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C Sheard

Publications and source records attributed to C Sheard.

11 recordsLinked to original sources
PubMed1992

Pre-frontal structural and functional deficits associated with individual differences in schizotypal personality.

This study tests the hypothesis that pre-frontal deficits underlie schizotypal personality in the normal population. Personality measures assessing features of DSM-IIIR schizotypal personality disorder (SPD) were related to left and right pre-frontal brain area assessed by magnetic resonance imaging (MRI), and neuropsychological measures of pre-frontal functioning (Wisconsin Card Sorting Task, WCST) in a group of non-institutionalized, unmedicated normal subjects. High schizotypal scores were significantly associated with reduced pre-frontal area and more WCST perseveration errors; conversely no relationships were observed between these pre-frontal measures and measures of psychosis-proneness unrelated to SPD traits. Pre-frontal structural findings were not found to be mediated by temporal lobe and posterior cortical structural deficits, height, weight, socio-economic status, education level and sex differences, while pre-frontal functional findings were not mediated by non-prefrontal cognitive ability. These findings of pre-frontal structural and functional deficits associated with schizotypal personality provide some initial converging support for a pre-frontal explanation of individual differences in schizotypal personality in the general population.

Adult↗
PubMed1992

An evaluation of structural and functional prefrontal deficits in schizophrenia: MRI and neuropsychological measures.

Magnetic resonance imaging was used to assess prefrontal brain structure in 17 schizophrenic, 18 psychiatric control, and 19 normal control subjects of comparable age, social background, and educational status, while three neuropsychological measures were used to assess prefrontal functioning. Schizophrenic patients had significantly smaller prefrontal areas than both psychiatric control and normal control subjects in all three planes. When posterior brain area and temporal lobe were entered into statistical analysis as covariates, they did not explain the prefrontal deficits. Schizophrenic patients made more perseveration errors on the Wisconsin Card Sorting Task and had fewer correct responses on the Spatial Delayed Response Task than normal control subjects. Schizophrenic patients performed more poorly than psychiatric control subjects on the Block Design Test. No group differences were found on three other nonfrontal tasks. These data lend some support to the role of prefrontal deficits in the development of schizophrenia.

Adult↗
PubMed1991

Reliability and agreement of ratings of ataxic dysarthric speech samples with varying intelligibility.

Indices of interjudge reliability and inter- and intrajudge agreement were calculated from the ratings made by 15 experienced speech clinicians on five deviant speech dimensions with respect to 15 speakers with ataxic dysarthria. Speakers were chosen to cover a wide range of speech intelligibility (16-97%) as measured by the sentence intelligibility transcriptions of the Assessment of Intelligibility of Dysarthric Speech (Yorkston & Beukelman, 1981). Intraclass correlation coefficients derived from each judge on two occasions were above .6 for imprecise consonants, excess and equal stress, and harsh voice, but below .6 for distorted vowels and below .5 for irregular articulatory breakdown. The last dimension also had the lowest percent agreement for the interjudge and intrajudge comparisons. Poor speech dimension definition seems to be the most likely source of error on irregular articulatory breakdown. Judges agreed equally well in rating dysarthric speech across the range from low to high intelligibility.

Aged↗
PubMed1991

Neuroanatomical correlates of skin conductance orienting in normal humans: a magnetic resonance imaging study.

Although little is known about the neuroanatomical basis of skin conductance orienting in intact normal humans, the limited literature on animals and humans with neurological and clinical disorders implicate prefrontal, temporal/amygdala, and pons brain areas in mediating skin conductance orienting. This study relates area of these structures using magnetic resonance imaging techniques to skin conductance orienting responses in 17 normal humans in order to test hypotheses that larger area of these excitatory structures will be associated with more orienting responses. Left and right hand skin conductance orienting was significantly associated with left and right prefrontal area (r = .44-.60), area of the pons (r = .43-.54), and left but not right temporal/amygdala area (r = .47-.53). No relationships were observed with areas thought to be unrelated to skin conductance activity (cerebellum, nonfrontal cortical area), medial prefrontal cortex, or the third ventricle. This appears to be the first study relating brain structure to skin conductance orienting in intact normal humans. Although preliminary at the present time, these results implicate prefrontal, pons, and temporal/amygdala areas in the mediation of skin conductance orienting in normal humans.

Adult↗
PubMed1990

Structural and functional characteristics of the corpus callosum in schizophrenics, psychiatric controls, and normal controls. A magnetic resonance imaging and neuropsychological evaluation.

In 1986 Nasrallah and colleagues found that increased thickness of the corpus callosum may be specific to right-handed female schizophrenics. Male and female right-handed schizophrenics were compared with normal and psychiatric controls of comparable age, sex, education, and social class on measures of callosal thickness from a midsagittal magnetic resonance imaging cut and neuropsychological tests of interhemispheric transfer. The sex difference in anterior and posterior callosal thickness in normal controls was reversed in schizophrenics, with the corpus callosum being thicker in female schizophrenics and thinner in male schizophrenics. Similar findings were also observed in the psychiatric control group. These structural differences were not paralleled by evidence of impaired interhemispheric transfer on neuropsychological tasks. These results support the finding of sex-dependent callosal abnormalities in schizophrenia but indicate that these abnormalities may not be specific to this illness.

Adult↗
PubMed1989

Interhemispheric transfer in schizophrenics, depressives, and normals with schizoid tendencies.

Although several studies suggest that schizophrenics suffer from an impairment in the interhemispheric transfer (IHT) of information, methodological weaknesses in these studies preclude clear interpretation of their results. This study addresses these criticisms in order to provide a clearer test of the IHT theory. Schizophrenics, depressives, normal controls, and normals with schizoid tendencies were assessed on five measures of IHT (verbal and nonverbal dichotic listening, intermanual transfer, bimanual block design, finger sequence repetition) and two measures of unilateral hemispheric processing (lateral eye movements, auditory thresholds). Results consistently failed to support an IHT deficit interpretation of schizophrenia. Schizoid normals had a significantly greater right-ear advantage on verbal dichotic listening than both psychiatric groups, a result suggesting enhanced left-hemisphere activation in schizoid normals. It is concluded that the IHT theory requires stronger empirical substantiation than has been obtained to date to warrant further consideration as a central theory of schizophrenia.

Adult↗
PubMed1987

Low dose aminophylline accelerates recovery from diazepam premedication for digestive endoscopy.

The value of intravenous aminophylline in accelerating recovery from premedication with diazepam was assessed against placebo in a randomized, double-blind trial. One hundred ten patients undergoing routine diagnostic upper gastrointestinal endoscopy received diazepam intravenously in a dosage sufficient to achieve adequate sedation. On completion of the endoscopy, patients received either aminophylline (1.5 mg/kg) or placebo. Recovery from sedation was assessed on clinical grounds by a nurse, objectively using a serial reaction time test, and by the patient on a visual analogue scale. The number of patients judged to be fully alert at 30 and 60 min after the procedure was significantly greater in the aminophylline group than in the placebo group. Compared with values obtained before sedation, the placebo group had significantly prolonged reaction times 30 min after completion of the endoscopy, whereas patients who received aminophylline did not. However, according to their self-assessments, patients in both groups felt more uncoordinated following sedation. Aminophylline appears to hasten recovery from sedation with diazepam, and its use may permit earlier mobilization of patients after endoscopy.

Adult↗