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Biomedical subjects

V E Pollock

Publications and source records attributed to V E Pollock.

At least 19 recordsLinked to original sources
PubMed1996

Alcohol and aggression: a meta-analysis on the moderating effects of inhibitory cues, triggering events, and self-focused attention.

The authors conducted a meta-analysis of 49 studies to investigate 2 explanations of how alcohol increases aggression by decreasing sensitivity to cues that inhibit it. Both the level of anxiety and inhibition conflict moderated the difference between the aggressive behavior of sober and intoxicated participants, but neither level adequately accounted for variation in effect sizes. Additional analyses of 3 social psychological moderating variables-provocation, frustration, and self-focused attention-showed that the aggressiveness of intoxicated participants relative to sober ones increased as a function of frustration but decreased as a function of provocation and self-focused attention. The authors also examined the moderating effects of dose.

Aggression↗
PubMed1995

P300 topography in Alzheimer's disease.

This study assessed whether P300 scalp topography distinguished subjects with Alzheimer's disease (AD) from controls. Specifically, it was predicted that the AD group would show maximum P300 amplitude over frontal areas and the largest P300 reduction over parietal and left hemisphere areas. These hypotheses were tested using a standard auditory oddball paradigm to compare 26 AD subjects and 26 controls matched on age, sex, handedness, and education. P300 was measured at frontal, central, parietal, and occipital sites over left and right hemispheres and along the midline. Results revealed that the distribution of P300 was different for the two groups such that the controls manifested a maximum over parietal areas, whereas the AD subjects showed a maximum at frontal sites with the largest reductions in P300 over parietal areas. No hemispheric differences in P300 were found. These results are consistent with the hypothesis that P300 represents the activity of multiple neural generators that are differentially disrupted by the disease process.

Adult↗
PubMed1995

Personality and EEG beta in older adults with alcoholic relatives.

Research indicates that biological relatives of alcoholics are more likely to develop alcoholism than individuals without alcoholic relatives. Most research on these groups had focused on individuals who were relatively young (i.e., under 30 years old). In the present study, we evaluated middle-aged and elderly nonalcoholic men and women who did and did not have alcoholic biological relatives to assess factors that might be involved in a later, rather than an earlier, onset of alcoholism. Psychological characteristics were assessed using the Tridimensional Personality Questionnaire. Biological characteristics were assessed using quantitative measures of the spontaneous electroencephalogram. The psychological measures did not distinguish the groups, but biological measures did. The results indicated that nonalcoholic individuals with alcoholic relatives showed elevated beta as compared with sex- and age-matched control subjects. Factors that might have mediated these findings are discussed, as are the implications of these outcomes.

Adult↗
PubMed1995

Use of meta-analysis for testing theory.

Within the context of the general superiority of meta-analytic reviews over qualitative reviews, we emphasize the fragility of meta-analytic outcomes, especially when the effects of moderator variables remain unexamined. We consider the contribution to increased theoretical understanding made by moderator analyses both of methodological and substantive variables in psychological, health, and medical research. The potential contribution of meta-analysis to understanding the process underlying established relationships and to assessment of the convergent and discriminative construct validity of previously used concepts is discussed.

Bias↗
PubMed1994

Meta-analysis of P300 amplitude from males at risk for alcoholism.

The P3(00) event-related brain potential (ERP) is used to study the development of alcoholism by comparing males who have a positive family history of alcoholism with control Ss who have no such familial history. Meta-analysis indicated that overall, smaller P3 amplitudes were obtained from males with family histories of alcoholism compared to controls. Moderator analysis indicated that paradigms using difficult visual tasks yielded the most reliable effects. Furthermore, no differences in outcomes were obtained among studies that recruited positive family history Ss exclusively from among individuals whose father had received treatment for alcoholism as compared with other studies. These findings are discussed in the context of using ERPs as an evaluative tool in the study of psychopathology.

Adolescent↗
PubMed1992

Principal components and multidimensional scaling of auditory and visual event-related potential topography.

Principal components analysis and metric multidimensional scaling were used to assess auditory and visual event-related potential topography in healthy late-middle-aged and elderly adults (n = 20). Binaurally elicited auditory evoked potentials and full-field checkerboard pattern reversal visual event-related potentials were recorded from 28 scalp sites. The zero-lag, cross-correlations of all waveforms for 300 msec post-stimulus epochs were obtained and separate analyses of the auditory and visual data were performed. Ultimately, three of the four dimensions identified in the principal components and multidimensional scaling solutions were similar and represented electrode site differences in (1) the anterior-posterior plane; (2) laterality; and, (3) the proximal-distal relation to midline. The remaining multidimensional scaling axis appeared to reflect effects specific to the modality of stimulation. Under auditory stimulation, the temporal and central-parietal sites were distinct from other scalp regions, whereas under visual stimulation, the occipital and frontal sites were distinctive. Although the results of the principal component analyses were conceptually similar to the multidimensional scaling outcomes, there were consistent differences between them. The findings provide empirical support for the validity of these multivariate methods in topographic analysis.

