An fMRI study of executive functioning after severe diffuse TBI

PRIMARY OBJECTIVE

Preliminary study of whether severe diffuse traumatic brain injury (TBI) increases extent of frontal tissue recruited by cognitive control tasks.

RESEARCH DESIGN

Functional magnetic resonance imaging (fMRI) on N-back working memory (WM)and arrows inhibition tasks in a 46 year old man who had severe diffuse TBI 1 year earlier, a 44 year old man (inhibition task) and three women (working memory task), age 20-26 years. Images were acquired by 1.5 T magnet with BOLD method and PRESTO pulse sequence and analysed using SPM.

MAIN OUTCOMES AND RESULTS

Frontal activation increased under 2-back relative to 1-back condition of working memory in all participants with more extensive activation in the TBI patient relative to controls. Frontal activation increased with inhibition on the arrows task, but was greater in the TBI patient.

CONCLUSION

Severe diffuse TBI results in recruitment of additional neural resources for cognitive control.

Utilization of emergency center services by older adults with a psychiatric diagnosis

Information regarding older adult emergency center (EC) patient characteristics remains limited, despite its increasing importance in health care delivery systems. This retrospective study encompasses all EC visits over an eight-year period (n = 825,682) to a large urban county hospital. Only participants with a primary psychiatric diagnosis were examined, and included a total of 53,894 adults, 18-64 years old and 1,478 adults, > or =65 years old. Despite an increasing aging population, EC visits for older adults with psychiatric disorders did not increase over time. Within the older adult sample, cognitive, psychotic, and bipolar disorders were associated with higher rates of admission to the hospital, while substance use, depressive, and anxiety disorders were associated with lower numbers of inpatient admissions. African-Americans were over-represented in the EC and admitted to the hospital at higher rates, compared to other ethnic groups. Caucasian patients were the group most frequently diagnosed with a substance use disorder. In conclusion, differences in race, and diagnosis support the idea that such variables directly relate to utilization rates, presentation, and disposition within the EC.

Depression and posttraumatic stress disorder at three months after mild to moderate traumatic brain injury

To investigate the frequency and risk factors of major depressive disorder (MDD) after mild to moderate traumatic brain injury (TBI), 69 TBI and 52 general trauma (GT) patients were prospectively recruited and studied at 3-months postinjury. There was a nonsignificant difference in the proportion of MDD patients in the TBI and GT groups. Therefore, a composite MDD group (TBI and GT patients) was compared to patients who were nondepressed. Female gender was related to MDD, but no other risk factors were identified. MDD was associated with disability (Glasgow Outcome Scale, Community Integration Questionnaire) and cognitive impairment. MDD was comorbid with posttraumatic stress disorder. Implications for postacute management of mild to moderate TBI are discussed.

Validity and sensitivity to change of the extended Glasgow Outcome Scale in mild to moderate traumatic brain injury

Using a structured outcome interview, this study addressed the validity and sensitivity to change of the Glasgow Outcome Scale (GOS) and the Extended GOS (GOSE) in a prospective study of patients who sustained mild (n = 30) to moderate (n = 13) traumatic brain injury (TBI) or general trauma (n = 44). The patients were recruited from the emergency center or inpatient units of Ben Taub General Hospital and invited to participate in follow-up examinations at 3 and 6 months. Using a series of functional outcome measures, assessment of affective status, and neuropsychological tests as criteria, the validity of the GOSE generally exceeded the GOS. Analysis of the outcome data for the patients who completed both the 3-month and 6-month assessments disclosed that the GOSE was more sensitive to change than the GOS. Comparison of the 3-month outcome data disclosed that the GOSE and GOS scores did not differ for the TBI and general trauma groups. These findings lend further support for utilization of the GOSE in clinical trials when it is based on a structured interview.

Rapid response of emotional incontinence to selective serotonin reuptake inhibitors

Emotional incontinence (EI) is a perturbing condition characterized by uncontrollable outbursts of exaggerated, involuntary facial expressions and pathological crying or laughter. There is increasing evidence that serotonergic neurotransmission may be damaged in EI. The authors report 4 pathological crying cases (3 poststroke and 1 with multiple sclerosis) and 1 case of pathological laughter after traumatic brain injury. EI improved dramatically with three different selective serotonin reuptake inhibitors (fluoxetine, sertraline, and paroxetine) in the context of these different CNS diseases.

