine, and nicotine were tested in the first task only. Amphetamine made animals more impulsive and decreased overall accuracy but increased accuracy when the target was presented early in the image sequence. Atomoxetine improved accuracy overall with a specific reduction in false-alarm responses and a shift in the attentional curve reflecting improved accuracy for targets later in the image sequence. However, atomoxetine also slowed responding and increased omissions. Ketamine, nicotine, and methylphenidate had no specific effects at the doses tested. These results suggest that stimulant versus nonstimulant treatments have different effects on attention and impulsive behaviour in this rat version of an RSVP task. These results also suggest that RSVP-like tasks have the potential to be used to study attention in rodents.

Graph analysis uncovers an opposing impact of methylphenidate on connectivity patterns within default mode network sub-divisions.

BACKGROUND: The Default Mode Network (DMN) is a central neural network, with recent evidence indicating that it is composed of functionally distinct sub-networks. Methylphenidate (MPH) administration has been shown before to modulate impulsive behavior, though it is not yet clear whether these effects relate to MPH-induced changes in DMN connectivity. To address this gap, we assessed the impact of MPH administration on functional connectivity patterns within and between distinct DMN sub-networks and tested putative relations to variability in sub-scales of impulsivity. METHODS: Fifty-five right-handed healthy adults underwent two resting-state functional MRI (rs-fMRI) scans, following acute administration of either MPH (20 mg) or placebo, via a randomized double-blind placebo-controlled design. Graph modularity analysis was implemented to fractionate the DMN into distinct sub-networks based on the impact of MPH (vs. placebo) on DMN connectivity patterns with other neural networks. RESULTS: MPH administration led to an overall decreased DMN connectivity, particularly with the auditory, cinguloopercular, and somatomotor networks, and increased connectivity with the parietomedial network. Graph analysis revealed that the DMN could be fractionated into two distinct sub-networks, with one exhibiting MPH-induced increased connectivity and the other decreased connectivity. Decreased connectivity of the DMN sub-network with the cinguloopercular network following MPH administration was associated with elevated impulsivity and non-planning impulsiveness. CONCLUSION: Current findings highlight the intricate effects of MPH administration on DMN rs-fMRI connectivity, uncovering its opposing impact on distinct DMN sub-divisions. MPH-induced dynamics in DMN connectivity patterns with other neural networks may account for some of the effects of MPH administration on impulsive behavior.

Long-term medication for ADHD (LMA) trial: 2-year prospective observational study in children and adolescents. Core symptoms, daily functioning, and comorbidity outcomes.

More knowledge is needed about long-term ADHD medication and symptom, daily functioning, comorbidity, and tolerability outcomes. This "Long-term Medication for ADHD (LMA) trial" was a prospective observational 2-year trial in children and adolescents aged 6-18 years (extension of 1-year trial). Participants met criteria for DSM-5 ADHD (inattentive or combined), with complex comorbidities; autism spectrum disorder (31%), autistic traits (24%), oppositional symptoms (59%), anxiety (32%), dyslexia/language disorder (16%), borderline intellectual functioning (17%). Medication was individually tailored and followed-up at clinical visits (1, 2, 3, 6, 12, 18, 24 months). Primary outcome: Clinical Global Impression-Severity and Improvement scales (CGI-S, CGI-I). Secondary outcomes: Investigator-rated ADHD-Rating Scale, Weiss Functional Impairment Rating Scale-Parent report (WFIRS-P; Family, School Learning and Behavior, Life Skills, Self-Concept, Social Activities, and Risky Activities domains), comorbidity symptoms and adverse events (AEs). One hundred twenty-eight participants were enrolled (1-year trial only n = 27, LMA trial n = 101). Of these 29 (23%) discontinued, mainly due to AEs (n = 7), moving (n = 7), or no longer needing medication (n = 6). Main AEs were poor appetite, low mood, anxiety, irritability, fatigue. Improvements from baseline to 2 years were large in CGI-S (effect size (ES) 2.28), ADHD-RS (ES 2.06), and moderate to large in WFIRS-P (ES total 0.73, learning 0.4, family 0.67). Overall, the trial showed robust and sustained improvements in ADHD symptom severity and daily functioning over a period of 2 years of ADHD medication in children and adolescents with ADHD and complex comorbidities. Most AEs were mild. Comorbidity symptoms were improved after 1 year, particularly oppositional symptoms, depression, and anxiety.

The Use of Methylphenidate During Inpatient Rehabilitation After Pediatric Traumatic Brain Injury: Population Characteristics and Prescribing Patterns.