Acoustic Stimulation↗
PubMed1992

P3 from auditory stimuli in healthy elderly subjects: hearing threshold and tone stimulus frequency.

The P3 event-related potential (ERP) was elicited by auditory stimuli under two conditions: (1) 250 Hz standard, 500 Hz target; and, (2) 1000 Hz standard, 2000 Hz target. A group with normal hearing (n = 10), defined as subjects with less than a 16 dB loss at each tone frequency was compared to a group with hearing impairment (n = 8), defined as subjects with a loss of 16 dB or more at each tone frequency. The hearing impaired group showed significant P3 latency prolongations compared to those with normal hearing under the 2000 Hz, but not the 500 Hz target, even though subject age was used as a covariate. Under both conditions, hearing impaired subjects showed reduced P3 amplitudes compared to those with normal hearing. These findings are discussed in relation to the sensitivity of ERP assessment procedures in older adults.

Acoustic Stimulation↗
PubMed1992

Topographic quantitative EEG amplitude in recovered alcoholics.

Topographic measures of electroencephalographic (EEG) amplitude were used to compare recovered alcoholics (n = 14) with sex- and age-matched control subjects. Delta, alpha, and beta activity did not distinguish the groups, but regional differences in theta distribution did. Recovered alcoholics showed more uniform distributions of theta amplitudes in bilateral anterior and posterior regions compared with controls. Because a minimum of 5 years had elapsed since the recovered alcoholic subjects fulfilled DSM-III-R criteria for alcohol abuse or dependence, it is unlikely these EEG theta differences reflect the effects of withdrawal.

Adult↗
PubMed1992

Reliability of late positive component activity (P3) in healthy elderly adults.

Auditory oddball paradigms (20% targets) were used to elicit components of the event-related brain potential in healthy, late middle-aged and elderly adults (N = 32) in two separate sessions approximately 4.5 months apart. Within each session data were acquired under two conditions: (a) 250 Hz standard, 500 Hz target; and, (b) 1000 Hz standard, 2000 Hz target. Measures of P3 latency and amplitude showed moderate to high reliability (.55 to .89) over the 4.5-month interval under both stimulus conditions using data acquired from the midline frontal (Fz), central (Cz), and parietal (Pz) sites. In the second session, latencies were prolonged in the 500 Hz target tone condition, and amplitudes tended to be reduced in the 2000 Hz target tone condition. These results suggest that P3 measures in studies of older adults are reliable over time, and the findings are discussed in conjunction with prior P3 reliability studies of younger adults.

Aged↗
PubMed1992

Analysis of pattern-reversal visual evoked-potential topography: replicability in normal subjects and comparisons with Alzheimer's disease.

This paper reports two studies using multivariate analysis to aid the interpretation of cross-coherence of multiple electrode sites in evoked potential responses. In the first study, the replicability of principal components and multidimensional scaling was evaluated by applying both methods to pattern-reversal visual evoked potentials recorded from 28 scalp sites in two subgroups of sex- and age-matched healthy subjects, and then comparing the results. Four dimensions replicated in the two initial multidimensional scaling solutions and appeared to reflect differences in: 1) anterior versus posterior scalp areas, 2) laterality, 3) separation of frontal and occipital sites from other scalp regions, and 4) proximal versus distal placements. The initial principal components did not match well in the two groups, but rotation to congruence improved their replicability and ultimately yielded axes similar to those of the multidimensional scaling dimensions. In the second study, Alzheimer's disease and sex- and age-matched control subjects were evaluated. The four axes identified were the same as those described above, but after the solutions were rotated to align them, the group differences appeared negligible. Examination of the components and dimensions from both studies showed some consistent departures from being merely reflectors of site location, and the apparently visual dimension appeared clearly in all four groups. Judged on the basis of initial interpretability and replicability of the solutions, the results suggest that multidimensional scaling, with appropriate transformation, may provide an effective tool for analyzing pattern-reversal visual evoked-potential topography.

Aged↗
PubMed1992

Meta-analysis of subjective sensitivity to alcohol in sons of alcoholics.

OBJECTIVE: Meta-analysis was used to review the research literature on self-reported sensitivity to alcohol among sons of alcoholic and among normal control subjects. METHOD: Computerized and manual searches identified 17 eligible independent articles; nine contained the information necessary to compute effect sizes, and additional data on two other studies were provided by authors in response to written and telephone requests. RESULTS: Findings from 10 studies indicated that sons of alcoholics report significantly less sensitivity to alcohol than normal control subjects overall and during the ascending (i.e., 0-35 minutes after alcohol) and descending (i.e., 40-240 minutes after alcohol) limbs of the blood alcohol curve. Response to placebo did not significantly distinguish these groups in the five studies that included such assessment. CONCLUSIONS: It may be appropriate to appraise the biological sons of male alcoholics that they may experience less subjective sensitivity to alcohol than other individuals, but it is not possible to predict whether any particular individual will experience such lower sensitivity. In addition, self-report data can be influenced by many factors, and further research that assesses multiple psychological and physiological measures and uses longitudinal designs is needed to determine the relationship between specific factors and the development of alcoholism.

