Mapping of cerebrovascular reactivity using BOLD magnetic resonance imaging.

Blood oxygen level-dependent (BOLD) contrast MRI is a simple non-invasive method of estimating "perfusion," and combined with a vasodilatory stimulus, may allow estimation of cerebral vascular reserve. We compared BOLD carbon dioxide (CO2) reactivity in the middle cerebral artery (MCA) perfusion territory to MCA flow velocity reactivity determined using transcranial Doppler ultrasound (TCD) in 16 patients with unilateral carotid artery stenosis or occlusion. Both BOLD and TCD reactivities were calculated from measurements acquired when the subjects were breathing air, and again when breathing a 6% CO2/air mixture, and were normalized by dividing by the difference in end tidal (ET) CO2.

Auditory hallucinations: phenomenology, neuropsychology and neuroimaging update.

Auditory verbal hallucinations (AVHs) are a cardinal feature of psychosis. Recent research is reviewed which has attempted to advance our knowledge of the mechanisms underlying this symptom. Phenomenological surveys have confirmed the importance of the content of such hallucinations and their meaning to the voice-hearer.

Peripheral hormonal responses to D-fenfluramine as a probe of central serotonergic function in humans.

We tested the hypothesis that D-fenfluramine (DFEN)-elicited cortisol (CORT) release in humans may be mediated by a direct effect on the adrenal gland by pretreating subjects with dexamethasone (DEX), to prevent release of ACTH from the pituitary, followed by a DFEN challenge test. Eight healthy subjects (four males; four female) (mean age = 38.1 +/- 8.

Grading of cerebral dynamic autoregulation from spontaneous fluctuations in arterial blood pressure.

Background And Purpose: Assessment of cerebral autoregulation has been traditionally performed with static changes in arterial blood pressure. Newer dynamic methods require the induction of sudden drops in arterial blood pressure with the sudden release of bilateral thigh cuffs. An alternative method is proposed, based on the spontaneous variability of arterial blood pressure that does not require its manipulation.

Endothelial nitric oxide synthase exon 7 polymorphism, ischemic cerebrovascular disease, and carotid atheroma.

Background And Purpose: The role of endothelial nitric oxide synthase (eNOS) in normal physiology suggests that it could be a potential candidate gene for stroke. Reduced eNOS activity could mediate an increased stroke risk through hypertension or independent of hypertension through abnormal vasomotor responses, promoting atherogenesis, or increased platelet adhesion and aggregation. Recently, a common polymorphism in exon 7 of the eNOS gene (894G-->T) has been reported to be a strong risk factor for coronary artery disease.

A comparative study of iatrogenesis, medication abuse, and psychiatric morbidity in chronic pain patients with and without medically explained symptoms.

We report a case control study comparing patients attending a pain clinic whose symptoms were not considered medically explained (cases) with those whose symptoms were considered medically explained (controls). Principal comparisons were psychiatric morbidity, medication use, and iatrogenic factors assessed by interview, and questionnaire measures of anxiety, depression, functional impairment, coping strategies and pain beliefs. Medically unexplained symptoms were associated with the presence of psychiatric morbidity (odds ratio = 3.

Nitric oxide synthase inhibition in humans reduces cerebral blood flow but not the hyperemic response to hypercapnia.

Background And Purpose: Animal studies suggest that nitric oxide (NO) is important in basal cerebral blood flow (CBF) regulation and that it may mediate the vasodilatory response to carbon dioxide. We investigated its role in the human circulation using the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA).

Methods: L-NMMA was administered as an intravenous bolus at three doses (1, 3, and 10 mg/kg).

Helicobacter pylori infection: a risk factor for ischaemic cerebrovascular disease and carotid atheroma.

Objectives: Chronic Helicobacter pylori infection has been associated with ischaemic heart disease although the mechanism by which it mediates this effect remains unclear. The objective was to determine whether it is also a risk factor for ischaemic cerebrovascular disease

Methods: A total of 238 patients and 119 controls were studied. Patients were characterised into stroke subtypes based on pathogenic mechanisms and carotid atheroma load was estimated using duplex ultrasound.

Imaging as a tool in exploring the neurodevelopment and genetics of schizophrenia.

Neuroimaging has enabled us to address questions about the timing and origin of brain abnormalities in schizophrenia. First episode and longitudinal computed tomography (CT) and magnetic resonance imaging (MRI) studies of schizophrenic patients have shown that the brain abnormalities are present at onset of psychosis and are non-progressive. Such findings support the idea that schizophrenia is a developmental rather than a degenerative condition.

Magnetic resonance spectroscopy in psychiatry: basic principles and applications.

In vivo magnetic resonance spectroscopy (MRS) is a safe and non-invasive tool which can be used to study aspects of brain chemistry and metabolism. Although a relatively recent technique in the field of psychiatric research, it has already been used in the study of anxiety and affective disorders, dementia, schizophrenia, and neurodevelopmental disorders. This review outlines the basic principles of MRS and summarises the research findings in psychiatric disorders.