OBJECTIVE: To understand how methylphenidate (MPH) is used in youth with traumatic brain injury (TBI) during inpatient pediatric rehabilitation. SETTING: Inpatient pediatric rehabilitation. PARTICIPANTS: In total, 234 children with TBI; 62 of whom received MPH and 172 who did not. Patients were on average 11.6 years of age (range, 2 months to 21 years); 88 of 234 were female; the most common mechanism of injury was motor vehicle collision (49%); median (IQR) acute hospital length of stay (LOS) and inpatient rehabilitation LOS were 16 (10-29) and 23 (14-39), respectively; 51 of 234 were in a disorder of consciousness cognitive state at time of inpatient rehabilitation admission. DESIGN: Multicenter, retrospective medical record review. MAIN MEASURES: Patient demographic data, time to inpatient pediatric rehabilitation admission (TTA), cognitive state, MPH dosing (mg/kg/day). RESULTS: Patients who received MPH were older (P = .011); TTA was significantly longer in patients who received MPH than those who did not (P =.002). The lowest recorded dose range by weight was 0.05 to 0.89 mg/kg/d, representing an 18-fold difference; the weight-based range for the maximum dose was 0.11 to 0.97 mg/kg/d, a 9-fold difference. Patients in lower cognitive states at admission (P = .001) and at discharge (P = .030) were more likely to receive MPH. Five patients had side effects known to be associated with MPH; no serious adverse events were reported. CONCLUSION: This multicenter study indicates that there is variable use of MPH during acute inpatient rehabilitation for children with TBI. Children who receive MPH tend to be older with lower cognitive states. Dosing practices are likely consistent with underdosing. Clinical indications for MPH use during inpatient pediatric rehabilitation should be better defined. The use of MPH, as well as its combination with other medications and treatments, during inpatient rehabilitation needs to be further explored.

Evaluation of corneal endothelial cell morphology off and on treatment by specular microscopy in children and adolescents with attention deficit hyperactivity disorder.

PURPOSE: To determine the structure and properties of corneal endothelial cells in children and adolescents with ADHD who received methylphenidate treatment at least six months. METHOD: The prospective, observational study included 33 eyes of 33 patients diagnosed with ADHD who received methylphenidate treatment for at least six months, 33 eyes of 33 patients newly diagnosed with ADHD who did not start medication treatment, and 33 eyes of 33 healthy individuals. Average cell density, coefficient of variation, maximum cell area, normal cell area, minimum cell area, average cell area, and hexagonality ratio values were evaluated by non-contact specular microscopy. The parameters recorded in all three groups were compared. RESULTS: The average age of children in the ADHD + MPH, ADHD, and control groups is 9 ± 1.7, 8.9 ± 2.3, and 8.9 ± 1.8 years, respectively. (p > 0.05) The average MPH treatment dose is 0.94 ± 0.19 mg/kg, the average daily MPH intake is 34.12 ± 14.04 mg, and the average duration of use of MPH is 24.03 ± 12.46 months. Central corneal thickness (CCT) was measured as an average of 540.45 ± 31.23 in the ADHD + MPH group, 540.61 ± 29.69 in the ADHD group, and 546.58 ± 27.72 in the control group. (p = 0.499) The average coefficient of variation (CV) values were measured as 25.48 ± 4.22 in the ADHD + MPH group, 26.12 ± 3.48 in the ADHD group, and 26.12 ± 3.64 in the control group. (p = 0.491) The average hexagonality ratio (%) (HEX) values were measured as 69.45 ± 8.41 in the ADHD + MPH group, 68.21 ± 6.82 in the ADHD group, and 68.91 ± 7.97 in the control group. (p = 0.892) No statistically significant difference was observed between all three groups in terms of all parameters. CONCLUSION: Methylphenidate treatment administered for at least six months with a diagnosis of ADHD did not have a toxic effect on the corneal endothelium.

Perception-Action Integration Is Modulated by the Catecholaminergic System Depending on Learning Experience.

BACKGROUND: The process underlying the integration of perception and action is a focal topic in neuroscientific research and cognitive frameworks such as the theory of event coding have been developed to explain the mechanisms of perception-action integration. The neurobiological underpinnings are poorly understood. While it has been suggested that the catecholaminergic system may play a role, there are opposing predictions regarding the effects of catecholamines on perception-action integration. METHODS: Methylphenidate (MPH) is a compound commonly used to modulate the catecholaminergic system. In a double-blind, randomized crossover study design, we examined the effect of MPH (0.25 mg/kg) on perception-action integration using an established "event file coding" paradigm in a group of n = 45 healthy young adults. RESULTS: The data reveal that, compared with the placebo, MPH attenuates binding effects based on the established associations between stimuli and responses, provided participants are already familiar with the task. However, without prior task experience, MPH did not modulate performance compared with the placebo. CONCLUSIONS: Catecholamines and learning experience interactively modulate perception-action integration, especially when perception-action associations have to be reconfigured. The data suggest there is a gain control-based mechanism underlying the interactive effects of learning/task experience and catecholaminergic activity during perception-action integration.

