Atomoxetine for Individuals With Traumatic Brain Injury

Noradrenergic antagonists mitigate amphetamine-induced recovery

Brain injury, including that due to stroke, leaves individuals with cognitive deficits that can disrupt daily aspect of living. As of now there are few treatments that shown limited amounts of success in improving functional outcome. The use of stimulants such as amphetamine have shown some success in improving outcome following brain injury. While the pharmacological mechanisms for amphetamine are known; the specific processes responsible for improving behavioral outcome following injury remain unknown. Understanding these mechanisms can help to refine the use of amphetamine as a potential treatment or lead to the use of other methods that share the same pharmacological properties. One proposed mechanism is amphetamine's impact upon noradrenaline (NA). In the current, study noradrenergic antagonists were administered prior to amphetamine to pharmacologically block α- and β-adrenergic receptors. The results demonstrated that the blockade of these receptors disrupted amphetamines ability to induce recovery from hemispatial neglect using an established aspiration lesion model. This suggests that amphetamine's ability to ameliorate neglect deficits may be due in part to noradrenaline. These results further support the role of noradrenaline in functional recovery. Finally, the development of polytherapies and combined therapeutics, while promising, may need to consider the possibility that drug interactions can negate the effectiveness of treatment.

Right hemisphere role in cognitive reserve

High levels of education, occupational complexity, and/or premorbid intelligence are associated with lower levels of cognitive impairment than would be expected from a given brain pathology. This has been observed across a range of conditions including Alzheimer's disease (Roe et al., 2010), stroke (Ojala-Oksala et al., 2012), traumatic brain injury (Kesler et al., 2003), and penetrating brain injury (Grafman, 1986). This cluster of factors, which seemingly protect the brain from expressing symptoms of damage, has been termed "cognitive reserve" (Stern, 2012). The current review considers one possible neural network, which may contribute to cognitive reserve. Based on the evidence that the neurotransmitter, noradrenaline mediates cognitive reserve's protective effects (Robertson, 2013) this review identifies the neurocognitive correlates of noradrenergic (NA) activity. These involve a set of inter-related cognitive processes (arousal, sustained attention, response to novelty, and awareness) with a strongly right hemisphere, fronto-parietal localization, along with working memory, which is also strongly modulated by NA. It is proposed that this set of processes is one plausible candidate for partially mediating the protective effects of cognitive reserve. In addition to its biological effects on brain structure and function, NA function may also facilitate networks for arousal, novelty, attention, awareness, and working memory, which collectively provide for a set of additional, cognitive, mechanisms that help the brain adapt to age-related changes and disease. It is hypothesized that to the extent that the lateral surface of the right prefrontal lobe and/or the right inferior parietal lobe maintain structural (white and gray matter) and functional integrity and connectivity, cognitive reserve should benefit and behavioral expression of pathologic damage should thus be mitigated.

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.

Fatigue in Parkinson disease, stroke, and traumatic brain injury

Fatigue is a serious, QoL-limiting symptom of many neurologic conditions. Physicians should be thorough and consistent in their assessment for this problem and not let motor symptoms monopolize an office visit. Although the use of pharmacology to treat this problem has predominantly only anecdotal evidence of efficacy, several nonpharmacologic interventions may prove helpful. The directions of future research should aim to create clear treatment guidelines using the pharmacologic agents available.

Pharmacological management of neurobehavioural sequelae of traumatic brain injury: a survey of current physiatric practice

OBJECTIVE

To describe pharmacological preference for the treatment of neurobehavioural sequela of traumatic brain injury (TBI).

DESIGN

Survey.

PARTICIPANTS

TBI physiatrists were divided into specialists (completed a TBI fellowship or commit >70% of clinical practice time to TBI) and non-specialists.

OUTCOME MEASURES

Participants were asked to list the drugs most frequently prescribed for each of 15 neurobehavioural symptoms commonly encountered during TBI rehabilitation and enumerate neurobehavioural symptom for which they prescribed each listed drug or drug class.

RESULTS

There was no clear consensus on drug of choice for each target symptom. There were differences in drug choice patterns between specialists and non-specialists, especially for agitation.

CONCLUSION

There is limited uniformity in drug selection for various TBI neurobehavioural sequela. Potential explanations include the availability of various medications with similar clinical effect, the variability of clinical presentation and severity of neurobehavioural symptoms and the lack of clinical practice guidelines.

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.

Pharmacological enhancement of cognitive and behavioral deficits after traumatic brain injury

PURPOSE OF REVIEW

To provide the clinician with a reasonable overview of the modern pharmacological alternatives to treat the cognitive and behavioral sequels of traumatic brain injury.

RECENT FINDINGS

Original research in this area is sparse and more than half of the articles published on the subject recently have been reviews. Of the three randomized controlled trials, one studied methylphenidate (n = 18), one methylphenidate and sertraline (n = 30) and one amantadine (n = 27). All these studies reported beneficial effects on various cognitive measures, but because of the study protocols, the evidence provided may be questioned. The various reviews, uncontrolled studies and case reports suggest that at least psychostimulants, cholinergic agents, dopaminergic agents and antidepressants may be beneficial in treating the cognitive and behavioral symptoms of traumatic brain injury.

SUMMARY

The clinician trying to ameliorate the cognitive and behavioral symptoms of traumatic brain injury has to make decisions about pharmacotherapy that are still based mainly on clinical experience. Large randomized controlled trials giving high-quality evidence are so far missing. This review discusses the problems facing both the clinician and the scientist treating the cognitive and behavioral sequels of traumatic brain injury. A symptom-based approach is suggested for current practice.