Positive symptoms and white matter microstructure in never-medicated first episode schizophrenia

Author name used in this publication: V. Cheung2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Instrumental values of organizational citizenship behavior for promotion: A field quasi-experiment

The present study examined the relationship between promotion, perceived instrumentality of organizational citizenship behavior (OCB) for promotion, and employees' OCB before and after promotion. A field quasi-experiment involving 293 tellers of a multinational bank was conducted. Both supervisors and employees provided OCB ratings 3 months before and 3 months after the promotion decision was announced. The authors found employees who perceived OCB as instrumental to their promotion and who were promoted were more likely to decline in their OCB after me promotion

Use of state trajectory prediction in hysteresis control for achieving fast transient response of the buck converter

A dynamic hysteresis control of the buck converter for achieving high slew-rate response to disturbances is proposed. The hysteresis band is derived from the output capacitor current that predicts the output voltage magnitude after a hypothesized switching action. Four switching criteria are formulated to dictate the state of the main switch. The output voltage can revert to the steady state in two switching actions after a large-signal disturbance. The technique is verified with the experimental results of a 50W buck converter.link_to_subscribed_fulltex

Boundary controller for dynamic voltage restorers to achieve fast dynamic response

The performance of using second-order switching surface in boundary control of dynamic voltage restorers (DVR) for improving the voltage stability of power system is examined. The switching surface is derived to estimate the state trajectory movement of the DVR after a hypothesized switching action. It results in a high state trajectory velocity along the switching surface. This phenomenon accelerates the trajectory moving towards the target operating point. The proposed boundary control method has been studied with computer simulations, as well as a low-power prototype. The dynamic responses of the DVR with different voltage sags and different loads, including a resistive load, inductive load and nonlinear load have been examined. It has been shown that the proposed boundary control scheme can achieve a faster transient and damping responses than the other control methods. © 2006 IEEE.link_to_subscribed_fulltex

Executive function in first-episode schizophrenia: A three-year prospective study of the Hayling Sentence Completion Test

In recent decade, deficits in the mechanism of Supervisory Attentional System (SAS) have become increasingly influential in explaining the nature of dysexecutive syndrome experienced by schizophrenic patients. The SAS model is characterized by having a detailed sub-classification of specific executive function components, among which semantic inhibition has been investigated using the Hayling Sentence Completion Test (HSCT). Several studies thus far have indicated that schizophrenic patients show impairment in HSCT performance. However, HSCT data concerning first-episode patients is still scarce. Besides, as previous HSCT studies were all cross-sectional in nature, they were not able to assess changes in HSCT performance over time. In order to address the paucity of knowledge about the longitudinal trajectories and correlates of semantic inhibition deficits in early schizophrenia, this paper reports a three-year prospective study of HSCT performance in medication-naïve, first-episode patients with schizophrenia-spectrum disorders. HSCT performance was assessed in 34 patients at four times over a period of three years, while the 34 healthy controls were assessed once. We found that medication-naïve patients demonstrated impairment in the inhibition condition in HSCT as compared to controls, but not in the initiation condition. Such HSCT impairment gradually improved in the three years following the first psychotic episode; however, HSCT performance did not predict improvement in negative or positive symptoms over the three-year period. The present findings suggest that semantic inhibition impairment is a specific deficit in schizophrenia that may require early intervention efforts, with the goal of facilitating more successful verbal communication and thereby better interpersonal functioning. © 2011 Elsevier B.V.link_to_subscribed_fulltex

Perception of <it>Deqi </it>by Chinese and American acupuncturists: a pilot survey

<p>Abstract</p> <p>Background</p> <p>In acupuncture, <it>deqi </it>is the sensory experience related to clinical efficacy. As the first study taking into account cultural differences on <it>deqi </it>sensation, this pilot survey aims to corroborate the acupuncturists' general experience in clinical practice with functional magnetic resonance imaging (fMRI) findings.</p> <p>Methods</p> <p>Questionnaires were distributed to acupuncturists of TCM (traditional Chinese medicine)hospitals and acupuncturists attending workshops and seminars in the United States and China. Questions covered clinical significance of <it>deqi</it>, patient attitude and the nature of some pain-related sensations elicited by manual needling.</p> <p>Results</p> <p>47 out of a total of 86 acupuncturists agreed that dull pain was <it>deqi </it>and over half regarded it beneficial, while sharp pain was non-<it>deqi </it>and harmful instead. The patients' attitude toward <it>deqi </it>sensation showed a difference between US and China. There was no other dimension showing a difference.</p> <p>Conclusion</p> <p>Results of this pilot survey indicate that the acupuncturists' perception is consistent with our previous fMRI findings. Results showed almost complete agreement that dull pain is considered <it>deqi </it>and beneficial to treatment, while sharp pain is not <it>deqi </it>and harmful. Particularly, dull pain was <it>deqi </it>and was beneficial to treatment whereas sharp pain was not. Patients in China liked the <it>deqi </it>experience whereas those in the US did not.</p

A three-year prospective study of spontaneous eye-blink rate in first-episode schizophrenia: Relationship with relapse and neurocognitive function