The Use of Methylphenidate for Cognitive Enhancement in Young Healthy Adults: The Clinical and Ethical Debates.

OBJECTIVE: Methylphenidate (MP), a drug of choice for attention-deficit/hyperactivity disorder (ADHD), is a federally restricted substance CII in the United States because of abuse and dependence, and similar restrictions are practiced in Canada and around the world. This designation is given to drugs with medical value that present a high potential for abuse. In view of these severe restrictions, it is concerning to find out that a large group of healthy young adults, at least as large as the ADHD group of patients, take MP for cognitive enhancement, in an attempt to improve their academic achievements during studies and examinations. These young adults buy MP illegally and consume it without any medical supervision. The objective of the present debate piece is to present the ethical and clinical issues that need to be addressed in an attempt to solve this dilemma. METHODS: The issues presented here are systematically reviewed and discussed along the following lines: MP effectiveness in enhancing cognitive achievements in healthy people; "As these are normal healthy people, what is the duty of physicians to 'treat' them?"; potential benefits of cognitive enhancement to healthy people; the risks of MP; "How do these young people get their MP?"; and "What can be done?" RESULTS: Methylphenidate is widely used for cognitive enhancement without medical supervision. The effectiveness of MP for cognitive enhancement is well documented along a dose-response curve. Congruent with the results of the randomized trials, repeated studies based on interviews suggest that numerous young people report that cognitive enhancement helps them in improving their academic achievements, and hence also improve their feeling of well-being. Presently, most regulatory and medical organizations limit the use of MP to ADHD and narcolepsy. Yet, the American Academy of Neurology ruled that there is a moral, ethical, and legal basis to prescribe the drug for cognitive enhancement. The drug has known dose-dependent adverse effects that can have serious ramifications and may often lead to poor adherence. The relative risk of MP causing sudden death/arrhythmia is 1.46 (95% confidence interval, 1.03-2.07), and there are estimated 20 million college and university students in the United States in 2020. The rate of sudden death/arrhythmias in this age group ranges between 1 and 10 per 100,000. This translates to an excess of 146 deaths caused by MP every year in the United States considering postsecondary students only. DISCUSSION: We propose that an ethical-clinical debate should be followed by an action plan to ensure that the present reality of millions of young people taking unsupervised MP is not accepted as a force majeure that cannot be changed.

How Frequent Is Switching From an Initial Stimulant Family to the Alternative One in the Clinical Setting?: A Pilot Study of 49 Consecutively Referred Medication-Naive Adults With Attention-Deficit/Hyperactivity Disorder.

PURPOSE/BACKGROUND: This study aimed to evaluate the frequency of needing to switch the initial treatment of a stimulant to the alternative family in newly referred, medication-naive adults with attention-deficit/hyperactivity disorder (ADHD) initiating treatment with stimulants. METHODS/PROCEDURES: Subjects were 49 unmedicated adults (18-45 years old) with Diagnostic and Statistical Manual of Disorders (Fifth Edition) ADHD who initiated treatment with a stimulant. Before the clinical assessment with an expert clinician, participants completed the Adult Self-Report, Behavior Rating Inventory of Executive Function-Adult Version, Emotional Dysregulation Subscale of the Barkley Current Behavior Scale-Self-report, and Mind Wandering Questionnaire. The rate of switching was examined using information from the electronic medical record for up to three clinical follow-up visits. Comparisons were made between those who did and did not need to switch on baseline demographic and clinical characteristics. FINDINGS/RESULTS: Sixty-seven percent of ADHD patients were initially prescribed a methylphenidate product, and 33%, an amphetamine product. Forty-one percent of ADHD patients needed to switch from their initially prescribed stimulant family within 90 days of initiating treatment because of poor tolerability. Whereas the rate of switching was significantly higher in those initially prescribed methylphenidate, the rate of patients who required changes in formulation (long- to short-acting and vice versa) or additional antianxiety or antidepressant treatment ("strugglers") was higher in those taking amphetamine. Switchers were more impaired on the Adult Self-Report Intrusive scale, whereas nonswitchers were more impaired on the Behavior Rating Inventory of Executive Function Inhibit and Task Monitor scales. However, these findings were small and of unclear clinical significance. IMPLICATIONS/CONCLUSIONS: Forty-one percent of medication-naive adults with ADHD initiating stimulant treatment required a switch from the initially prescribed stimulant family to the alternative one because of poor tolerability. Switching could not be adequately predicted by baseline demographic or clinical characteristics. These findings call for improved efforts to help identify predictors of response to stimulant treatment in adults with ADHD to avoid unnecessary delays in identifying a safe and effective treatment for these patients.

