Biological psychiatry
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Biological psychiatry · Feb 2000
Reduced glutamate in the anterior cingulate cortex in depression: an in vivo proton magnetic resonance spectroscopy study.
Functional imaging studies suggest a specific role of the anterior brain regions in the pathogenesis of major depression. The aim of this study was to evaluate possible neurochemical alterations in the frontomesial cortex in patients with major depressive episode using in vivo proton magnetic resonance spectroscopy ((1)H-MRS). ⋯ This study suggests a possible role of altered glutamatergic neurotransmission within the anterior cingulate in the pathogenesis of mood disorders. The otherwise unremarkable findings of major brain metabolites confirms lack of neurodegenerative or membrane metabolic changes in major depression.
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Biological psychiatry · Jan 2000
Dissociation of ketamine effects on rule acquisition and rule implementation: possible relevance to NMDA receptor contributions to executive cognitive functions.
The demands of the Wisconsin Card Sorting Test (WCST) change with experience. This report contains two studies designed to examine N-methyl-D-aspartate (NMDA) receptor contributions to the executive components of WCST performance. These aspects of WCST performance figure more prominently in the initial completion of this task than in subsequent task repetitions in healthy populations. ⋯ This order dependency further implicates NMDA receptors in executive cognitive functions associated with the frontal cortex.
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Biological psychiatry · Dec 1999
Sensory gating in chronic posttraumatic stress disorder: reduced auditory P50 suppression in combat veterans.
Posttraumatic stress disorder (PTSD) may be associated with a general impairment of cognitive function that extends beyond the processing of trauma-specific stimuli. Suppression of the auditory P50 response to repeated stimuli occurs in normal subjects and reflects the central nervous system's ability to screen out repetitive stimuli, a phenomenon referred to as sensory gating. This study examines P50 sensory gating to nonstartle auditory stimuli in PTSD subjects and normal controls. ⋯ This study provides evidence that PTSD is associated with impaired gating to nonstartle trauma-neutral auditory stimuli.
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Biological psychiatry · Oct 1999
ReviewPsychiatric research ethics: an overview of evolving guidelines and current ethical dilemmas in the study of mental illness.
The field of psychiatry has an opportunity to construct a more refined, perhaps more enduring understanding of the ethical basis of mental illness research. The aim of this paper is to help advance this understanding by 1) tracing the evolution of the emerging ethic for biomedical experimentation, including recent recommendations of the President's National Bioethics Advisory Commission, and 2) reviewing data and concepts related to compelling ethical questions now faced in the study of mental disorders. Empirical findings on informed consent, the ethical safeguards of institutional review and surrogate decision making, and the relationship between scientific and ethical imperatives are outlined. ⋯ Most importantly, psychiatric investigators will need to demonstrate their appreciation and respect for ethical dimensions of investigation with special populations. Further empirical study and greater sophistication with respect to the distinct ethical issues in psychiatric research are needed. Although such measures present many challenges, they should not interfere with progress in neuropsychiatric science so long as researchers in our field seek to guide the process of reflection and implementation.
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Biological psychiatry · Aug 1999
Global variation in the frequencies of functionally different catechol-O-methyltransferase alleles.
Catechol-O-methyltransferase (COMT) has been investigated as a candidate gene in many neurologic disorders involving catecholaminergic systems. The NlaIII restriction site polymorphism (RSP) at COMT is a G<-->A (site absent<-->site present) single nucleotide polymorphism (SNP) at nucleotide 322/472 (in the short or long mRNA) that results in a Val<-->Met polymorphism at amino acid 108/158 (in soluble or membrane-bound) COMT protein and different enzyme activity levels, high for Val, low for Met. COMT enzyme activity is known to vary among ethnic groups, presumably as a result of different population frequencies of these COMT alleles. We have undertaken a direct survey of allele frequencies of this polymorphism in a global sample of populations. ⋯ This is the first global survey of the COMT*L and COMT*H allele frequencies, confirming and extending earlier studies to show significant world-wide variation. This is also the first study establishing the COMT*L allele as the derived allele unique to humans. Henceforth, in any population-based association studies of this polymorphism, the control allele frequencies should be in agreement with these published values for corresponding ethnic groups.