1,721,293 research outputs found
Detecting semantic memory abnormalities in psychosis : quantification using semantic space modelling and network approaches
No full textBackground: Language disorganization is central to the conceptualization of psychosis. Prior literature has consistently reported the presence of various semantic memory impairments in psychosis across a range of neuropsychological tests. However, the underlying factors of these semantic abnormalities remain inconclusive. The quantification of semantic abnormalities have improved with the recent advancements in semantic space modelling and network analyses. The current study applied such computational methods to a continued word association task, using immediate response to cue-words as a means to explore semantic associations. This study aims to quantify and characterize semantic abnormalities in patients with psychotic disorders, in comparison to healthy controls. Furthermore, a prospective 6-month longitudinal study design was employed to investigate the semantic abnormalities during an active psychotic episode compared with the same patients after remission 6-months later, in order to clarify the state-trait status of the semantic abnormalities, and their relationships with clinical symptoms and cognitive functioning.
Methodology: Fifty-one patients with psychotic disorders and 51 healthy controls matched in terms of age, gender and years of education have been included in the study. The study assessed a battery of clinical, cognitive, functioning and semantic associations in patients at two time points. A battery of cognitive assessments and semantic associations were also collected from healthy controls at two time points. A continued word association task was used to elicit three association responses per cue from a set of 200 Cantonese cue-words. The association responses were used to quantify and characterize semantic memory processing through three distinct levels of analyses, namely semantic similarity, individual-level and grouped-level semantic networks.
Results: First, the current study showed that the semantic similarity changed over time with the change in patient’s symptom severity, while it remained stable across time in healthy controls. In particular, semantic similarity change over time significantly correlated with the change in formal thought disorder (FTD) symptoms. Second, there were significant structural differences between patients and controls on individual-level and grouped-level semantic networks at two time points. Third, there were significant changes across time in the control’s individual-level network structure, while the grouped-level network structural anomalies found in patients remained stable over time. Lastly, the individual-level semantic network properties were found significantly contribute to FTD symptoms and affective symptom severity at baseline.
Discussion: This is an exploratory attempt in applying a novel approach through semantic space modelling and network analyses to investigate the semantic abnormalities in Cantonese-speaking patients with psychotic disorders. Generally, differences in semantic memory processing between patients and controls have been demonstrated across all three levels of analyses. Semantic similarity has been observed to be a state-dependent measure that changes along with patient’s mental states. Whereas, the semantic network structures remained stable over time despite the changes in mental states, suggesting a trait-like measure. This study is one of the first studies to identify potential differences in semantic deficits in psychotic disorders due to language differences.published_or_final_versionPsychiatryMasterMaster of Philosoph
Semantic networks and their disruptions in psychotic disorders
No full textBackground
Loosening of association and cognitive impairments are important core features of psychotic disorders (Bleuler, 1911/1950; Elvevåg & Goldberg, 2000). Over the past decades, research has identified various anomalies in linguistic functions in patients with psychosis. Nevertheless, despite numerous research into linguistic disruptions in psychosis, it remains inconclusive as to whether and how are language disrupted in psychosis, and what is the relationship between language disruptions and the other symptoms observed in psychosis, many of which are related to language. With the development of computational analysis methods, recent studies have attempted to apply these methods into the study of semantic disruptions in psychosis. The current study aimed to investigate the semantic network, its disruptions, and the factors behind these disruptions in patients by combining a continued word association task with semantic network analysis method. Using a longitudinal design, the current study also hopes to investigate whether semantic network changes across time as patients’ mental states change.
Methodology
Forty-two Cantonese-speaking patient subjects with psychotic disorders and 40 matching control subjects in Hong Kong have been included in the study. The study assessed the clinical, cognitive, functioning and semantic association profile of patients at baseline recruitment and at a 6-month follow-up. The study also collected cognitive and semantic association data from healthy control at baseline recruitment. The word association data collected using the continued word association task was analysed using an exploratory semantic network analysis method.
Results
First, the current study found that semantic networks properties differed between patients and controls. Patients’ network had less positive responses, and a denser network with slightly longer shortest path length, higher clustering coefficient, and lower modularity. Second, the study found that part of semantic network properties changed across time in patients alongside improvement in symptoms and functioning. Patients’ baseline semantic network was also less positive, denser, and with higher clustering coefficient than patients’ network at 6- month.
Discussion
This is the first attempt in studying the semantic network differences in Cantonese-speaking psychosis, anomalies in patients’ semantic association was found at an active psychotic state, when compared with controls. An across-time change was also noted in the study. This suggests that some of the semantic anomalies noted perhaps are state-dependent measures, which may change as the symptoms of patients change, while some other anomalies may remain as traits that remain unchanged despite the fluctuation in mental states.Li Ka Shing Prize, The Best M.Phil Thesis in the Faculties of Dentistry, Engineering, Medicine and Science (University of Hong Kong), 2017-2018published_or_final_versionPsychiatryMasterMaster of Philosoph
Psychopathology in response to multiple population stressors
No full textA series of large-scale social unrest and co-occurring COVID-19 have erupted in Hong Kong during early 2020. How population-level and personal stressors can interact with intrinsic factors to affect mental health as the events evolve remains to be elucidated.
