The Effects of Bromocriptine on Attention Deficits After Traumatic Brain Injury: A Placebo-Controlled Pilot Study

Current and Potential Pharmacologic Therapies for Traumatic Brain Injury

The present article reviewed the pharmacologic therapies of traumatic brain injury (TBI), including current and potential treatments. Pharmacologic therapies are an essential part of TBI care, and several agents have well-established effects in TBI care. In the acute phase, tranexamic acid, antiepileptics, hyperosmolar agents, and anesthetics are the mainstay of pharmacotherapy, which have proven efficacies. In the post-acute phase, SSRIs, SNRIs, antipsychotics, zolpidem and amantadine, as well as other drugs, have been used to manage neuropsychological problems, while muscle relaxants and botulinum toxin have been used to manage spasticity. In addition, increasing numbers of pre-clinical and clinical studies of pharmaceutical agents, including potential neuroprotective nutrients and natural therapies, are being carried out. In the present article, we classify the treatments into established and potential agents based on the level of clinical evidence and standard of practice. It is expected that many of the potential medicines under investigation will eventually be accepted as standard practice in the care of TBI patients.

Role of the Dopaminergic System in the Striatum and Its Association With Functional Recovery or Rehabilitation After Brain Injury

Disabilities are estimated to occur in approximately 2% of survivors of traumatic brain injury (TBI) worldwide, and disability may persist even decades after brain injury. Facilitation or modulation of functional recovery is an important goal of rehabilitation in all patients who survive severe TBI. However, this recovery tends to vary among patients because it is affected by the biological and physical characteristics of the patients; the types, doses, and application regimens of the drugs used; and clinical indications. In clinical practice, diverse dopaminergic drugs with various dosing and application procedures are used for TBI. Previous studies have shown that dopamine (DA) neurotransmission is disrupted following moderate to severe TBI and have reported beneficial effects of drugs that affect the dopaminergic system. However, the mechanisms of action of dopaminergic drugs have not been completely clarified, partly because dopaminergic receptor activation can lead to restoration of the pathway of the corticobasal ganglia after injury in brain structures with high densities of these receptors. This review aims to provide an overview of the functionality of the dopaminergic system in the striatum and its roles in functional recovery or rehabilitation after TBI.

A Review of Pharmacologic Neurostimulant Use During Rehabilitation and Recovery After Brain Injury

OBJECTIVE

To describe the efficacy and safety of pharmacologic neurostimulants after neurological injuries such as ischemic or hemorrhagic stroke and traumatic brain injury (TBI), critically evaluate the available literature, and make recommendations regarding which neurostimulants should be considered for use in clinical practice.

DATA SOURCES

A literature search of PubMed was performed (1953 to October 2020) to identify relevant articles. Search terms included the following: "neurostimulant, neurorehabilitation" AND "traumatic brain injury, cerebrovascular accident, or stroke." This review is limited to prospective studies and observational trials.

STUDY SELECTION AND DATA EXTRACTION

Relevant English-language studies conducted in humans were considered.

DATA SYNTHESIS

Cognitive and motor deficits caused by stroke and TBI account for high rates of long-term disability. Although not well-established, pharmacologic agents, broadly characterized as neurostimulants, may be prescribed after brain injury to treat these deficits. When prescribing these medications, it is imperative to be aware of the supporting evidence in order to accurately gauge the risk-benefit profile of each agent.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

The following presents a literature review critically evaluating clinical studies that investigate neurostimulant use after brain injury. The intent of this review is to serve as an evidence-based guide for clinicians.

CONCLUSIONS

The pharmacologic agent with the most supporting literature is amantadine used for cognitive improvement after TBI. Other neurostimulants with positive, despite more limited, evidence include methylphenidate, modafinil, levodopa, and citalopram. Caution is warranted with other neurostimulants given higher rates of adverse effects or lack of benefit observed in clinical trials.

