Thi Minh m Ta

Event-related potentials associated with Attention Network Test

Selective visual attention is thought to be comprised of distinct neuronal networks that serve different attentional functions. The Attention Network Test (ANT) has been introduced to allow for assessment of alerting, orienting, and response inhibition. Information on associated measures of neural processing during ANT is still scarce. We topographically analyzed top-down ANT effects on visual event-related potential morphology in 44 healthy participants. Significant reaction time effects were obtained for all attention networks. Posterior cue-locked target N1 amplitude was significantly increased during both alerting and orienting. P3 amplitude was significantly modulated at frontal and parietal leads as a function of inhibition. Our data suggests that attentional mechanisms of alerting and orienting are employed simultaneously at early stages of the visual processing stream to amplify perceptual discrimination and load onto the same ERP component. Fronto-parietal modulations of P3 amplitude seem to mirror both response inhibition and visual target detection and may be interesting markers for further studies.

Attention Network Test reveals alerting network dysfunction in multiple sclerosis

Attention is one of the cognitive domains typically affected in multiple sclerosis. The Attention Network Test was developed to measure the function of the three distinct attentional networks, alerting, orienting, and executive control. The Attention Network Test has been performed in various neuropsychiatric conditions, but not in multiple sclerosis. Our objective was to investigate functions of attentional networks in multiple sclerosis by means of the Attention Network Test. Patients with relapsing—remitting multiple sclerosis (n = 57) and healthy controls (n = 57) matched for age, sex, and education performed the Attention Network Test. Significant differences between patients and controls were detected in the alerting network (p = 0.003), in contrast to the orienting (p = 0.696) and the conflict (p = 0.114) network of visual attention. Mean reaction time in the Attention Network Test was significantly longer in multiple sclerosis patients than in controls (p = 0.032), Multiple sclerosis patients benefited less from alerting cues for conflict resolution compared with healthy controls. The Attention Network Test revealed specific alterations of the attention network in multiple sclerosis patients which were not explained by an overall cognitive slowing.

Test-retest reliability of Attention Network Test measures in schizophrenia.

BACKGROUND The Attention Network Test (ANT) is a well established behavioral measure in neuropsychological research to assess three different facets of selective attention, i.e., alerting, orienting, and conflict processing. Although the ANT has been applied in healthy individuals and various clinical populations, data on retest reliability are scarce in healthy samples and lacking for clinical populations. The objective of the present study was a longitudinal assessment of relevant ANT network measures in healthy controls and schizophrenic patients. METHODS Forty-five schizophrenic patients and 55 healthy controls were tested with ANT in a test-retest design with an average interval of 7.4 months between test sessions. Test-retest reliability was analyzed with Pearson and Intra-class correlations. RESULTS Healthy controls revealed moderate to high test-retest correlations for mean reaction time, mean accuracy, conflict effect, and conflict error rates. In schizophrenic patients, moderate test-retest correlations for mean reaction time, orienting effect, and conflict effect were found. The analysis of error rates in schizophrenic patients revealed very low test-retest correlations. CONCLUSIONS The current study provides converging statistical evidence that the conflict effect and mean reaction time of ANT yield acceptable test-retest reliabilities in healthy controls and, investigated longitudinally for the first time, also in schizophrenia. Obtained differences of alerting and orienting effects in schizophrenia case-control studies should be considered more carefully. The analysis of error rates revealed heterogeneous results and therefore is not recommended for case control studies in schizophrenia.

Dissection of early bottom-up and top-down deficits during visual attention in schizophrenia

OBJECTIVE To characterize the interplay of bottom-up and top-down processing deficits of the early visual ERP component N1 in schizophrenia. METHODS Thirty-three schizophrenic patients and 61 healthy controls underwent a visual selective attention paradigm while 32-channel electroencephalogram was recorded. Visual N1 responses were calculated and source localization was applied. RESULTS Significant reductions of the cue N1 as well as the target N1 components were found in schizophrenia patients. Linear regression slopes for the cue N1 and for the cue-locked target N1 indicated significantly reduced early bottom-up and top-down modulation in patients relative to controls. Source analyses indicated that bottom-up as well as top-down N1 deficits in schizophrenia are associated with partially overlapping current density deficits in posterior cortex areas. Differential functional deficits were observed in right parietal lobe during bottom-up processing and in anterior cingulate cortex during top-down attention. CONCLUSIONS The results provide evidence for both early visual bottom-up and top-down deficits in schizophrenia and illustrate how disturbances in these processing streams converge on the visual N1 amplitude. SIGNIFICANCE Visual top-down disturbances in schizophrenia appear to be confounded by visual bottom-up deficits.