Alcohol Drinking↗
PubMed1992

Intravenous versus intramuscular atropine in ECT.

Twelve patients receiving ECT consented to random assignment to either intravenous or intramuscular administration of atropine for a total of 48 ECTs. There were no statistically significant differences between routes of administration in heart rate, blood pressures, or sialorrhea, but intravenous administration eliminated one injection per treatment and the development of dry mouth and tachycardia between the intramuscular injection and ECT. The authors recommend that atropine for ECT be administered intravenously.

Adult↗
PubMed1992

Fasting serum insulin levels in essential hypertension. A meta-analysis.

UNLABELLED: BACKGROUND--The role of insulin in the genesis of essential hypertension remains an area of intense controversy. Most clinical evidence suggests a definite association. Several pathophysiologic mechanisms have been proposed. However, current data remain disparate and contradictory. METHODS--Meta-analysis allows data pooling of primary study findings and subsequent integration into a statistically meaningful outcome. This method was used to study the relationship in euglycemic individuals between blood pressure and fasting serum insulin level, age, body mass index, and fasting plasma glucose level. RESULTS: -A significant correlation was demonstrated between fasting serum insulin concentration and both systolic blood pressure and diastolic blood pressure. Age and body mass index also revealed meaningful associations. The meta-analytic correlation between plasma glucose level and both systolic blood pressure and diastolic blood pressure failed to achieve significance. CONCLUSIONS--Data from a meta-analytic review examining fasting serum insulin levels in euglycemic individuals demonstrate a significant correlation with systolic and diastolic blood pressure. This study supports the role of hyperinsulinemia in the pathogenesis of essential hypertension.

Blood Pressure↗
PubMed1991

Reliability of topographic quantitative EEG amplitude in healthy late-middle-aged and elderly subjects.

Reliabilities of quantitative measures of absolute and relative EEG amplitudes were assessed in healthy older adults under the eyes closed (n = 46) and eyes opened (n = 45) conditions. For the theta, alpha, beta 1, and beta 2 bands, reliabilities of 28 scalp derivations were stable over the 4.5 month test interval. Reliabilities of delta were lower. When appropriate transformations were applied, the reliabilities of absolute EEG amplitude measures tended to exceed those of relative measures. There were not, however, striking differences in reliabilities under the eyes closed, as compared to eyes opened condition. We concluded that when coupled with the criterion of interpretability, the generally higher reliabilities of absolute, as opposed to relative, amplitude measures render them preferable in clinical research.

Aged↗
PubMed1990

Quantitative, waking EEG research on depression.

Research published in the past decade that used quantitative indices to evaluate the waking EEG characteristics of depressed patients is reviewed. Methodological problems that make results of different research laboratories difficult to compare include diagnostic heterogeneity of depressed groups, lack of inclusion of control subjects, and differences in the EEG techniques. Despite interpretive problems that arise from such substantial variation, consistencies nevertheless emerge. Unmedicated, actively depressed patients appear to exhibit elevated EEG alpha and beta compared to control subjects. Delta and theta distinguished depressed patients from controls in some single studies, but variation in age, specific diagnostic depression categories, and EEG acquisition and analysis techniques rendered these results less definitive. Quantitative EEG differences that may distinguish depressed subject samples from those with other psychiatric disorders are considered. Factors that limit comparability of the findings are discussed in conjunction with strategies that deserve systematic study in future research.

Cerebral Cortex↗
PubMed1990

EEG amplitudes in healthy, late-middle-aged and elderly adults: normality of the distributions and correlations with age.

The interindividual distributions of EEG amplitudes were evaluated in 60 healthy subjects, aged 56-76. Skew and kurtosis were used to assess the normality of the amplitude distributions in 5 frequency bands (delta, theta, alpha and 2 beta ranges) and 28 scalp derivations while the subjects were awake and rested with their eyes closed and opened. Most of the interindividual EEG amplitude distributions were not normally distributed. Two transformations were applied to the EEG amplitudes: the square root and the natural logarithm. Evaluation of skew and kurtosis indicated that the natural logarithmic transformation was more effective than the square root in reducing the positive skew and leptokurtosis that characterized the untransformed interindividual EEG amplitude distributions. For all frequency bands except theta, the log transformation rendered the distributions approximately normal in form. Correlations between log transformed EEG amplitudes and age were not statistically significant. These findings are discussed in the context of previous research, aging, and methodological features.

Aged↗