Search PubMed⌕ Search

Biomedical subjects

S V Catts

Publications and source records attributed to S V Catts.

28 records · Page 2Linked to original sources
PubMed1991

Auditory selective attention and event-related potentials in schizophrenia.

Brain ERPs were recorded in ten unmedicated schizophrenic patients and age- and sex-matched healthy controls during a multidimensional listening task. Patients showed a marked reduction in a long-duration attention-related negative ERP component, termed 'processing negativity' (PN), which was elicited by attended stimuli. The amplitude of PN was significantly correlated with SANS and SAPS scores of schizophrenic symptoms. The P300 component was also reduced in amplitude in patients, and was significantly correlated with SANS ratings of negative thought disorder. These findings provide neurophysiological evidence of impairment in the maintenance of selective attention and the cognitive processes associated with target detection among schizophrenic patients. The reduced PN in schizophrenics implicates frontostriatal pathways in the aetiology of attentional deficits in schizophrenia.

Adult↗
PubMed1990

Event-related potential indices of selective attention and cortical lateralization in schizophrenia.

Auditory event-related potentials (ERPs) from a multidimensional selective attention task were recorded from 10 unmedicated schizophrenic patients and 10 age- and sex-matched healthy controls. Tone pip stimuli varying on the dimensions of pitch (high or low) and location (left or right ear) formed four 'channels' of stimuli: left low, left high, right low, and right high. The pitch difference was considerably more difficult to discriminate than the location difference. Subjects were instructed to pay attention to a designated channel and press a button whenever they detected a long-duration, rare target tone that occurred amongst frequent short-duration standard tones. There were a number of differences between unmedicated schizophrenics and controls in processing negativity elicited by standard tones. There was no evidence of hierarchical processing of stimulus dimensions in the early processing negativity component, and the late frontal component was virtually absent in schizophrenics. Furthermore, there was evidence that in schizophrenics the processing of the location dimension was delayed for standard tones having the same pitch as the target. The P300 component to attended target tones was substantially reduced in schizophrenics over parietal sites but there was no difference between the two groups over frontal sites. The results are interpreted in terms of multiple attentional deficits in schizophrenics that are indicative of a failure in the planning and execution of selective listening strategies. Such a failure may result from a dysfunction in the prefrontal regions of the brain.

Adult↗
PubMed1988

Somatosensory evoked potential activity: a measure of interhemispheric transfer in schizophrenia?

Jones and Miller (1981) reported that schizophrenics could be distinguished from healthy controls by latency differences in their ipsilateral and contralateral somatosensory evoked potentials (SEPs), considered a measure of corpus callosum conduction time. Subsequent replication studies failed to follow the method of the original study. The present study represents a precise replication. An additional control for contamination of SEPs by an auditory stimulus generated by the vibrotactile stimulus was used. Ipsilateral SEP activity was identified but poor definition of a positive peak in the range of interest prevented measurement of peak latency. Evidence was advanced to suggest that such ipsilateral potentials result from activity at the vertex. It was concluded that this method is inappropriate for the investigation of interhemispheric transmission.

Adult↗
PubMed1987

Low platelet monoamine oxidase and sensation seeking in males: an established relationship?

A significant negative correlation between platelet monoamine oxidase (MAO) activity, a stable peripheral enzyme measure under genetic control, and sensation seeking, as measured using the Zuckerman Sensation Seeking Scale (SSS), has been reported for male subjects in several studies. As tobacco smoking has been related to both these measures, in the present study correlations were calculated among smoking and non-smoking male university students. Platelet MAO activity was negatively correlated with the Disinhibition and Total scales of the SSS. These correlations were not significantly different in smokers and non-smokers. The results are discussed in terms of recent evidence of reduced platelet MAO activity in psychiatric patients.

Adult↗
PubMed1986

Reduced P200 latency and allusive thinking: an auditory evoked potential index of a cognitive predisposition to schizophrenia?

Auditory evoked potentials were recorded in healthy medical students who were grouped according to whether they obtained a high or low score on an Object Sorting Test (OST), on which schizophrenics also obtain high scores. High-OST scoring male students compared to Low-OST scoring male students showed reduced P200 latency. This finding was replicated in a second study of medical students. The authors believe these results support the hypothesis that schizophrenic thought disorder and an equivalent loosening of thinking in nonschizophrenic populations (allusive thinking) have a neurophysiological basis in common, namely a relative weakness of inhibition operating on cortical and subcortical structures.

