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Biomedical subjects

A Pfefferbaum

Publications and source records attributed to A Pfefferbaum.

At least 109 records · Page 6Linked to original sources
PubMed1994

Effects of raclopride treatment on plasma and CSF HVA: relationships with clinical improvement in male schizophrenics.

Thirty-two acutely psychotic, male schizophrenic patients received raclopride, at 2, 6, or 12 mg/day, or haloperidol, 15 mg/day for 4 weeks after randomized, double-blind assignment. Twenty-six patients, including 19 who had been assigned one of the three doses of raclopride, completed the study. Raclopride, particularly at 12 mg/day, increased CSF homovanillic acid (HVA) at 4 weeks, and plasma HVA at 2 days, of treatment. The clinical response to raclopride was significantly correlated with plasma raclopride concentrations and baseline plasma HVA concentrations. Although raclopride is a substituted benzamide with atypical properties in animals, these results suggest that the doses of raclopride required for clinical efficacy and elevation of clinical indices of brain dopamine turnover are similar.

Adult↗
PubMed1994

The relationship between P300 amplitude and regional gray matter volumes depends upon the attentional system engaged.

Event-related potentials (ERPs) and brain magnetic resonance images (MRIs) were acquired from 28 normal men, age 21-60 years. ERPs were recorded during 3 paradigms designed to elicit automatic or effortful attention, and a combination of both. MRI-derived measures of brain gray matter, white matter and cerebral spinal fluid (CSF) volumes were computed from frontal, parietal and temporal lobes. P300 amplitude correlated significantly with gray matter volumes but not with white matter or CSF volumes. Furthermore, the relationships between P300 amplitude and gray matter volumes reflected functional rather than direct topographical relationships: P300 recorded at Pz during automatically elicited attention correlated significantly with frontal but not parietal lobe gray matter volumes, P300 recorded during effortful attention correlated significantly with parietal but not frontal lobe gray matter volumes, and P300 recorded when both types of attention were invoked correlated significantly with both frontal and parietal gray matter volumes. Startle blinks, also elicited during automatic attention-engaging paradigms, were significantly correlated with frontal but not parietal lobe gray matter volumes. There was no evidence for a direct spatial relationship between P300 amplitude and the gray matter volumes underlying the recording electrode.

Adult↗
PubMed1993

Greater abnormalities of brain cerebrospinal fluid volumes in younger than in older patients with Alzheimer's disease.

OBJECTIVE: This study used a semiautomated analysis technique to quantify differences in regional brain cerebrospinal fluid volumes observed with computed tomography between healthy adults and patients with Alzheimer's disease (AD). DESIGN: Cross-sectional, between-subject design, using an age-regression model. SETTING: Palo Alto (Calif) Department of Veterans Affairs Medical Center. PATIENTS AND OTHER PARTICIPANTS: The 117 patients with probable or definite AD were recruited from the Geriatric Psychiatry Research Unit and National Institute of Mental Health Clinical Research Center of the Palo Alto Department of Veterans Affairs Medical Center. The 114 healthy volunteers were recruited from the local community. MAIN OUTCOME MEASURES: Cerebrospinal fluid volumes estimated from computed tomographic scans and neuropsychological test scores. RESULTS: The computed tomographic estimates of ventricular and sulcal cerebrospinal fluid volumes increased significantly in all sampled brain regions in normal aging and were vastly larger in AD than in normal aging. Furthermore, younger patients with AD had significantly greater cerebrospinal fluid volume enlargement than did older patients with AD compared with healthy controls of their age. When the AD group was divided on the basis of reported age at symptom onset, patients in the early-onset group (onset before age 65 years) were quantitatively more abnormal than and showed a different pattern of abnormality from the patients in the late-onset group. This onset difference was also evident in neuropsychological test performance. CONCLUSIONS: This cross-sectional study revealed a number of converging findings that suggested greater abnormality in the early-onset than in the late-onset group of patients with AD. The possibility remains, however, that the two onset groups represent different stages along a continuum of pathologic changes.

Adult↗
PubMed1993

Factors of the Wisconsin Card Sorting Test as measures of frontal-lobe function in schizophrenia and in chronic alcoholism.

The purpose of this study was to examine the factor structure of the Wisconsin Card Sorting Test (WCST). The scores of 22 patients with schizophrenia, 20 patients with chronic alcoholism, and 16 normal control subjects were entered into a principal components analysis, which yielded three factors: Perseveration, Inefficient Sorting, and Nonperseverative Errors. WCST performance of seven patients with lesions invading the dorsolateral prefrontal cortex, available from another study, provided criterion validity for the Perseveration factor and, less strongly, for the Inefficient Sorting factor. Two patterns of performance characterized the three patient groups: the schizophrenic group and frontal lobe group had the highest Perseveration factor scores, whereas the alcoholic group had the highest Inefficient Sorting scores; the Nonperseverative Errors factor showed no significant group differences. Construct validity of these factors involved assessing, in all but the frontal group, the degree of overlap (convergent validity) and separation (discriminant validity) of each WCST factor with scores from tests of other cognitive functions. The convergent and discriminant validity of the Perseveration factor, but not the remaining two factors, received support only within the group of schizophrenic patients.

