The therapeutic potential of bromocriptine in neuropsychological rehabilitation of patients with acquired brain damage

Apathy following traumatic brain injury: A review

Apathy is a common problem after traumatic brain injury (TBI) and can have a major impact on cognitive function, psychosocial outcome and engagement in rehabilitation. For scientists and clinicians it remains one of the least understood aspects of brain-behaviour relationships encompassing disturbances of cognition, motivation, emotion and action, and is variously an indication of organic brain disease or psychiatric disorder. Apathy can be both sign and symptom and has been proposed as a diagnosis in its own right as well as a secondary feature of other conditions. This review considers previous approaches to apathy in terms of relevant psychological constructs and those neural counterparts most likely to be implicated after TBI. Neurobehavioural disorders of apathy are characterised chiefly by dysfunction of executive control of goal-oriented behaviour or the neural substrates of reward-based and emotional learning. We argue that it is possible to distinguish a primary disorder of apathy as an organic neurobehavioural state from secondary presentations due to an impoverished environment or psychological disturbance which has implications for treatment.

Apathy following traumatic brain injury

Traumatic brain injury (TBI) may result in significant emotional and behavioral changes, such as depression, impulsivity, anxiety, aggressive behavior, and posttraumatic stress disorder. Apathy has been increasingly recognized as a relevant sequela of TBI, with a negative impact on the patients' quality of life as well as their participation in rehabilitation activities. This article reviews the nosologic and phenomenological aspects of apathy in TBI, diagnostic issues, frequency and prevalence, relevant comorbid conditions, potential mechanisms, and treatment.

Apathy After Traumatic Brain Injury: An Overview of the Current State of Play

Apathy is a decrease in behavioural, cognitive and emotional components of goal-directed behaviour. Clinically, it is characterised by diminished initiation, reduced concern, and decreased activity. Apathy is a common occurrence following traumatic brain injury (TBI), occurring in around 60% of people. Consequences are widespread, negatively impacting independence, social integration, rehabilitation outcome, vocational outcome, coping and caregiver burden. The current knowledge base on apathy following TBI is presented, with implications for clinical practice. This includes a review of clinical presentations, neuroanatomical and neurochemical substrates associated with apathy, and differential diagnoses. Instruments to measure apathy are presented, highlighting those with demonstrated reliability and validity for the TBI population. Current evidence for pharmacological and non-pharmacological methods of treatment is described, with a model for non-pharmacological interventions provided and discussion of challenges faced by clinicians when treating the patient with apathy. In the TBI arena, greater understanding of apathy and methods of treatment is pivotal given the frequency of occurrence and widespread negative consequences.

Parcellating the neuroanatomical basis of impaired decision-making in traumatic brain injury

Cognitive dysfunction is a devastating consequence of traumatic brain injury that affects the majority of those who survive with moderate-to-severe injury, and many patients with mild head injury. Disruption of key monoaminergic neurotransmitter systems, such as the dopaminergic system, may play a key role in the widespread cognitive dysfunction seen after traumatic axonal injury. Manifestations of injury to this system may include impaired decision-making and impulsivity. We used the Cambridge Gambling Task to characterize decision-making and risk-taking behaviour, outside of a learning context, in a cohort of 44 patients at least six months post-traumatic brain injury. These patients were found to have broadly intact processing of risk adjustment and probability judgement, and to bet similar amounts to controls. However, a patient preference for consistently early bets indicated a higher level of impulsiveness. These behavioural measures were compared with imaging findings on diffusion tensor magnetic resonance imaging. Performance in specific domains of the Cambridge Gambling Task correlated inversely and specifically with the severity of diffusion tensor imaging abnormalities in regions that have been implicated in these cognitive processes. Thus, impulsivity was associated with increased apparent diffusion coefficient bilaterally in the orbitofrontal gyrus, insula and caudate; abnormal risk adjustment with increased apparent diffusion coefficient in the right thalamus and dorsal striatum and left caudate; and impaired performance on rational choice with increased apparent diffusion coefficient in the bilateral dorsolateral prefrontal cortices, and the superior frontal gyri, right ventrolateral prefrontal cortex, the dorsal and ventral striatum, and left hippocampus. Importantly, performance in specific cognitive domains of the task did not correlate with diffusion tensor imaging abnormalities in areas not implicated in their performance. The ability to dissociate the location and extent of damage with performance on the various task components using diffusion tensor imaging allows important insights into the neuroanatomical basis of impulsivity following traumatic brain injury. The ability to detect such damage in vivo may have important implications for patient management, patient selection for trials, and to help understand complex neurocognitive pathways.

