Effects of single-dose methylphenidate on cognitive performance in patients with traumatic brain injury: a double-blind placebo-controlled study

Amphetamine and methylphenidate potential on the recovery from stroke and traumatic brain injury: a review

The prevalence of stroke and traumatic brain injury is increasing worldwide. However, current treatments do not fully cure or stop their progression, acting mostly on symptoms. Amphetamine and methylphenidate are stimulants already approved for attention deficit hyperactivity disorder and narcolepsy treatment, with neuroprotective potential and benefits when used in appropriate doses. This review aimed to summarize pre-clinical and clinical trials testing either amphetamine or methylphenidate for the treatment of stroke and traumatic brain injury. We used PubMed as a database and included the following keywords ((methylphenidate) OR (Ritalin) OR (Concerta) OR (Biphentin) OR (amphetamine) OR (Adderall)) AND ((stroke) OR (brain injury) OR (neuroplasticity)). Overall, studies provided inconsistent results regarding cognitive and motor function. Neurite outgrowth, synaptic proteins, dendritic complexity, and synaptic plasticity increases were reported in pre-clinical studies along with function improvement. Clinical trials have demonstrated that, depending on the brain region, there is an increase in motor activity, attention, and memory due to the stimulation of the functionally depressed catecholamine system and the activation of neuronal remodeling proteins. Nevertheless, more clinical trials and pre-clinical studies are needed to understand the drugs' full potential for their use in these brain diseases namely, to ascertain the treatment time window, ideal dosage, long-term effects, and mechanisms, while avoiding their addictive potential.

Pharmacotherapy to Improve Cognitive Functioning After Acquired Brain Injury: A Meta-Analysis and Meta-Regression

Cognitive impairments, common sequelae of acquired brain injury (ABI), significantly affect rehabilitation and quality of life. Currently, there is no solid evidence-base for pharmacotherapy to improve cognitive functioning after ABI, nevertheless off-label use is widely applied in clinical practice. This meta-analysis and meta-regression aims to quantitatively aggregate the available evidence for the effects of pharmacological agents used in the treatment of cognitive impairments following ABI. We conducted a comprehensive search of Embase, Medline Ovid, and Cochrane Controlled Trials Register databases for randomized controlled and crossover trials. Meta-analytic effects were calculated for each pharmaceutical agent and targeted neuromodulator system. Cognitive outcome measures were aggregated across cognitive domains. Of 8,216 articles, 41 studies (4,434 patients) were included. The noradrenergic agent methylphenidate showed a small, significant positive effect on cognitive functioning in patients with traumatic brain injury (TBI; k = 14, d = 0.34, 95% confidence interval: 0.12-0.56, P = 0.003). Specifically, methylphenidate was found to improve cognitive functions related to executive memory, baseline speed, inhibitory control, and variability in responding. The cholinergic drug donepezil demonstrated a large effect size, albeit based on a limited number of studies (k = 3, d = 1.68, P = 0.03). No significant effects were observed for other agents. Additionally, meta-regression analysis did not identify significant sources of heterogeneity in treatment response. Our meta-analysis supports the use of methylphenidate for enhancing cognitive functioning in patients with TBI. Although donepezil shows potential, it warrants further research. These results could guide clinical decision making, inform practice guidelines, and direct future pharmacotherapeutic research in ABI.

Protective effects of amphetamine and methylphenidate against dopaminergic neurotoxicants in SH-SY5Y cells

Full treatment of the second most common neurodegenerative disorder, Parkinson's disease (PD), is still considered an unmet need. As the psychostimulants, amphetamine (AMPH) and methylphenidate (MPH), were shown to be neuroprotective against stroke and other neuronal injury diseases, this study aimed to evaluate their neuroprotective potential against two dopaminergic neurotoxicants, 6-hydroxydopamine (6-OHDA) and paraquat (PQ), in differentiated human dopaminergic SH-SY5Y cells. Neither cytotoxicity nor mitochondrial membrane potential changes were seen following a 24-hour exposure to either therapeutic concentration of AMPH or MPH (0.001-10 μM). On the other hand, a 24-hour exposure to 6-OHDA (31.25-500 μM) or PQ (100-5000 μM) induced concentration-dependent mitochondrial dysfunction, assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and lysosomal damage, evaluated by the neutral red uptake assay. The lethal concentrations 25 and 50 retrieved from the concentration-toxicity curves in the MTT assay were 99.9 µM and 133.6 µM for 6-OHDA, or 422 µM and 585.8 µM for PQ. Both toxicants caused mitochondrial membrane potential depolarization, but only 6-OHDA increased reactive oxygen species (ROS). Most importantly, PQ-induced toxicity was partially prevented by 1 μM of AMPH or MPH. Nonetheless, neither AMPH nor MPH could prevent 6-OHDA toxicity in this experimental model. According to these findings, AMPH and MPH may provide some neuroprotection against PQ-induced neurotoxicity, but further investigation is required to determine the exact mechanism underlying this protection.

Effectiveness of biomedical interventions on the chronic stage of traumatic brain injury: a systematic review of randomized controlled trials

Traumatic brain injury (TBI), in any form and severity, can pose risks for developing chronic symptoms that can profoundly hinder patients' work/academic, social, and personal lives. In the past 3 decades, a multitude of pharmacological, stimulation, and exercise-based interventions have been proposed to ameliorate symptoms, memory impairment, mental fatigue, and/or sleep disturbances. However, most research is preliminary, thus limited influence on clinical practice. This review aims to systematically appraise the evidence derived from randomized controlled trials (RCT) regarding the effectiveness of pharmacological, stimulation, and exercise-based interventions in treating chronic symptoms due to TBI. Our search results indicate that despite the largest volume of literature, pharmacological interventions, especially using neurostimulant medications to treat physical, cognitive, and mental fatigue, as well as daytime sleepiness, have yielded inconsistent results, such that some studies found improvements in fatigue (e.g., Modafinil, Armodafinil) while others failed to yield the improvements after the intervention. Conversely, brain stimulation techniques (e.g., transcranial magnetic stimulation, blue light therapy) and exercise interventions were effective in ameliorating mental health symptoms and cognition. However, given that most RCTs are equipped with small sample sizes, more high-quality, larger-scale RCTs is needed.