Spatiotemporal mapping of sex differences during attentional processing.

Functional neuroimaging studies have increasingly aimed at approximating neural substrates of human cognitive sex differences elicited by visuospatial challenge. It has been suggested that females and males use different behaviorally relevant neurocognitive strategies. In females, greater right prefrontal cortex activation has been found in several studies. The spatiotemporal dynamics of neural events associated with these sex differences is still unclear. We studied 22 female and 22 male participants matched for age, education, and nicotine with 29‐channel‐electroencephalogram recorded under a visual selective attention paradigm, the Attention Network Test. Visual event‐related potentials (ERP) were topographically analyzed and neuroelectric sources were estimated. In absence of behavioral differences, ERP analysis revealed a novel frontal‐occipital second peak of visual N100 that was significantly increased in females relative to males. Further, in females exclusively, a corresponding central ERP component at around 220 ms was found; here, a strong correlation between stimulus salience and sex difference of the central ERP component amplitude was observed. Subsequent source analysis revealed increased cortical current densities in right rostral prefrontal (BA 10) and occipital cortex (BA 19) in female subjects. This is the first study to report on a tripartite association between sex differences in ERPs, visual stimulus salience, and right prefrontal cortex activation during attentional processing. Hum Brain Mapp 2009.

Smoking improves divided attention in schizophrenia

RationaleSmoking is highly prevalent in schizophrenia, and there is evidence for beneficial effects on neurocognition. Smoking is therefore hypothesized a self-medication in schizophrenia. Although much effort is devoted to characterize those cognitive domains that potentially benefit from smoking, divided attention has not yet been investigated.ObjectivesThe aim of this study was to analyze the interactional effects of diagnosis of schizophrenia and smoking history on divided attention.MethodsWe investigated behavioral measures of divided attention in a sample of 48 schizophrenic patients and 48 controls (24 current smokers and non-smokers each) carefully matched for age, sex, education, verbal IQ, and smoking status with general linear models.ResultsMost important within the scope of this study, significant interactions were found for valid reactions and errors of omission: Performance substantially increased in smoking schizophrenic patients, but not in controls. Further, these interactions were modified by sex, driven by female schizophrenic patients who showed a significant behavioral advantage of smokers over non-smokers, other than male schizophrenic patients or healthy controls who did not express this sex-specific pattern.ConclusionsResults suggest a positive effect of smoking history on divided attention in schizophrenic patients. This study provides first evidence that the complex attention domain of divided attention is improved by smoking, which further substantiates the self-medication hypothesis of smoking in schizophrenia, although this has been shown mainly for sustained and selective attention. Gender-specific effects on cognition need to be further investigated.

Influence of urbanity on perception of mental illness stigma: a population based study in urban and rural Hanoi, Vietnam

Background and Aims: To examine, for the first time in Vietnam, whether urbanity of respondents among other socio-demographic factors affects the public perception of stigma attached to persons with mental illness in Hanoi. Methods: A general population-based survey was carried out in 2013 in the greater Hanoi area. The perception of stigma attached to people with mental illness was elicited using Link’s perceived discrimination and devaluation scale (PDDS) carried out in Vietnamese language. The survey sample (n = 806) was stratified for gender, urban/rural location, age, household size and marital status, in accordance with the 2013 Vietnamese census. Results: Comparing the total score of the PDDS and its single items, we found less perceived stigma and discrimination among the rural population of Hanoi and in respondents who reported religious attainment to either Buddhism or Christianity. Logistic regression analyses found no significant influences of gender, age, household size or marital status regarding the perceived stigma toward persons with mental illness. Conclusion: Less negative perception of stigma attached to persons with mental illness that was observed among the rural population in the Hanoi area may be interpreted in the light of possibly more demanding living conditions in modern urban Vietnam with less opportunities for mentally ill patients and points toward a dynamic interaction with rapidly changing living conditions in Asian megacities.