Differential Effects of Pergolide and Bromocriptine on Working Memory Performance and Brain Activation after Mild Traumatic Brain Injury

Dopamine D1 and D2 receptors differ with respect to patterns of regional brain distribution and behavioral effects. Pre-clinical work suggests that D1 agonists enhance working memory, but the absence of selective D1 agonists has constrained using this approach in humans. This study examines working memory performance in mild traumatic brain injury (mTBI) patients when given pergolide, a mixed D1/D2 agonist, compared with bromocriptine, a selective D2 agonist. Fifteen individuals were studied 1 month after mTBI and compared with 17 healthy controls. At separate visits, participants were administered 1.25 mg bromocriptine or 0.05 mg pergolide prior to functional magnetic resonance imaging (MRI) using a working memory task (visual-verbal n-back). Results indicated a significant group-by-drug interaction for mean performance across n-back task conditions, where the mTBI group showed better performance on pergolide relative to bromocriptine, whereas controls showed the opposite pattern. There was also a significant effect of diagnosis, where mTBI patients performed worse than controls, particularly while on bromocriptine, as shown in our prior work. Functional MRI activation during the most challenging task condition (3-back > 0-back contrast) showed a significant group-by-drug interaction, with the mTBI group showing increased activation relative to controls in working memory circuitry while on pergolide, including in the left inferior frontal gyrus. Across participants there was a positive correlation between change in activation in this region and change in performance between drug conditions. Results suggest that activation of the D1 receptor may improve working memory performance after mTBI. This has implications for the development of pharmacological strategies to treat cognitive deficits after mTBI.

The application of Strategy-based Training to Enhance Memory (STEM) in multiple sclerosis: A pilot RCT

New learning and memory (NLM) impairments are common in multiple sclerosis (MS), negatively impacting daily life. Few studies seek to remediate these deficits to improve everyday functioning. Self-generation, spaced learning and retrieval practice have been shown to improve NLM in healthy persons and have been incorporated into an 8-session treatment protocol, Strategy-based Training to Enhance Memory (STEM). STEM teaches participants about each of the techniques, how to apply them in daily life and provides practice. Participants are taught to restructure a memory-demanding situation to optimize self-generation, spaced learning and retrieval practice. This pilot double-blind, placebo-controlled, randomized clinical trial (RCT) tested the efficacy of STEM in 20 learning-impaired participants with clinically definite MS (9 treatment, 11 control). Significant treatment effects were noted on self-report measures of daily functioning (primary outcome). Objective neuropsychological testing approached significance, showing a medium-large effect on verbal NLM. Results suggest that STEM may improve everyday functioning in individuals with MS. A full-scale RCT is warranted to validate findings in a larger sample so that findings may be generalized to the broader MS community.

Neurotransmitter changes after traumatic brain injury: an update for new treatment strategies

Traumatic brain injury (TBI) is a pervasive problem in the United States and worldwide, as the number of diagnosed individuals is increasing yearly and there are no efficacious therapeutic interventions. A large number of patients suffer with cognitive disabilities and psychiatric conditions after TBI, especially anxiety and depression. The constellation of post-injury cognitive and behavioral symptoms suggest permanent effects of injury on neurotransmission. Guided in part by preclinical studies, clinical trials have focused on high-yield pathophysiologic mechanisms, including protein aggregation, inflammation, metabolic disruption, cell generation, physiology, and alterations in neurotransmitter signaling. Despite successful treatment of experimental TBI in animal models, clinical studies based on these findings have failed to translate to humans. The current international effort to reshape TBI research is focusing on redefining the taxonomy and characterization of TBI. In addition, as the next round of clinical trials is pending, there is a pressing need to consider what the field has learned over the past two decades of research, and how we can best capitalize on this knowledge to inform the hypotheses for future innovations. Thus, it is critically important to extend our understanding of the pathophysiology of TBI, particularly to mechanisms that are associated with recovery versus development of chronic symptoms. In this review, we focus on the pathology of neurotransmission after TBI, reflecting on what has been learned from both the preclinical and clinical studies, and we discuss new directions and opportunities for future work.

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.

