Eric F. C. Cheung

No association between T102C polymorphism of serotonin-2A receptor gene and clinical phenotypes of Chinese schizophrenic patients.

Serotonin dysfunction has been implicated in the pathogenesis of schizophrenia. Previous studies have shown an association between the T102C polymorphism of the 5HT2a receptor gene and schizophrenia. However, negative findings have also been reported. One possible explanation for such discrepancy is disease heterogeneity due to the current limitations in the diagnosis of schizophrenia. We conducted a case-control study of the T102C polymorphism with detailed characterisation of the clinical phenotypes to investigate the possible association with schizophrenia not only at the diagnostic level, but also with reference to other clinical phenotypes potentially related to serotonin dysfunction. Four hundred and seventy-one biologically unrelated schizophrenic patients and 523 unrelated healthy controls of Han Chinese descent in Hong Kong were compared for genotypes and allele frequencies of the T102C polymorphism by PCR amplification and restriction analysis. No evidence of association was detected at the diagnostic level and various clinical phenotypes. However, we found a trend association with small effect size between genotype 102T/102C and patients with better verbal fluency and less motor co-ordination soft neurological signs. There is a need for future large-scale studies on the possible associations between genetic polymorphisms and neurocognitive function impairments in schizophrenia.

Suicidal ideation in patients with systemic lupus erythematosus: incidence and risk factors

OBJECTIVE To study the incidence of suicidal ideation in patients with SLE and the associated risk factors. METHODS Consecutive patients who fulfilled four or more ACR criteria for SLE were recruited. Suicidal thought in the preceding month was assessed by three direct questions. The intensity of suicidal ideation was assessed by the validated Beck Scale for Suicidal Ideation (BSSI). Socio-demographic data, clinical manifestations, Hospital Anxiety and Depression Scale (HADS), SLEDAI and SLICC/ACR Damage Index (SDI) scores were compared between patients with and without suicidal thoughts. Linear regression was used to study the factors associated with higher BSSI scores. RESULTS Of the 367 SLE patients studied (96% women; mean age 40.2 years (S.D. 13), mean disease duration 9.3 years (S.D. 7.2), 67 (18.3%) patients had clinically active SLE and 137 (37.3%) had organ damage (SDI ≥ 1). Suicidal thoughts were present in 44 (12%) patients. Patients with suicidal thoughts, compared with those without, had significantly higher mean SLEDAI scores in the preceding year [5.1 (S.D. 4.0) vs 2.9 (S.D. 2.7), P < 0.001], higher SDI [1.4 (S.D. 1.7) vs 0.6 (S.D. 1.1), P < 0.001], HADS-depression [11.2 (S.D. 4.7) vs 4.4 (S.D. 3.8), P < 0.001] and anxiety [12.2 (S.D. 4.9) vs 5.6 (S.D. 4.1), P < 0.001] scores, and were more likely to be unemployed (P = 0.02), have a past history of psychiatric disorders (P = 0.03) and previous suicide attempts (P = 0.02), as well as major life events in the preceding month (P = 0.006). Linear regression revealed that the BSSI score correlated significantly with the HADS-depression score (β = 0.27, P = 0.001), previous suicide attempts (β = 0.12, P = 0.03), major life events (β = 0.13, P = 0.01) and cardiovascular SDI score (β = 0.27, P < 0.001). CONCLUSION Suicidal ideation is common in SLE and is more intense in patients with depressive symptoms, cardiovascular damage, recent life events and previous suicide attempts.

Sustained Attention Deficit Along the Psychosis Proneness Continuum A Study on the Sustained Attention to Response Task (SART)

