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Biomedical subjects

Anthony S David

Publications and source records attributed to Anthony S David.

At least 19 recordsLinked to original sources
PubMed2007

Role of processing speed and depressed mood on encoding, storage, and retrieval memory functions in patients diagnosed with schizophrenia.

The role of various types of slowing of processing speed, as well as the role of depressed mood, on each stage of verbal memory functioning in patients diagnosed with schizophrenia was investigated. Mixed lists of high- and low-frequency words were presented, and immediate and delayed free recall and recognition were required. Two levels of encoding were studied by contrasting the relatively automatic encoding of the high-frequency words and the more effortful encoding of the low-frequency words. Storage was studied by contrasting immediate and delayed recall. Retrieval was studied by contrasting free recall and recognition. Three tests of motor and cognitive processing speed were administered as well. Regression analyses involving the three processing speed measures revealed that cognitive speed was the only predictor of the recall and recognition of the low-frequency words. Furthermore, slowing in cognitive speed accounted for the deficit in recall and recognition of the low-frequency words relative to a healthy control group. Depressed mood was significantly associated with recognition of the low-frequency words. Neither processing speed nor depressed mood was associated with storage efficiency. It is concluded that both cognitive speed slowing and depressed mood impact on effortful encoding processes.

Brain↗
PubMed2006

The inter-rater reliability of mental capacity assessments.

BACKGROUND: Assessing mental capacity involves complex judgements, and there is little available information on inter-rater reliability of capacity assessments. Assessment tools have been devised in order to offer guidelines. We aimed to assess the inter-rater reliability of judgements made by a panel of experts judging the same interview transcripts where mental capacity had been assessed. METHOD: We performed a cross sectional study of consecutive acute general medical inpatients in a teaching hospital. Patients had a clinical interview and were assessed using the MacArthur Competence Assessment Tool for Treatment (MacCAT-T) and Thinking Rationally About Treatment (TRAT), two capacity assessment interviews. The assessment was audiotaped and transcribed. The raters were asked to judge whether they thought that the patient had mental capacity based on the transcript. We then divided participants into three groups - those in whom there was unanimous agreement that they had capacity; those in whom there was disagreement; and those in whom there was unanimous agreement that they lacked capacity. RESULTS: We interviewed 40 patients. We found a high level of agreement between raters' assessments (mean kappa=0.76). Those thought unanimously to have capacity were more cognitively intact, more likely to be living independently and performed consistently better on all subtests of the two capacity tools, compared with those who were unanimously thought not to have capacity. The group in whom there was disagreement fell in between. CONCLUSIONS: This study indicates that clinicians can rate mental capacity with a good level of consistency.

Cardiovascular Diseases↗
PubMed2006

Emotional memory in depersonalization disorder: a functional MRI study.

This study examines emotional memory effects in primary depersonalization disorder (DPD). A core complaint of DPD sufferers is the dulling of emotional responses, and previous work has shown that, in response to aversive stimuli, DPD patients do not show activation of brain regions involved in normal emotional processing. We hypothesized that DPD sufferers would not show the normal emotional enhancement of memory, and that they would not show activation of brain regions concerned with emotional processing during encoding and recognition of emotional verbal material. Using fMRI, 10 DPD patients were compared with an age-matched healthy control group while performing a test of emotional verbal memory, comprising one encoding and two recognition memory tasks. DPD patients showed significantly enhanced recognition for overtly emotive words, but did not show enhancement of memory for neutral words encoded in an emotive context. In addition, patients did not show activation of emotional processing areas during encoding, and exhibited no substantial difference in their neural responses to emotional and neutral material in the encoding and emotional word recognition tasks. This study provides further evidence that patients with DPD do not process emotionally salient material in the same way as healthy controls, in accordance with their subjective descriptions of reduced or absent emotional responses.

Adult↗
PubMed2006

Autonomic response in the perception of disgust and happiness in depersonalization disorder.

Patients with depersonalization disorder have shown attenuated responses to emotional unpleasant stimuli, hence supporting the view that depersonalization is characterised by a selective inhibition on the processing of unpleasant emotions. It was the purpose of this study to establish if autonomic responses to facial emotional expressions also show the same blunting effect. The skin conductance responses (SCRs) of 16 patients with chronic DSM-IV depersonalization disorder, 15 normal controls and 15 clinical controls with DSM-IV anxiety disorders were recorded in response to facial expressions of happiness and disgust. Patients with anxiety disorders were found to have greater autonomic responses than patients with depersonalization, in spite of the fact that both groups had similarly high levels of subjective anxiety as measured by anxiety scales. SCR to happy faces did not vary across groups. The findings of this study provide further support to the idea that patients with depersonalization have a selective impairment in the processing of threatening or unpleasant emotional stimuli.