Methylphenidate Ameliorates Behavioural and Neurobiological Deficits in Executive Function for Patients with Chronic Traumatic Brain Injury

(1) Background: Traumatic brain injury (TBI) often results in cognitive impairments, including in visuospatial planning and executive function. Methylphenidate (MPh) demonstrates potential improvements in several cognitive domains in patients with TBI. The Tower of London (TOL) is a visuospatial planning task used to assess executive function. (2) Methods: Volunteers with a history of TBI (n = 16) participated in a randomised, double-blinded, placebo-controlled, fMRI study to investigate the neurobiological correlates of visuospatial planning and executive function, on and off MPh. (3) Results: Healthy controls (HCs) (n = 18) and patients on placebo (TBI-placebo) differed significantly in reaction time (p < 0.0005) and accuracy (p < 0.0001) when considering all task loads, but especially for high cognitive loads for reaction time (p < 0.001) and accuracy (p < 0.005). Across all task loads, TBI-MPh were more accurate than TBI-placebo (p < 0.05) but remained less accurate than HCs (p < 0.005). TBI-placebo substantially improved in accuracy with MPh administration (TBI-MPh) to a level statistically comparable to HCs at low (p = 0.443) and high (p = 0.175) cognitive loads. Further, individual patients that performed slower on placebo at low cognitive loads were faster with MPh (p < 0.05), while individual patients that performed less accurately on placebo were more accurate with MPh at both high and low cognitive loads (p < 0.005). TBI-placebo showed reduced activity in the bilateral inferior frontal gyri (IFG) and insulae versus HCs. MPh normalised these regional differences. MPh enhanced within-network connectivity (between parietal, striatal, insula, and cerebellar regions) and enhanced beyond-network connectivity (between parietal, thalamic, and cerebellar regions). Finally, individual changes in cerebellar-thalamic (p < 0.005) and cerebellar-parietal (p < 0.05) connectivity with MPh related to individual changes in accuracy with MPh. (4) Conclusions: This work highlights behavioural and neurofunctional differences between HCs and patients with chronic TBI, and that adverse differences may benefit from MPh treatment.

Optimising recovery of consciousness after coma. From bench to bedside and vice versa

BACKGROUND

Several methods have been proposed to foster recovery of consciousness in patients with disorders of consciousness (DoC).

OBJECTIVE

Critically assess pharmacological and non-pharmacological treatments for patients with chronic DoC.

METHODS

A narrative mini-review, and critical analysis of the scientific literature on the various proposed therapeutic approaches, with particular attention to level of evidence, risk-benefit ratio, and feasibility.

RESULTS AND DISCUSSION

Personalised sensory stimulation, median nerve stimulation, transcranial direct current stimulation (tDCS), amantadine and zolpidem all have favourable risk-benefit ratios and are easy to implement in clinical practice. These treatments should be proposed to every patient with chronic DoC. Comprehensive patient management should also include regular lifting, pain assessment and treatment, attempts to restore sleep and circadian rhythms, implementation of rest periods, comfort and nursing care, and a rehabilitation program with a multi-disciplinary team with expertise in this field. More invasive treatments may cause adverse effects and require further investigation to confirm preliminary, encouraging results and to better define responders' intervention parameters. Scientific studies are essential and given the severity of the disability and handicap that results from DoC, research in this area should aim to develop new therapeutic approaches.

Effects and neuroprotective mechanisms of vagus nerve stimulation on cognitive impairment with traumatic brain injury in animal studies: A systematic review and meta-analysis

Introduction

Cognitive impairment is the main clinical feature after traumatic brain injury (TBI) and is usually characterized by attention deficits, memory loss, and decreased executive function. Vagus nerve stimulation (VNS) has been reported to show potential improvement in the cognition level after traumatic brain injury in clinical and preclinical studies. However, this topic has not yet been systematically reviewed in published literature. In this study, we present a systematic review and meta-analysis of the effects of VNS on cognitive function in animal models of TBI and their underlying mechanisms.

Methods

We performed a literature search on PubMed, PsycINFO, Web of Science, Embase, Scopus, and Cochrane Library from inception to December 2021 to identify studies describing the effects of VNS on animal models of TBI.

Results

Overall, nine studies were identified in animal models (36 mice, 268 rats, and 27 rabbits). An analysis of these studies showed that VNS can improve the performance of TBI animals in behavioral tests (beam walk test: SMD: 4.95; 95% confidence interval [CI]: 3.66, 6.23; p < 0.00001) and locomotor placing tests (SMD: -2.39; 95% CI: -4.07, -0.71; p = 0.005), whereas it reduced brain edema (SMD: -1.58; 95% CI: -2.85, -0.31; p = 0. 01) and decrease TNF-α (SMD: -3.49; 95% CI: -5.78, -1.2; p = 0.003) and IL-1β (SMD: -2.84; 95% CI: -3.96, -1.71; p < 0.00001) expression level in the brain tissue. However, the checklist for SYRCLE showed a moderate risk of bias (quality score between 30% and 60%), mainly because of the lack of sample size calculation, random assignment, and blinded assessment.

Conclusion

The present review showed that VNS can effectively promote cognitive impairment and neuropathology in animal models of TBI. We hope that the results of this systematic review can be applied to improve the methodological quality of animal experiments on TBI, which will provide more important and conclusive evidence on the clinical value of VNS. To further confirm these results, there is a need for high-quality TBI animal studies with sufficient sample size and a more comprehensive outcome evaluation.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021290797, identifier: CRD42021290797.

Pharmacotherapy for mild traumatic brain injury: an overview of the current treatment options

INTRODUCTION

Accounting for 90% of all traumatic brain injuries (TBIs), mild traumatic brain injury (mTBI) is currently the most frequently seen type of TBI. Although most patients can recover from mTBI, some may suffer from prolonged symptoms for months to years after injury. Growing evidence indicates that mTBI is associated with neurodegenerative diseases including dementias and Parkinson's disease (PD). Pharmacological interventions are necessary to address the symptoms and avoid the adverse consequences of mTBI.

AREAS COVERED

To provide an overview of the current treatment options, the authors herein review the potential drugs to reduce the secondary damage and symptom-targeted therapy as well as the ongoing clinical trials about pharmacotherapy for mTBI.

EXPERT OPINION

There has been no consensus on the pharmacotherapy for mTBI. Several candidates including n-3 PUFAs, melatonin, NAC and statins show potential benefits in lessening the secondary injury and improving neurological deficits in pre-clinic studies, which, however, still need further investigation in clinical trials. The current pharmacotherapy for mTBI is empirical in nature and mainly targets to mitigate the symptoms. Well-designed clinical trials are now warranted to provide high level evidence.

Methylphenidate augmentation of escitalopram to enhance adherence to antidepressant treatment: a pilot randomized controlled trial

BACKGROUND

Adherence to treatment, i.e. the extent to which a patient's therapeutic engagement coincides with the prescribed treatment, is among the most important problems in mental health care. The current study investigated the influence of pairing an acute positive reinforcing dopaminergic/noradrenergic effect (methylphenidate, MPH) with a standard antidepressant on the rates of adherence to medication treatment. The primary objective of this study was to determine whether MPH + escitalopram resulted in higher rates of medication adherence relative to placebo + escitalopram.

METHODS

Twenty participants with moderate to severe depression were 1-1 randomized to either (1) 5 mg MPH + 10 mg escitalopram or (2) placebo + 10 mg escitalopram with the possibility for a dose increase at 4 weeks. A Bayesian analysis was conducted to evaluate the outcomes.

RESULTS

First, neither percent Pill count nor Medication Electronic Monitoring System adherence showed that MPH was superior to placebo. In fact, placebo showed slightly higher adherence rates on the primary (7.82% better than MPH) and secondary (7.07% better than MPH) outcomes. There was a less than 25% chance of MPH augmentation showing at least as good or better adherence than placebo. Second, both groups showed a significant effect of treatment on the QIDS-SR with a median effect of an 8.6-point score reduction. Third, neither subjective measures of adherence attitudes nor socio-demographic covariates had a significant influence on the primary or secondary outcome variables.

