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Biomedical subjects

D L Braff

Publications and source records attributed to D L Braff.

125 records · Page 7Linked to original sources
PubMed1981

Impaired speed of information processing in nonmedicated schizotypal patients.

There is increasing evidence that schizophrenia is associated with an attentional or information processing deficit or both. These "early deficit" theories challenge the position that schizophrenia is primarily a disorder of thinking and higher cognitive operations. A tachistoscopic backward masking task was applied in matched groups of 20 schizophrenic, 20 schizotypal, and 20 depressive psychiatric inpatients. Resulting data are an index of visual input factors and speed of information processing. Paranoid schizophrenic and schizotypal subjects had unimpaired visual input thresholds but abnormally slow processing compared with the depressives. Since all the schizotypal subjects were nonmedicated, the data add important support to the hypothesis that impaired speed of information processing in schizophrenia spectrum disorders is due to schizophrenia per se and is not secondary to medication effects. These data also support the theoretical link between schizophrenic and schizotypal patients. The importance of the results is discussed, with emphasis on the hypothesized relationship between information processing dysfunction and symptom formation in the schizophrenias.

Adult↗
PubMed1981

Outcome of irregularly discharged psychiatric patients.

Clinicians' attitudes about the posthospitalization outcome of patients who are irregularly discharged from the hospital (i.e., against medical advice or AWOL) have been pessimistic, but unsystematic follow-up data of such patients compared with regularly discharged patients suggest that outcomes for the two groups are similar. Because of this discrepancy, the authors used data from a controlled, systematic study of a large sample of voluntary inpatients that measured global outcome over 2 years. Their findings suggest that 1 year and 2 years after admission, most patients who were irregularly discharged had outcomes similar to those of patients with regular discharges. There was, however, a subgroup of irregularly discharged patients who had worse outcomes.

Humans↗
PubMed1981

Impaired speed of visual information processing in marijuana intoxication.

The authors conducted a double-blind crossover study to investigate the effects of marijuana on visual information processing. The authors used a tachistoscopic paradigm, and the results show no marijuana effect on the critical stimulus duration, a measure of stimulus intake. The visual backward masking data are compatible with a marijuana-induced slowness of information processing from labile unconscious iconic memory to more permanent memory processes. These results are discussed in relation to reports of marijuana's effects on perception and early information processing.

Adult↗
PubMed1981

Information processing dysfunction in paranoid schizophrenia: a two-factor deficit.

The authors investigated information processing in schizophrenia by studying 30 paranoid schizophrenic patients and 30 depressed inpatients. The basic methodology relied on tachistoscopic presentation of stimuli. First, the critical stimulus duration needed for identification of a target stimulus was determined. Second, when the target stimulus was followed by a masking stimulus, a measure of speed of information processing was obtained. The schizophrenic patients were imparied on input factors and speed of processing. The authors think it is unlikely that the results were due to medication effect or to gross psychopathology. Their discussion centers on how this two-factor deficit in information processing may result in cognitive disruption and how this study relates to other investigations.

Adult↗
PubMed1980

Associative cognitive dysfunction in schizophrenia and old age.

This study employed Chapman's matched associative distractor test in order to determine whether an associative dysfunction is unique to the schizophrenias. Schizophrenic and control subjects were administered two matched multiple choice subtests, with only one containing an incorrect associative alternative choice. Only the schizophrenics and the institutionalized elderly made significantly more errors on the associative subtest than on the no-associative subtest. Our results indicate that vulnerability to associative distractors is not a unique pathological response pattern of schizophrenia, and add support to the growing body of knowledge that many of the so-called pathognomonic dysfunctions of schizophrenia can also be found in other groups.

Adult↗
PubMed1980

Acute and chronic LSD effects on rat startle: data supporting an LSD--rat model of schizophrenia.