SPECT findings on psychosis in Alzheimer's disease

OBJECTIVE

This study examined whether psychosis in Alzheimer's disease is associated with cerebral perfusion patterns appreciable by single photon emission computed tomography (SPECT) scans.

METHOD

All cooperative outpatients enrolled in an Alzheimer's disease research center with the diagnosis of probable Alzheimer's disease and a Clinical Dementia Rating of mild or moderate were interviewed with their primary caregivers. Current and past psychiatric functioning was assessed by using the Hamilton Depression Rating Scale, the Structured Clinical Interview for DSM-III-R, and the Behavioral Pathology in Alzheimer's Disease Rating Scale. Patients without premorbid psychosis received SPECT scans, and the scans of the patients with delusions or hallucinations (N = 30) were compared to the scans of patients without these symptoms (N = 16).

RESULTS

The patients with delusions (N = 29) had hypoperfusion of the left frontal lobe in relation to the right frontal lobe. The patients with hallucinations (N = 10) had hypoperfusion in the parietal lobe.

CONCLUSIONS

Psychotic patients with Alzheimer's disease had a pattern of cerebral blood flow deficits significantly different from that of nonpsychotic patients. This suggests that patterns of cerebral dysfunction may be expressed symptomatically as psychosis.

Clinical variables associated with psychosis in Alzheimer's disease

OBJECTIVE

The authors explored whether personal or family history of major mental illness, negative symptoms, or behavioral measures are associated with positive psychotic symptoms in Alzheimer's disease.

METHOD

Fifty-seven patients with Alzheimer's disease were studied prospectively during interviews with the patients and their primary caregivers.

RESULTS

Psychotic patients with Alzheimer's disease did not differ in cognitive functioning from nonpsychotic patients with Alzheimer's disease. No association was found between personal or family history of mental illness and psychosis. Asociality was the only negative symptom associated with psychosis. Psychotic patients had more behavioral disturbances.

CONCLUSIONS

Positive psychotic symptoms in Alzheimer's disease are not associated with certain aspects of cerebral functioning but are associated with behavioral disturbances.

Brain mapping with functional MR imaging: comparison of gradient-echo--based exogenous and endogenous contrast techniques

PURPOSE

To compare directly the two most widely used methods of functional magnetic resonance (MR) imaging--dynamic contrast material-enhanced MR imaging and blood oxygenation level-dependent (BOLD) MR imaging.

MATERIALS AND METHODS

Five healthy volunteers underwent dynamic contrast-enhanced and BOLD MR imaging with a conventional 1.5-T MR unit during visual stimulation and a dark control state. BOLD studies were performed with a gradient-echo sequence, and dynamic MR imaging was performed with an echo-shifted gradient-echo sequence after intravenous administration of a bolus of gadopentetate dimeglumine.

RESULTS

A significantly greater percentage signal change was found with dynamic MR imaging than with the BOLD technique. The extent of area activated was also significantly greater.

CONCLUSION

With standard clinical imagers and these gradient-echo-based techniques, greater percentage activation and area of activation can be achieved with dynamic MR imaging than with BOLD MR imaging.

Brain imaging in schizophrenia

Neuroimaging provides an unprecedented means by which to study psychiatric disorders. Structural imaging methods, i.e. computerized tomography (CT) and magnetic resonance imaging (MRI), have revealed subtle differences in the brains of schizophrenic patients that appear to be present before symptom onset. Radionuclide functional methods such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) have led to hypotheses about dysfunction in specific neuronal networks in schizophrenia. New advances in MRI allow functional data to be obtained noninvasively in a single individual using conventional MRI scanners. This chapter discusses the parallels between the historical technical developments in neuroimaging and the deepening understanding of the etiology and manifestations of schizophrenia.