Three symptom dimensions with varying degrees of responsiveness to external stressors were examined throughout this thesis: PTSD and depressive symptoms (more reactive) and psychotic-like experiences (PLEs; typically considered to be more endogenous), with a key focus on ideas of reference (IOR). Event-based rumination, defined as repetitive thoughts about external events, and smartphone overuse were hypothesised to be transdiagnostic mediators between different stressor types and all three psychopathological states.
Using timely data collected through a large-scale locally adapted online tool, Study 1 (n = 10,110) revealed that social unrest-related traumatic events (TEs), COVID-19 events, and personal stressful life events (SLEs) additively and interactively contributed to PTSD and depressive symptoms. Notably, event-based rumination was significantly associated with both symptom dimensions and mediated the effects of all three event types. The predictive capability of event-based rumination for one-month PTSD and depressive symptoms amid such ongoing population-level stressors was further demonstrated in Study 2 (n = 150), highlighting its clinical significance.
Study 3 (n = 9,873) provided novel evidence in showing that IOR experiences, as a form of PLEs, could also be triggered by population-level stressors. While extrinsic factors, such as severe TEs and SLEs, played more prominent roles in attenuated IOR (feeling of being particularly referred to) and intrinsic factors, such as cognitive ability, played more prominent roles in exclusive IOR (feeling of being exclusively referred to), event-based rumination was associated with both spectra of IOR.
With a wider range of environmental and personal risk and protective factors considered, Study 4 (n = 9,688) highlighted the transdiagnostic effects of not only event-based rumination but also smartphone overuse. Some support was found for both these factors as serial mediators between extrinsic events and all three symptom outcomes, although most of the effects were explained by event-based rumination. Smartphone overuse may possibly contribute to symptoms via a separate pathway.
Furthermore, the transdiagnostic effects of event-based rumination and smartphone overuse remained robust in both Study 5 (n = 6,988), using data from a large subgroup of young people further collected through the tool, and in Study 6 (n = 669), using data from an epidemiological youth sample collected one year later (during which TEs have subsided and COVID-19 was ongoing). Using path analysis, the mediating effects of event-based rumination between extrinsic events and IOR severity were again supported, with some of the effects of SLEs on both event-based rumination and IOR severity explained by individual subjective stress.
Finally, Study 7 offered initial evidence suggesting IOR experiences as a higher class of psychopathology. Symptom network analysis revealed that event-based rumination also contributed to specific symptom-level associations between IOR and both PTSD and depressive symptoms.
The increasingly observed co-occurring large-scale crises globally demands valid, context-relevant, agile, and timely action. It is hoped this thesis could inform such future work.published_or_final_versionPsychiatryDoctoralDoctor of Philosoph
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Cognitive deterioration in predicting relapse of psychosis
No full textA large proportion of patients with psychosis experience the obstacles imposed by relapse, incurring huge economic and psychological burden. Therefore, relapse prevention is an important target in long-term management of psychosis, and accurate identification of individuals who are at increased risks will largely facilitate this process. Only few predictors have been confirmed to predict relapse, such as medication non-adherence and stressful life events.
Because cognitive deficits have been found to precede initial onset, they could also be relevant to predict subsequent psychotic episodes. Given its potential to be objectively measured and prospectively traced over time, and further echoing the recent trend in mobile health technologies that could support timely and remote assessments, cognitive deficits and/or deterioration could contribute useful insights to relapse monitoring. Nevertheless, its role as an early warning sign in relapse prediction remains largely unexplored.
In this study, cognitive deterioration was explored as a main predictor of relapse, alongside some other clinical and psychosocial factors, in a naturalistic observational study with a one-year prospective follow-up design. A total of 120 patients with psychosis who were in full clinical remission for at least six months were included and followed up for one year, or until relapse, whichever earlier. Following baseline assessment, follow-up assessments were scheduled on a monthly basis, where cognitive performance was measured at each assessment with a verbal (Letter Number Sequencing) and a visual (Visual Patterns Test) working memory task, via a mobile App. Cognitive deterioration was defined as worsened performance over a two-month period prior to relapse, or study termination.
At one year, 18 of 110 (16.36%) patients relapsed. Potential factors related to relapse were first identified through univariate between-group comparisons, which were then entered into a binary multiple logistic regression. The final model explained around 60% of variance in relapse, and revealed the independent and statistically significant contributions of three factors, i.e., cognitive deterioration on the verbal working memory task (Letter Number Sequencing), low resilience, as well as medication non-adherence.
This is one of the first studies to establish the predictive role of cognitive deterioration in psychotic relapse. It not only supports the promising direction for further research into cognitive predictors, but also uncovers important clinical significance of cognitive deterioration in relapse monitoring, early relapse identification, as well as suggests the therapeutic potentials of cognition-based training programs that could further translate into favorable clinical outcomes.published_or_final_versionPsychiatryMasterMaster of Philosoph
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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