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Biomedical subjects

A S David

Publications and source records attributed to A S David.

At least 145 records · Page 8Linked to original sources
PubMed1992

Categorical-semantic and spatial-imagery judgements of non-verbal stimuli in the cerebral hemispheres.

A divided visual field task was given to two groups of normal subjects to investigate hemisphere differences in the processing of standardised pictorial stimuli. There were two conditions: subjects were asked to decide whether an entity represented by a picture was living or non-living, a task involving a categorical judgement based on semantic information, or, in the second condition, whether these depictions represented entities which were bigger or smaller than a cat. This latter task, it is suggested, requires visual imagery to compare spatial dimensions. The first, categorical task produced an LH advantage in reaction time. The second, imagery task, produced an RH advantage provided the comparison involved items whose sizes were relatively close to that of a cat. Furthermore, the size difference was inversely related to reaction time, only when items were presented to the RH. The data obtained are consistent with the notion that there are at least two systems for processing visual information, one specializing in categorical and semantic distinctions related to LH functions, and the other, specialized in spatial coordinates, an aspect of visual imagery, related to the RH.

Adult↗
PubMed1992

Diagnostic criteria in schizophrenia: accentuate the positive.

In a recent article, Andreasen and Flaum (Schizophrenia Bulletin, Vol. 17, No. 1, 1991) argued that greater emphasis should be placed on negative symptoms in the diagnosis of schizophrenia, leading to a less important role for positive symptoms. This article presents a counter-argument to this view. Positive symptoms are common and reliable and therefore highly useful diagnostically. First-rank symptoms, although not specific to schizophrenia, show good discriminability. No other type of symptom or investigative method can make such claims to usefulness. Although positive symptoms do not predict outcome, this is not a necessary function of diagnostic criteria. The predictive power of negative symptoms is, in any case, based largely on studies of patients with chronic disorder. Premorbidly impaired social development may interact with schizophrenia, worsening the prognosis. We believe positive symptoms have always been the essence of psychiatric disorder and should remain so. Increasing the diagnostic weight given to negative symptoms risks restricting the definition of schizophrenia excessively.

Activities of Daily Living↗
PubMed1992

'I thought it would go away': patient denial in breast cancer.

A significant proportion of patients with cancer present late to the doctor. The characteristics of these patients and the reasons behind their delaying behaviour is poorly understood. In this study a group of 30 women with breast cancer who delayed their presentation were compared with a randomly selected group with the same disease. The women who presented late did not appear to fit into any particular socio-demographic category, but examination of their histories revealed widespread denial of illness and a diversity of beliefs and behaviour.

Aged↗
PubMed1991

Postviral fatigue syndrome and psychiatry.

The postviral fatigue syndrome overlaps with psychiatry at a number of points. First, there is the influence that some psychological states have on physiological processes, such as immunity. Second, psychological symptoms, particularly depression but also anxiety, are a major feature of the syndrome. Third, difficulties in the doctor-patient relationship are common. Each of these three areas are discussed in detail. Special attention is given to the possible mechanisms underlying the occurrence of psychological symptoms, which are sufficient to make a psychiatric diagnosis in at least two thirds of cases. It is concluded that the bulk of the scientific evidence points to psychiatric disturbances being primary but that this does not account for the syndrome in its entirety and other mechanisms probably operate as well. Much of the conflict between doctor and patient arises from misconceptions about the nature and cause of psychological disturbances.

Fatigue Syndrome, Chronic↗
PubMed1991

Chronic fatigue syndrome: signs of a new approach.

Persistent media highlighting of the plight of patients suffering from severe fatigue of unknown cause (postviral fatigue syndrome or myalgic encephalomyelitis) has at last been matched by professional attention. Recent research has started to clarify the roles of infective, neuromuscular and psychiatric factors in the illness, but pathophysiological mechanisms remain obscure.

Fatigue Syndrome, Chronic↗
PubMed1990

On insight and psychosis: discussion paper.

The concept of insight into psychosis has received scant attention in the psychiatric literature. Various types of insight are described after drawing on such sources as phenomenology, clinical observation and experimental psychology. It is proposed that insight is far from an all or none phenomenon but comprises three overlapping dimensions, namely, the recognition that one has a mental illness, compliance with treatment and the ability to re-label unusual mental events (delusions and hallucinations) as pathological.