Working memory and dopamine: clinical and experimental clues

Working memory has been successively considered as a mnesic or executive process. The cognitive processes involved in working memory and the executive functions are closely linked. Most authors currently agree that executive functions include planning, attentional maintenance, mental flexibility and attentional inhibition. Considering that the role of the central administrator, the main module of the working memory model, is to manage new situations, inhibit old non-pertinent schemes, or carry out attentional control, it is clear that it involves the different executive processes mentioned above. Therefore, even though the working memory model has its origins in the classic concept of short-term memory, it is now situated at the interface between memory and executive functions. The identification of the neuroanatomical support of these processes has been widely explored for many years. The involvement of monoaminergic neurotransmitter systems, and in particular of the dopaminergic system, in these complex cognitive functions has been suggested by numerous studies, both in humans and in non-human primates.

Bromocriptine-responsive akinetic mutism following endoscopy for ventricular neurocysticercosis. Case report and review of the literature

A 26-year-old woman with obstructive hydrocephalus caused by a cysticercal cyst blocking the left foramen of Monro was initially treated with an external ventriculostomy and subsequent endoscopically assisted cyst resection and septostomy. Postoperatively, the patient developed the clinical syndrome of akinetic mutism, but her condition improved after the administration of the dopaminergic agonist bromocriptine. This result indicates that a disruption in the ascending dopaminergic pathway involved in behavior formation was likely the cause of these neurological symptoms.

Apathy and cognitive performance in older adults with depression

OBJECTIVES

Recent studies have linked apathy to frontal lobe dysfunction in persons with dementia, but few studies have explored this relationship in older, depressed persons without dementia. We examined the association between apathy and cognitive function in a group of older persons with major depression using standardized neuropsychological tests. We hypothesized that presence of apathy in depression is associated with poorer frontal executive performance.

METHODS

We analyzed data from 89 older adults with major depression. We defined apathy using four items from the Hamilton Psychiatric Rating Scale for Depression which reflect the clinical state of apathy, including 'diminished work/interest,' 'psychomotor retardation,' 'anergy' and 'lack of insight.'

RESULTS

Apathy most strongly correlated with two verbal executive measures (Stroop C and FAS), a nonverbal executive measure (Wisconsin Card Sorting Test-Other Responses), and a measure of information processing speed (Stroop B). Apathy was not associated with age, sex, education, medical illness burden, Mini-Mental State Examination score and Full Scale IQ score. Stepwise regression analyses of significant cognitive tests showed that apathy alone or apathy plus depression severity, age, or education accounted for a significant amount of the variance.

CONCLUSIONS

The results of this study provide support for an apathy syndrome associated with poorer executive function in older adults with major depression.

Positive outcomes in traumatic brain injury-vegetative state: patients treated with bromocriptine

OBJECTIVE

To assess the effects of multidisciplinary rehabilitation interventions and use of bromocriptine on outcome in patients with traumatic brain injury-vegetative state (TBI-VS).

DESIGN

Retrospective review of clinical cases.

SETTING

Free-standing rehabilitation hospital; Acute and extended rehabilitation hospital.

PARTICIPANTS

Five consecutive TBI-VS patients, as well as 33 TBI-VS patients and 37 traumatic brain injury-minimally conscious state (TBI-MCS) patients reported in the literature.

INTERVENTIONS

Bromocriptine administration, systematic neuropsychologic testing, sensory stimulation, and traditional comprehensive rehabilitation with physical therapy, occupational therapy, and speech therapy.

