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A Pfefferbaum

Publications and source records attributed to A Pfefferbaum.

At least 127 records · Page 7Linked to original sources
PubMed1990

In vivo quantification of the limbic system using MRI: effects of normal aging.

Limbic system structures are of central interest in many neuropsychiatric disorders. Magnetic resonance imaging (MRI) has a unique potential for imaging limbic system structures in vivo, but methodological constraints can limit the usefulness and interpretation of the collected image data. In this article, we present approaches for the acquisition and quantification of high resolution MR images of the limbic system. We used a long TR, cardiac gated, flow compensated, spin echo sequence to collect 22, 3-mm thick contiguous sections encompassing the limbic system. The sections were oriented relative to standard internal neuroanatomical landmarks. The sequence provided good gray matter/white matter/cerebrospinal fluid (CSF) and CSF/bone contrast; the latter is necessary for quantifying intracranial size and total CSF volume. Using operationalized criteria, we achieved high interrater reliability in volumetric measurement of temporal horn and hippocampus. This technique was then used to examine the effect of normal aging by comparing eight young (mean = 24 years) and seven old (mean = 73 years) healthy community members. We were able to demonstrate a significant age-related increase in temporal horn volume and a trend toward an age-related decrease in hippocampal volume.

Adult↗
PubMed1990

Volumetric assessment of cerebral asymmetry from CT scans.

The advent of computed tomography (CT) of the brain has facilitated the study of brain asymmetries in normal individuals and in patients with various diseases. A computerized volumetric approach to quantifying CT scan data is used to demonstrate that imperfect alignment of the subject's head in the CT scanner can be a major source of artifact in the assessment of cerebral asymmetry. An approach for estimating the extent of misalignment of the head in the scanner is described. This approach can be used to take variations in head alignment into account when studying cerebral asymmetries. When volumetric measures were used, left-handed subjects (n = 5) were found to have a significantly lower left/right ratio of total cerebral hemispheric tissue than right-handed subjects (n = 41). The amount of asymmetry in the lateral ventricles was found to depend on their total size. A method for controlling for the effect of size when measuring asymmetry of the lateral ventricles is described. In both right- and left-handed subjects, the left lateral ventricles were significantly larger than the right. A magnetic resonance (MR) scan was performed with standard alignment and with a deliberate 10 degrees misalignment, using a volunteer subject. These data are presented to demonstrate how artifactual cerebral asymmetries can be generated by head tilt and to test the quantification procedures developed.

Adult↗
PubMed1990

A quantitative analysis of CT and cognitive measures in normal aging and Alzheimer's disease.

Patients with presumptive Alzheimer's disease (AD) and healthy community volunteers received computed tomographic (CT) brain scans and cognitive tests. The CT scans were quantitatively analyzed with a semiautomated thresholding technique to derive volumetric measures of cerebrospinal fluid (CSF)-to-tissue ratios in six regions of interest (ROIs): lateral ventricles; vertex sulci, frontal sulci, Sylvian fissures, parieto-occipital sulci, and third ventricle. Regression analysis was performed on CT data from 85 older volunteers (ages 51-82) to generate age norms for each ROI. Within this group, tissue loss, as measured by the % CSF in each ROI, was highly correlated with age, although each ROI showed different rates of change over age. For all ROIs, the AD group had significantly more tissue loss than expected in normal aging. In addition, AD patients with a presenescent onset (before age 65) tended to have greater vertex sulcal and frontal sulcal tissue reduction than AD patients with a senescent onset (age 65 or after). When regional tissue reduction, corrected for age, was correlated with cognitive test scores, two sets of double dissociations emerged within the AD group: large CT z scores (i.e., decreased tissue and increased CSF) of frontal sulci, but not of the third ventricle, correlated with low Comprehension and Boston Naming Test scores, whereas large CT z scores of the third ventricle, but not of the frontal sulci, correlated with low scores on Digit Symbol and Picture Arrangement. These results suggest that heterogeneity of structural and functional integrity exists among patients with AD.

Adult↗
PubMed1990

Brain magnetic resonance imaging: approaches for investigating schizophrenia.

Magnetic resonance imaging (MRI) offers the potential for identifying, in vivo, specific brain abnormalities associated with schizophrenia. The detection of small morphological differences in areas such as the prefrontal cortex, limbic structures, and basal ganglia requires attention to a number of technical and methodological details. The effects of age, height, sex, head size, and overall tissue loss are of particular concern and are discussed. MRI acquisition and processing techniques for improving gray/white tissue contrast and image resolution are described, as are techniques for quantitative, volumetric measurement of localized regions of interest and specific brain structures as well as of the brain as a whole. Techniques for evaluating frontal lobes, temporal lobes, and basal ganglia integrity are reviewed, and recent observations on these brain regions in patients with schizophrenia are described.

Basal Ganglia↗
PubMed1989

P3 in schizophrenia is affected by stimulus modality, response requirements, medication status, and negative symptoms.