Catecholaminergic Modulation of Semantic Processing in Sentence Comprehension.

Catecholamine (CA) function has been widely implicated in cognitive functions that are tied to the prefrontal cortex and striatal areas. The present study investigated the effects of methylphenidate, which is a CA agonist, on the electroencephalogram (EEG) response related to semantic processing using a double-blind, placebo-controlled, randomized, crossover, within-subject design. Forty-eight healthy participants read semantically congruent or incongruent sentences after receiving 20-mg methylphenidate or a placebo while their brain activity was monitored with EEG. To probe whether the catecholaminergic modulation is task-dependent, in one condition participants had to focus on comprehending the sentences, while in the other condition, they only had to attend to the font size of the sentence. The results demonstrate that methylphenidate has a task-dependent effect on semantic processing. Compared to placebo, when semantic processing was task-irrelevant, methylphenidate enhanced the detection of semantic incongruence as indexed by a larger N400 amplitude in the incongruent sentences; when semantic processing was task-relevant, methylphenidate induced a larger N400 amplitude in the semantically congruent condition, which was followed by a larger late positive complex effect. These results suggest that CA-related neurotransmitters influence language processing, possibly through the projections between the prefrontal cortex and the striatum, which contain many CA receptors.

Immediate-release methylphenidate for attention deficit hyperactivity disorder (ADHD) in adults.

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) is characterized by symptoms of inattention or impulsivity or both, and hyperactivity, which affect children, adolescents, and adults. In some countries, methylphenidate is the first option to treat adults with moderate or severe ADHD. However, evidence on the efficacy and adverse events of immediate-release (IR) methylphenidate in the treatment of ADHD in adults is limited and controversial. OBJECTIVES: To evaluate the efficacy and harms (adverse events) of IR methylphenidate for treating ADHD in adults. SEARCH METHODS: In January 2020, we searched CENTRAL, MEDLINE, Embase, eight additional databases and three trial registers. We also searched internal reports on the European Medicines Agency and the US Food and Drug Administration websites. We checked citations of included trials to identify additional trials not captured by the electronic searches. SELECTION CRITERIA: Randomized controlled trials (RCTs) comparing IR methylphenidate, at any dose, with placebo or other pharmacological interventions (including extended-release formulations of methylphenidate) for ADHD in adults. Primary outcomes comprised changes in the symptoms of ADHD (efficacy) and harms. Secondary outcomes included changes in the clinical impression of severity and improvement, level of functioning, depression, anxiety and quality of life. Outcomes could have been rated by investigators or participants. DATA COLLECTION AND ANALYSIS: Two review authors extracted data independently on the characteristics of the trials, participants, interventions; outcomes and financial conflict of interests. We resolved disagreements by discussion or consulting a third review author. We obtained additional, unpublished information from the authors of one included trial that had reported efficacy data in a graph. We calculated mean differences (MDs) or standardized MDs (SMDs) with 95% confidence intervals (CIs) for continuous data reported on the same or different scales, respectively. We summarized dichotomous variables as risk ratios (RRs) with 95% CI. MAIN RESULTS: We included 10 trials published between 2001 and 2016 involving 497 adults with ADHD. Three trials were conducted in Europe and one in Argentina; the remaining trials did not report their location. The RCTs compared IR methylphenidate with placebo, an osmotic-release oral system (OROS) of methylphenidate (an extended-release formulation), an extended-release formulation of bupropion, lithium, and Pycnogenol® (maritime pine bark extract). Participants comprised outpatients, inpatients in addiction treatment, and adults willing to attend an intensive outpatient program for cocaine dependence. The duration of the follow-up ranged from 6 to 18 weeks. IR methylphenidate versus placebo We found very low-certainty evidence that, compared with placebo, IR methylphenidate may reduce symptoms of ADHD when measured with investigator-rated scales (MD -20.70, 95% CI -23.97 to -17.43; 1 trial, 146 participants; end scores; Adult ADHD Investigator Symptom Report Scale (AISRS), scored from 0 to 54), but the evidence is uncertain. The effect of IR methylphenidate on ADHD symptoms when measured with participant-rated scales was moderate, but the certainty of the evidence is very low (SMD -0.59, 95% CI -1.25 to 0.06; I2 = 69%; 2 trials, 138 participants; end scores). There is very low-certainty evidence that, compared with placebo, IR methylphenidate may reduce the clinical impression of the severity of ADHD symptoms (MD -0.57, 95% CI -0.85 to -0.28; 2 trials, 139 participants; I2 = 0%; change and end scores; Clinical Global Impression (CGI)-Severity scale (scored from 1 (very much improved) to 7 (very much worse))). There is low-certainty evidence that, compared with placebo, IR methylphenidate may slightly impact the clinical impression of an improvement in symptoms of ADHD (MD -0.94, 95% CI -1.37 to -0.51; 1 trial, 49 participants; end scores; CGI-Improvement scale (scored from 1 (very much improved) to 7 (very much worse))). There is no clear evidence of an effect on anxiety (MD -0.20, 95% CI -4.84 to 4.44; 1 trial, 19 participants; change scores; Hamilton Anxiety Scale (HAM-A; scored from 0 to 56); very low-certainty evidence) or depression (MD 2.80, 95% CI -0.09 to 5.69; 1 trial, 19 participants; change scores; Hamilton Depression Scale (HAM-D; scored from 0 to 52); very low-certainty evidence) in analyses comparing IR methylphenidate with placebo. IR methylphenidate versus lithium Compared with lithium, it is uncertain whether IR methylphenidate increases or decreases symptoms of ADHD (MD 0.60, 95% CI -3.11 to 4.31; 1 trial, 46 participants; end scores; Conners' Adult ADHD Rating Scale (scored from 0 to 198); very low-certainty evidence); anxiety (MD -0.80, 95% CI -4.49 to 2.89; 1 trial, 46 participants; end scores; HAM-A; very low-certainty evidence); or depression (MD -1.20, 95% CI -3.81 to 1.41, 1 trial, 46 participants; end scores; HAM-D scale; very low-certainty evidence). None of the included trials assessed participant-rated changes in symptoms of ADHD, or clinical impression of severity or improvement in participants treated with IR methylphenidate compared with lithium. Adverse events were poorly assessed and reported. We rated all trials at high risk of bias due to selective outcome reporting of harms and masking of outcome assessors (failure to blind outcome assessor to measure adverse events). Overall, four trials with 203 participants who received IR methylphenidate and 141 participants who received placebo described the occurrence of harms. The use of IR methylphenidate in these trials increased the risk of gastrointestinal complications (RR 1.96, 95% CI 1.13 to 2.95) and loss of appetite (RR 1.77, 95% CI 1.06 to 2.96). Cardiovascular adverse events were reported inconsistently, preventing a comprehensive analysis. One trial comparing IR methylphenidate to lithium reported five and nine adverse events, respectively. We considered four trials to have notable concerns of vested interests influencing the evidence, and authors from two trials omitted information related to the sources of funding and conflicts of interest. AUTHORS' CONCLUSIONS: We found no certain evidence that IR methylphenidate compared with placebo or lithium can reduce symptoms of ADHD in adults (low- and very low-certainty evidence). Adults treated with IR methylphenidate are at increased risk of gastrointestinal and metabolic-related harms compared with placebo. Clinicians should consider whether it is appropriate to prescribe IR methylphenidate, given its limited efficacy and increased risk of harms. Future RCTs should explore the long-term efficacy and risks of IR methylphenidate, and the influence of conflicts of interest on reported effects.