Adult↗
PubMed1993

Increase in brain cerebrospinal fluid volume is greater in older than in younger alcoholic patients: a replication study and CT/MRI comparison.

This cross-sectional study used a semi-automated analysis technique to quantify regional brain cerebrospinal fluid (CSF) volumes derived from computed tomography (CT) in 84 healthy men ranging from 21 to 82 years of age and 28 patients meeting Research Diagnostic Criteria for alcohol dependence. The goals were to replicate an earlier CT study of an independent sample of alcoholic and control subjects (Pfefferbaum et al., 1988a; Zipursky et al., 1988) and to compare CT assessments of brain changes with magnetic resonance imaging (MRI) assessments made in the same alcoholic patients (Pfefferbaum et al., 1992). Regional brain changes associated with normal aging were derived by regression analysis, using CT data collected from the healthy control subjects. As in the earlier CT study and in the concurrent MRI study, ventricular and sulcal CSF volumes in alcoholic patients were greater than would be expected for their age. Furthermore, the present CT study replicated the previous CT and MRI findings of a positive relationship between age and CSF volume enlargement in alcoholic patients over and above the normal age-related increase in CSF volume, suggesting greater vulnerability of the aging brain to alcohol. Comparison of CT- and MRI-derived estimates of ventricular and cortical sulcal volume revealed high correlations (> 0.80). MRI and CT produced similar absolute ventricular volumes, while MRI produced larger sulcal volume estimates than did CT. The difference in sulcal volume estimate may be due to differences between CT and MRI in slice thickness and sensitivity to partial volume effects.

Adult↗
PubMed1993

Correction for head size in brain-imaging measurements.

Structural brain-imaging measurements based on computed tomography (CT) or magnetic resonance imaging (MRI) are often corrected or adjusted for normal variation in head size. Some methods of head-size correction, such as the ventricle-brain ratio (VBR), are based on taking the brain structure size as a proportion of the estimated head size, while other methods have used a regression model to obtain head-size residualized structure measures. Recently, head-size correction was shown to result in less reliable volumetric measures of brain structures (Arndt et al., 1991). In the present study, MRI was used to examine the effects of head-size correction on the interrater reliability of volumetric measures of gray matter, white matter, and cerebrospinal fluid. Four raters independently scored MRI brain images from 26 subjects, generating separate estimates of head size and region of interest (ROI) size. Two methods were used to correct MRI values for differences in head size, one based on proportions and the other based on linear regression. Results confirmed that head-size correction did produce measures with lower reliability; however, further analysis based on classical measurement theory showed that the lower reliability was attributable not only to increased measurement error variance, but also to reduced true score variance. Subsequent analyses of criterion validity compared the raw (uncorrected) and head-size-corrected ROI measures in terms of their correlations with age in a sample of 43 normal control subjects, and in terms of their ability to differentiate schizophrenic patients (n = 22) from normal control subjects (n = 20). Results indicated that head-size correction often improved criterion validity, producing higher correlations with age and with diagnostic status than those produced by the raw measures. These findings suggest that head-size correction removes irrelevant true-score variance which reduces reliability yet improves the correlations with validity criteria such as age and diagnostic status.

Adult↗
PubMed1993

Magnetic resonance spectroscopic imaging of ethanol in the human brain: a feasibility study.

The in vivo distribution of ethanol in normal human brain following the consumption of a moderate amount of alcohol was measured using magnetic resonance spectroscopic imaging. Three subjects were studied, and the spatial distribution of brain ethanol, 60-min postingestion and measured at a spatial resolution of 1.5 cm, was found to be highly nonuniform with the relative ethanol signal in cerebral spinal fluid, gray matter, and white matter determined to be 1.00, 0.72, and 0.37, respectively. These spectroscopic imaging results indicate that whereas in vivo magnetic resonance studies of ethanol are feasible, quantitative studies of alcohol need to account carefully for the various tissue types within the observed volume.

Alcoholic Intoxication↗
PubMed1992

The contribution of constructional accuracy and organizational strategy to nonverbal recall in schizophrenia and chronic alcoholism.