Animal models of human schizophrenia using LSD and related hallucinogens have been challenged on several grounds. One compelling argument against the LSD model is that while schizophrenia can be chronically debilitating, animal and human effects of LSD exhibit behavioral tolerance following chronic administration. The present study tested the effects of acute and chronic LSD on measures of rat startle, a widely used behavioral measure of reactivity and habituation. The results suggest that behavioral tolerance after chronic LSD administration is incomplete, with tolerance exhibited to the acute impairment of habituation but potentiation of startle magnitude on both the first response and the first block of 30 trials. These results are interpreted as supporting the viability of LSD as a model for one or more of the group of schizophrenias.

Animals↗
PubMed1979

The therapeutic community as a research ward: myths and facts.

The clinical research ward run as a therapeutic community has been criticized as inefficient and scientifically unsound. This article discusses the therapeutic community as a research ward and identifies certain misconceptions which underlie many criticisms. The following myths are discussed and refuted: (1) There is an insurmountable community-research chasm. (2) The therapeutic community induces stress that interferes with research. (3) Patient passivity is engendered by research and this is destructive to the therapeutic community. (4) Symptoms are exacerbated by a research ward that is disruptive to the community. (5) Normal research subjects cannot live in a therapeutic community without pathologic psychic changes. These inaccurate myths are seen as a reflection of attempts to oversimplify very complex clinical and research issues. The use of mythology to simplify experiments, to artificially "clarify" complex issues, or to "protect" patients is seen as a disservice. The therapeutic community and research are syntonic when both receive appropriate support.

Adult↗
PubMed1977

Very short-term memory dysfunction in schizophrenia. Defective short time constant information processing in schizophrenia.

Disordered, very short-term memory (VSTM) has been hypothesized as the fundamental cognitive deficit in schizophrenia. We describe a method that measures VSTM using self-stimulated auditory average evoked potentials. This paradigm allows the VSTM hyothesis to be tested relatively free of superficial attentional and motivational artifacts. The experimental results are consistent with a VSTM dysfunction in schizophrenia. Very short-term memory dysfunction is discussed in light of recent blink reflex evidence that there is a short time constant information processing system with a time base similar to VSTM (ie, 1 to 1,000 msec). This leads to new testable hypotheses about information processing and VSTM in schizophrenia. It also lays the basis for interpreting this phenomenon as a pathologic exaggeration of an adaptive neurophysiologic mechanism.

Adaptation, Psychological↗
PubMed1976

Management of interpersonal issues in systematic desensitization.

The authors use the management of typical clinical problems that arise during systematic desensitization as a model for the analysis and solution of problems associated with behavior therapy techniques. Three main problem areas are considered: initiation of the technique, therapist and patient difficulties, and therapeutic decision making. The discussion is designed primarily to help therapists with varied backgrounds to deal with clinical issues that arise in the application of behavior therapy techniques such as systematic desensitization.

Behavior Therapy↗
PubMedDate not supplied

Effects of task relevance and attention on P3 in schizophrenic patients.

The P3 component of the event-related potentials (ERPs) to auditory task-relevant and task-irrelevant stimuli in 'Attend Auditory' (i.e., reaction time task) and 'Attend Visual' (i.e., when the auditory stimuli were being ignored) conditions was investigated in 13 RDC/DSM-III diagnosed schizophrenic patients. ERPs were recorded from Fz, Cz, and Pz. Compared to controls, schizophrenics had a significantly smaller P3 in the Attend Auditory than in the Attend Visual condition and to the task-relevant than to the task-irrelevant stimuli. Furthermore, the patients' P3 response to the most salient task-irrelevant stimuli in the Attend visual condition was normal. The results are discussed as suggesting that schizophrenics either allocate relatively more resources to task-irrelevant than task-relevant stimuli or that they fail to habituate to task-irrelevant stimuli.

Adult↗
PubMedDate not supplied

Middle latency auditory evoked potentials (MAEPs) in chronic schizophrenics.

Middle latency auditory evoked potentials were recorded in medicated chronic schizophrenics and controls at stimulation rates of 10/s, 2/s, and 1/s. Increasing the stimulation rate did not change Pa amplitude but decreased Pb amplitude. There was no difference between the two groups.

Acoustic Stimulation↗