Adult↗
PubMed1980

Auditory hallucinations and the Verbal Transformation Effect.

In an attempt to replicate findings reported by Slade (1976), 12 hallucinating and 12 non-hallucinating shcizophrenic subjects were compared on tests of verbal ability, personality and mental imagery variables and the Verbal Transformation Effect. No significant differences between the groups was demonstrated. When the data from both groups of schizophrenics were combined, a significant correlation was found between 2 measures of the Verbal Transformation Effect and the P-score of the Eysenck Personality Questionnaire.

Adult↗
PubMedDate not supplied

Active and passive attention in schizophrenia: an ERP study of information processing in a linguistic task.

Attentional dysfunctions in schizophrenia were investigated using a sentence priming task. Schizophrenic patients and healthy control subjects were presented with sentences to which they were required to make a response based on either semantic or physical stimulus features. Schizophrenics' behavioural responses were slower than those of controls, particularly when attending to semantic relationships, but their performance was no less accurate. Both the P300 and the N400 components of the event-related potentials (ERPs) recorded to the sentence completions were attenuated in the schizophrenic sample. The results are interpreted in terms of a deficit in the active maintenance of semantic information in memory and the integration of new information with this representation.

Adult↗
PubMedDate not supplied

Risperidone versus haloperidol: I. Meta-analysis of efficacy and safety.

Haloperidol is widely considered a reference standard in antipsychotic therapy and is commonly used in comparative studies of the efficacy and safety of antipsychotic medication. Comparative clinical trials have shown that the novel antipsychotic agent risperidone tends to have greater efficacy (i.e., clinical response defined as a > or = 20% reduction in total scores on the Positive and Negative Syndrome Scale) than haloperidol in patients with chronic schizophrenia and poses less risk of extrapyramidal symptoms (EPS). We used DerSimonian and Laird's random-effects model to analyze pooled patient data from available randomized, double-masked, comparative trials of risperidone and haloperidol in patients with schizophrenia treated for at least 4 weeks at recommended doses. The purpose of the analysis was to determine whether there are significant overall differences in the rates of patient clinical response, prescription of anticholinergic agents, and treatment dropout. Six of the nine trials revealed in a literature search met all criteria for inclusion in the meta-analysis. The meta-analysis showed that in patients with chronic schizophrenia, risperidone therapy is associated with significantly higher response rates, significantly less prescribing of anticholinergic medication, and significantly lower treatment dropout rates than haloperidol. These results demonstrate the greater treatment efficacy associated with risperidone compared with haloperidol and suggest both a lower incidence of EPS and improved treatment compliance.

Antipsychotic Agents↗
PubMedDate not supplied

Risperidone versus haloperidol: II. Cost-effectiveness.

Australia and Canada are currently the only Western nations with government guidelines for analyzing the cost-effectiveness of drugs. We used guidelines issued by the Australian Pharmaceutical Benefits Advisory Committee to construct a model for comparing the cost-effectiveness of risperidone and haloperidol over a 2-year period in patients with chronic schizophrenia. Use of clozapine was also included in the analysis as an alternative treatment given to patients who proved unresponsive to therapy with haloperidol or risperidone. Results are expressed in Australian dollars. Cost-effectiveness was determined by using decision-analytic modeling to compare clinical outcomes and costs. The analytic model contained a decision tree for each of the compared agents that tracked the distribution of patients between treatment outcome pathways (i.e., scenarios). Distributions were based on probabilities derived from our meta-analysis results reported elsewhere and from other sources. Each scenario had an associated monetary cost that included all significant direct costs (i.e., hospital costs; outpatient costs; and the cost of drugs, the services of health care professionals, and government-subsidized hostel accommodation). The cost for a given outcome was the sum of costs for all scenarios leading to that outcome. Cost-effectiveness was expressed as the total cost per favorable outcome. The definition of a favorable outcome was one in which the patient was in a response phase at the end of the 2-year period. The probability of a patient experiencing a favorable outcome at the end of 2 years was 78.9% for risperidone versus 58.9% for haloperidol. The total cost of treatment for 2 years was $15,549.00 for risperidone versus $18,332.00 for haloperidol. The expected cost per favorable outcome was $19,709.00 for risperidone and $31,104.00 for haloperidol. Risperidone was more cost-effective than haloperidol and therefore was "dominant" in pharmacoeconomic terms because it produced a higher proportion of favorable outcomes at lower cost. Sensitivity analysis showed that the difference in clinical response rate was a key determinant of cost-effectiveness.

Antipsychotic Agents↗