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Biomedical subjects

S Channon

Publications and source records attributed to S Channon.

At least 19 recordsLinked to original sources
PubMed2007

Theory of mind, humour processing and executive functioning in alcoholism.

AIMS: Alcoholism is associated with cognitive deficits, which have been interpreted in terms of a specific vulnerability of the frontal lobes to the toxic effects of alcohol. While executive functions in alcoholism have been investigated extensively, only little work has been carried out on social cognition. The aim of the present study was to investigate the association between executive functions, theory of mind and humour processing in alcoholism. DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS: A comprehensive neuropsychological test battery was administered to 29 alcoholic patients (Alc) and 29 healthy controls (HC). The test battery included measurements of affect, general intellectual abilities, executive functions, humour processing and theory of mind. The two groups were comparable with respect to affective variables, IQ, gender and age. FINDINGS AND CONCLUSIONS: Group comparisons revealed cognitive as well as affective humour processing deficits of alcoholics in comparison with HC. The observed impairments were related to theory of mind and executive functions. The deficits may contribute to interpersonal problems and are thus of relevance to rehabilitation.

Adult↗
PubMed2003

A pilot study of motivational interviewing in adolescents with diabetes.

AIMS: To obtain preliminary data on the impact of motivational interviewing, a counselling approach to behaviour change, on glycaemic control, wellbeing, and self-care of adolescents with diabetes. METHODS: Twenty two patients aged 14-18 years participated in motivational interviewing sessions during a six month intervention. The effects of the intervention on HbA1c and a range of psychological factors were assessed. RESULTS: Mean HbA1c decreased from 10.8% to 9.7% during the study and remained significantly lower after the end of the study. Fear of hypoglycaemia was reduced and diabetes was perceived as easier to live with. There were no other significant changes in the psychological measures. By contrast no reduction in HbA1c values was observed in a comparison group who did not receive the motivational interviewing intervention. CONCLUSION: The findings of this pilot study indicate that motivational interviewing may be a useful intervention in helping adolescents improve their glycaemic control. A larger, longer term randomised controlled study is indicated to clarify the mechanisms and extent of these benefits.

Adolescent↗
PubMed2002

Dissociation between performance on abstract tests of executive function and problem solving in real-life-type situations in normal aging.

This study examined the effects of normal aging on real-life-type problem-solving performance, using problems that had previously been found to be sensitive to lesions involving the frontal lobes. Executive skills assessed on abstract neuropsychological tests tend to decrease with normal aging. The effects of aging on tasks reliant on everyday knowledge and experience are less well understood. In the present study, groups of healthy older and younger people were compared on ability to solve real-life-type problems covering a range of everyday interpersonal situations. Performance was also examined on a range of standardized neuropsychological tests involving executive skills. Older people were similar to younger people in most aspects of everyday problem-solving performance, although the older group appeared to use a different strategy to the younger group in generating potential problem solutions. Both groups performed normally for their age on the executive tests. Comparisons based on raw scores rather than age-adjusted scores showed the younger group to perform better on the executive tests, but not on the problem-solving task. The possible contribution of knowledge and experience to problem solving on the current task is discussed. The greater life experience of the older group is likely to be the biggest contributory factor in maintaining problem-solving performance.

Adult↗
PubMed2001

Real-life-type problem-solving in Asperger's syndrome.

This study compared adolescents with Asperger's syndrome with typically developing adolescents on a novel problem-solving task that presented videotaped scenarios in real-life-type social contexts. The Asperger's group was impaired in several aspects of problem-solving, including recounting the pertinent facts, generating possible high-quality problem solutions, and selecting optimal and preferred solutions. This group's solutions differed most from those of the typically developing group in social appropriateness. The contributions of social experience, social understanding, and executive skills to performance on the novel problem-solving task are discussed.

Adolescent↗
PubMed2001

Dissociation between intentional and incidental sequence learning in Huntington's disease.

The ability to acquire and act upon serial order information is fundamental to almost all forms of adaptive behaviour. There is growing evidence that such knowledge may be acquired through a number of different means, each perhaps with its own neuronal substrate. One major distinction is between serial order information acquired intentionally and leading to explicit conscious knowledge of the sequence structure, and information acquired incidentally through experience. While this latter form of knowledge influences behaviour, it may do so without the participant being aware of the sequential information, i.e. it is acquired implicitly. Evidence from physiological and lesion studies in animals and imaging studies in humans suggests that these two forms of learning may have dissociable neuronal substrates. Specifically, the striato-thalamo-cortical circuit centred on the caudate nucleus is proposed to be involved in intentional sequence learning and that based on the putamen on incidental learning. The present study tested one part of this proposed dissociation by assessing patients with Huntington's disease on tasks of the two forms of learning. On the test of trial-and-error intentional learning there were marked deficits, which were closely related to disease progression and to measures of executive cognitive dysfunction. This finding was in contrast to the finding from the incidental learning task. Performance of the Huntington's disease group was essentially normal and unrelated to measures of disease progression and cognitive status. The results, although supportive of the proposed dual-system hypothesis, offer only partial confirmation. Further direct study is required using similar tasks in patients with putamenal disorder or lesions within the skeletomotor striato-thalamo-cortical circuit.

