Applying imagined contact to improve physiological responses in anticipation of intergroup interactions and the perceived quality of these interactions

This experiment (N 5 49) is the first to show that imagined contact can bufferanticipatory physiological responses to future interactions, and improve the qualityof these interactions. Participants imagined a positive interaction with a person withschizophrenia, or in a control condition, a person who did not have schizophrenia. They then interacted with a confederate whom they believed had schizophrenia. Participants in the imagined contact condition reported more positive attitudes andless avoidance of people with schizophrenia, displayed smaller anticipatory physio-logical responses, specifically smaller changes in interbeat interval and skin conduct-ance responses, and had a more positive interaction according to the confederate.These findings support applying imagined contact to improve interactions with people with severe mental illnesses.

A new comparator account of auditory verbal hallucinations: how motor prediction can plausibly contribute to the sense of agency for inner speech

The comparator account holds that processes of motor prediction contribute to the sense of agency by attenuating incoming sensory information and that disruptions to this process contribute to misattributions of agency in schizophrenia. Over the last 25 years this simple and powerful model has gained widespread support not only as it relates to bodily actions but also as an account of misattributions of agency for inner speech, potentially explaining the etiology of auditory verbal hallucination (AVH). In this paper we provide a detailed analysis of the traditional comparator account for inner speech, pointing out serious problems with the specification of inner speech on which it is based and highlighting inconsistencies in the interpretation of the electrophysiological evidence commonly cited in its favor. In light of these analyses we propose a new comparator account of misattributed inner speech. The new account follows leading models of motor imagery in proposing that inner speech is not attenuated by motor prediction, but rather derived directly from it. We describe how failures of motor prediction would therefore directly affect the phenomenology of inner speech and trigger a mismatch in the comparison between motor prediction and motor intention, contributing to abnormal feelings of agency. We argue that the new account fits with the emerging phenomenological evidence that AVHs are both distinct from ordinary inner speech and heterogeneous. Finally, we explore the possibility that the new comparator account may extend to explain disruptions across a range of imagistic modalities, and outline avenues for future research.

Exposure to Political Violence in Northern Ireland and Outcome of First Episode Psychosis

The impact of political violence on individuals presenting with an episode of first episode psychosis has not been examined. Individuals were assessed for exposure to political violence in Northern Ireland (the “Troubles”) by asking for a response to 2 questions: one asked about the impact of violence “on your area”; the second about the impact of violence “on you or your family’s life.” The participants were separated into 2 groups (high and low impact) for each question. Symptom profiles and rates of substance misuse were compared across the groups at baseline and at 3-year follow up. Of the 178 individuals included in the study 66 (37.1%) reported a high impact of the “Troubles” on their life and 81 (45.5%) a high impact of the “Troubles” on their area. There were no significant differences in symptom profile or rates of substance misuse between high and low groups at presentation. At 3-year follow-up high impact of the “Troubles” on life was associated with higher Positive and Negative Symptom Scale (PANSS) Total (P = .01), PANSS-Positive (P < .05), and PANSS-General (P < .01) scores and lower global assessment of functioning disability (P < .05) scores, after adjusting for confounding factors. Impact of the “Troubles” on area was not associated with differences in symptom outcomes. This finding adds to the evidence that outcomes in psychosis are significantly impacted by environmental factors and suggests that greater attention should be paid to therapeutic strategies designed to address the impact of trauma.

Modeling Linkage Disequilibrium Increases Accuracy of Polygenic Risk Scores

Polygenic risk scores have shown great promise in predicting complex disease risk and will become more accurate as training sample sizes increase. The standard approach for calculating risk scores involves linkage disequilibrium (LD)-based marker pruning and applying a p value threshold to association statistics, but this discards information and can reduce predictive accuracy. We introduce LDpred, a method that infers the posterior mean effect size of each marker by using a prior on effect sizes and LD information from an external reference panel. Theory and simulations show that LDpred outperforms the approach of pruning followed by thresholding, particularly at large sample sizes. Accordingly, predicted R(2) increased from 20.1% to 25.3% in a large schizophrenia dataset and from 9.8% to 12.0% in a large multiple sclerosis dataset. A similar relative improvement in accuracy was observed for three additional large disease datasets and for non-European schizophrenia samples. The advantage of LDpred over existing methods will grow as sample sizes increase.

LD Score regression distinguishes confounding from polygenicity in genome-wide association studies

Both polygenicity (many small genetic effects) and confounding biases, such as cryptic relatedness and population stratification, can yield an inflated distribution of test statistics in genome-wide association studies (GWAS). However, current methods cannot distinguish between inflation from a true polygenic signal and bias. We have developed an approach, LD Score regression, that quantifies the contribution of each by examining the relationship between test statistics and linkage disequilibrium (LD). The LD Score regression intercept can be used to estimate a more powerful and accurate correction factor than genomic control. We find strong evidence that polygenicity accounts for the majority of the inflation in test statistics in many GWAS of large sample size.