BackgroundSustained attention deficits have been associated with schizophrenia. However, these findings were limited to patients with schizophrenia and cannot be generalized to a wider nonclinical sample with schizotypal personality features. ObjectivesThis study aimed to examine the sensitivity of a theory-driven test, the Sustained Attention Response to Task (SART), in individuals with schizotypal personality features. We also investigated the relationships between different parameters of SART and different dimensions of schizotypal features. MethodsOne hundred and ninety-nine participants (74 individuals with schizophrenia, 69 individuals with psychometrically determined schizotypal features, and 56 healthy controls) took part in this study. Participants scoring in the top 10% of the Schizotypal Personality Questionnaire (SPQ) score were identified as having schizotypal features, and those scoring in the bottom 10% were recruited as healthy controls. All participants were administered the SART in an experimental cubicle. ResultsThe findings indicated that: (1) significant differences were found in SART commission error and sensitivity between the 3 experimental groups, with patients with schizophrenia and individuals with schizotypal features performing worse than healthy controls; (2) there was a trend toward statistical significance for SART efficiency score and d′, with controls performing better than patients with schizophrenia and individuals with schizotypal features; (3) some associations between some SART indices and schizotypal traits were found; and (4) there was no significant relationship between SART indices and clinical symptoms in patients with schizophrenia in this study. Conclusions:This investigation demonstrated the potential value of a relatively new sustained attention paradigm for research in schizophrenia spectrum disorders.

Domain-specific hedonic deficits towards social affective but not monetary incentives in social anhedonia

Anticipatory and consummatory dissociation of hedonic experience may manifest as anhedonia in schizophrenia. However, it is unclear if this temporal dissociation of pleasure experience is also relevant in other symptoms like social anhedonia in the schizophrenia disorder spectrum. The present study applied two incentive delay tasks involving different incentive types (money vs. social affective images) to a sample of 28 participants with elevated social anhedonia (SocAnh) and 38 healthy controls from a population of 476 college students. The results showed that the SocAnh group had comparable anticipatory sensitivity and consummatory pleasure towards monetary incentives as the controls; but they exhibited significant decrease in both anticipatory sensitivity and consummatory experience to positive social affective images. These findings demonstrate the presence of a domain-specific deficit in people with social anhedonia towards social affective information, and suggest that incentive types could confound the findings on the dissociation of anticipatory vs. consummatory hedonic capacities.

Course of neurological soft signs in first-episode schizophrenia: Relationship with negative symptoms and cognitive performances

This prospective study examined the course of neurological soft signs (NSS) in patients with first-episode schizophrenia and its relationship with negative symptoms and cognitive functions. One hundred and forty-five patients with first-episode schizophrenia were recruited, 29 were classified as having prominent negative symptoms. NSS and neuropsychological measures were administered to all patients and 62 healthy controls at baseline. Patients were then followed-up prospectively at six-month intervals for up to a year. Patients with prominent negative symptoms exhibited significantly more motor coordination signs and total NSS than patients without prominent negative symptoms. Patients with prominent negative symptoms performed worse than patients without negative symptoms in working memory functions but not other fronto-parietal or fronto-temporal functions. Linear growth model for binary data showed that the prominent negative symptoms were stable over time. Despite general improvement in NSS and neuropsychological functions, the prominent negative symptoms group still exhibited poorer motor coordination and higher levels of NSS, as well as poorer working memory than patients without prominent negative symptoms. Two distinct subtypes of first-episode patients could be distinguished by NSS and prominent negative symptoms.

Dimensional schizotypy and social cognition: an fMRI imaging study

Impairment in empathy has been demonstrated in patients with schizophrenia and individuals with psychosis proneness. In the present study, we examined the neural correlates underlying theory of mind (ToM) and empathy and the relationships between these two social cognitive abilities with schizotypy. Fifty-six first-year college students (31 males, 25 females) between 17 and 21 years of age (M = 19.3, SD = 0.9) from a medical university in China participated. All participants undertook a comic strips functional imaging task that specifically examined both empathy and ToM. In addition, they completed two self-report scales: the Chapman Psychosis Proneness scale and the Interpersonal Responsivity Index (IRI). Results showed that both empathy and ToM conditions of the task were associated with brain activity in the middle temporal gyrus, the temporo-parietal junction (TPJ), the precuneus and the posterior cingulate gyrus. In addition, we found positive correlations between negative schizotypy and brain activity in regions involved in social cognition, namely, the middle temporal gyrus, the TPJ, as well as the medial prefrontal gyrus. These findings highlight that different dimensions of schizotypy may show different associations with brain regions involved in social cognitive abilities. More importantly, the positive correlation between brain activity and anhedonia suggests the presence of compensatory mechanisms in high-risk populations.