Eighteen schizophrenics who were not taking medication, 13 schizophrenics who were taking medication, and 37 age-matched controls were tested with event-related potential paradigms designed to elicit P3 response automatically or effortfully (ie, with a choice reaction time task). Electroencephalograms were recorded from the 19 standard 10-20 electrode sites. Compared with controls, both groups of schizophrenics had reduced P3 amplitudes for both effortful and automatic paradigms. P3 latencies were delayed relative to controls for the medication-taking schizophrenics in the effortful paradigms. Negative symptoms derived from the Brief Psychiatric Rating Scale within 1 week of event-related potential testing correlated negatively with both auditory and visual P3 amplitude in the subjects who were not taking medication. There was no evidence that P3 is smaller over left temporal electrode sites in schizophrenics, as has been reported by others. P3 amplitude reduction in schizophrenia is a robust psychobiological phenomenon that is present regardless of medication status or task demands.

Adult↗
PubMed1989

MRI study of brain changes with short-term abstinence from alcohol.

Magnetic resonance brain scans were obtained from 10 chronic alcoholics within 2 weeks of alcohol withdrawal, and 19 to 28 days later. Age-matched control subjects were scanned at comparable intervals. At the initial scan, the alcoholics had larger lateral ventricles than the controls; at the second scan, their ventricles were significantly smaller than at the first scan. Among the controls, there was no mean change in the size of the lateral ventricles between the first and second scan. This study demonstrates reversibility in ventricular enlargement with short-term abstinence from alcohol. The role of rehydration in this process and the possibility of further changes with continued abstinence remain to be tested.

Alcoholism↗
PubMed1988

Computed tomographic evidence for generalized sulcal and ventricular enlargement in schizophrenia.

Quantification of ventricular and sulcal volumes from the computed tomographic (CT) scans of 45 schizophrenic patients and 57 normal controls was carried out using a semi-automated computerized approach. The sizes of all cerebrospinal fluid spaces measured were significantly related to age in the control population. An age regression model was used to compare patients and controls. Schizophrenics had slightly larger ventricles and considerably larger sulci than controls. Enlargement of the ventricles and sulci was not correlated with measures of negative symptoms or neuropsychological impairment. The CT scans of eight very ill chronically institutionalized schizophrenics were also analyzed. Their CT findings did not differ significantly from the larger group of schizophrenics studied. Our results show that the cerebral atrophy found in schizophrenia is diffuse in nature and does not relate clearly to measures of disease severity or chronicity.

Adult↗
PubMed1988

Oscillatory potentials as a marker for dopaminergic disease.

In an effort to find electrophysiologic correlates of dopaminergic disease in man, we measured oscillatory potentials of the electroretinogram in normal and unmedicated schizophrenic subjects, and in rabbits given D1 agonist or antagonist drugs. We found highly reproducible oscillatory potentials in twelve male schizophrenics that were indistinguishable from those in nine male normal volunteers. We also found little electroretinographic difference among four rabbits given intramuscular injections of SKF 38393 (a D1 agonist) and four control animals injected with saline. However, four animals given SCH 23390 (a D1 antagonist) showed diminution of the b-wave and selective suppression of the second oscillatory potential. This effect was more prominent in oscillatory potentials generated by 5-Hz flicker than by a single flash. These rabbit data suggest that further efforts at finding clinical correlations may be worthwhile, possibly with trial of flicker oscillatory potentials, and they support the concept that different oscillatory potentials have different generators.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1988

Brain computerized tomography in subtypes of severe chronic schizophrenia.

Computerized tomographic (CT) brain scans were obtained in severely ill, chronic schizophrenic patients hospitalized in a long-term in-patient facility of a Veterans Administration hospital, and compared to CT brain scans from an age, sex and education-matched normal control population. In contrast to results obtained in our previous studies with younger, less severely ill, chronic schizophrenic patients, the current study population exhibited significantly increased rankings of third ventricular size and of fronto-tempero-sylvian atrophy, compared to normal control subjects.

Adult↗
PubMed1988

Brain CT changes in alcoholics: effects of age and alcohol consumption.

A computerized tomographic (CT) brain scan and assessments of lifetime alcohol consumption, body size, and cognitive performance were performed in 37 male alcoholics, aged 26-62 years. Hematocrit and mean corpuscular volume (MCV) were also measured. CT data were analyzed using a semiautomated scoring system yielding measures of percentage of fluid at the ventricles and cortical sulci. Normative brain CT data from 57 community controls spanning the adult age range allowed Z-score assessment of deviation from age norms for each alcoholic. Across the entire group, alcoholics had significantly enlarged ventricles and sulci for their age. Enlargement at both sites correlated significantly with lifetime alcohol consumption. Sulcal enlargement in alcoholics was found across all ages. In contrast, ventricular enlargement was apparent only in older alcoholics and became increasingly exaggerated with age. Measures of body size, hematocrit, and MCV correlated with ventricular but not sulcal enlargement, suggesting that nutritional factors play a role in ventricular enlargement. Associations between neuropsychological performance and CT changes or alcohol consumption were less pronounced and at times counterintuitive. The findings support a modest dose-effect relationship between ethanol exposure and changes in brain morphology, and suggest that ventricles and sulci show a different time course of response. The role of nutritional status needs to be more closely investigated.

Adult↗