Awareness↗
PubMed1990

Affect, affective disorder and schizophrenia. A neuropsychological investigation of right hemisphere function.

Performance on a happy-sad chimeric face test was used to examine the role of right hemisphere activation in positive and negative affect, both normal and abnormal, as well as in schizophrenia. This test is known to elicit a left-sided perceptual bias in right-handed normal subjects. Happy and sad mood in normals did not influence the perceptual bias. Depression and mania were associated with reduced and increased biases respectively, while schizophrenics showed no bias to either side. Possible explanations are right hemisphere hyperfunction in mania, moderate relative hypofunction in depression, and severe relative hypofunction in schizophrenia. The marked difference between mania and schizophrenia supports distinct pathophysiologies underlying the two conditions.

Affect↗
PubMed1990

Insight and psychosis.

The concept of insight into psychosis has received scant attention in the psychiatric literature. Drawing on sources such as phenomenology, clinical research and experimental psychology, it is proposed that insight is not an 'all-or-none' phenomenon but is composed of three distinct, overlapping dimensions, namely, the recognition that one has a mental illness, compliance with treatment, and the ability to relabel unusual mental events (delusions and hallucinations) as pathological. A scheme is proposed to standardise the assessment of insights to assist further research.

Attitude to Health↗
PubMed1989

Perceptual asymmetry for happy-sad chimeric faces: effects of mood.

Happy-sad chimeric face drawings were viewed in free vision by normal subjects. A significant and reliable perceiver bias toward the left hemiface when judging facial expression was found in right-handers whereas no consistent bias was found in non-right handers. This bias tended to be more pronounced in females. Subjects' current mood influenced their choice of facial affect but not their perceptual bias. In a further experiment, subjects were tested during induced elation and once more during induced depression. Again, though these moods increased the number of happy and sad choices respectively, the magnitude of the left hemifacial bias remained unchanged. The results are best explained by stable properties of the right hemisphere rather than arousal mechanisms. The implications of these findings are discussed in the light of the proposed hemispheric asymmetries in emotional perception and the possible lateralized effects of depressed mood on cognition.

Adult↗
PubMed1988

On the street in America.

Explore the source record for details and available documents.

Commitment of Persons with Psychiatric Disorders↗
PubMed1988

Postviral fatigue syndrome: time for a new approach.

Controversial views on the postviral fatigue syndrome ("myalgic encephalomyelitis") were critically appraised in their historical context and recent advances in research (virology, immunology, neurophysiology, histopathology, and epidemiology) reviewed. Flaws detected in certain aspects of recent research included in particular failure to define fatigue, inadequate assessment of psychological features, and absent or inappropriate control groups. The findings suggest that the fruitless dichotomy of "organic versus functional" should be replaced by a multifactorial approach. Most important, epidemiological studies with explicit operational case definition are essential before progress can be made in the management of this distressing disorder.

Adult↗
PubMed1988

Agenesis of the corpus callosum and schizophrenia: a case report.

Clinical, radiological and neuropsychological findings in the first reported case of schizophrenia with complete agenesis of the corpus callosum are described. Although causal inferences were made difficult by the co-existence of a left frontotemporal cyst and a family history of affective disorder, some theories of the role of callosal dysfunction in schizophrenia require revision in the light of this case.

Agenesis of Corpus Callosum↗
PubMed1987

Tachistoscopic tests of colour naming and matching in schizophrenia: evidence for posterior callosum dysfunction?

Neuropsychological studies have shown that the integrity of the posterior corpus callosum is necessary for accurate colour naming in the left visual field (LVF) and colour matching across hemifields. Using this model, 22 schizophrenics, 14 depressive and 16 healthy matched controls were given a battery of tachistoscopic tests of colour perception. The schizophrenics made significantly more errors, in naming colours in the LVF compared to depressives, and in matching colours across fields compared to depressives and normals. There were no differences between groups for right visual (RVF) colour naming or matching within right and left visual fields. These findings support the hypothesis that trans-callosal transmission may be impaired in schizophrenia and are unlikely to be due to a specific disorder of colour perception, neuroleptic drugs or generally impaired performance. Those schizophrenics whose LVF naming errors exceeded RVF errors were more likely to have first rank symptoms and showed less cerebral atrophy but did not differ on other variables. The techniques described may be useful for further research into interhemispheric function in schizophrenia.

Adult↗