MAIN OUTCOME MEASURES

Disability Rating Scale (DRS) at 1, 3, 6, and 12 months postinjury and FIM instrument scores at 1 month and 12 months postinjury, Coma Recovery Scale, and Barry Rehabilitation Inpatient Screening of Cognition.

RESULTS

The 5 TBI-VS patients emerged from a VS into a MCS and regained functional status. Their recovery of physical and cognitive functioning, as rated by the DRS, was greater than previously reported in the literature for patients in a VS or MCS at 3, 6, and 12 months postinjury.

CONCLUSION

Bromocriptine administration, systematic neuropsychologic testing, sensory stimulation, a comprehensive rehabilitation program, or a combination of these treatments may enhance functional recovery in this TBI-VS patient group. Further systematic study to quantify the contribution of these variables and to reproduce this data in a larger patient population should be performed.

Depressive syndromes in dementia

BACKGROUND

Depressive syndromes in dementia are common, treatment is challenging and controlled intervention studies are small in number. The goal of this paper is to review known information about the etiology, epidemiology and treatment of these syndromes, as summarized at the recent Canadian Consensus Conference on Dementia.

METHODS

A number of Medline searches were performed (most recently updated in October 2000) using the subject categories dementia and depression, or apathy or emotional lability and other relevant articles were also reviewed. The background article was edited and amended at the Consensus Conference on Dementia. Final recommendations appearing in the summary article by Patterson et al were accepted by the group consensus process. Clinical discussion and informational updates were added for the current text by the authors.

RESULTS

Depressive syndromes, ranging in severity from isolated symptoms to full depressive disorders, increase in dementia. While clear-cut depressive disorder is increased in this population, sub-syndromal disorders are even more common and cause considerable distress. Antidepressant treatment may improve the quality of life in depressed, demented people, although it is less successful than in those without cognitive impairment and carries more risk of iatrogenic effects.

CONCLUSIONS

Physicians should be alert to the presence of depressive syndromes in dementia. Depressive illness should be treated and, when necessary, referral should be made to an appropriate specialist. Treatment must minimize iatrogenic effects. Although there is some support for treatment of syndromes that do not meet criteria for depressive disorder or dysthymia, the first line of intervention in these situations should involve nonpharmacological approaches.

Spatial hemineglect in humans

The paper reviews the main findings of studies of hemispatial neglect after acquired brain lesions in people. The behavioral consequences of experimentally induced lesions in animals and electrophysiological studies, which shed light on the nature of the disorder, are briefly considered. Neglect is behaviorally defined as a deficit in processing or responding to sensory stimuli in the contralateral hemispace, a part of the own body, the part of an imagined scene, or may include the failure to act with the contralesional limbs despite intact motor functions. Neglect in humans is frequently encountered after right parieto-temporal lesions and leads to a multicomponent syndrome of sensory, motor and representational deficits. Relevant findings relating to neglect, extinction and unawareness are reviewed and include the following topics: etiological and anatomical basis, recovery; allocentric, egocentric, object-centered and representational neglect; motor neglect and directional hypokinesia; elementary sensorimotor and associated disorders; subdivisions of space and frames of reference; extinction versus neglect; covert processing of information; unawareness of deficits; human and animal models; effects of sensory stimulation and rehabilitation techniques.

An open-label trial of bromocriptine in nonfluent aphasia: a qualitative analysis of word storage and retrieval

Anomia is a commonly found in aphasia and has been attributed to a loss of representations (storage deficit) or to a loss of access to these representations (retrieval deficit). Bromocriptine, a dopamine agonist, was tested on four patients, two men and two women, with nonfluent aphasia. The patients were tested in an open-label ABBA design using a stochastic model that measured the degree of storage and retrieval deficits. All patients showed significant improvements in word retrieval. Bromocriptine may be a useful adjunct in the treatment of selected patients with a nonfluent aphasia in which retrieval deficits play a major role.

Frontal lobe dysfunction in patients with non-frontal malignant gliomas: a monoaminergic dysregulation?