The Visuo-Motor Attention Test in Boys with Attention Deficit Hyperactivity Disorder (ADHD): Methylphenidate-Placebo Randomized Controlled Trial.

To assess the visuomotor attention ability in children with ADHD and controls and their response to placebo and Methylphenidate (MPH) treatment. 36 boys with ADHD and 36 age matched typical controls were administered the visuomotor attention test (VMAT) as a baseline and following a week of MPH(IR) or placebo administered to the study group, in a randomized crossover design. A significant difference between the study and control groups was found on several VMAT measures. No performance difference between ADHD dimensional sub-types was observed at the baseline assessment. Under MPH treatment a significant improvement in VMAT measures was observed and particularly in the combined and predominantly hyperactive (C\HI) type. The VMAT results obtained in the present study are consistent with previous findings. ADHD subtypes appear similarly short of visuomotor attention resources; a visuomotor test can be used in the assessment of gains derived from MPH treatment.

Effect of Methylphenidate and buspirone-methylphenidate co-administration on biochemical and hematological parameters in rats: Implications for safe and confrontational use.

Methylphenidate (MPH) is a psychostimulant, beneficial in attention deficit hyperactivity disorder (ADHD). Previously it has been shown that MPH-induced locomotor sensitization could be attenuate by buspirone co administration however the effect of chronic MPH and co-administration of MPH-buspirone on biochemical and hematological parameters are unknown. This study is designed to investigate these parameters after long term administration of MPH, Buspirone and their combination in rats. 40 male Wister rats were divided in to 4 groups, and treated with saline, MPH (2mg/kg/day), Buspirone (10mg/kg/day) and MPH-Buspirone co-administration (2mg/kg/day ±10mg/kg/day; respectively) up to six weeks. Administration of MPH significantly increase blood glucose level in saline treated control rats, however co-administration of MPH-buspirone exhibited less effect on blood glucose levels. Serum creatinine levels significantly decreased in all treated groups as compared to control but highly significant results were seen with combination treatment. Co-administration of MPH-buspirone and buspirone treated rats exhibited increased cholesterol and hemoglobin values. All treated groups showed increased values of hematocrit, MCV, MCH and MCHC compared to control group. RBCs and WBC's count were decreased in all treated groups. The platelet count rose significantly by Buspirone and MPH-buspirone administration, while MPH showed decreased platelet count. Thus, results suggested that prolong co-administration of MPH-buspirone is safe and effective for ADHD patients by preventing adverse effects not only on behavioral but also on biochemical and hematological parameter.