Adult↗
PubMed2006

Temporal context discrimination in patients with schizophrenia: associations with auditory hallucinations and negative symptoms.

BACKGROUND: A deficit in remembering the temporal context of events (a type of source memory) has been observed in schizophrenia, and suggested to be associated with positive symptoms. METHODS: In order to investigate memory for temporal context, we administered a list discrimination task to a sample of schizophrenia patients and a sample of healthy controls. Participants were required to learn two lists of mixed high- and low-frequency words separated by 10 min, then to remember whether each word had been presented in the first or in the second list. RESULTS: The number of misattributions to the wrong list was significantly higher in patients than in healthy controls. However, the group difference was eliminated when recall efficiency was covaried. The number of list misattributions was higher in patients with auditory hallucinations than in the other patients, independently of verbal recall efficiency. By contrast, affective flattening and anhedonia were associated with fewer list misattributions of the high-frequency words. CONCLUSIONS: It is suggested that auditory hallucinations are associated with deficit in processing or remembering the temporal context. Conversely, certain negative symptoms are associated with reduced temporal context errors. The possible neural mechanisms involved in temporal context deficit as well as in these specific clinical symptoms are discussed.

Adult↗
PubMed2006

How metaphors influence semantic relatedness judgments: the role of the right frontal cortex.

We used event-related fMRI (ER-fMRI) to test the hypothesis that metaphors bias cognitive processing of semantic relatedness towards a search for a wider range of associations. Twelve right-handed male volunteers read a mixture of metaphoric and literal sentences, each sentence being followed by a single word, which could be semantically related or not to the preceding sentence context. We found that judging unrelated words as contextually irrelevant was associated with increased blood oxygenation level-dependent (BOLD) signal in the right ventrolateral prefrontal cortex in the metaphoric but not in the literal condition. The same region was also activated when subjects endorsed a semantic relation between words and metaphoric sentence primes but not between words and literal sentence primes. We argue that these results are consistent with the notion of semantic open-endedness, whereby figurative statements bias cognitive processing towards a search for a wider range of semantic relationships compared to literal statements, and thus lend further support to the view that coarse semantic coding occurs preferentially in the right hemisphere.

Brain Mapping↗
PubMed2006

Time-resolved fMRI of mental rotation revisited--dissociating visual perception from mental rotation in female subjects.

Functional neuroimaging studies have demonstrated that mental rotation paradigms activate a network of spatially distributed cortical areas rather than a discrete brain region. Although the neuro-anatomical nodes of the rotation network are well established, their specific functional role is less well identified. It was the aim of the present study to dissociate network components involved in the visual perception of 3D cubic objects from regions involved in their mental spatial transformation. This was achieved by desynchronizing the time course of the perceptional process (i.e., stimulus duration) from the duration of the cognitive process (i.e., reaction times) and by comparing these with the temporal characteristics of the hemodynamic response functions (HRFs) in regions of interest. To minimize intersubject variability, an all-female subject group was chosen for this investigation. Time-resolved fMRI analysis revealed a significant increase in the full width at half maximum (FWHM) of the HRF with reaction times in the supplementary motor area (pre-SMA), in the bilateral premotor cortex (PMd-proper), and in the left parietal lobe (PP). The FWHM in visual system components such as the bilateral lateral occipital complex (LOC) and dorsal extrastriate visual areas (DE) was constant across trials and roughly equal to the stimulus duration. These findings suggest that visual system activation during mental rotation reflects visual perception and can be dissociated from other network components whose response characteristics indicates an involvement in the mental spatial transformation itself.

Adult↗
PubMed2006

Insight into psychosis and quality of life.

BACKGROUND: Insight into having a psychotic disorder is often considered to be a positive characteristic that improves quality of life. However, the evidence regarding this controversy is mixed. The present study examined the relation between insight and quality of life. METHOD: One hundred thirty-one participants with a psychotic disorder (103 with schizophrenia, 28 with schizoaffective disorder) underwent an assessment of insight, psychotic symptoms, and quality of life. The relation between insight and quality of life was assessed using regression analyses. RESULTS: Contrary to our hypothesis, better insight into having a psychotic disorder was related to reduced emotional well-being (beta = .23, P < .01), lower vocational status (beta = .31, P < .01), and less economic satisfaction (beta = .27, P < .01). Insight into the need for taking medication was positively correlated with higher emotional well-being (beta = -.18, P < .05). No relation was found between insight and psychotic symptoms. DISCUSSION: In light of our findings, the potential importance of combining insight with mechanisms for coping is discussed.

Adaptation, Psychological↗
PubMed2006

A reversal of the normal pattern of parahippocampal response to neutral and fearful faces is associated with reality distortion in schizophrenia.

