Biomedical subjects

Anthony S David

Publications and source records attributed to Anthony S David.

At least 37 records · Page 2Linked to original sources

PubMed2006

Insight in psychosis and neuropsychological function: meta-analysis.

BACKGROUND: One factor contributing to impaired awareness of illness (poor insight) in psychotic disorders may be neurocognitive deficits. METHOD: A systematic review and meta-analysis were conducted after data extraction. Following an overall analysis, in which measures of different cognitive domains were taken together, more fine-grained analyses investigated whether there was a specific relation with frontal executive functioning, and whether this was influenced by diagnosis or the insight scales used. RESULTS: There was a significant mean correlation between insight ratings and neurocognitive performance (mean weighted r=0.17, 95% CI 0.13-0.21, z=8.3, P<0.0001), based on 35 studies with a total of 2354 individuals. Further analyses revealed that the effect of general intellectual impairment was smaller than the specific association with executive function. This was only the case for psychosis in general, and not in an analysis limited to schizophrenia, where all cognitive domains were associated with impaired insight to a similar degree. CONCLUSIONS: Neuropsychological dysfunction, specifically impairment of set-shifting and error monitoring, contributes to poor insight in psychosis. Specific relations with different dimensions of insight and the putative role of metacognitive functions require further study.

Cognition Disorders↗

PubMed2005

Are semantic deficits in schizophrenia due to problems with access or storage?

Semantic processing deficits are central to cognitive abnormalities in schizophrenia. Such semantic deficits may be related to either poor access or poor storage of semantic knowledge. 32 schizophrenia patients and 32 matched normal controls performed five semantic processing tasks that examined item-specific consistency over time, the word frequency effect and semantic priming. A subgroup of patients performed tasks on three separate occasions. It is generally assumed that a storage deficit is signalled by item-specific consistent performance, an exaggerated effect of word frequency, and the occurrence of hyperpriming; an access deficit is signalled by the absence of these effects. The data demonstrated item-specific consistency, a frequency effect and significant hyperpriming. The pattern is consistent with a storage deficit of semantic memory in schizophrenia.

Adult↗

PubMed2005

Deriving meaning: Distinct neural mechanisms for metaphoric, literal, and non-meaningful sentences.

In this study, we used a novel cognitive paradigm and event-related functional magnetic resonance imaging (ER-fMRI) to investigate the neural substrates involved in processing three different types of sentences. Participants read either metaphoric (Some surgeons are butchers), literal (Some surgeons are fathers), or non-meaningful sentences (Some surgeons are shelves) and had to decide whether they made sense or not. We demonstrate that processing of the different sentence types relied on distinct neural mechanisms. Activation of the left inferior frontal gyrus (LIFG), BA 47, was shared by both non-meaningful and metaphoric sentences but not by literal sentences. Furthermore, activation of the left thalamus appeared to be specifically involved in deriving meaning from metaphoric sentences despite lack of reaction times differences between literals and metaphors. We assign this to the ad hoc concept construction and open-endedness of metaphoric interpretation. In contrast to previous studies, our results do not support the view the right hemispheric is specifically involved in metaphor comprehension.

Adult↗

PubMed2005

Emotional memory: separating content and context.

It is now well established that emotion enhances episodic memory. However, it remains unclear whether the same neural processes underlie enhancement of memory for both emotional stimuli and neutral stimuli encoded in an emotive context. We designed an experiment that specifically attempted to separate these effects and that was validated on 30 participants. We then used functional magnetic resonance imaging (fMRI) to examine the neural correlates of encoding and retrieval of the two classes of stimuli in 12 healthy male volunteers. We predicted that aversive emotional context would enhance memory regardless of content and that activation of anterior cingulate would be inversely related to retrieval of aversive items. Both predictions were supported. Furthermore we demonstrated apparent asymmetrical lateralisation of activation in the hippocampal/parahippocampal complex during recognition of words from aversive sentences: more left-sided activation for neutral words from aversive contexts, and more right-sided activation for aversive content words. These findings, if applicable to the wider population, may have application in a range of psychiatric disorders where interactions between emotion and cognition are relevant.