Treating Disorders of Consciousness With Apomorphine: Protocol for a Double-Blind Randomized Controlled Trial Using Multimodal Assessments

Background: There are few available therapeutic options to promote recovery among patients with chronic disorders of consciousness (DOC). Among pharmacological treatments, apomorphine, a dopamine agonist, has exhibited promising behavioral effects and safety of use in small-sample pilot studies. The true efficacy of the drug and its neural mechanism are still unclear. Apomorphine may act through a modulation of the anterior forebrain mesocircuit, but neuroimaging and neurophysiological investigations to test this hypothesis are scarce. This clinical trial aims to (1) assess the treatment effect of subcutaneous apomorphine infusions in patients with DOC, (2) better identify the phenotype of responders to treatment, (3) evaluate tolerance and side effects in this population, and (4) examine the neural networks underlying its modulating action on consciousness. Methods/Design: This study is a prospective double-blind randomized parallel placebo-controlled trial. Forty-eight patients diagnosed with DOC will be randomized to receive a 30-day regimen of either apomorphine hydrochloride or placebo subcutaneous infusions. Patients will be monitored at baseline 30 days before initiation of therapy, during treatment and for 30 days after treatment washout, using standardized behavioral scales (Coma Recovery Scale-Revised, Nociception Coma Scale-Revised), neurophysiological measures (electroencephalography, body temperature, actigraphy) and brain imaging (magnetic resonance imaging, positron emission tomography). Behavioral follow-up will be performed up to 2 years using structured phone interviews. Analyses will look for changes in behavioral status, circadian rhythmicity, brain metabolism, and functional connectivity at the individual level (comparing before and after treatment) and at the group level (comparing apomorphine and placebo arms, and comparing responder and non-responder groups). Discussion: This study investigates the use of apomorphine for the recovery of consciousness in the first randomized placebo-controlled double-blind trial using multimodal assessments. The results will contribute to define the role of dopamine agonists for the treatment of these challenging conditions and identify the neural correlates to their action. Results will bring objective evidence to further assess the modulation of the anterior forebrain mesocircuit by pharmacological agents, which may open new therapeutic perspectives. Clinical Trial Registration: EudraCT n°2018-003144-23; Clinicaltrials.gov n°NCT03623828 (https://clinicaltrials.gov/ct2/show/NCT03623828).

Traumatic brain injury pharmacological treatment: recommendations

ABSTRACT This article presents the recommendations on the pharmacological treatment employed in traumatic brain injury (TBI) at the outpatient clinic of the Cognitive Rehabilitation after TBI Service of the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil. A systematic assessment of the consensus reached in other countries, and of articles on TBI available in the PUBMED and LILACS medical databases, was carried out. We offer recommendations of pharmacological treatments in patients after TBI with different symptoms.

Role of bromocriptine in multi-spectral manifestations of traumatic brain injury

PURPOSE

Despite the prevalence and cost of traumatic brain injury related disabilities, there is paucity in the literature on modern approaches to pharmacotherapy. Medications may promote recovery by enhancing some neurological functions without impacting others. Herein we discussed the role of bromocriptine in neurorehabilitation for patients with traumatic brain injury.

METHODS

A cohort comprising of 36 selective nonsurgical cases of traumatic brain injury in minimally conscious state were enrolled in the study. After hemodynamic stability, bromocriptine was given at paediatric dose of 3.75 mg/d and adult dose of 7.5 mg/d. It was administered through a naso-gastric (NG) feeding tube in the patients with minimally conscious state, then changed to oral route after proper swallowing and good gag reflex were ensured in the patient. The drug was slowly reduced over three weeks after neurological improvement in the patients. Positive result was determined by improved GCS score of 2 and motor power by at least 1 British Medical Council (BMC) motor score. Improvement of deficits was evaluated in terms of fluency of speech for aphasia, task switching, digit span double tasking and trail-making test for cognition and attention, and functional independence measure score for motor functioning and self-independence.