A case of organic mania associated with open heart surgery

Organic mania has been reported to have multiple etiologies. A case is described of a patient who developed mania following a coronary artery bypass graft and mitral valve replacement. Cerebral abnormalities were not detected by computed tomographic or magnetic resonance imaging scans, but an area of dysfunction was found using single photon emission computed tomographic (SPECT) imaging. The lesion resolved when the patient became clinically asymptomatic. The area of decreased cerebral perfusion associated with the patient's mania was in an atypical location, raising questions about which brain regions can result in well-defined psychiatric syndromes.

Evaluation of the role of antinociception in self-injurious behavior following intranigral injection of muscimol

In rats, bilateral injection of muscimol (30-60 ng/site) into the medial substantia nigra zona reticulata exerted an antinociceptive effect in the hotplate and tail-flick tests. Injections of muscimol into the substantia nigra also induced intense stereotyped behavior and self-injurious behavior (SIB). Tail-flick and hindpaw-lick responses were inhibited between 30 and 120 min after muscimol, but recovered by 240 min. The antinociceptive responses were not due to motor impairment or ataxia induced by muscimol because a variety of highly-coordinated stereotyped behavioral responses, including rearing, sniffing, head bobbing and licking occurred concurrently. Injection of muscimol into the deep mesencephalic nucleus (DpMcN) also inhibited the tail-flick and hindpaw-lick responses and caused stereotyped behavior but did not induce self-injurious behavior. Injections of muscimol into the substantia nigra, angled (45 degrees) to avoid passing through the deep mesencephalic nucleus, still exerted antinociceptive activity and caused self-injurious behavior. Bilateral microinjections of baclofen (300 ng), 4,5,6,7-tetrahydroisoxazols (5,40c)pyridin-3-ol (THIP; 300 ng), sodium valproate + D,L-diaminobutyric acid (1 microgram), substance P (2.5 micrograms) or D-Pro2-D-Trp7.9-substance P (2.5 micrograms), all suppressed hindpaw-lick responses, although only THIP reduced tail-flick responses. None of these treatments evoked self-injurious behavior. Naloxone (10 mg/kg), picrotoxin (5 mg/kg) or atropine (10 mg/kg) injection of muscimol into the substantia nigra (60 ng) or a single pretreatment with p-chlorophenylalanine diethyl ester (PCPA; 500 mg/kg; 48 hr prior to muscimol) failed to suppress the hindpaw-lick response or self-injurious behavior. These results suggest that the injection of muscimol into the substantia nigra evokes a centrally-mediated antinociception which alone is not sufficient to induce self-injurious behavior. Both antinociception and self-injurious behavior after injection of muscimol into the substantia nigra appear unrelated to cholinergic, serotoninergic, or naloxone-sensitive nociceptive systems; however, the role of activation of gamma-aminobutyric acid (GABA) receptors in these actions of muscimol also remains to be clarified.

Transient expression of a surface antigen on a small subset of neurones during embryonic development

During development, neurones find and interconnect with their targets in a remarkably precise way. The unfolding of neuronal specificity involves a series of highly specific recognition events which are likely to be coordinated by the spatial and temporal expression of many different surface molecules. At early stages of development, neuronal recognition occurs most dramatically at the tips of growing axons, at growth cones and their filopodia. Previous studies on the grasshopper embryo suggest that specific filopodial contacts lead to the stereotyped patterns of selective axonal fasciculation; these results support the 'labelled pathways' hypothesis which predicts that the different neighbouring axon fascicles in the embryonic neuropil within filopodial grasp are differentially labelled. To uncover the molecular labels on fasciculating embryonic axons, we screened 2,000 monoclonal antibodies generated against the embryonic neuroepithelium. Here we describe three antibodies which reveal surface antigens whose temporal and spatial expression during embryogenesis correlate with the predictions of the model. In particular, the Mes-2 antibody recognizes an antigen which is transiently expressed on the surface of only 4 out of approximately 1,000 neurones in each metathoracic hemisegment during a short period of embryogenesis. The growth cones of two of these neurones fasciculate in the periphery and innervate the same target. Moreover, they transiently express the Mes-2 surface antigen while doing so.