The Rey-Osterrieth complex figure was used to assess the separate influences of the constructional accuracy and the organizational strategy employed while copying the figure on the later, incidental recall of the figure. We tested a model, which hypothesized that subjects who copied the main framework of the figure holistically would be more likely to achieve good copy accuracy scores and to reproduce the figure more accurately at recall than subjects who used a piecemeal approach during copy. Subjects included 68 detoxified, chronic alcoholics (ALC), 28 patients with schizophrenia (SZ), and 69 normal control subjects (NCS). The results showed that the ALC and the SZ groups, on average, had lower accuracy and strategy scores at copy than did the NCS group, and furthermore, that the combined contributions of copy accuracy and copy strategy accounted for group differences at recall. A path analysis revealed that, for all three groups, copy strategy had a significant direct effect on copy accuracy. Moreover, copy accuracy and copy strategy made independent contributions to recall accuracy within the ALC and NCS groups; by contrast, within the SZ group, copy strategy made an independent contribution to recall performance but copy accuracy did not. These results suggest that (1) organizational strategy can influence constructional accuracy at both copy and recall; (2) copy accuracy and strategy have the potential to influence recall independently; and (3) the recall deficit in ALC could be attributed to abnormalities in both accuracy and strategy at copy, whereas in SZ it could be attributed only to strategy abnormalities. The deficits observed on the complex figure test in the ALC and SZ were primarily nonmnemonic and were related to ability in figure construction and organizational strategy.

Adult↗
PubMed1992

Widespread cerebral gray matter volume deficits in schizophrenia.

Magnetic resonance imaging was used to investigate whether the structural brain differences commonly observed in patients with schizophrenia as compared with normal control subjects are specific to gray or white matter, and furthermore whether such abnormalities are localizable to circumscribed cortical regions. Accordingly, 22 patients meeting DSM-III-R criteria for schizophrenia and 20 healthy community volunteers, all 23 to 45 years old, received magnetic resonance imaging scans. Seven axial magnetic resonance imaging sections of 5-mm thickness were segmented into cerebrospinal fluid, gray matter, and white matter compartments and used for volumetric quantification. For the healthy control subjects, age correlated significantly with the percentage of all magnetic resonance imaging sections taken up by gray matter but not white matter. After correcting for the normal effect of age, the schizophrenic group was found to have significantly less gray matter than the control group but no difference in white matter; ventricular volume was 34% greater in the schizophrenic group. The schizophrenic group had less gray matter in all six cortical subregions analyzed; these differences attained statistical significance for all but the parietal measure. These findings have implications for studies of localized gray matter abnormalities and suggest that regional brain volume measurements need to be expressed in the context of possible widespread gray matter volume deficits in schizophrenia.

Adult↗
PubMed1992

Decreased gray matter in normal aging: an in vivo magnetic resonance study.

Using in vivo magnetic resonance (MR) images, the percentages of gray matter, white matter, and cerebrospinal fluid (CSF) in the brains of 8 young and 6 elderly normal male community volunteers were quantified. Compared with the young men, the elderly men had a significantly lower percentage of gray matter (p less than .01) and higher percentage of CSF (p less than .01). The percentage of white matter was not significantly different between the two groups. This finding suggests that the age-related decrease in brain tissue is chiefly due to loss of gray matter.

Adult↗
PubMed1992

Brain gray and white matter volume loss accelerates with aging in chronic alcoholics: a quantitative MRI study.

Magnetic resonance imaging (MRI) was used to study in vivo the brains of 49 patients with chronic alcoholism, 3 to 4 weeks post-withdrawal, and 43 normal healthy controls, all right-handed male veterans between the ages of 23 and 70 years. MRI scans were analyzed using a semi-automated procedure, which allowed the subcortical regions to be segmented into cerebrospinal fluid (CSF) and brain tissue and the cortical regions to be segmented into CSF, gray matter, and white matter. An age regression model was used to examine the effects of alcohol on brain structure, over and above that expected from the normal aging process. The alcoholics exhibited decreased tissue and increased CSF after correcting for aging. In the cortex, there was significant loss of both gray matter and white matter volume. In this sample of alcoholics, no particular cortical region was preferentially affected or spared. Furthermore, brain tissue volume loss increased with advanced age in the alcoholics. In this group of alcoholics there was no relationship between length of illness and age, i.e., the younger alcoholics had as heavy alcohol use histories as did the older alcoholics. Thus, the increased brain tissue loss with advanced age is interpreted as evidence for age-related increase in brain vulnerability to chronic alcohol abuse.

Adult↗
PubMed1991

Auditory event-related potentials and electrodermal activity in medicated and unmedicated schizophrenics.