RESULTS

Accelerated arousal was seen in 47.0% of cases (8/17) in 4-40 days. In 41.2% of cases (7/17), Glasgow outcome score (GOS) was improved to 4/5 in 90 days. Improvement in hemiparesis by at least 1 BMC score was seen in 55.6% of cases (5/9) in 40 days. Aphasia was improved in 80% of cases (4/5) in 7-30 days. Moderate improvement in cognitive impairment was seen in 66.7% of cases (2/3) in 14-20 days. Improvement in memory was observed in 50% of cases (1/2) in over 30 days. No cases were withdrawn from the study because of adverse reactions of the drug. There was no mortality in the study group.

CONCLUSION

Bromocriptine improves neurological sequelae of traumatic brain injury as well as the overall outcome in the patients. If medication is given to promote recovery and treat its associated disabilities, clinicians should thoroughly outline the goals and closely monitor adverse effects.

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.

The effectiveness of dopamine agonists for treatment of neuropsychiatric symptoms post brain injury and stroke

OBJECTIVE

Traumatic brain injury and stroke are among the leading causes of neurological disability worldwide. Although dopaminergic agents have long been associated with improvement of neuropsychiatric outcomes, to date much of the evidence to date has been in case reports and case series or open label trials.

METHODS

We undertook a systematic review of double-blinded randomised controlled trials (RCT) to determine the effect of dopaminergic agents on pre-defined outcomes of (a) apathy; (b) psychomotor retardation; (c) behavioural management and (d) cognitive function. Databases searched were: Medline, EMBASE, and PsychInfo for human studies. The Cochrane Clinical Trials Database and the TRIP Medical database were also searched. All identified studies, were further hand-searched.

RESULTS

We identified six studies providing data on 227 participants, 150 of whom received dopaminergic therapy. Trials were compromised by cross-over design, inadequate wash out period, small numbers and heterogeneous outcome measures. However one good quality RCT demonstrates the efficacy of amantadine in behavioural management. One further RCT shows methylphenidate-levodopa is efficacious for mood post-stroke. One study shows rotigotine to improve hemi-inattention caused by prefrontal damage.

CONCLUSION

Our systematic review demonstrates an evolving evidence base to suggest some benefits in agitation and aggression, mood and attentional deficits. However, there are key limitations of the studies undertaken to date involving small numbers of participants, heterogeneous outcome measures, and variable study designs. There is a need for on-going large prospective double-blind RCTs in these medications using standardised criteria and outcomes to fully understand their effectiveness in this patient group.

Divergent long-term consequences of chronic treatment with haloperidol, risperidone, and bromocriptine on traumatic brain injury-induced cognitive deficits

Antipsychotic drugs (APDs) are provided in the clinic to manage traumatic brain injury (TBI)-induced agitation and aggression. Experimental TBI studies consistently show that daily administration of the APDs, haloperidol (HAL) and risperidone (RISP), hinder recovery. However, it is unknown how long the adverse effects remain after cessation of treatment. To elucidate this clinically relevant issue, anesthetized male rats were randomly assigned to four TBI (controlled cortical impact) and four sham groups administered HAL (0.5 mg/kg), RISP (0.45 mg/kg), bromocriptine (BRO; 5.0 mg/kg, included as a control for D2 receptor action), or vehicle (VEH; 1 mL/kg) 24 h after surgery and once-daily for 19 days. Motor and cognitive recovery was assessed on days 1-5 and 14-19, respectively, and again at 1 and 3 months after drug withdrawal. No overall group differences were observed for motor function among the TBI groups, although the HAL group showed a greater beam-walk deficit on day 5 versus the VEH and BRO groups. Cognitive recovery was significantly impaired in the HAL and RISP groups during the treatment phase versus VEH and BRO. Further, BRO was superior to VEH (p=0.0042). At 1 month, both groups that received APDs continued to exhibit significant cognitive impairment versus VEH and BRO; at 3 months, only the HAL group was impaired. Moreover, the HAL, RISP, and VEH groups continued to be cognitively deficient versus BRO, which also reduced cortical damage. These data replicate previous reports that HAL and RISP impede cognitive recovery after TBI and expand the literature by revealing that the deleterious effects persist for 3 months after drug discontinuation. BRO conferred cognitive benefits when administered concomitantly with behavioral testing, thus replicating previous findings, and also after cessation demonstrating enduring efficacy.