Adolescent↗

PubMed2005

Cognitive-behaviour therapy for depersonalisation disorder: an open study.

Depersonalisation (DP) and derealisation (DR) are subjective experiences of unreality in, respectively, one's sense of self and the outside world. These experiences occur on a continuum from transient episodes that are frequently reported in healthy individuals to a chronic psychiatric disorder that causes considerable distress (depersonalisation disorder: DPD). Despite the relatively high rates of reporting these symptoms, little research has been conducted into psychological treatments for this disorder. We report on an open study where 21 patients with DPD were treated individually with cognitive behavioural therapy (CBT). The therapy involved helping the patients re-interpret their symptoms in a non-threatening way as well as reducing avoidances, safety behaviours and symptom monitoring. Significant improvements in patient-defined measures of DP/DR severity as well as standardised measures of dissociation, depression, anxiety and general functioning were found at post-treatment and six-months follow-up. Moreover, there were significant reductions in clinician ratings on the Present State Examination (Wing, Cooper & Sartorius, 1974), and 29% of participants no longer met criteria for DPD at the end of therapy. These initial results suggest that a CBT approach to DPD may be effective, but further trials with larger sample sizes and more rigorous research methodology are needed to determine the specificity of this approach.

Adult↗

PubMed2005

Comparative efficacy and safety of long-acting risperidone and risperidone oral tablets.

A double-blind study of long-acting injectable risperidone and oral risperidone tablets was conducted in 640 patients with schizophrenia. All patients received flexible doses of 1-6 mg of oral risperidone for 8 weeks. Doses were stable during weeks 5-8. At the end of week 8, symptomatically stable patients were randomly assigned to receive long-acting risperidone (active injections, dummy oral) or continued oral risperidone (dummy injections, active oral) for 12 weeks. Significant improvements were demonstrated from baseline to endpoint in Positive and Negative Syndrome Scale (PANSS) total (P<0.001) and factor scores (P<0.05) in both groups. According to a noninferiority analysis, the two treatments showed comparable efficacy in total PANSS scores over the short-term. No unexpected adverse events were recorded. The findings indicate that symptomatically stable patients can be safely switched from oral risperidone to long-acting injectable risperidone without compromising efficacy.

Adolescent↗

PubMed2005

Word frequency effects on free recall and recognition in patients with schizophrenia.

BACKGROUND: Word frequency paradigms have been used repeatedly in healthy populations to help understand the functioning of verbal memory. We investigated the word frequency effects in a sample of patients with schizophrenia, assuming these data may shed light on certain encoding processes. METHODS: Two mixed lists of high- and low-frequency words were presented to 46 patients with schizophrenia and 43 healthy control subjects. List learning was followed by free recall and recognition in immediate and delayed conditions. RESULTS: Overall the high-frequency words were better recalled, whereas the low-frequency words were better recognised. The lack of interaction with diagnosis indicates that these effects were equivalent in both groups. In immediate recognition, the discrimination deficit for the high-frequency words in patients tended to be increased relative to that for the low-frequency words, suggesting greater impairment in the encoding of those words. CONCLUSION: It is argued that the encoding of the distinct low-frequency words is less efficient in patients, but qualitatively unimpaired. By contrast, the familiar words might be more difficult for patients to encode, as they are more easily confused with other common words stored in long-term memory.

Adult↗

PubMed2005

The cognitive neuropsychiatry of delusions: from psychopathology to neuropsychology and back again.

BACKGROUND: The nature of delusions remains unclear despite their interest to researchers and importance in psychopathology. Here we present a review of the contributions from various disciplines, principally cognitive neuroscience, towards a new understanding. METHOD: Narrative review of published research. RESULTS: The main areas of activity revolve around reasoning biases, attributional and attentional biases, theory of mind, and the role of emotion, with each area beginning to be explored using functional neuroimaging techniques. Of heuristic interest are neurological models, which include confabulation and delusional misidentification and the one- versus two-stage (perceptual versus reasoning plus perceptual) accounts of the latter. CONCLUSIONS: These different approaches are shown to each highlight mechanisms which are suggested to cause, contribute to, or modulate the genesis and form of delusions. Such contributions coupled with traditional phenomenological methods should provide the foundations for a cognitive neuropsychiatry of delusions.