CONCLUSIONS

These data do not support the use of MPH to increase adherence to antidepressant medication in individuals with moderate to severe depression. CLINICALTRIALS.

GOV IDENTIFIER

NCT03388164 , registered on 01/02/2018.

Methylphenidate for attention problems in epilepsy patients: Safety and efficacy

Children with attention deficit hyperactivity disorder (ADHD) have an increased risk of seizures, and children with epilepsy have an increased prevalence of ADHD. Adults with epilepsy often have varying degrees of attentional dysfunction due to multiple factors, including anti-seizure medications, frequent seizures, interictal discharges, underlying lesions, and psychiatric comorbidities. Currently, there are no approved medications for the treatment of epilepsy-related attentional dysfunction. Methylphenidate (MPH) is a stimulant, FDA-approved for the treatment of ADHD, and often used for ADHD in the setting of pediatric epilepsy. Large database and registry studies indicate safety of MPH in children with ADHD and epilepsy, with no significant effect on seizure frequency. Small single-dose and open-label studies suggest efficacy of MPH in adults with epilepsy-related attention deficits. Methylphenidate represents a possible treatment for attentional dysfunction due to epilepsy, but large, randomized, placebo-controlled, double-blinded studies are needed.

123I-Iofluopane Single-Photon Emission Computed Tomography as an Imaging Biomarker of Pre-Synaptic Dopaminergic System after Moderate-to-Severe Traumatic Brain Injury

Dopaminergic (DA) system function is frequently disrupted after traumatic brain injury (TBI). However, published interventions that target the DA system with the hope of enhancing functional outcomes are inconclusive, partially because of the lack of DA signaling biomarkers that can be used to select patients likely to benefit from DA-directed therapies or to monitor treatment efficacy. The aim of this study was to evaluate the feasibility of using ¹²³I-iofluopane single-photon emission computerized tomography (SPECT) to assess pre-synaptic DA system dysfunction after severe TBI. Eighteen patients with severe TBI were enrolled in this study. ¹²³I-iofluopane SPECT imaging was performed at baseline and again 2.5 h after a single dose of methylphenidate (MP) administered enterally. DA transporter (DAT) specific binding ratio (SBR) before and after MP was measured. Functional outcomes included the Disability Rating Scale, JFK Coma Recovery Scale-Revised, Functional Independence Measure, and Functional Assessment Measure. Thirteen of 18 patients completed the study. Average time from injury to SPECT scan was 48 days (standard deviation [SD], 24 days; median, 31). Baseline ioflupane striatal SBR was 1.51 ± 0.46 (median, 1.67). A 43.1% (SD, 16; median, 46.5) displacement of ioflupane from pre-synaptic DAT was observed after MP administration. Baseline SBR positively correlated with functional status at baseline and 4 weeks after completion of the study. Serum MP levels correlated with relative change in SBR (r_s = 0.60; p = 0.04). Our findings suggest that ¹²³I-iofluopane SPECT is a promising tool to determine the severity of pre-synaptic DA terminal disruption and for monitoring pharmacokinetics and pharmacodynamics of therapeutic interventions targeting the DA system.

Effects of Methylphenidate on Cognitive Function in Adults with Traumatic Brain Injury: A Meta-Analysis

This meta-analysis evaluated the effects of methylphenidate (MPH) on cognitive outcome and adverse events in adults with traumatic brain injuries (TBI). We searched PubMed, EMBASE, and PsycINFO for randomized controlled trials (RCTs) published before July 2019. Studies that compared the effects of MPH and placebos in adults with TBI were included. The primary outcome was cognitive function, while the secondary outcome was adverse events. Meta-regression and sensitivity analysis were conducted to evaluate heterogeneity. Seventeen RCTs were included for qualitative analysis, and ten RCTs were included for quantitative analysis. MPH significantly improved processing speed, measured by Choice Reaction Time (standardized mean difference (SMD): -0.806; 95% confidence interval (CI): -429 to -0.182, p = 0.011) and Digit Symbol Coding Test (SMD: -0.653; 95% CI: -1.016 to -0.289, p < 0.001). Meta-regression showed that the reaction time was inversely associated with the duration of MPH. MPH administration significantly increased heart rate (SMD: 0.553; 95% CI: 0.337 to 0.769, p < 0.001), while systolic or diastolic blood pressure did not exhibit significant differences. Therefore, MPH elicited better processing speed in adults with TBI. However, MPH use could significantly increase heart rate. A larger study is required to evaluate the effect of dosage, age, or optimal timing on treatment of adults with TBI.

The effectiveness of methylphenidate in improving cognition after brain injury in adults: a systematic review

Objective: To conduct a systematic review investigating the effectiveness of methylphenidate in improving cognition following brain injury in an adult population.Data sources: CINAHL, PsychINFO, MEDLINE, and PubMed databases were searched for all relevant articles published from January 1980 up to December 2017.Study selection: Studies were included if participants had a diagnosis of new onset or previous acquired brain injury and were age 16 or over. Studies must have administered methylphenidate and measured its effectiveness on cognition using at least one measure of cognitive function.Data extraction: Data extracted included study design, sample size, participant characteristics, intervention method, outcome measures, and findings. The quality of included randomized controlled trials was assessed using the Physiotherapy Evidence Database. An overall level of evidence was assigned using a modified Sackett scale.Data synthesis: Included studies consisted of seven randomized controlled trials, two pre-post trials, one prospective controlled trial, and one case study. All included studies reported improved cognitive abilities following methylphenidate treatment post-injury.Conclusions: There is the strongest level of evidence (Level 1a) suggesting methylphenidate may alleviate cognitive impairments in adults with brain injury. However, longitudinal studies are warranted examining the effectiveness and safety of long-term methylphenidate use in this population.

Executive (dys)function after traumatic brain injury: special considerations for behavioral pharmacology

Executive function is an umbrella term that includes cognitive processes such as decision-making, impulse control, attention, behavioral flexibility, and working memory. Each of these processes depends largely upon monoaminergic (dopaminergic, serotonergic, and noradrenergic) neurotransmission in the frontal cortex, striatum, and hippocampus, among other brain areas. Traumatic brain injury (TBI) induces disruptions in monoaminergic signaling along several steps in the neurotransmission process - synthesis, distribution, and breakdown - and in turn, produces long-lasting deficits in several executive function domains. Understanding how TBI alters monoamingeric neurotransmission and executive function will advance basic knowledge of the underlying principles that govern executive function and potentially further treatment of cognitive deficits following such injury. In this review, we examine the influence of TBI on the following measures of executive function - impulsivity, behavioral flexibility, and working memory. We also describe monoaminergic-systems changes following TBI. Given that TBI patients experience alterations in monoaminergic signaling following injury, they may represent a unique population with regard to pharmacotherapy. We conclude this review by discussing some considerations for pharmacotherapy in the field of TBI.