BACKGROUND: Individuals with schizophrenia demonstrate impaired recognition of facial expressions and may misattribute emotional salience to otherwise nonsalient stimuli. The neural mechanisms underlying this deficit and the relationship with different symptoms remain poorly understood. METHODS: We used event-related functional magnetic resonance imaging to measure neural responses to neutral, mildly fearful, and prototypically fearful facial expressions. The sample included 15 medicated individuals with chronic schizophrenia (SZ) and 11 healthy control individuals (CON), matched for gender (all male), age, and years of education. RESULTS: A repeated measures 3 x 2 analysis of variance (ANOVA) revealed a significant interaction between expression intensity and group in right parahippocampal gyrus (p < .01). Individuals with chronic schizophrenia demonstrated a decrease, whereas CON showed an increase, in right parahippocampal gyrus response to increasingly fearful expressions. Between-group comparison revealed greater activation in SZ than CON in right parahippocampal gyrus to neutral faces. The reality distortion dimension, but not neuroleptic medication dose, was positively associated with the right parahippocampal gyral and right amygdalar response to neutral faces in SZ. CONCLUSIONS: An abnormally increased parahippocampal response to neutral faces was positively associated with reality distortion in SZ. This may underlie the previously reported finding of a misattribution of emotional salience to nonsalient social stimuli in schizophrenia.

Adult↗
PubMed2006

Lexical and sentential processing in British Sign Language.

Studies of spoken and written language suggest that the perception of sentences engages the left anterior and posterior temporal cortex and the left inferior frontal gyrus to a greater extent than non-sententially structured material, such as word lists. This study sought to determine whether the same is true when the language is gestural and perceived visually. Regional neural activity was measured using functional MRI while Deaf and hearing native signers of British Sign Language (BSL) detected semantic anomalies in well-formed BSL sentences and when they detected nonsense signs in lists of unconnected BSL signs. Processing BSL sentences, when contrasted with signed lists, was reliably associated with greater activation in the posterior portions of the left middle and superior temporal gyri and in the left inferior frontal cortex, but not in the anterior temporal cortex, which was activated to a similar extent whether lists or sentences were processed. Further support for the specificity of these areas for processing the linguistic-rather than visuospatial-features of signed sentences came from a contrast of hearing native signers and hearing sign-naïve participants. Hearing signers recruited the left posterior temporal and inferior frontal regions during BSL sentence processing to a greater extent than hearing non-signers. These data suggest that these left perisylvian regions are differentially associated with sentence processing, whatever the modality of the linguistic input.

Adolescent↗
PubMed2006

A systematic review and quantitative appraisal of fMRI studies of verbal fluency: role of the left inferior frontal gyrus.

The left inferior frontal gyrus (LIFG) has consistently been associated with both phonologic and semantic operations in functional neuroimaging studies. Two main theories have proposed a different functional organization in the LIFG for these processes. One theory suggests an anatomic parcellation of phonologic and semantic operations within the LIFG. An alternative theory proposes that both processes are encompassed within a supramodal executive function in a single region in the LIFG. To test these theories, we carried out a systematic review of functional magnetic resonance imaging studies employing phonologic and semantic verbal fluency tasks. Seventeen articles meeting our pre-established criteria were found, consisting of 22 relevant experiments with 197 healthy subjects and a total of 41 peak activations in the LIFG. We determined 95% confidence intervals of the mean location (x, y, and z coordinates) of peaks of blood oxygenation level-dependent (BOLD) responses from published phonologic and semantic verbal fluency studies using the nonparametric technique of bootstrap analysis. Significant differences were revealed in dorsal-ventral (z-coordinate) localizations of the peak BOLD response: phonologic verbal fluency peak BOLD response was significantly more dorsal to the peak associated with semantic verbal fluency (confidence interval of difference: 1.9-17.4 mm). No significant differences were evident in antero-posterior (x-coordinate) or medial-lateral (y-coordinate) positions. The results support distinct dorsal-ventral locations for phonologic and semantic processes within the LIFG. Current limitations to meta-analytic integration of published functional neuroimaging studies are discussed.

Brain Mapping↗
PubMed2006

A method for studies of madness.

In these series of articles honouring John Marshall for his contributions to psychology, linguistics, the history of ideas and many other fields we should not forget his contribution to psychiatry. This has been mostly from the point of view of a critical observer, but also someone deeply interested in the application of cognitive neuropsychology to a broader range of disorders than the traditional ones. This "cognitive neuropsychiatric approach" is discussed in relation to attempts to understand thought disorder, delusions and lack of insight.

Cognition Disorders↗
PubMed2006

Building up linguistic context in schizophrenia: evidence from self-paced reading.