Previous investigations concerned with the neuropsychological function of patients with intracerebral supratentorial malignant gliomas has revealed the frequent occurrence of signs suggestive of an inhibitory frontal lobe dysfunction regardless of the intracerebral localization of the tumor and before the diagnosis was known to either the investigator or the patient. Upon closer analysis, the frontal lobe dysfunction has been verified by the demonstration of reduced blood flow in frontal areas in these patients. Since many of the findings can be related to a dysfunction of dopaminergic neurotransmission, we hypothesize that abnormal astrocytes interfere with the metabolism, transport and release of various neurotransmitters of which dopamine may be the one responsible for the most striking neuropsychological abnormalities in patients with malignant gliomas.

Light deprivation soon after frontal brain trauma accelerates recovery from attentional deficits and promotes functional normalization of basal ganglia

BACKGROUND

Light deprivation significantly accelerates recovery from attention deficits (neglect) after cortical ablation in rats. We hypothesized that light deprivation would improve recovery after traumatic contusive brain injury (TBI) and do so by enhancing dopaminergic function in the ipsilateral basal ganglia.

METHODS

Adult rats received left frontal contusion injury and were placed into darkness or standard light/dark cycling for 48 hours. Neurologic evaluation included attentional and sensorimotor tasks. Amphetamine-induced production of the immediate early gene protein product Fos was quantified to determine neuronal dopaminergic response in caudate-putamen (striatum).

RESULTS

Unilateral frontal TBI produced severe contralateral deficits in all tasks. Postoperative light deprivation resulted in improved recovery from attentional but not sensorimotor deficits. Five days after injury, ipsilateral striatal Fos expression was reduced by 51% in TBI rats experiencing normal light cycling (p < 0.006). In contrast, postoperative light deprivation normalized striatal Fos expression. By 6 weeks, all TBI rats demonstrated nearly full recovery and striatal Fos expression was symmetrical between the two striata.

CONCLUSION

Postoperative light deprivation may improve recovery from TBI-induced attention deficits by normalizing basal ganglia function.

Neuropsychiatrie of biologische psychiatrie; een toekomstvisie in historisch perspectief

Neuropsychiatry or Biological Psychiatry There is an urgent need to reconsider the position of psychiatry within the neurosciences because of the exploding knowledge about the relationship between brain and behaviour and the delay in implementation of new findings due to the separation of neurology and psychiatry. Biological psychiatry and psychopharmacology originate from the discovery by chance of psycho-active compounds in the early fifties and have contributed to the scientification of psychiatry. The impact of biological psychiatry for the pathophysiology of psychiatric disorders, however, is limited as a result of its biased orientation on neurotransmitters and receptors. The neuropsychiatric paradigm integrates knowledge from several domains, such as functional neuroanatomy, genetics and endocrinology and opens new vistas for the involvement of neuronal circuits in the initiation and maintenance of behavioural disturbances. In addition, novel and more specific treatment modalities may emerge.

Adverse effect of dopamine agonist therapy in a patient with motor-intentional neglect

Studies in animals and humans report dopamine agonists can improve neglect. Because dopamine deficit reduces intention to act, it has been suspected the dopamine agonist bromocriptine would improve deficient hemispatial intention. Thus, the effect of bromocriptine on line bisection was examined in a patient with neglect and failure of the action-intention system. The 58-year-old patient had left-sided neglect from a right cerebral infarction involving both cortical and subcortical (striatal) structures. It was determined that neglect on a line bisection task was attributable to a motor-intentional bias by testing under congruous and incongruous video monitoring. Testing sessions were held before starting bromocriptine, on 20 mg/d, and after stopping bromocriptine. The patient's ipsilesional bias increased on bromocriptine, and improved when bromocriptine was stopped. Bromocriptine may worsen neglect if putamenal receptors are damaged. Dopamine agonists may activate the normal hemisphere, increasing an intentional bias. Clinicians using dopaminergic pharmacotherapy should assess patients for this possible adverse effect.