Brain↗

PubMed2005

Unpacking the depersonalization syndrome: an exploratory factor analysis on the Cambridge Depersonalization Scale.

BACKGROUND: Depersonalization has long been considered a syndrome but there is poor agreement on its constituent symptoms. METHOD: In order to establish whether different symptoms of depersonalization represent the expression of a single or several underlying dimensions, an exploratory factor analysis on the Cambridge Depersonalization Scale (CDS) was carried out on 138 consecutive patients diagnosed with depersonalization disorder. RESULTS: Four well determined factors accounting for 73.3% of the variance were extracted. These were labelled 'Anomalous Body Experience'; 'Emotional Numbing'; 'Anomalous Subjective Recall' and 'Alienation from Surroundings'. CONCLUSIONS: Symptoms of depersonalization belong to distinct but related psychopathological domains.

Adult↗

PubMed2005

Hallucinations, negative symptoms, and response bias in a verbal recognition task in schizophrenia.

Several studies have reported an association between hallucinations and tendency to make false alarms in acoustic signal detection tasks. Previous work on patients with schizophrenia has suggested that false recognitions and other types of memory error were positively associated with hallucinations and inversely associated with certain negative symptoms of withdrawal. In this study, 40 patients with schizophrenia were administered a word recognition task. Mixed lists of high- and low-frequency words were presented, then the target words had to be recognized among distractors in immediate and delayed recognition conditions. Hallucination scores were correlated with an increased bias toward false recognitions of nonpresented words. Affective flattening tended to be correlated with a reduced bias toward false recognitions. Anhedonia was significantly correlated with a reduced response bias. Hallucinations and anhedonia therefore presented an opposite association with the response bias. The influence of word frequency and delay on this association is discussed.

Adult↗

PubMed2005

Reliability of mental capacity assessments in psychiatric in-patients.

BACKGROUND: Previous work on the reliability of mental capacity assessments in patients with psychiatric illness has been limited. AIMS: To describe the interrater reliability of two independent assessments of capacity to consent to treatment, as well as assessments made by a panel of clinicians based on the same interview. METHOD: Fifty-five patients were interviewed by two interviewers 1-7 days apart and a binary (yes/no) capacity judgement was made, guided by the MacArthur Competence Assessment Tool for Treatment (MacCAT-T). Four senior clinicians used transcripts of the interviews to judge capacity. RESULTS: There was excellent agreement between the two interviewers for capacity judgements made at separate interviews (kappa=0.82). A high level of agreement was seen between senior clinicians for capacity judgements of the same interview (mean kappa=0.84). CONCLUSIONS: In combination with a clinical interview, the MacCAT-T can be used to produce highly reliable judgements of capacity.

Adult↗

PubMed2005

Prevalence and predictors of mental incapacity in psychiatric in-patients.

BACKGROUND: Little is known about the proportion of psychiatric in-patients who lack capacity to make treatment decisions, or the associations of lack of capacity. AIMS: To determine the prevalence of psychiatric in-patients who lack capacity to make decisions about current treatment and to identify demographic and clinical associations with lack of mental capacity. METHOD: Patients (n=112) were interviewed soon after admission to hospital and a binary judgement of capacity was made, guided by the MacArthur Competence Tool for Treatment. Demographic and clinical information was collected from an interview and case notes. RESULTS: Of the 112 participants, 49 (43.8%) lacked treatment-related decisional capacity. Mania and psychosis, poor insight, delusions and Black and minority ethnic group were associated with mental incapacity. Of the 49 patients lacking capacity, 30 (61%) were detained under the Mental Health Act 1983. Of the 63 with capacity, 6 (9.5%) were detained. CONCLUSIONS: Lack of treatment-related decisional capacity is a common but by no means inevitable correlate of admission to a psychiatric in-patient unit.