An impairment in the build-up and use of context has been proposed as a core feature of schizophrenia. The current study tested the hypothesis that schizophrenia patients show impairments in building up context within sentences because of abnormalities in combining semantic with syntactic information. Schizophrenia patients and healthy controls read and made acceptability judgments about sentences containing verbs that were semantically associated with individual preceding words but that violated either the meaning (animacy/semantic constraints) or the syntactic structure (morphosyntactic constraints) of their preceding contexts. To override these semantic associations and determine that such sentences are unacceptable, participants must integrate semantic with syntactic information. These sentences were compared with congruous and pragmatically/semantically violated sentences that imposed fewer semantic-syntactic integration demands. At sentence-final words and decisions, patients showed smaller reaction time differences than controls to animacy/semantically violated or morphosyntactically violated sentences relative to pragmatically/semantically violated or nonviolated sentences. The relative insensitivity to these violations in patients with schizophrenia may arise from impairments in combining semantic and syntactic information to build up sentence context.

Adult↗
PubMed2006

Self-awareness after acquired and traumatic brain injury.

Self-awareness deficits are common after acquired and (traumatic) brain injury (ABI), particularly in social behaviour, yet the underlying cognitive and neuroanatomical structures supporting social self-awareness are not fully understood. This paper reviews the current literature on prevalence, type and severity of self-awareness deficits in ABI. Neuropsychological and neuroanatomical models are reviewed and theoretical frameworks are examined. We summarise results of a case-control comparison of 20 ABI patients with and 20 ABI patients without behavioural disturbance. Our research found that lack of social self-awareness predicts behavioural disturbance in acquired and traumatic brain injury independent of cognitive and executive function. Theory of mind ability was related to self-awareness and a possible role for metacognition and affective processes in self-awareness is discussed to account for social self-awareness deficits.

Adult↗
PubMed2006

Processing speed: a strong predictor of verbal memory performance in schizophrenia.

The role of slowing of processing speed in verbal memory impairment in patients with schizophrenia was investigated. Forty-one patients with schizophrenia and 41 healthy control subjects were administered a verbal memory task involving free recall of three lists of words, which varied in their degree of semantic organization. Standard processing speed tests were administered as well. Regression analyses were conducted on the number of words recalled in each list. A global processing speed measure was a significant predictor of the recall of each list in patients. Patients were very significantly impaired in the recall of the three lists relative to healthy controls. However, when the processing speed measure was entered in the regression, the significance of diagnosis was considerably reduced for one of the lists, with no semantic organization, and eliminated for the other two lists which contained semantic organization. These findings suggest that slowing in processing speed is an important contributor to verbal memory impairment in patients with schizophrenia. The possible role of various specific slowing functions is discussed.

Adult↗
PubMed2006

Depersonalization in psychiatric patients: a transcultural study.

There is evidence suggesting that the prevalence of depersonalization in psychiatric patients can vary across cultures. To explore the possible influence of culture on the prevalence of depersonalization, we compared psychiatric inpatient samples from the United Kingdom (N = 31), Spain (N = 68), and Colombia (N = 41) on standardized and validated self-rating measures of dissociation and depersonalization: the Cambridge Depersonalization Scale and the Dissociative Experiences Scale (DES). Colombian patients were found to have lower global scores on the Cambridge Depersonalization Scale and the DES and all its subscales, with the exception of DES-Absorption. No differences were found for measures of depression or anxiety. These findings seem to support the view that depersonalization is susceptible to cultural influences. Attention is drawn to the potential relevance of the sociological dimension "individualism-collectivism" on the experience of the self, and it is proposed that cultures characterized by high individualism may confer vulnerability to depersonalization experiences.

Adult↗
PubMed2006

Social outcomes in schizophrenia: from description to action.

PURPOSE OF REVIEW: The reality of schizophrenia is not fully expressed by measures of psychopathology and both descriptive research and research into interventions benefit from the investigation of social outcomes. We define these as measures which reflect performance compared to normal social expectations, either of oneself or of another. The studies we reviewed looked at the effects on summary measures, for example, quality of life, as well as simpler, more self-explanatory outcomes such as employment, marital status, financial independence and housing. RECENT FINDINGS: The review contrasts studies which describe the determinants of social outcomes and studies designed to estimate the effects of interventions on these outcomes. Recent descriptive studies demonstrate that social outcomes have both longitudinal and cross-sectional associations with cognitive impairment, preexisting functional impairment and certain symptoms. Studies of both pharmacological and social interventions suggest that, at best, these can affect social outcomes. SUMMARY: Simpler social outcomes are reported less frequently than summary measures which can make interpretation more difficult, thus diluting a potential advantage of social outcome measures to researchers and clinicians alike. Social outcomes are underreported compared to measures of psychopathology, particularly in trials of interventions.

Employment↗