Akinetic mutism after fourth ventricle choroid plexus papilloma: treatment with a dopamine agonist

BACKGROUND

Akinetic mutism is a behavioral state wherein a patient seems to be awake but does not move or speak. Several patients are reported to have developed mutism after posterior fossa surgery. We present a patient who developed akinetic mutism after total excision of a choroid plexus papilloma of the fourth ventricle, and who was treated with bromocriptine.

CASE DESCRIPTION

An 18-year-old woman was admitted with akinetic mutism, which had developed 6 days after posterior fossa surgery. She had had no neurologic deficit in the first 5 days after surgery and could communicate with her family. Despite antioedematous therapy and daily lumbar punctures to drain cerebrospinal fluid, there was no clinical improvement after she entered the akinetic mute state. Brain magnetic resonance revealed ventriculomegaly; brain single photon emission computed tomography revealed bilateral reduction of perfusion in the frontal region. Because daily lumbar drainage did not result in clinical improvement, shunt placement was not considered. Bromocriptine therapy was begun at a dose of 2x2.5 mg; 24 hours later, the patient started to speak and move her upper extremities. Further improvement occurred over the following week when the dose was increased to 3x2.5 mg. Bromocriptine was replaced with a placebo to determine whether the neurologic improvement was caused by the medicine. The patient's neurologic status deteriorated progressively; therefore, bromocriptine was restarted and she was discharged from the hospital. During the 6 months of follow-up, the patient has remained in good health.

CONCLUSIONS

The etiology of akinetic mutism is not clear. Monoaminergic pathways, particularly dopaminergic cell groups, are most probably involved in this syndrome, because bromocriptine has a dramatic effect on these patients, as demonstrated in our case.

D1- versus D2-receptor modulation of visuospatial working memory in humans

The effects of pergolide, a mixed D1/D2 receptor agonist, and bromocriptine, a selective D2 receptor agonist, were assessed in a visual delay task to further investigate the "dopamine link" of working memory in humans and to look for differential D1 versus D2 receptor contributions. Two groups of 32 healthy young adults (16 female) received either 0.1 mg of pergolide or 2.5 mg of bromocriptine in a placebo-controlled cross-over design. A pretreatment with domperidone, a peripherally active D2 antagonist, was performed in both groups to reduce side effects. Interindividual differences in pharmacokinetics were controlled by the time course of serum prolactin inhibition. The working memory paradigm was a visuospatial delayed matching task; the location of a randomly generated seven-point pattern had to be memorized and compared after 2, 8, or 16 sec with a second pattern that was either identical or slightly shifted within a reference frame. The task was designed with the intention to present unique stimuli at each trial and to require minimal motor demands. Practice effects between the two pharmacological test days were minimized by training sessions that preceded the tests. The paradigm showed significant error and reaction time increases with longer delays. After comparable doses, only pergolide, but not bromocriptine, facilitated visuospatial working memory performance as demonstrated by a significant drug-by-delay interaction. These findings are in accordance with the monkey literature as well as with neuroanatomical findings, and they confirm a preferential role of prefrontal D1 receptors for working memory modulation in humans.

Motivational deficits after brain injury: effects of bromocriptine in 11 patients

OBJECTIVE

To test the hypothesis that treatment with bromocriptine would ameliorate deficits in clinical motivation, responsiveness to reward, and frontal cognitive function after brain injury.

METHOD

An open trial in six men and five women who had had either traumatic brain injury or subarachnoid haemorrhage between two months and five years previously. After repeated baseline assessments, bromocriptine was given in gradually increasing doses. Assessments were repeated at increasing doses, during maintenance, and after withdrawal. Novel structured instruments for quantifying motivation were developed; measures of anxiety and depression, and cognitive tests sensitive to motivation or frontal lobe involvement were also given.

RESULTS

Bromocriptine treatment was followed by improved scores on all measures other than mood. Improvement was maintained after bromocriptine withdrawal in eight of the patients.

CONCLUSION

Poor motivation in patients with brain injury may result from dysfunction in the mesolimbic/mesocortical dopaminergic circuitry, giving rise to associated deficiencies in reward responsiveness and frontal cognitive function.