Decoding hippocampal signaling deficits after traumatic brain injury

There are more than 3.17 million people coping with long-term disabilities due to traumatic brain injury (TBI) in the United States. The majority of TBI research is focused on developing acute neuroprotective treatments to prevent or minimize these long-term disabilities. Therefore, chronic TBI survivors represent a large, underserved population that could significantly benefit from a therapy that capitalizes on the endogenous recovery mechanisms occurring during the weeks to months following brain trauma. Previous studies have found that the hippocampus is highly vulnerable to brain injury, in both experimental models of TBI and during human TBI. Although often not directly mechanically injured by the head injury, in the weeks to months following TBI, the hippocampus undergoes atrophy and exhibits deficits in long-term potentiation (LTP), a persistent increase in synaptic strength that is considered to be a model of learning and memory. Decoding the chronic hippocampal LTP and cell signaling deficits after brain trauma will provide new insights into the molecular mechanisms of hippocampal-dependent learning impairments caused by TBI and facilitate the development of effective therapeutic strategies to improve hippocampal-dependent learning for chronic survivors of TBI.

The effect of environmental enrichment on substantia nigra gene expression after traumatic brain injury in rats

Experimental investigations into the effects of traumatic brain injury (TBI) have demonstrated significant alterations in dopaminergic systems. Dopaminergic fibers originating within the substantia nigra and ventral tegmental area (VTA) are important for reward learning, addiction, movement, and behavior. However, little is known about the effect of TBI on substantia nigra and VTA function. Environmental enrichment (EE) has been shown to improve functional outcome after TBI, and a number of studies suggest that it may exert some benefits via dopaminergic signaling. To better understand the role of dopamine in chronic TBI pathophysiology and the effect of EE, we examined the mRNA expression profile within the substantia nigra and VTA at 4 weeks post-injury. Specifically, three comparisons were made: 1) TBI versus sham, 2) sham+EE versus sham+standard (STD) housing, and 3) TBI+EE versus TBI+STD. There were differential expressions of 25, 4, and 40 genes in these comparisons, respectively. Chronic alterations in genes post-injury within the substantia nigra and VTA included genes important for cellular membrane homeostasis and transcription. EE-induced gene alterations after TBI included genes important for signal transduction, in particular calcium signaling pathways, membrane homeostasis, and metabolism. Elucidation of these alterations in gene expression within the substantia nigra and VTA provides new insights into chronic changes in dopamine signaling post-TBI, and the potential role of EE in TBI rehabilitation.

Treatment of post-traumatic cognitive impairments

OPINION STATEMENT

• Cognitive impairment is a common consequence of traumatic brain injury (TBI) and a substantial source of disability. Across all levels of TBI severity, attention, processing speed, episodic memory, and executive function are most commonly affected.• The differential diagnosis for post-traumatic cognitive impairments is broad, and includes emotional, behavioral, and physical problems as well as substance use disorders, medical conditions, prescribed and self-administered medications, and symptom elaboration. Thorough neuropsychiatric assessment for such problems is a prerequisite to treatments specifically targeting cognitive impairments.• First-line treatments for post-traumatic cognitive impairments are nonpharmacologic, including education, realistic expectation setting, environmental and lifestyle modifications, and cognitive rehabilitation.• Pharmacotherapies for post-traumatic cognitive impairments include uncompetitive N-methyl-D-aspartate receptor (NMDA) antagonists, medications that directly or indirectly augment cerebral catecholaminergic or acetylcholinergic function, or agents with combinations of these properties.• In the immediate post-injury period, treatment with uncompetitive NMDA receptor antagonists reduces duration of unconsciousness. The mechanism for this effect may involve attenuation of neurotrauma-induced glutamate-mediated excitotoxicity and/or stabilization of glutamate signaling in the injured brain.• During the subacute or late post-injury periods, medications that augment cerebral acetylcholinergic function may improve declarative memory. Among responders to this treatment, secondary benefits on attention, processing speed, and executive function impairments as well as neuropsychiatric disturbances may be observed. During these post-injury periods, medications that augment cerebral catecholaminergic function may improve hypoarousal, processing speed, attention, and/or executive function as well as comorbid depression or apathy.• When medications are used, a "start-low, go-slow, but go" approach is encouraged, coupled with frequent reassessment of benefits and side effects as well as monitoring for drug-drug interactions. Titration to either beneficial effect or medication intolerance should be completed before discontinuing a treatment or augmenting partial responses with additional medications.