Visual P3 amplitude modulation deficit in schizophrenia is independent of duration of illness

BACKGROUND In the search for markers of schizophrenia, functional deficits during inhibition have been a major focus. In previous studies, we found a reduced amplitude modulation of the visual P3 component of the event-related potential (ERP) in schizophrenic patients during inhibition in the Attention Network Test (ANT). The objective of the present study was to explore whether this deficit exhibits properties of a trait or state marker of schizophrenia. METHODS Eighteen recent onset inpatients and eighteen chronic schizophrenic outpatients as well as 36 healthy controls, including a young adult and an old adult group to match recent onset and chronic illness groups for age and sex, were included. Participants were tested with ANT while 32-channel electroencephalogram was recorded and visual P3 amplitudes were analyzed. Amplitude modulation was defined as the variation of P3 amplitude at Pz as a function of ANT flanker conditions. RESULTS There were no significant behavioral between-group differences in terms of alerting, orienting, and inhibition. Mean visual P3 was significantly lower in schizophrenic patients than in healthy controls. Parietal P3 amplitude was significantly less modulated in both recent onset (-0.035) and chronic schizophrenic patients (-0.081) compared with young (-0.588; p<0.05) and older healthy controls, respectively (-0.556; p<0.05). No correlations were obtained between P3 modulation and clinical or demographic variables. CONCLUSION The results provide evidence that the observed deficit of visual P3 amplitude modulation is independent of duration of illness and age and may contain properties of a trait marker of schizophrenia.

Public attitudes towards psychiatrists in the metropolitan area of Hanoi, Vietnam

OBJECTIVES Mental health associated stigmatization remains problematic in low and middle-income countries, thus preventing patients from adequate access to psychiatric care. Public attitudes towards psychiatrists have not been examined in many countries, especially not in Vietnam where merely one psychiatrist per 300.000 population is available. The study aims to explore attitudes towards psychiatrists in the Hanoi municipality and to identify socio-demographical factors that influence these attitudes. METHODS Between April and August 2013, a general population-based survey was carried out in the greater Hanoi area, Vietnam. The sample of 817 participants was stratified according to the latest Vietnamese census (2009) and micro-census (2013) with regards to socio-demographic factors. Multivariate analyses were conducted to determine the influence of these factors on attitudes towards psychiatrists. RESULTS Gender and religious beliefs significantly influenced public attitudes towards psychiatrists. Male participants reported significantly more negative perception towards psychiatrists compared to female respondents. Participants following a religion reported significantly more negative attitudes toward psychiatrists than those without self-reported religious attainment. CONCLUSIONS Negative attitudes towards psychiatrists are associated with religious beliefs and gender affiliation in the greater Hanoi area. A strategy that involves religious institutions in raising awareness about mental health issues while considering publics socio-cultural attitudes may pave the way for greater potentialities of adequate psychiatric care, destigmatize the mental health system, and care provider.

Attitude towards psychiatrists: A comparison between two metropolitan cities in India

BACKGROUND Few patients in need of mental health care have access to psychiatric care in low and middle income countries. Public attitudes towards psychiatrists have not been adequately studied in most developing countries and especially in India, where on average one trained psychiatrist is available for 300,000 people. The aim of our study was to explore attitudes towards psychiatrists in the general population in two Indian metropolitan cities (Chennai and Kolkata) and to identify factors that could influence these attitudes. SUBJECTS AND METHODS Explorative surveys in the context of public attitudes towards psychiatrists were conducted in a convenience sample from the general population in Chennai (n=166) and Kolkata (n=158). Sampling was balanced for age, gender and school education. RESULTS Comparing the two samples using a multivariate analysis, we found more negative attitudes towards psychiatrists in Chennai compared to Kolkata (p<0.0001). Negative attitudes correlated with lower education levels (p<0.001) and stronger religious beliefs (p<0.05) in both cities. CONCLUSION Attitudes towards psychiatrists differed widely between two large metropolitan cities in India. In line with previous studies, negative attitudes correlated with lower level of education and stronger religious beliefs across both cities. Future studies may identify finer cultural and social factors that play an important role in attitudes towards psychiatrists in a diverse country like India.