Adult↗

PubMed2005

Perception of facial and vocal affect by people with schizophrenia in early and late stages of illness.

BACKGROUND: Emotion recognition impairments have been demonstrated in schizophrenia, but few studies have examined whether these reflect generalised or specific perceptual deficits or are associated with illness course. AIMS: To examine the nature of emotion recognition abnormalities in patients with schizophrenia at different stages of illness. METHOD: We examined the performance of 50 in-patients with early-stage schizophrenia, 50 with chronic schizophrenia and 50 healthy controls on the Benton Facial Recognition Test, Facial Emotion Recognition Test and Voice Emotion Recognition Test. RESULTS: Patients with chronic schizophrenia were significantly more impaired than other groups on the emotional tasks, even after controlling for impairments in non-emotional stimuli. Individual emotion recognition accuracy for the two sensory modalities was not significantly positively correlated for either group with schizophrenia. CONCLUSIONS: Emotion recognition deficits in schizophrenia are trait features of the disorder and increase with illness duration.

Adolescent↗

PubMed2004

A longitudinal study of premorbid IQ Score and risk of developing schizophrenia, bipolar disorder, severe depression, and other nonaffective psychoses.

CONTEXT: Longitudinal studies indicate that a lower IQ score increases risk of schizophrenia. Preliminary evidence suggests there is no such effect for nonpsychotic bipolar disorder. To our knowledge, there are no prior population-based, longitudinal studies of premorbid IQ score and risk of developing severe depression requiring hospital admission. OBJECTIVES: To investigate the association between premorbid IQ score and risk of developing schizophrenia, other nonaffective psychoses, bipolar disorder, and severe depression and to investigate effects of confounding and examine possible causal pathways by which IQ may alter these risks. DESIGN: Historical cohort study, using record linkage for hospital admissions during a 27-year follow-up period. SETTING: Survey of Swedish conscripts (1969-1970). PARTICIPANTS: Population-based sample of 50,087 male subjects. Data were available on IQ score at conscription and on other social and psychological characteristics. MAIN OUTCOME MEASURES: International Classification of Diseases, Eighth Revision or Ninth Revision diagnoses of schizophrenia, bipolar disorder, severe depression, and other nonaffective psychoses. RESULTS: There was no association between premorbid IQ score and risk of bipolar disorder. Lower IQ was associated with increased risk of schizophrenia, severe depression, and other nonaffective psychoses. Risk of schizophrenia was increased in subjects with average IQ compared with those with high scores, indicating that risk is spread across the whole IQ range. CONCLUSIONS: Lower IQ score was associated with increased risk for schizophrenia, severe depression, and other nonaffective psychoses, but not bipolar disorder. This finding indicates that at least some aspects of the neurodevelopmental etiology of bipolar disorder may differ from these other disorders.

Adolescent↗

PubMed2004

Dissociating linguistic and nonlinguistic gestural communication in the brain.

Gestures of the face, arms, and hands are components of signed languages used by Deaf people. Signaling codes, such as the racecourse betting code known as Tic Tac, are also made up of such gestures. Tic Tac lacks the phonological structure of British Sign Language (BSL) but is similar in terms of its visual and articulatory components. Using fMRI, we compared the neural correlates of viewing a gestural language (BSL) and a manual-brachial code (Tic Tac) relative to a low-level baseline task. We compared three groups: Deaf native signers, hearing native signers, and hearing nonsigners. None of the participants had any knowledge of Tic Tac. All three groups activated an extensive frontal-posterior network in response to both types of stimuli. Superior temporal cortex, including the planum temporale, was activated bilaterally in response to both types of gesture in all groups, irrespective of hearing status. The engagement of these traditionally auditory processing regions was greater in Deaf than hearing participants. These data suggest that the planum temporale may be responsive to visual movement in both deaf and hearing people, yet when hearing is absent early in development, the visual processing role of this region is enhanced. Greater activation for BSL than Tic Tac was observed in signers, but not in nonsigners, in the left posterior superior temporal sulcus and gyrus, extending into the supramarginal gyrus. This suggests that the left posterior perisylvian cortex is of fundamental importance to language processing, regardless of the modality in which it is conveyed.