Adult↗
PubMed2000

The effects of anterior lesions on performance on a story comprehension test: left anterior impairment on a theory of mind-type task.

Participants with unilateral anterior or posterior lesions were compared to a healthy group on a theory of mind-type task that involved explaining the words or actions of story characters in a series of brief vignettes. Participants also carried out a set of non-social neuropsychological tests. Those with left anterior brain lesions (n=6) showed impairment relative to those with right anterior (n=13), left (n=4) and right (n=8) posterior lesions and healthy participants (n=60) in story comprehension, and their errors commonly involved failure to make non-literal interpretations. The left anterior lesion participants also showed impairment on some measures of executive function. The implications of the findings for our understanding of impairments in story comprehension after brain injury are discussed in terms of models of executive function and theory of mind.

Adult↗
PubMed2000

The effect of semantic categorisation on recall memory in amnesia.

Amnesic patients were compared to a healthy control group on recall of word lists containing semantically-related or unrelated words. As expected on the basis of previous literature, the amnesic group performed below the control group on all measures of recall. When total recall scores for each list were used as the index of performance, their scores were not significantly affected by the type of list, unlike those of the control group. Comparison of serial position effects for different parts of the lists revealed that the control group derived greater benefit from semantic relatedness in recall of items from the middle positions. This effect was not shown by the amnesic group, who showed similar U-shaped serial position curves for recall of all three lists, and appeared to use a more passive recall strategy than the control group. The findings are discussed in relation to our current understanding of amnesic deficits.

Journal Article↗
PubMed1999

Problem-solving in real-life-type situations: the effects of anterior and posterior lesions on performance.

Clinical studies have described patients who show marked impairments in everyday life, including planning, problem-solving and decision-making. Several factors potentially contribute to such impairments, including difficulties in generating possible problem solutions, and difficulties in selecting an appropriate solution. The present study describes the performance of participants with unilateral anterior or posterior lesions compared to healthy controls in ability to solve real-life-type problems. These covered a range of everyday interpersonal situations, and were presented both in video and story format. Participants also carried out a set of more abstract neuropsychological tests. Those with brain lesions showed impairment relative to controls in both everyday problem-solving and on more abstract tests involving executive function and memory. The anterior group was impaired on more aspects of everyday problem-solving than the posterior group, showing reduced fluency in generating possible solutions, and also impairment in selecting appropriate problem solutions. The implications of the findings for our understanding of impairments in everyday life problem-solving after brain injury are discussed.

Adolescent↗
PubMed1999

Executive function in depression: the role of performance strategies in aiding depressed and non-depressed participants.

OBJECTIVES: Depression has been found to be associated with dysfunction in executive processes, whereas relatively automatic processes are thought to remain intact. Failure to generate or implement adequate performance strategies has been postulated in depressed participants. The present study investigated spontaneous strategy usage in depressed and control participants, and the effectiveness of providing a hint about performance strategies. METHODS: Unipolar depressed participants were compared with matched healthy controls on three tasks sensitive to executive function: memory for categorised words, response suppression, and multiple scheduling. Participants in each group were randomly allocated to strategy aid and no strategy aid conditions. Those in the strategy aid condition were given a hint about the use of an appropriate performance strategy for each task, in addition to the standard instructions given to those in the no strategy aid condition. RESULTS: Depressed participants performed worse than controls on each of the three tasks, and were found to use appropriate performance strategies less often. Provision of strategy hints increased the use of performance strategies in two of the three tasks, memory for categorised words, and response suppression, but did not significantly improve overall performance for either group. CONCLUSIONS: The findings were consistent with the view that depressed participants fail to use appropriate performance strategies spontaneously to the same extent as controls. However, provision of information alone does not seem to be an adequate means of enhancing performance. The role of performance strategies in cognitive impairment in depression is discussed, both in terms of initiating use of such strategies and carrying these out efficiently.

Adult↗
PubMed1996

Executive dysfunction in depression: the Wisconsin Card Sorting Test.

This study compared dysphoric undergraduates with controls on the Wisconsin Card Sorting Test. The task is to match a series of cards to key cards varying in colour, shape and number, according to correct/wrong feedback. The groups differed in the efficiency with which they were able to use feedback to match cards appropriately, and shift between the different sorting categories. The dysphoric subjects were poorer in the matching task, and also showed slight impairment in describing the sorting categories accurately in a post-task interview. The implications of the findings for our understanding of depression are discussed.

Adolescent↗
PubMed1995

The therapeutic potential of moclobemide, a reversible selective monoamine oxidase A inhibitor in Parkinson's disease.