Methylphenidate does not affect convergent and divergent creative processes in healthy adults.

An increasing number of healthy people use methylphenidate, a psychostimulant that increases dopamine and noradrenaline transmission in the brain, to help them focus over extended periods of time. While methylphenidate has been shown to facilitate some cognitive functions, like focus and distractor-resistance, the same drug might also contribute to cognitive impairment, for example, in creativity. In this study, we investigated whether acute administration of a low oral dose (20 mg) of methylphenidate affected convergent and divergent creative processes in a sample of young healthy participants. Also, we explored whether such effects depended on individual differences in ADHD symptoms and working memory capacity. Contrary to our expectations, methylphenidate did not affect participants' creative performance on any of the tasks. Also, methylphenidate effects did not depend on individual differences in trait hyperactivity-impulsivity or baseline working memory capacity. Thus, although the effects of methylphenidate on creativity might be underestimated in our study due to several methodological factors, our findings do not suggest that methylphenidate impairs people's ability to be creative.

Natural Products as Modulators of CES1 Activity.

Carboxylesterase (CES) 1 is the predominant esterase expressed in the human liver and is capable of catalyzing the hydrolysis of a wide range of therapeutic agents, toxins, and endogenous compounds. Accumulating studies have demonstrated associations between the expression and activity of CES1 and the pharmacokinetics and/or pharmacodynamics of CES1 substrate medications (e.g., methylphenidate, clopidogrel, oseltamivir). Therefore, any perturbation of CES1 by coingested xenobiotics could potentially compromise treatment. Natural products are known to alter drug disposition by modulating cytochrome P450 and UDP-glucuronosyltransferase enzymes, but this issue is less thoroughly explored with CES1. We report the results of a systematic literature search and discuss natural products as potential modulators of CES1 activity. The majority of research reports reviewed were in vitro investigations that require further confirmation through clinical study. Cannabis products (Δ 9-tetrahydrocannabinol, cannabidiol, cannabinol); supplements from various plant sources containing naringenin, quercetin, luteolin, oleanolic acid, and asiatic acid; and certain traditional medicines (danshen and zhizhuwan) appear to pose the highest inhibition potential. In addition, ursolic acid, gambogic acid, and glycyrrhetic acid, if delivered intravenously, may attain high enough systemic concentrations to significantly inhibit CES1. The provision of a translational interpretation of in vitro assessments of natural product actions and interactions is limited by the dearth of basic pharmacokinetic data of the natural compounds exhibiting potent in vitro influences on CES1 activity. This is a major impediment to assigning even potential clinical significance. The modulatory effects on CES1 expression after chronic exposure to natural products warrants further investigation. SIGNIFICANCE STATEMENT: Modulation of CES1 activity by natural products may alter the course of treatment and clinical outcome. In this review, we have summarized the natural products that can potentially interact with CES1 substrate medications. We have also noted the limitations of existing reports and outlined challenges and future directions in this field.

Randomized Controlled Crossover Trials of the Pharmacokinetics of PRC-063, a Novel Multilayer Extended-Release Formulation of Methylphenidate, in Healthy Adults.

PURPOSE/BACKGROUND: PRC-063 is a once-daily, extended-release oral formulation of methylphenidate hydrochloride developed to provide early and prolonged symptom improvement in patients with attention-deficit/hyperactivity disorder. METHODS/PROCEDURES: We conducted 3 randomized, open-label crossover studies of the pharmacokinetics of PRC-063 in healthy, nonobese men and women aged 18 to 45 years. PRC-063 (100 mg/d) was compared with immediate-release methylphenidate (20 mg, 3 times daily) when administered on a single day under fasted and fed conditions and at steady state (day 5 of repeat dosing under fasted conditions). The pharmacokinetics of PRC-063 administered as capsule contents sprinkled on apple sauce, yoghurt, or ice cream were also investigated. FINDINGS/RESULTS: PRC-063 demonstrated biphasic absorption, with 2 distinct peak plasma concentrations. Intake of a high-fat, high-calorie meal did not increase the peak plasma methylphenidate concentration (Cmax) or extent of absorption (area under the curve), however; it resulted in slower uptake versus a fasted state. During repeated dosing, steady state was reached with no further accumulation of methylphenidate from day 3. At steady state, PRC-063 gave higher evening and trough plasma methylphenidate levels than immediate-release methylphenidate (3 times daily). The pharmacokinetics of PRC-063 sprinkled on food were comparable to that of intact capsules. Reported adverse events (AEs) were consistent with the established safety profile of methylphenidate. There were no serious AEs, but 3 subjects discontinued the repeat-dosing study because of AEs assessed as possibly related to study treatment. IMPLICATIONS/CONCLUSIONS: Our data indicate that PRC-063 can be taken with or without food or by sprinkling capsule contents on food.