Psychopharmacology of traumatic brain injury

The pathophysiology of traumatic brain injury (TBI) can be highly variable, involving functional and/or structural damage to multiple neuroanatomical networks and neurotransmitter systems. This wide-ranging potential for physiologic injury is reflected in the diversity of neurobehavioral and neurocognitive symptoms following TBI. Here, we aim to provide a succinct, clinically relevant, up-to-date review on psychopharmacology for the most common sequelae of TBI in the postacute to chronic period. Specifically, treatment for neurobehavioral symptoms (depression, mania, anxiety, agitation/irritability, psychosis, pseudobulbar affect, and apathy) and neurocognitive symptoms (processing speed, attention, memory, executive dysfunction) will be discussed. Treatment recommendations will reflect general clinical practice patterns and the research literature.

Effects of Amphetamine on Sensorimotor Gating and Neurocognition in Antipsychotic-Medicated Schizophrenia Patients

Prepulse inhibition (PPI) of startle is being explored both as an indicator of target engagement for, and a biomarker predicting the sensitivity to, procognitive effects of drugs. We now report the effects of the pro-attentional drug, d-amphetamine, on PPI and neurocognition in antipsychotic-medicated schizophrenia patients and healthy subjects (HS) who were also tested in a targeted cognitive training (TCT) module. 44 HS and 38 schizophrenia patients completed a double-blind, placebo-controlled crossover study of the effects of a single dose of amphetamine (10 mg po) on PPI and MATRICS Consensus Cognitive Battery (MCCB) performance; TCT results were previously reported from 60 of these subjects. Moderators predicting AMPH sensitivity were assessed, including the rs4680 single-nucleotide polymorphism for catechol-O-methyltransferase (COMT). After placebo, patients exhibited PPI deficits with 60 ms prepulse intervals; these deficits were 'rescued' by amphetamine. The magnitude of amphetamine-enhanced PPI was greater in patients than in HS (p<0.032), and was associated with positive symptoms (p<0.007), antipsychotic load (p<0.015), hedonic effects of AMPH (p<0.003), and with the presence of at least one methionine allele in rs4680 (p<0.008). No significant effects of amphetamine on MCCB performance were detected in either group, though pro-attentional effects of amphetamine in patients were associated with greater amphetamine-enhanced TCT learning. Amphetamine acutely 'normalized' PPI in antipsychotic-medicated schizophrenia patients; no concurrent acute neurocognitive changes were detected by the MCCB. Findings suggest that in the context of appropriate antipsychotic medication, a low dose of amphetamine enhances brain processes associated with higher function in schizophrenia patients, without accompanying changes in MCCB performance.

Plasticity in the Working Memory System: Life Span Changes and Response to Injury

Working memory acts as a key bridge between perception, long-term memory, and action. The brain regions, connections, and neurotransmitters that underlie working memory undergo dramatic plastic changes during the life span, and in response to injury. Early life reliance on deep gray matter structures fades during adolescence as increasing reliance on prefrontal and parietal cortex accompanies the development of executive aspects of working memory. The rise and fall of working memory capacity and executive functions parallels the development and loss of neurotransmitter function in frontal cortical areas. Of the affected neurotransmitters, dopamine and acetylcholine modulate excitatory-inhibitory circuits that underlie working memory, are important for plasticity in the system, and are affected following preterm birth and adult brain injury. Pharmacological interventions to promote recovery of working memory abilities have had limited success, but hold promise if used in combination with behavioral training and brain stimulation. The intense study of working memory in a range of species, ages and following injuries has led to better understanding of the intrinsic plasticity mechanisms in the working memory system. The challenge now is to guide these mechanisms to better improve or restore working memory function.

Working Memory after Traumatic Brain Injury: The Neural Basis of Improved Performance with Methylphenidate

Traumatic brain injury (TBI) often results in cognitive impairments for patients. The aim of this proof of concept study was to establish the nature of abnormalities, in terms of activity and connectivity, in the working memory network of TBI patients and how these relate to compromised behavioral outcomes. Further, this study examined the neural correlates of working memory improvement following the administration of methylphenidate. We report behavioral, functional and structural MRI data from a group of 15 Healthy Controls (HC) and a group of 15 TBI patients, acquired during the execution of the N-back task. The patients were studied on two occasions after the administration of either placebo or 30 mg of methylphenidate. Between group tests revealed a significant difference in performance when HCs were compared to TBI patients on placebo [F_{(1, 28)} = 4.426, p < 0.05, η_p² = 0.136]. This difference disappeared when the patients took methylphenidate [F_{(1, 28)} = 3.665, p = 0.66]. Patients in the middle range of baseline performance demonstrated the most benefit from methylphenidate. Changes in the TBI patient activation levels in the Left Cerebellum significantly and positively correlated with changes in performance (r = 0.509, df = 13, p = 0.05). Whole-brain connectivity analysis using the Left Cerebellum as a seed revealed widespread negative interactions between the Left Cerebellum and parietal and frontal cortices as well as subcortical areas. Neither the TBI group on methylphenidate nor the HC group demonstrated any significant negative interactions. Our findings indicate that (a) TBI significantly reduces the levels of activation and connectivity strength between key areas of the working memory network and (b) Methylphenidate improves the cognitive outcomes on a working memory task. Therefore, we conclude that methylphenidate may render the working memory network in a TBI group more consistent with that of an intact working memory network.

Anything goes? Regulation of the neural processes underlying response inhibition in TBI patients

Despite evidence for beneficial use of methylphenidate in response inhibition, no studies so far have investigated the effects of this drug in the neurobiology of inhibitory control in traumatic brain injury (TBI), even though impulsive behaviours are frequently reported in this patient group. We investigated the neural basis of response inhibition in a group of TBI patients using functional magnetic resonance imaging and a stop-signal paradigm. In a randomised double-blinded crossover study, the patients received either a single 30mg dose of methylphenidate or placebo and performed the stop-signal task. Activation in the right inferior frontal gyrus (RIFG), an area associated with response inhibition, was significantly lower in patients compared to healthy controls. Poor response inhibition in this group was associated with greater connectivity between the RIFG and a set of regions considered to be part of the default mode network (DMN), a finding that suggests the interplay between DMN and frontal executive networks maybe compromised. A single dose of methylphenidate rendered activity and connectivity profiles of the patients RIFG near normal. The results of this study indicate that the neural circuitry involved in response inhibition in TBI patients may be partially restored with methylphenidate. Given the known mechanisms of action of methylphenidate, the effect we observed may be due to increased dopamine and noradrenaline levels.

Methylphenidate, cognition, and epilepsy: A double-blind, placebo-controlled, single-dose study

OBJECTIVE

To evaluate the potential efficacy of immediate-release methylphenidate (MPH) for treating cognitive deficits in epilepsy.

METHODS

This was a double-blind, randomized, single-dose, 3-period crossover study in patients with epilepsy and chronic cognitive complaints comparing the effects of placebo and MPH 10 and 20 mg given 1 week apart. Cognitive outcome was evaluated on the basis of an omnibus z score calculated from performance on the Conners Continuous Performance Test 3 (ability to discriminate between target and nontarget stimuli [d'] and hit reaction time standard deviation), Symbol-Digit Modalities Test, and Medical College of Georgia Paragraph Memory Test. Adverse events and seizure frequency were monitored. An open-label follow-up is reported elsewhere.