Lifetime Prevalence and Correlates of Schizophrenia-Spectrum, Affective, and Other Non-affective Psychotic Disorders in the Chinese Adult Population

Lifetime prevalence of psychotic disorders varies widely across studies. Epidemiological surveys have rarely examined prevalences of specific psychotic disorders other than schizophrenia, and the majority used a single-phase design without employing clinical reappraisal interview for diagnostic verification. The current study investigated lifetime prevalence, correlates and service utilization of schizophrenia-spectrum, affective, and other non-affective psychotic disorders in a representative sample of community-dwelling Chinese adult population aged 16-75 years (N = 5719) based on a territory-wide, population-based household survey for mental disorders in Hong Kong. The survey adopted a 2-phase design comprising first-phase psychosis screening and second-phase diagnostic verification incorporating clinical information from psychiatrist-administered semi-structured interview and medical record review to ascertain DSM-IV lifetime diagnosis for psychotic disorders. Data on sociodemographics, psychosocial characteristics and service utilization were collected. Our results showed that lifetime prevalence was 2.47% for psychotic disorder overall, 1.25% for schizophrenia, 0.15% for delusional disorder, 0.38% for psychotic disorder not otherwise specified, 0.31% for bipolar disorder with psychosis, and 0.33% for depressive disorder with psychosis. Schizophrenia-spectrum disorder was associated with family history of psychosis, cigarette smoking and variables indicating socioeconomic disadvantage. Victimization experiences were significantly related to affective psychoses and other non-affective psychoses. Around 80% of participants with any psychotic disorder sought some kind of professional help for mental health problems in the past year. Using comprehensive diagnostic assessment involving interview and record data, our results indicate that approximately 2.5% of Chinese adult population had lifetime psychotic disorder which represents a major public health concern.

Temporal perception deficits in schizophrenia: integration is the problem, not deployment of attentions.

Patients with schizophrenia are known to have impairments in sensory processing. In order to understand the specific temporal perception deficits of schizophrenia, we investigated and determined to what extent impairments in temporal integration can be dissociated from attention deployment using Attentional Blink (AB). Our findings showed that there was no evident deficit in the deployment of attention in patients with schizophrenia. However, patients showed an increased temporal integration deficit within a hundred-millisecond timescale. The degree of such integration dysfunction was correlated with the clinical manifestations of schizophrenia. There was no difference between individuals with/without schizotypal personality disorder in temporal integration. Differently from previous studies using the AB, we did not find a significant impairment in deployment of attention in schizophrenia. Instead, we used both theoretical and empirical approaches to show that previous findings (using the suppression ratio to correct for the baseline difference) produced a systematic exaggeration of the attention deficits. Instead, we modulated the perceptual difficulty of the task to bring the baseline levels of target detection between the groups into closer alignment. We found that the integration dysfunction rather than deployment of attention is clinically relevant, and thus should be an additional focus of research in schizophrenia.

What does the nose know? Olfactory function predicts social network size in human

Olfaction is an important medium of social communication in humans. However, it is not known whether olfactory function is associated with social network size. This study aimed to explore the underlying neural mechanism between olfactory function and social network. Thirty-one healthy individuals participated in this study. Social network size was estimated using the Social Network Index. Olfactory function was assessed with the Sniffin’ Stick Test. The results showed that there is a significant positive correlation between the size of an individual’s social network and their olfactory sensitivity. We also found that amygdala functional connectivity with the orbitofrontal cortex appeared to be related to olfactory sensitivity and social network size.

Neural Correlates of Prospective Memory Impairments in Schizophrenia

OBJECTIVE Prospective memory (PM) refers to the ability to remember to carry out intended actions after a delay. PM impairments are common in schizophrenia patients and are thought to be related to their prefrontal cortex dysfunction; however, this has not yet been examined directly in the research literature. The current study aimed to examine abnormalities in brain activation during PM task performance in schizophrenia patients. METHOD Twenty-two schizophrenia patients and 25 matched healthy controls were scanned in a 3-T MRI machine while performing a PM task. RESULTS The results showed that compared to the healthy controls, schizophrenia patients performed significantly worse on the PM task. Furthermore, they exhibited decreased brain activation in frontal cortex including the right superior frontal gyri (Brodmann area 10), and other related brain areas like the anterior cingulate gyrus, parietal and temporal cortex, including precuneus, and some subcortext, including parahippocampal gyrus and putamen. CONCLUSIONS These findings confirm the involvement and importance of the prefrontal cortex in PM and show evidence of hypofrontality in schizophrenia patients while performing a PM task.