Adolescent↗

PubMed2004

Cellular immune activation in Gulf War veterans.

The etiology and pathology of illnesses related to the first Persian Gulf War are unclear. Among the constellation of symptoms noted in sick veterans, some, such as skin rashes, musculoskeletal pains, and neuropsychiatric problems, have been proposed to reflect an underlying immune dysfunction. In this study we explored the hypothesis that sickness following deployment to the Gulf in 1991 is associated with altered immune function, and we examine possible associated exposures. In particular, we focused on peripheral blood Th1/Th2 balance by measuring intracellular production of IFN-gamma, IL-2 (Th1), IL-4 (Th2), and IL-10 by CD4 T cells, using a nested case control study design within a large epidemiological survey. We compared symptomatic Gulf War veterans (sGWV) with well GWVs (wGWV), and a second control group of symptomatic veterans who served in Bosnia or were nondeployed military personnel of the same era. We found evidence for an altered immune status in sGWV in comparison to the other study groups. In particular, ongoing Th1-type immune activation was associated with multisymptom illness in GWVs, with sick veterans having significantly elevated levels of IFN-gamma and IL-2 producing CD4+ cells in the absence of in vitro stimulation compared with wGWVs (P = 0.01 and P =0.001). In vitro polyclonal activation revealed significantly elevated levels of IL-10 producing memory CD4 cells in sGWVs (P <0.001), but other cytokines were normal. In terms of possible exposures that might influence immune function, we found a trend for reduced levels of IFN-gamma producing cells after polyclonal activation with increasing numbers of vaccines administered (P <0.05) but no changes in other cytokines. These data show that multisymptom illness in Gulf War veterans is characterized by ongoing Th1-type immune activation and a biased generation of memory cells secreting the suppressor cytokine, IL-10.

Bosnia and Herzegovina↗

PubMed2004

Semantic organization and verbal memory efficiency in patients with schizophrenia.

The role of semantic organization in verbal memory efficiency in schizophrenia was investigated. Patients and healthy controls were administered a free-recall task involving 1 nonsemantically organizable list, 1 list organizable in semantic categories with typical instances, and 1 list organizable in semantic categories with atypical instances. Reduced semantic organization was observed in patients. Regression analyses showed that the semantic clustering score in the atypical organizable list made a significant contribution to recall performance in patients. When semantic clustering was controlled, the effect of diagnosis on free recall was significant. These results suggest that depth of semantic organization is a crucial factor of verbal memory performance in schizophrenia. However, semantic organizational deficit does not account for the whole recall impairment.

Adult↗

PubMed2004

Recognition of visual stimuli and memory for spatial context in schizophrenic patients and healthy volunteers.

Verbal and visual recognition tasks were administered to 40 patients with schizophrenia and 40 healthy comparison subjects. The verbal recognition task consisted of discriminating between 16 target words and 16 new words. The visual recognition task consisted of discriminating between 16 target pictures (8 black-and-white and 8 color) and 16 new pictures (8 black-and-white and 8 color). Visual recognition was followed by a spatial context discrimination task in which subjects were required to remember the spatial location of the target pictures at encoding. Results showed that recognition deficit in patients was similar for verbal and visual material. In both schizophrenic and healthy groups, men, but not women, obtained better recognition scores for the colored than for the black-and-white pictures. However, men and women similarly benefited from color to reduce spatial context discrimination errors. Patients showed a significant deficit in remembering the spatial location of the pictures, independently of accuracy in remembering the pictures themselves. These data suggest that patients are impaired in the amount of visual information that they can encode. With regards to the perceptual attributes of the stimuli, memory for spatial information appears to be affected, but not processing of color information.

Adult↗