Individualizing the dosage of Methylphenidate in children with attention deficit hyperactivity disorder.

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) is one of the most common childhood mental health disorders. Stimulant drugs as the most commonly used treatment and first-line therapy for ADHD have side effects. One of the newest approaches to select the best choices and optimize dosages of medications is personalized medicine. METHODS: This historical cohort study was carried out on the data taken from the period of 2008 to 2015. Eligible subjects were included in the study randomly. We used mixed-effects logistic regression models to personalize the dosage of Methylphenidate (MPH) in ADHD. The patients' heterogeneity was considered using subject-specific random effects, which are treated as the realizations of a stochastic process. To recommend a personalized dosage for a new patient, a two-step procedure was proposed. In the first step, we obtained estimates for population parameters. In the second step, the dosage of the drug for a new patient was updated at each follow-up. RESULTS: Of the 221 children enrolled in the study, 169 (76.5%) were male and 52 (23.5%) were females. The overall mean age at the beginning of the study is 82.5 (± 26.5) months. In multivariable mixed logit model, three variables (severity of ADHD, time duration receiving MPH, and dosage of MPH) had a significant relationship with improvement. Based on this model the personalized dosage of MPH was obtained. CONCLUSIONS: To determine the dosage of MPH for a new patient, the more the severity of baseline is, the more of an initial dose is required. To recommend the dose in the next times, first, the estimation of random coefficient should be updated. The optimum dose increased when the severity of ADHD increased. Also, the results show that the optimum dose of MPH as one proceeds through the period of treatment will decreased.

Case report: diagnosis and treatment of attention deficit hyperactivity disorder and autism spectrum disorder in patients diagnosed with oculocutaneous albinism.

Oculocutaneous albinism (OCA) is a group of autosomal recessive disorders characterized by impairment in the melanin synthesis. We report two siblings with OCA who presented with symptoms of autism spectrum disorder and attention deficit hyperactivity disorder (ADHD). Ocular side effects occured after methylphenidate (MPH) treatment in the patient with ADHD and OCA. The diagnosis of OCA has been associated with difficulties in academic and social fields due to decreased visual activity and differentiation of phenotypic characteristics. Delayed diagnosis of comorbid neuropsychiatric disorders and MPH therapy may increase these difficulties. Patients with OCA require careful evaluation and treatment for neuropsychiatric disorders.

Pharmacokinetics of methylphenidate and ritalinic acid in plasma correlations with exhaled breath and oral fluid in healthy volunteers.

PURPOSE: The primary aim of this study was to explore the potential of alternative sampling matrices for methylphenidate by assessing the correlations between dl-threo-methylphenidate and dl-threo-ritalinic acid concentrations in exhaled breath and oral fluid with those in plasma, in repeated samples collected after a single oral dose of methylphenidate. The secondary aim was to study the enantioselective pharmacokinetics of methylphenidate in plasma, with a focus on interindividual variability in the metabolism of methylphenidate to ritalinic acid. METHODS: Twelve healthy volunteers received a single oral dose of dl-threo-methylphenidate (Ritalin® capsules, 20 mg). Venous blood samples were collected for 24 h, and plasma analyzed for threo-enantiomers of methylphenidate and ritalinic acid with LC-MS/MS. Repeated sampling of exhaled breath, using a particle filter device, and of non-stimulated oral fluid, using a felt pad device, was also performed. Exhaled breath and oral fluid were analyzed with a non-enantioselective LC-MS/MS method for dl-threo-methylphenidate and dl-threo-ritalinic acid. RESULTS: In all subjects, d-threo-methylphenidate was detectable in plasma for at least 15 h after the dose with a biphasic profile. l-threo-Methylphenidate was measurable in only five subjects and in most cases in low concentrations. However, one female subject displayed a biphasic concentration-time profile for l-threo-methylphenidate. This subject also had the highest d-threo-methylphenidate AUC (191 ng*h/mL versus 32-119 ng*h/mL in the other subjects). d-threo-Ritalinic acid concentrations were on average 25-fold higher (range 6-126) than the corresponding d-threo-methylphenidate concentrations. Single-time point plasma concentration ratios between d-threo-ritalinic acid and d-threo-methylphenidate 1.5-12 h after dose correlated highly (r = 0.88-0.98) with the d-threo-ritalinic acid AUC/d-threo-methylphenidate AUC ratio. In eleven subjects, dl-threo-methylphenidate in oral fluid mirrored the biphasic profile of methylphenidate (sum of d- and l-threo-enantiomers) in plasma, but the concentrations in oral fluid were on average 1.8 times higher than in plasma. dl-threo-Methylphenidate was detected in exhaled breath in all subjects, but there was no consistent concentration-time pattern. CONCLUSIONS: In some subjects, the pharmacologically less active l-threo-enantiomer may contribute to the total plasma methylphenidate concentrations. Monitoring methylphenidate concentrations without enantiomeric determination carries the risk of missing such subjects, which might affect how the plasma concentrations of methylphenidate are interpreted and used for clinical decision making. The use of exhaled breath and oral fluid to assess medication adherence to MPH in patients with ADHD warrants further studies.