Event-related potentials (ERPs) and electrodermal activity were studied in 14 medicated schizophrenics, 17 unmedicated schizophrenics, and 23 age- and education-matched controls. Subjects were run in three auditory stimulus paradigms differing from the usual ERP paradigms in having interstimulus intervals greater than 12 sec to permit measurement of the longer latency skin conductance response (SCR). In every paradigm medicated but not unmedicated schizophrenics had smaller N120 amplitudes and fewer SCRs than controls. In addition, medicated schizophrenics showed reduced P200 amplitude and latency, longer P320 latency, and reduced skin conductance levels in certain paradigms. These effects cannot easily be attributed to different mental states of medicated and unmedicated patients, since their Brief Psychiatric Rating Scale scores were almost the same. It is more probable that antipsychotic and antiparkinsonian drugs reduced electrodermal activity through anticholinergic mechanisms and that the antipsychotic drugs attenuated N120 through other biological mechanisms.

Adult↗
PubMed1991

Event-related potentials and eyeblink responses in automatic and controlled processing: effects of age.

Seventeen young (mean age = 20.2 years old) and 16 elderly (mean age = 72.6 years old) women were tested with event-related potential (ERP) paradigms designed to elicit responses in reaction time tasks and to a startling noise burst. EEG was analyzed from 17 standard 10-20 electrode sites. Reaction time and performance data suggested that the elderly did not perform worse than the young. Nevertheless, the physiological responses of the elderly differed significantly from those of the young. While the task-dependent P3s at Pz were smaller in the elderly than in the young, the automatic P3 was smaller yet. The distribution of both types of P3 across the scalp was more uniform in the elderly than in the young. Single-trial analyses revealed that the P3 amplitude differences at Pz were not due to latency dispersal of single trials. Single-trial startle eye blink responses to intense noise bursts during the automatic paradigm were considerably less frequent in the elderly, although their individual startle blinks were actually larger. The data demonstrate that the electrophysiological responses of the elderly are different from the young both in tasks eliciting automatic responses and in tasks requiring controlled processing.

Adult↗
PubMed1991

Neuropsychological deficits accompanying striatonigral degeneration.

This study presents a structural and functional description of a case of striatonigral degeneration (SND) and emphasizes neuropsychological findings. The patient, a 55-year-old woman with progressive and relatively intractable rigidity and bradykinesia, particularly of the right side, was studied with brain MR scans and with a wide variety of sensory, motor, and cognitive tests known to be subserved by specific brain regions. T2-weighted MR images revealed curvilinear areas of high signal in the lateral putamen at low magnetic field strength (0.3T) and adjacent regions of marked low signal in the posterior-lateral putamen at high magnetic field (1.5T). High signal changes in the insular cortex were also noted on the high field images. Letter fluency and short-term memory as well as motor speed, strength, and sequencing were selectively impaired. Taken together, the data of this case suggest that structural involvement of the putamen resulted in dysfunctions usually associated with the primary motor cortex and orbitofrontal cortex, while sparing functions of other frontal regions as well as temporal and parietal cortices.

Brain Diseases↗
PubMed1991

Event-related potentials in alcoholic men: P3 amplitude reflects family history but not alcohol consumption.

Multilead event-related potentials (ERPs), elicited by auditory and visual stimuli requiring a button press response and by a startling noise requiring no response, were recorded from male alcoholics and age-matched male controls (26-60 years old). Single-trial analyses of blink responses to the startling stimuli indicated that alcoholics startle less frequently but with equivalent amplitude as the controls. In contrast, single-trial analyses of P3 indicated that alcoholics generate a P3 as often as controls, but that their individual P3s are smaller. Alcoholics who reported a positive family history of problem drinking had larger startle blink amplitudes and smaller auditory and visual P3s than did alcoholics who reported a negative family history. Hierarchical regression analysis was used to demonstrate that smaller P3s in family history positive alcoholics were independent of lifetime alcohol consumption.

Adult↗
PubMed1991

Hepatobiliary MR imaging: first human experience with MnDPDP.

The first human MR imaging results for the hepatobiliary contrast agent manganese(II)N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate) (MnDPDP) are reported. MnDPDP is a paramagnetic contrast agent specific for hepatobiliary imaging. An imaging study was performed to investigate the presence of contrast enhancement or facilitated visualization of normal structures. Twelve healthy subjects receiving MnDPDP at doses of 3, 10, or 15 mumol/kg were imaged after injection for approximately 30 minutes at 1-5-minute intervals. Transaxial abdominal images were obtained at 1.5 T in a single breath-hold interval of 21 seconds with use of a spin-echo pulse sequence (repetition time = 150 msec, echo time = 20 msec). Liver parenchyma enhancement was observed 1 minute after injection and persisted for at least 30 minutes. Clearance into the gallbladder was visualized within 15 minutes. Enhancement was dose-dependent; a dose of 10 mumol/kg produced a 75%-100% signal enhancement of the liver at 10 minutes after injection.

Adult↗