RESULTS

Thirty-five adult patients with epilepsy participated, of whom 31 finished. Demographics included the following: mean age = 35.3 years (range 20-62 years), 13 men and 18 women, and baseline seizure frequency of 2.8 per month. Epilepsy types were focal (n = 24), generalized (n = 6), or unclassified (n = 1). Mean epilepsy duration was 12.5 years. A statistically significant performance benefit was present at both 10-mg (p = 0.030) and 20-mg (p = 0.034) MPH doses. No seizures were associated with either MPH dose. Adverse effects leading to withdrawal included cognitive "fogginess" (n = 1 on 20 mg), anxiety/agitation (n = 1 on 10 mg), and tachycardia (n = 1). One participant was lost to follow-up after one 20-mg dose without side effect.

CONCLUSIONS

This single-dose study suggests that MPH may be effective in ameliorating some cognitive deficits in patients with epilepsy. Additional studies are required.

CLINICALTRIALSGOV IDENTIFIER

NCT02178995.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that single doses of MPH improve cognitive performance on some measures of attention and processing speed in patients with epilepsy and cognitive complaints.

Methylphenidate on Cognitive Improvement in Patients with Traumatic Brain Injury: A Meta-Analysis

Although methylphenidate has been used as a neurostimulant to treat patients with attention deficit hyperactivity disorder, its therapeutic role in the psychomotor or cognitive recovery of patients with traumatic brain injuries (TBIs) in both intensive care and rehabilitation settings has not been adequately explored. To address this issue, this meta-analysis searched the available electronic databases using the key words “methylphenidate”, “brain injuries”, “head injuries”, and “traumatic brain injury”. Analysis of the ten double-blind RCTs demonstrated significant benefit in using methylphenidate for enhancing vigilance-associated attention (i.e., selective, sustained, and divided attention) in patients with TBIs (standardized mean difference: 0.45, 95% CI: 0.10 to 0.79), especially in sustained attention (standardized mean difference: 0.66, 95% CI: 0.22 to 1.10). However, no significant positive impact was noted on the facilitation of memory or processing speed. More studies on the efficacy and safety of methylphenidate for the cognitive improvement of patients with TBIs are warranted.

Catecholamines and cognition after traumatic brain injury

Cognitive problems are one of the main causes of ongoing disability after traumatic brain injury. The heterogeneity of the injuries sustained and the variability of the resulting cognitive deficits makes treating these problems difficult. Identifying the underlying pathology allows a targeted treatment approach aimed at cognitive enhancement. For example, damage to neuromodulatory neurotransmitter systems is common after traumatic brain injury and is an important cause of cognitive impairment. Here, we discuss the evidence implicating disruption of the catecholamines (dopamine and noradrenaline) and review the efficacy of catecholaminergic drugs in treating post-traumatic brain injury cognitive impairments. The response to these therapies is often variable, a likely consequence of the heterogeneous patterns of injury as well as a non-linear relationship between catecholamine levels and cognitive functions. This individual variability means that measuring the structure and function of a person’s catecholaminergic systems is likely to allow more refined therapy. Advanced structural and molecular imaging techniques offer the potential to identify disruption to the catecholaminergic systems and to provide a direct measure of catecholamine levels. In addition, measures of structural and functional connectivity can be used to identify common patterns of injury and to measure the functioning of brain ‘networks’ that are important for normal cognitive functioning. As the catecholamine systems modulate these cognitive networks, these measures could potentially be used to stratify treatment selection and monitor response to treatment in a more sophisticated manner.

Cognitive Impairment and Rehabilitation Strategies After Traumatic Brain Injury

Traumatic brain injury (TBI) is among the significant causes of morbidity and mortality in the present world. Around 1.6 million persons sustain TBI, whereas 200,000 die annually in India, thus highlighting the rising need for appropriate cognitive rehabilitation strategies. This literature review assesses the current knowledge of various cognitive rehabilitation training strategies. The entire spectrum of TBI severity; mild to severe, is associated with cognitive deficits of varying degree. Cognitive insufficiency is more prevalent and longer lasting in TBI persons than in the general population. A multidisciplinary approach with neuropsychiatric evaluation is warranted. Attention process training and tasks for attention deficits, compensatory strategies and errorless learning training for memory deficits, pragmatic language skills and social behavior guidance for cognitive-communication disorder, meta-cognitive strategy, and problem-solving training for executive disorder are the mainstay of therapy for cognitive deficits in persons with TBI. Cognitive impairments following TBI are common and vary widely. Different cognitive rehabilitation techniques and combinations in addition to pharmacotherapy are helpful in addressing various cognitive deficits.

Care management of the agitation or aggressiveness crisis in patients with TBI. Systematic review of the literature and practice recommendations

The agitation crisis in the awakening phase after traumatic brain injury (TBI) is one of the most difficult behavioral disorders to alleviate. Current treatment options are heterogeneous and may involve excessive sedation. Practice guidelines are required by professionals in charge of TBI patients. Few reviews were published but those are old and based on expert opinions. The purpose of this work is to propose evidence-based guidelines to treat the agitation crisis.

METHODS

The elaboration of these guidelines followed the procedure validated by the French health authority for good practice recommendations, close to the Prisma statement. Guidelines were elaborated on the basis of a systematic and critical review of the literature.

RESULTS

Twenty-eight articles concerning 376 patients were analyzed. Recommendations are: when faced with an agitation crisis, the management strategy implies to search for an underlying factor that should be treated such as pain, acute sepsis, and drug adverse effect (expert opinion). Physical restraints should be discarded when possible (expert opinion). Neuroleptic agent with a marketing authorization can be used in order to obtain a quick sedation so as to protect the patient from himself, closed ones or the healthcare team but the duration should be as short as possible (expert opinion). The efficacy of beta-blockers and antiepileptics with mood regulation effects like carbamazepine and valproate yield the most compelling evidence and should be preferably used when a background regimen is envisioned (grade B for beta-blocker and C for antiepileptics). Neuroleptics, antidepressants, benzodiazepines, buspirone may be prescribed but are considered second-line treatments (expert opinion).

CONCLUSION

This study provides a strategy for treating the agitation crisis based on scientific data and expert opinion. The level of evidence remains low and published data are often old. New studies are essential to validate results from previous studies and test new drugs and non-pharmaceutical therapies.

Effects of single dose mixed amphetamine salts--extended release on processing speed in multiple sclerosis: a double blind placebo controlled study

RATIONALE

Multiple sclerosis (MS) commonly affects cognitive function, most frequently presenting as impaired processing speed (PS). There are currently no approved treatments for PS in this population, but previous studies suggest amphetamines may be beneficial.

OBJECTIVE

The objective of this study is to determine if mixed amphetamine salts, extended release (MAS-XR) has the potential to improve impaired PS in MS patients in a randomized controlled pre- and post-dose testing study.

METHODS

Fifty-two MS patients demonstrating PS impairment on either the Symbol Digit Modalities Test (SDMT) or Paced Auditory Serial Addition Test (PASAT) were randomized to a single dose of 5 mg MAS-XR (n = 18), 10 mg MAS-XR (n = 20), or placebo (n = 14). Subjects were evaluated a second time, after taking the blinded medication. ANOVA was used to compare the change on the SDMT and PASAT in each of the treatment groups compared to the placebo. Cohen's d was used to calculate effect size.