Methylphenidate and Morphine Combination Therapy in a Rat Model of Chronic Pain.

BACKGROUND: The incremental dose of opioids used in chronic pain management often leads to a reduced opioid analgesic effect, opioid misuse, and addiction. Central dopamine (DA) dysfunction contributes to the chronicity of pain and a decreased opioid analgesic effect. Methylphenidate (MPH/Ritalin) enhances central DA function by inhibiting DA reuptake. In this study, we used a rat model of chronic pain to examine whether combination of MPH with morphine (MOR) would improve the MOR analgesic effect under a chronic pain condition. METHODS: Tibiotarsal joint Complete Freund's Adjuvant (CFA) injection in rats was utilized to induce chronic nociception. The analgesic effect of low-dose MPH (0.25 mg/kg), low-dose MOR (2.5 mg/kg), and their combination was examined in CFA rats. Nociceptive behavior was assessed by von Frey test. Conditioned place preference (CPP) and open field tests (OFTs) were used to examine the rewarding behavior and locomotor activity in rats, respectively. RESULTS: Our findings are as follows: (1) in CFA rats with chronic pain, 2.5 mg/kg of MOR had less analgesic effect than 10 mg/kg of MOR at 28 days after injury (95% confidence intervals [CIs] for difference of means of von Frey threshold in gram: -11.9 [-6.5 to -17.3]); (2) in the 1-hour time window of 30-90 minutes after injection, the combination of MPH (0.25 mg/kg) with MOR (2.5 mg/kg) increased synergistically and prolonged the analgesic effect in CFA rats as compared with MPH or MOR alone (P = .01 for MPH by MOR interaction, and 95% CIs for difference of means of von Frey threshold in gram: 3.3 [1.37-6.12] for the combination versus MPH and 3.2 [1.35-5.74] for the combination versus MOR); (3) at the low dose (0.25 mg/kg), MPH did not increase locomotor activity (MOR + MPH versus MOR, P = .13) nor significantly enhanced MOR reward behavior (MOR + MPH versus MOR, P = .63) in CFA rats. CONCLUSIONS: Our data suggest that a combination therapy using low-dose MPH and MOR may produce a MOR-sparing effect in chronic pain management.

Methylphenidate challenge test in adults with attention deficit/hyperactivity disorder (ADHD): Clinical effects and their predictors.

OBJECTIVE: Adult and children attention deficit/hyperactivity disorder (ADHD) share similar symptoms and responses to drugs such as methylphenidate (MPH). Yet, in Europe, these drugs remain unlicensed for adults. We aimed to assess the effects of an acute MPH challenge on the four dimensions concentration, impulsivity, tension, and general well-being in ADHD adults, and identify predictors of improvement. METHODS: Therapeutic Drug Monitoring was performed to measure MPH plasma levels. A Visual Analogue Scale was administered to patients before and after the acute MPH challenge to measure self-reported changes in the four dimensions. RESULTS: After the acute MPH challenge, our 71 patients showed significant improvement in concentration and tension. The MPH challenge dose correlated with lower patients' age, greater side effects, increased concentration (p = .008) and decreased tension (p = .001). At multiple linear regression MPH plasma levels and absence of postdose side effects predicted concentration improvement, MPH plasma levels predicted tension improvement. MPH plasma levels were significantly higher in patients who reported an improvement in concentration, tension, and impulsivity compared to nonimprovers (p's from .001 to .004). CONCLUSIONS: These findings point to the efficacy of MPH challenge in improving concentration and tension in adult ADHD, thus emphasizing the need for a broader treatment access for these patients.