Dopamine is equally well deaminated oxidatively by monoamine oxidase (MAO) A and B types. Selegiline (L-deprenyl), a selective inhibitor of MAO-B, ameliorates the "wearing off" akinesia and delays the need for levodopa in mild, previously untreated Parkinson's disease. The therapeutic potential of selective inhibition of MAO-A in Parkinson's disease has not been examined in detail. MAO-A accounts for only about 20% of total MAO activity in the human basal ganglia, and it differs from MAO-B in distribution. In contrast to MAO-B, which is confined to the extraneuronal compartment, MAO-A is found both extraneuronally and within the presynaptic dopaminergic terminals. The inhibition of MAO-A might alter the intraneuronal handling of dopamine reuptaken from synaptic clefts and thereby prolong oral levodopa benefit. We have given moclobemide, a selective, reversible inhibitor of MAO-A, to nondepressed patients with Parkinson's disease receiving standard levodopa/peripheral decarboxylase inhibitor or levodopa with dopaminergic agonist (bromocriptine, pergolide). Selegiline was discontinued at least 8 weeks earlier. A standard oral levodopa challenge was performed at the patient's entry to the study and repeated on the 22nd day of moclobemide treatment (150 mg thrice daily). The overall time spent "on" and "off" before the onset of treatment and during the last week on the drug was estimated from the patients' diaries. Neuropsychological assessments were also made before and after 3 weeks of moclobemide to measure possible effects on cognitive performance and mood. In acute levodopa challenge, the latency of motor response was significantly shortened and its duration was prolonged during moclobemide treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

1% amino acid peritoneal dialysate: single-cycle study in diabetic patients with end-stage renal disease.

Uremia is associated with multiple abnormalities of carbohydrate and protein metabolism, which are partially corrected by continuous ambulatory peritoneal dialysis with dextrose-based solutions. The hormonal and metabolic effects of amino acid (AA)-based peritoneal dialysis have been studied in nondiabetic uremic patients. Such solutions may be particularly suitable for diabetic patients with end-stage renal disease provided the safety and efficacy of such solutions can be established. We have studied and compared the metabolic and hormonal responses to a single-cycle exchange of dextrose versus a 1% AA-based continuous ambulatory peritoneal dialysis solution in six diabetic patients with end-stage renal disease. In the fasting state and under similar free insulin concentrations, use of the AA solution led to a higher mean glucose concentration (109 +/- 16 mg/dL with dextrose solution v 128 +/- 25 mg/dL with AA solution, P < 0.05). Levels of alanine, lactate, pyruvate, glycerol, non-esterified fatty acids, and triglycerides were similar with the use of either solution. Use of the AA-based solution led to increases in the mean values of the branched chain AAs for the period of the study (valine 131 +/- 10 mumol/L with dextrose solution v 331 +/- 40 mumol/L with AA solution, P < 0.01; leucine 72 +/- 7 mumol/L with dextrose solution v 129 +/- 11 mumol/L with AA solution, P < 0.01; isoleucine 48 +/- 5 mumol/L with dextrose solution v 103 +/- 11 mumol/L with AA solution, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Cognitive strategies and hypothesis testing during discrimination learning in Parkinson's disease.

This study investigated the nature and extent of impairments in the use of hypotheses and cognitive strategies in medicated subjects with idiopathic Parkinson's disease (PD) and matched control subjects. PD subjects did not differ from controls in solving one- or two-dimensional discrimination learning problems, but showed impairment on four-dimensional problems which did not appear to be attributable to memory deficits. They achieved fewer correct solutions, used fewer hypotheses, and were less likely to use appropriate lose-shift strategies following negative feedback. The pattern of findings was similar to those previously reported for subjects with frontal lobe lesions.

Aged↗
PubMed1993

Operant conditioning after temporal lobe lesions in man: conditional and simple discrimination learning.

Temporal lobe lesions have been found to impair the acquisition of classical conditional discrimination learning in an eyelid conditioning paradigm, with sparing of simple eyelid conditioning. In the present study, subjects with left or right temporal resections were compared with normal controls on two operant conditioning tasks using a conditional and a simple discrimination paradigm analogous to the previously reported classical conditioning tasks. Subjects with right temporal lesions, and to a lesser extent those with left temporal lesions, were impaired relative to frontal lobe and control subjects in the acquisition of a conditional discrimination within an operant conditioning setting. A subsequent experiment showed that both left and right temporal lobe subjects were unimpaired on a simple operant discrimination task. These findings are compatible with theory relating hippocampal function to the learning of if-then rules.

Adult↗
PubMed1993

Working memory in clinical depression: an experimental study.

This study compared clinically depressed subjects with normal controls on a range of working memory tasks. The findings suggested the articulatory loop and visuospatial sketch pad components of working memory to be unimpaired in depression. On a range of clinical tasks likely to involve central executive function, depressed subjects showed impairment only on some tasks.

Adult↗
PubMed1993

Effects of structure and clustering on recall and recognition memory in clinical depression.

The present study compared retrieval of high, medium, and low structured material, using word lists consisting of uncategorized words and categorized words presented in randomized and clustered order. Clinically depressed subjects were found to be significantly impaired relative to controls only on the medium level of structure and the randomized categories list when measured by free recall. There were no effects of group nor any interactions for recognition memory, although there was a main effect for group on d' when signal detection analysis was applied. The implications of the findings for models of memory deficits in depression are discussed.

Adult↗