RESULTS

At baseline, the mean SDMT score was 43.3 ± 7.2 and the mean PASAT was 34.8 ± 13.4, with 47 (90.4 %) and 25 (48.1 %) categorized as impaired on the SDMT and PASAT, respectively. The change in SDMT scores from baseline to post-treatment demonstrated significant improvement for the MAS-XR 10-mg dose compared to placebo, increasing by 5.2 ± 4.5 vs. 0.6 ± 4.4 points (p = 0.043), with a medium effect size of 0.47. Change on the PASAT was not significantly different in either treatment group.

CONCLUSIONS

This study supports MAS-XR 10 mg as a potential treatment for MS patients with demonstrated PS impairment, warranting a larger longitudinal study.

Pharmacotherapy of traumatic brain injury: state of the science and the road forward: report of the Department of Defense Neurotrauma Pharmacology Workgroup

Despite substantial investments by government, philanthropic, and commercial sources over the past several decades, traumatic brain injury (TBI) remains an unmet medical need and a major source of disability and mortality in both developed and developing societies. The U.S. Department of Defense neurotrauma research portfolio contains more than 500 research projects funded at more than $700 million and is aimed at developing interventions that mitigate the effects of trauma to the nervous system and lead to improved quality of life outcomes. A key area of this portfolio focuses on the need for effective pharmacological approaches for treating patients with TBI and its associated symptoms. The Neurotrauma Pharmacology Workgroup was established by the U.S. Army Medical Research and Materiel Command (USAMRMC) with the overarching goal of providing a strategic research plan for developing pharmacological treatments that improve clinical outcomes after TBI. To inform this plan, the Workgroup (a) assessed the current state of the science and ongoing research and (b) identified research gaps to inform future development of research priorities for the neurotrauma research portfolio. The Workgroup identified the six most critical research priority areas in the field of pharmacological treatment for persons with TBI. The priority areas represent parallel efforts needed to advance clinical care; each requires independent effort and sufficient investment. These priority areas will help the USAMRMC and other funding agencies strategically guide their research portfolios to ensure the development of effective pharmacological approaches for treating patients with TBI.

The effects of methylphenidate on resting-state striatal, thalamic and global functional connectivity in healthy adults

By blocking dopamine and norepinephrine transporters, methylphenidate affects cognitive performance and regional brain activation in healthy individuals as well as those with neuropsychiatric disorders. Resting-state connectivity evaluates the functional integrity of a network of brain regions. Here, we examined how methylphenidate effects resting-state functional connectivity of the dorsal striatum and thalamus, areas each with dense dopaminergic and noradrenergic innervations, as well as global cerebral connectivity. We administered a single, oral dose (45 mg) to 24 healthy adults and compared resting-state connectivity to 24 demographically matched adults who did not receive any medication. The results showed that methylphenidate alters seed-based and global connectivity between the thalamus/dorsal striatum with primary motor cortex, amygdala/hippocampus and frontal executive areas (p < 0.05, corrected). Specifically, while methylphenidate at this dosage enhances connectivity to the motor cortex and memory circuits, it dampens prefrontal cortical connectivity perhaps by increasing catecholaminergic signalling past the 'optimal' level. These findings advance our understanding of a critical aspect of the multifaceted effects of methylphenidate on brain functions. The results may also facilitate future studies of the aetiology and treatment of neurological and psychiatric disorders that implicate catecholaminergic dysfunction.

Use of translational pharmacodynamic biomarkers in early-phase clinical studies for schizophrenia

Schizophrenia is a severe mental disorder characterized by cognitive deficits, and positive and negative symptoms. The development of effective pharmacological compounds for the treatment of schizophrenia has proven challenging and costly, with many compounds failing during clinical trials. Many failures occur due to disease heterogeneity and lack of predictive preclinical models and biomarkers that readily translate to humans during early characterization of novel antipsychotic compounds. Traditional early-phase trials consist of single- or multiple-dose designs aimed at determining the safety and tolerability of an investigational compound in healthy volunteers. However, by incorporating a translational approach employing methodologies derived from preclinical studies, such as EEG measures and imaging, into the traditional Phase I program, critical information regarding a compound's dose-response effects on pharmacodynamic biomarkers can be acquired. Furthermore, combined with the use of patients with stable schizophrenia in early-phase clinical trials, significant 'de-risking' and more confident 'go/no-go' decisions are possible.

Methylphenidate modulates sustained attention and cortical activation in survivors of traumatic brain injury: a perfusion fMRI study

RATIONALE

Methylphenidate (MPH), the most widely prescribed psychostimulant to treat many neuropsychiatric conditions, is reported to improve attention and speed of processing in survivors of traumatic brain injury (TBI). The neural correlate of this efficacy, however, remains unclear.

OBJECTIVE

Using perfusion functional magnetic resonance imaging (fMRI) as a biomarker of regional neural activity, the current study aimed to examine the neural correlates of single-dose (0.3 mg/kg) MPH administration in a randomized double-blind placebo-controlled crossover study design.

METHODS

Twenty-three individuals with moderate to severe TBI were tested on two occasions approximately 1 week apart. Perfusion fMRI scanning was carried out at rest and while participants performed cognitive tasks requiring sustained attention and working memory.

RESULTS

Behaviorally, MPH significantly improved both accuracy and reaction time (RT) in the sustained attention task but only RT in the working memory task. A trend of global reduction of cerebral blood flow by MPH was observed in all task conditions including resting. Voxel-wise whole-brain analysis revealed an interaction effect of drug by condition (MPH-placebo X task-rest) for the sustained attention task in the left posterior superior parietal cortex and parieto-occipital junction (BA 7/19). The magnitude of drug-related deactivation of this area during task performance was correlated with improvement in RT.

CONCLUSION

Suppression of activity in this area during task performance may reflect a compensatory mechanism by which MPH ameliorates attention impairments in TBI.

Impact of pharmacological treatments on cognitive and behavioral outcome in the postacute stages of adult traumatic brain injury: a meta-analysis

Pharmacological treatments that are administered to adults in the postacute stage after a traumatic brain injury (TBI) (≥4 weeks after injury) have the potential to reduce persistent cognitive and behavioral problems. While a variety of treatments have been examined, the findings have yet to be consolidated, hampering advances in the treatment of TBI. A meta-analysis of research that has investigated the cognitive and behavioral effects of pharmacological treatments administered in the later stage after TBI was therefore conducted. The PubMed and PsycINFO databases were searched, and Cohen d effect sizes, percent overlap, and failsafe N statistics were calculated for each treatment. Both randomized controlled trials and open-label studies (prospective and retrospective) were included. Nineteen treatments were investigated by 30 independent studies, comprising 395 participants with TBI in the treatment groups and 137 control subjects. When treated in the postacute period, 1 dopaminergic agent (methylphenidate) improved behavior (anger/aggression, psychosocial function) and 1 cholinergic agent (donepezil) improved cognition (memory, attention). In addition, when the injury-to-treatment interval was broadened to include studies that administered treatment just before the postacute period, 2 dopaminergic agents (methylphenidate, amantadine) showed clinically useful treatment benefits for behavior, whereas 1 serotonergic agent (sertraline) markedly impaired cognition and psychomotor speed.

