Effects of Drugs and Hormones

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Authors

Miller DD. Andreasen NC. O'Leary DS. Rezai K. Watkins

GL. Ponto LL. Hichwa RD.

Institution

Mental Health Clinical Research Center--Major Psychoses, College of Medicine,

University of Iowa, Iowa City, USA.

Title

Effect of antipsychotics on regional cerebral blood flow measured with positron emission tomography.

Source

Neuropsychopharmacology. 17(4):230-40, 1997 Oct.

Abstract

Positron Emission Tomography (PET) imaging of regional cerebral blood flow (rCBF) provides an in vivo method for studying brain function. We used [15O]H20 PET to assess the effect of antipsychotic medications on rCBF in 17 subjects with schizophrenia. Each subject was scanned while receiving antipsychotic medication, and after having been withdrawn from antipsychotic medication for a 3-week period. The two scans were subtracted from one another, using a within subjects design, and the areas of difference were identified using the Montreal method. Subjects treated with antipsychotic medication had significantly higher rCBF in the left basal ganglia and left fusiform gyrus compared with the "off-medication" condition. Significantly higher relative rCBF in the anterior cingulate, left dorsolateral and inferior frontal cortex, and left and right cerebellum was observed when off antipsychotic medication. Upregulation of dopamine D2 receptors may lead to a regional increase of blood flow and metabolism in the basal ganglia, which may explain recently reported anatomical enlargement in these regions.

Authors

Paradiso S. Robinson RG. Andreasen NC. Downhill JE. Davidson RJ.

Kirchner PT. Watkins GL. Ponto LL. Hichwa RD.

Institution

University of Iowa Hospitals and Clinics, Department of Psychiatry Administration, Iowa City 52242, USA.

Title

Emotional activation of limbic circuitry in elderly normal subjects in a PET study.

Source

American Journal of Psychiatry. 154(3):384-9, 1997 Mar.

Abstract

OBJECTIVE: This study was undertaken to identify brain structures associated with emotion in normal elderly subjects. METHOD: Eight normal subjects aged 55-78 years were shown film clips intended to provoke the emotions of happiness, fear, or disgust as well as a neutral state. During emotional activation, regional cerebral blood flow was measured with the use of [15O]H2O positron emission tomography imaging, and subjective emotional responses were recorded. Data were analyzed by subtracting the values during the neutral condition from the values in the various emotional activations. RESULTS: The stimuli produced a general activation in visual pathways that included the primary and secondary visual cortex, involving regions associated with object and spatial recognition. In addition, the specific emotions produced different regional limbic activations, which suggests that different pathways may be used for different types of emotional stimuli. CONCLUSIONS: Emotional activation in normal elderly subjects was associated with increases in blood flow in limbic and paralimbic brain structures. Brain activation may be specific to the emotion being elicited but probably involves complex sensory, association, and memory circuitry. Further studies are needed to identify activations that are specific for emotion.

Authors

Hurtig RR. Hichwa RD. O'Leary DS. Boles

Ponto LL. Narayana S. Watkins GL.

Andreasen NC.

Institution

Department of Speech Pathology and Audiology, University of Iowa, Iowa City.

Title

Effects of timing and duration of cognitive activation in [15O]water PET studies.

Source

Journal of Cerebral Blood Flow & Metabolism. 14(3):423-30, 1994 May.

 Abstract

The multiple injection [15O]water method offers unique opportunities for studying cognitive processing by the human brain. The influence of the duration and temporal placement of an activation task, in relation to the arrival of the radiotracer in the brain, is a fundamental methodologic question for cognitive activation studies. A quantitative positron emission tomography (PET) study of five normal volunteers was performed in which the stimulation consisted of a visual activation task (alternating checkerboard pattern) superimposed on an auditory baseline task (syllable monitoring). Ten injection conditions, with varying duration and timing of the visual activation, were used. Regional CBF (rCBF) in visual cortex was measured quantitatively using the autoradiographic method. A 20-s stimulation, centered on the bolus arrival in the brain, produced significant changes in rCBF. Because varying the duration and timing of the activation task technically violates the temporal homogeneity assumption of the autoradiographic model, a mathematical simulation was formulated to evaluate the potential influence of these variations. Results of the simulation are consistent with the PET data and suggest that activation can be limited to a narrow temporal window centered on the radiotracer uptake. The ability to observe significant changes in rCBF with short stimulation intervals is of particular interest in the use of [15O]water PET for studies of cognitive processes with a short time course.

Authors

Giordani B. Boivin MJ. Berent S. Betley AT. Koeppe RA. Rothley JM.

Modell JG. Hichwa RD. Kuhl DE.

Institution

University of Michigan, Ann Arbor.

Title

Anxiety and cerebral cortical metabolism in normal persons.

Source

Psychiatry Research. 35(1):49-60, 1990 Apr.

 Abstract

The State-Trait Anxiety Inventory (STAI) was administered to 43 normalvolunteers immediately before and after a positron emission tomography (PET)procedure with [18F]-2-fluoro-2-deoxy-D-glucose (18F-FDG). High trait-anxiousindividuals had significantly higher state (situational) anxiety associatedwith the PET scan procedure than did low trait-anxious persons. State anxiety decreased significantly for all respondents following the PET scan procedure. No significant relationships between global or regional cortical metabolic rates and state anxiety were observed. The direct cortical metabolic effects of heightened anxiety in the scan setting, should they exist, are likely obscured in the normal variance of the 18F-FDG method.