Biologic and plastic effects of experimental traumatic brain injury treatment paradigms and their relevance to clinical rehabilitation

Neuroplastic changes, whether induced by traumatic brain injury (TBI) or therapeutic interventions, alter neurobehavioral outcome. Here we present several treatment strategies that have been evaluated by using experimental TBI models and discuss potential mechanisms of action (ie, plasticity) and how such changes affect function.

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.

Pharmacotherapy for traumatic brain injury: focus on sympathomimetics

Traumatic brain injury (TBI) is a devastating neurological injury with broad manifestations. Unfortunately, its diagnosis and efficacious treatments remain elusive. Different post injury symptoms are exhibited at different time frames, indicative of a time-related progression of the pathology. Therefore, particular treatments must be tailored to the post injury time frame. This overview is focused on the secondary chronic phase following TBI and the value of sympathomimetic therapy during this phase. The various direct- and indirect-acting drugs are reviewed, and the treatment protocol employed by the author is described.

Cognitive rehabilitation in traumatic brain injury

OPINION STATEMENT

Traumatic brain injury (TBI) is a major public health problem with neurobehavioral sequelae contributing to the long-term disability that is often associated with the moderate to severe levels of injury. Rehabilitation of cognitive skills is central to encouraging the full participation of the individual in home, vocational, and social roles. The review of available evidence points to four major recommendations for the rehabilitation of cognition following brain injury: 1) Access to subacute rehabilitation that is holistic in nature and involves a multidisciplinary or transdisciplinary team to work in an integrated fashion to support physical, cognitive, and social skill retraining is vital to support positive outcome following TBI. The collaborative effort of these individuals allows for continual reinforcement and evaluation of treatment goals and will often involve the family and/or important others in the individual's life to prepare for community re-entry. 2) Trials of medication, especially methylphenidate, to assist individuals with significant attention and memory impairment appear well supported by the available evidence. Though some data suggest that the use of cholinesterase inhibitors may be of use for individuals with memory impairments, there is less support for this practice and there are indications that it may worsen the behavioral sequelae of the injury. 3) Randomized controlled trials demonstrate the utility of specific rehabilitation approaches to attention retraining and retraining of executive functioning skills. Future research is needed on rehabilitation techniques in other domains of cognition. 4) Training in the use of supportive devices (either a memory book or more technologically enhanced compensatory devices) to support the individual's daily activities remains central to the independent function of the individual in the community. Though emerging treatments (eg, virtual reality environments) show relative degrees of promise for inclusion in the rehabilitation of the individual with TBI, these need further evaluation in systematic trials.

Dopaminergic challenge with bromocriptine one month after mild traumatic brain injury: altered working memory and BOLD response

Catecholamines, particularly dopamine, modulate working memory (WM). Altered sensitivity to dopamine might play a role in WM changes observed after traumatic brain injury (TBI). Thirty-one healthy controls (HC) and 26 individuals with mild TBI (MTBI) 1 month after injury were challenged with bromocriptine versus placebo before administration of a verbal WM functional MRI task. Bromocriptine was associated with improved WM performance in the HC but not the MTBI group. On bromocriptine, the MTBI group showed increased activation outside of a task-specific region of interest. Findings are consistent with the hypothesis that individuals with MTBI have altered responsivity to dopamine.

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.

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.

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.