Efficacy and safety of dopamine agonists in traumatic brain injury: a systematic review of randomized controlled trials

In the intensive care unit, dopamine agonists (DA) have been used in traumatic brain injury (TBI) patients to augment or accelerate cognitive recovery and rehabilitation. However, the efficacy and safety of DA in this population is not well established. We conducted a systematic review of randomized controlled trials (RCTs) examining the clinical efficacy and safety of DA in patients with TBI. We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials, comparing DA to either placebo, standard treatment, or another active comparator. There was no restriction for age, date, or language of publication. Sensitivity analyses were planned to evaluate the potential effect of timing of TBI, age, drugs, and year of publication on efficacy. Among the 790 citations identified, 20 RCTs evaluating methylphenidate, amantadine, and bromocriptine were eligible. Significant clinical heterogeneity was observed between and within studies, which precluded any pooling of data. Efficacy outcomes included mainly neuropsychological measures of cognitive functioning. A total of 76 different neuropsychological tests were used, but most of them (59%) only once. Only 5 studies systematically assessed safety. No trend could be drawn from the analysis of efficacy and safety. Important sources of bias in the studies were of major concern. Considering the absence of consensus regarding clinical outcome, the lack of safety assessment, and the high risk of bias in the included trials, more research is warranted before DA can be recommended in critically ill TBI patients.

Cerebellar mutism syndrome and its relation to cerebellar cognitive and affective function: Review of the literature

Tumors of the cerebellum and brainstem account for half of all brain tumors in children. The realization that cerebellar lesions produce clinically relevant intellectual disability makes it important to determine whether neuropsychological abnormalities occur in long-term survivors of pediatric cerebellar tumors. Little is known about the neurobehavioral sequale resulting specifically from the resection of these tumors in this population. We therefore reviewed neuropsychological findings associated with postoperative cerebellar mutism syndrome and discuss the further implications for cerebellar cognitive function.

Rehabilitation of traumatic brain injury

Rehabilitation following traumatic brain injury (TBI) is best provided by an interdisciplinary team of health care providers that takes advantage of the unique skills of multiple specialists, as well as their combined strengths that address problems that cut across disciplines. The setting where rehabilitation is provided is determined by the medical stability of patients, their ability to tolerate intensive therapies, and their likelihood of community reintegration within a reasonable period of time. Successful rehabilitation requires prompt recognition and treatment of TBI-related medical, cognitive, and behavioral problems to promote recovery and enhance community reintegration, using a combination of rehabilitation modalities and medications.

Oral methylphenidate normalizes cingulate activity in cocaine addiction during a salient cognitive task

Anterior cingulate cortex (ACC) hypoactivations during cognitive demand are a hallmark deficit in drug addiction. Methylphenidate (MPH) normalizes cortical function, enhancing task salience and improving associated cognitive abilities, in other frontal lobe pathologies; however, in clinical trials, MPH did not improve treatment outcome in cocaine addiction. We hypothesized that oral MPH will attenuate ACC hypoactivations and improve associated performance during a salient cognitive task in individuals with cocaine-use disorders (CUD). In the current functional MRI study, we used a rewarded drug cue-reactivity task previously shown to be associated with hypoactivations in both major ACC subdivisions (implicated in default brain function) in CUD compared with healthy controls. The task was performed by 13 CUD and 14 matched healthy controls on 2 d: after ingesting a single dose of oral MPH (20 mg) or placebo (lactose) in a counterbalanced fashion. Results show that oral MPH increased responses to this salient cognitive task in both major ACC subdivisions (including the caudal-dorsal ACC and rostroventromedial ACC extending to the medial orbitofrontal cortex) in the CUD. These functional MRI results were associated with reduced errors of commission (a common impulsivity measure) and improved task accuracy, especially during the drug (vs. neutral) cue-reactivity condition in all subjects. The clinical application of such MPH-induced brain-behavior enhancements remains to be tested.

Temperament and Character Correlates of Neuropsychological Performance

We investigate the association between temperament and character dimensions, on the one hand, and computerised neuropsychological test performance, on the other hand. Temperament and character dimensions were operationalised as scores on the subscales of the Temperament and Character Inventory (TCI), a 240-item measure that is based on the psychobiological theory of personality. Neuropsychological outcomes were measured on six computerised tests of executive functioning and abstract reasoning from the University of Pennsylvania Computerised Neuropsychological Test Battery (PennCNP). The executive and abstract reasoning tasks included a test of Motor Praxis (MPRAXIS), the Penn Abstraction, Inhibition and Working Memory Task (AIM), the Letter-N-Back (LNB2), the Penn Conditional Exclusion Task (PCET), the Penn Short Logical Reasoning Task (SPVRT) and the Short Raven's Progressive Matrices (SRAVEN). Results from this exploratory study yielded significant associations between neuropsychological performance and temperament and character traits. The temperament traits of Harm Avoidance and Reward Dependence were positively correlated with reaction time on the AIM and the SPVRT. The character dimension of Self-Transcendence was significantly associated with performance accuracy on the AIM and the temperament dimension of Novelty Seeking was inversely related to performance accuracy on the LNB2. These results confirm the importance of addressing the temperament and character correlates of neuropsychological performance in both clinical and non-clinical studies.

Pharmacotherapy for treatment of attention deficits after non-progressive acquired brain injury. A systematic review

Objective: To systematically review the effectiveness of medications used to improve attention in people with non-progressive acquired brain injury.

Design: A systematic review.

Methods: MEDLINE, EMBASE, CINALH, PUBMED and PsychINFO databases were used to identify studies published between 1987 and 2008 meeting the following criteria: studies with subjects older than 18 years; diagnosis of new onset or previous acquired brain injury; medication given to improve attention and use of outcome to measure attention. Studies involving subjects in low arousal states or with neurogenerative conditions were excluded. The studies were categorized into three evidence levels: I — Randomized controlled trials; II — Prospective studies, controlled trials with methodological limitations; and III — Retrospective studies, clinical case series.

Results: Forty-seven articles were identified on initial search. Twenty-six met the pre-specified criteria. Five articles were assessed as meeting the level I evidence criteria, 12 were level II studies and 9 were level III studies. Methylphenidate can improve information processing speed but not all attention aspects in some people after traumatic brain injury. There is weak evidence for use of dopamine agonists to improve neglect/inattention after stroke. There is little evidence on the frequency of adverse effects and long-term functional benefits.

Conclusion: Although there is lack of robust evidence to recommend the routine use of medication to improve attention after traumatic brain injury and stroke, the existing evidence indicates potential for benefit in some patents and therefore further research is warranted.

Rehabilitation of orthopaedic and neurologic boxing injuries

Clinical decision making for injured boxers follows the same therapeutic principles as the treatment plan for other injured athletes. Just as surgical techniques have improved, so has the scientific basis for implementing therapeutic exercises progressed to return the athletes to their former level of competition.