Objective: To examine the spontaneous blink rate over a 3-year period and its clinical and cognitive correlates among patients with first-episode schizophrenia. Methods: This study prospectively followed 93 patients with first-episode schizophrenia, schizophreniform and schizoaffective disorders for 3 years. Patients were longitudinally assessed for blink rate, their positive and negative symptoms, and a range of cognitive features including verbal fluency, verbal memory, visual memory, and the Wisconsin Card Sorting Test performance. Results: When compared with a matched control group, there was a significantly higher blink rate at their 3-year follow-up but not at initial presentation. The increase in blink rate over time correlated positively with the number of relapses. It also correlated with logical memory, verbal fluency, categories completed, and perseverative errors in the Wisconsin Card Sorting Test. The increased blink rate also correlated with pre-morbid schizoid and schizotypal traits. All these correlations were statistically significant. Conclusion: The change in the blink rate over time may reflect underlying involvement of the dopaminergic system in mediating relapse and cognitive functions. © 2010 Hong Kong College of Psychiatrists.link_to_subscribed_fulltex

Random number generation deficit in early schizophrenia

Random number generation with a written response mode provides a potentially appealing marker for executive processes. Impaired performance on written random number generation tasks has been reported in chronic schizophrenic patients. However, no study has investigated whether such a deficit occurs in early schizophrenia and whether its profile and severity are similar to those in patients with chronic illness. This study investigated the ability to generate random numbers in patients with early schizophrenia (n = 44) and a healthy control group (n = 48). Patients were less able to maintain several production strategies and generated more stereotyped response sequences, whereas their abilities to identify randomness with an even-handed treatment of digits and to monitor the equality of occurrence of single digits appeared to remain intact. These results provide evidence that some aspects of the deficits in random number generation among chronic schizophrenic patients are also present at early psychotic episode, while some other aspects are relatively less affected in the early years. © Perceptual and Motor Skills 2011.link_to_subscribed_fulltex

A three-year prospective study of spontaneous eye-blink rate in first-episode schizophrenia: relationships with relapse and neurocognitive function

Objective: To examine the spontaneous blink rate over a 3-year period and its clinical and cognitive correlates among patients with first-episode schizophrenia. Methods: This study prospectively followed 93 patients with first-episode schizophrenia, schizophreniform and schizoaffective disorders for 3 years. Patients were longitudinally assessed for blink rate, their positive and negative symptoms, and a range of cognitive features including verbal fluency, verbal memory, visual memory, and the Wisconsin Card Sorting Test performance. Results: When compared with a matched control group, there was a significantly higher blink rate at their 3-year follow-up but not at initial presentation. The increase in blink rate over time correlated positively with the number of relapses. It also correlated with logical memory, verbal fluency, categories completed, and perseverative errors in the Wisconsin Card Sorting Test. The increased blink rate also correlated with pre-morbid schizoid and schizotypal traits. All these correlations were statistically significant. Conclusion: The change in the blink rate over time may reflect underlying involvement of the dopaminergic system in mediating relapse and cognitive functions. © 2010 Hong Kong College of Psychiatrists.link_to_OA_fulltex

Relationship of neurocognitive function and impairment of insight in first episode schizophrenia

Poster 62BACKGROUND: Impairment of insight is one the common features of schizophrenia with clinical importance because of its relationship with treatment compliance and hence clinical outcomes. However, its etiology remains poorly understood. Various studies have suggested the link of poor insight with the neurocognitive functions particularly executive function and memory. The present study aim at evaluating the association between insight and measures of executive functions and working memory in patients with first episode schizophrenia and explore the contribution of these neurocognitive functions to the variance of insight. METHODS: Consecutive patients between ages 18 and 55 with first episode schizophrenia based on DSM-IV diagnostic criteria were recruited from adult psychiatric services covering a defined catchment area in Hong Kong. All the assessments were conducted within six months of starting treatment. Clinical symptoms were evaluated using Positive and Negative Syndrome Scale (PANSS). The Scale for Assessment of Unawareness of Mental Disorder (SUMD) was used to assess insight. Executive functioning was measured by the Wisconsin Card Sort Test (WCST) and Verbal fluency. Working memory was measured by the Letter Number Sequencing (LNS) test from the Wechsler Adult Intelligence Scale (WAIS). RESULTS: There were 79 patients completed the study. The average score of the first three items of SUMD were used as overall insight rating. Individual items were analyzed separately. After correction for multiple testing, WCST categories completed was found to be significantly correlated with overall insight rating (r=-0.337, p=0.003). After analyzing the sub-scale of SUMD in detail, both WCST categories (r=0.315, p=0.006) and WCST perseverative error (r=-0.291, p=0.011) were significantly correlated with awareness of consequence of mental illness (SUMD item 2) but not the awareness of having mental illness (SUMD item 1) and the awareness of need for medication (SUMD item 3). No significant correlations were found with other neurocognitive functions. While the symptomatology explained 27% of variance in overall insight rating, WCST categories explained 7.4% of the variance. The symptomatology explained 26.8% of variance in the awareness of consequence of mental illness, WCST categories completed and perseverative errors explained 5.7% of the variance. DISCUSSION: The current study shows a significant association of WCST performance, particularly categories completed and perseverative errors, with poor insight in patients with first episode schizophrenia. No other neurocognitive functions were found to be significantly associated. This is in line with previous findings in both chronic and first episode patients. Though the contribution of these neurocognitive functions to the variance of insight is small, the consistence of the finding indicating that executive function could be one of the important elements of underlying neurocognitive deficit explaining poor insight. Further studies are needed to explore the etiological models for poor insight