Cognitive interventions post acquired brain injury

OBJECTIVE

Cognitive rehabilitation represents a substantial portion of rehabilitative efforts put forth in increasing independence following an acquired brain injury.

MAIN OUTCOMES AND RESULTS

This review examined four major areas of cognitive therapy including: attention/concentration, learning and memory, executive functioning, and general cognitive rehabilitation approaches. In total, 64 studies were evaluated throughout the four major areas, which provided the evidence-base for 18 conclusions. The majority of the conclusions were based on moderate and limited evidence, however three strong and one conflicting conclusions were made.

CONCLUSIONS

Future research should explore functional outcome measures and long-term effects of treatment interventions through follow-up.

Effects of methylphenidate on working memory in traumatic brain injury: a preliminary FMRI investigation

As part of a preliminary investigation on the effects of methylphenidate on brain activation during a working memory (WM) task in patients with traumatic brain injury (TBI), patients with TBI received 15 mg of methylphenidate (N = 4) or placebo (N = 5) twice a day for one month in a double-blind, placebo-controlled design. Brain activation was assessed at pre-treatment and on the final treatment day using functional magnetic resonance imaging (fMRI) with an N-back task using faces as stimuli. In a whole brain voxel-wise analysis, methylphenidate, compared to placebo, produced a decrease in brain activation for the 2-load minus 0-load contrast in the anterior cingulate, thalamus, cuneus and cerebellum, regions associated with WM performance. Further, an a priori region of interest analysis with small volume correction found reduced activation in the anterior cingulate. Although based on a small sample size, these preliminary findings suggest methylphenidate may increase processing efficiency associated with cognitive control during WM tasks in patients with TBI.

Persistent cognitive dysfunction after traumatic brain injury: A dopamine hypothesis

Traumatic brain injury (TBI) represents a significant cause of death and disability in industrialized countries. Of particular importance to patients the chronic effect that TBI has on cognitive function. Therapeutic strategies have been difficult to evaluate because of the complexity of injuries and variety of patient presentations within a TBI population. However, pharmacotherapies targeting dopamine (DA) have consistently shown benefits in attention, behavioral outcome, executive function, and memory. Still it remains unclear what aspect of TBI pathology is targeted by DA therapies and what time-course of treatment is most beneficial for patient outcomes. Fortunately, ongoing research in animal models has begun to elucidate the pathophysiology of DA alterations after TBI. The purpose of this review is to discuss clinical and experimental research examining DAergic therapies after TBI, which will in turn elucidate the importance of DA for cognitive function/dysfunction after TBI as well as highlight the areas that require further study.

The effects of L-amphetamine sulfate on cognition in MS patients: results of a randomized controlled trial

Defects in processing speed and memory are common in multiple sclerosis (MS) patients. In other populations, amphetamines have been shown to enhance cognition, but their use is limited by adverse behavioral effects. The L-isomer may have equivalent cognition enhancement with less adverse effects due to decreased potency in subcortical areas. The aim of this study was to assess the safety and efficacy of L-amphetamine sulfate in the treatment of cognitive dysfunction in MS. This was a 2:1 randomized, placebo-controlled, double-blind trial, involving 33 MS clinics across the USA. One hundred and fifty-one clinically definite MS patients with documented cognitive dysfunction who were relapse free for >or=90 days, with an Expanded Disability Status Scale (EDSS) <or=6.5, and with no other medical/psychiatric condition that may cause psychological dysfunction were randomized to 30 mg of oral L-amphetamine sulfate or placebo for 29 days, including a dose escalation period. A history of cardiac disease, uncontrolled hypertension or electrocardiograph abnormalities resulted in exclusion. The primary outcomes were the Subject Global Assessment of Change and Symbol Digit Modalities Test (SDMT). Secondary outcomes were the results from the California Verbal Learning Test, second edition (CVLT2), Brief Visual Memory Test-Revised (BVMTR), and Paced Auditory Serial Addition Test (PASAT). One hundred and thirty-six subjects completed the study. No differences were found at baseline in demographics or in the results of the neuropsychological tests. After treatment, the active group performed significantly better for total learning (P = 0.041) and delayed recall (P < 0.01) on the BVMTR, and for delayed recall (P = 0.012) on the CVLT2. Five patients (four from the treatment group, one placebo) withdrew due to intolerable adverse events. L-amphetamine sulfate was associated with improved learning and memory and was well tolerated in this study. However, because the positive findings were observed on secondary outcome measures, the study requires replication before L: -amphetamine sulfate can be recommended for the treatment of cognitive impairment in MS.

Methylphenidate effect on hemispheric attentional imbalance in patients with traumatic brain injury: a psychophysical study

PRIMARY OBJECTIVE

We found spatially asymmetric allocation of attention in patients with traumatic brain injury (TBI) without overt asymmetry on neurological examination. The possible effect of Methylphenidate in reducing this asymmetry is evaluated in the current research.

RESEARCH DESIGN

Psychophysical study using a visual spatial attention task. Identification rates were measured after precuing attention to different visual field loci. TBI patients were tested before, during and after administration of Methylphenidate.

METHODS AND PROCEDURES

After precuing to a locus 5 degrees into the left or right hemifield, target patterns were presented briefly at the cued location (valid), or on the opposite side (invalid) - requiring an attentional shift. Patients were treated with a gradually increasing dosage of a psychostimulant over two weeks, followed by a similar two-week period of gradually diminishing dosage. Patients were tested before treatment, at its peak, and (twice) following its completion.

MAIN OUTCOME AND RESULTS

Patients demonstrated significantly worse performance with leftward than with rightward cross-hemifield shifts of attention. This difference was significantly reduced during and following treatment.

CONCLUSIONS

Asymmetric performance and improvement with treatment suggest that diffuse TBI damage leads to a lateralized attention-related deficit. These findings support the hypotheses that attention is a distributed and asymmetrically lateralized function. The findings are consistent with the conclusion that Methylphenidate may be an effective treatment for attentional deficits in TBI patients.

A review of pharmacological treatments used in experimental models of traumatic brain injury

PRIMARY OBJECTIVE

We provide a review of recent chronic and delayed rehabilitative pharmacological treatments examined in experimental models of traumatic brain injury. There is a specific emphasis on studies aiming to enhance cognitive recovery.

MAIN OUTCOMES AND RESULTS

Decreased neuronal activity is believed to contribute to persistent cognitive disabilities. Neurotransmitter based rehabilitative treatments that increase neuronal activity may assist in the recovery of cognitive function. However, timing and dosage of drug treatment are influential in cognitive enhancement. Drug treatments that affect single and multiple neurotransmitter systems have the ability to significantly influence recovery of function following brain injury.

CONCLUSIONS

Understanding the relationship between neural disturbances and functional deficits following brain injury is challenging. Cognitive impairment may be the result of a single event or multiple events that occur after the initial insult. Increasing neuronal activity during the chronic phase of injury seems to be an effective treatment strategy for facilitating cognitive recovery. Pharmacological agents do not necessarily display the same effects in an injured brain as in a non-injured brain. Thus, further research is needed to establish the effectiveness of rehabilitative drug treatments.