The structure of schizotypal personality traits: a cross-national study

BACKGROUND

Schizotypal traits are considered a phenotypic-indicator of schizotypy, a latent personality organization reflecting a putative liability for psychosis. To date, no previous study has examined the comparability of factorial structures across samples originating from different countries and cultures. The main goal was to evaluate the factorial structure and reliability of the Schizotypal Personality Questionnaire (SPQ) scores by amalgamating data from studies conducted in 12 countries and across 21 sites.

METHOD

The overall sample consisted of 27 001 participants (37.5% males, n = 4251 drawn from the general population). The mean age was 22.12 years (s.d. = 6.28, range 16-55 years). The SPQ was used. Confirmatory factor analysis (CFA) and Multilevel CFA (ML-CFA) were used to evaluate the factor structure underlying the SPQ scores.

RESULTS

At the SPQ item level, the nine factor and second-order factor models showed adequate goodness-of-fit. At the SPQ subscale level, three- and four-factor models displayed better goodness-of-fit indices than other CFA models. ML-CFA showed that the intraclass correlation coefficients values were lower than 0.106. The three-factor model showed adequate goodness of fit indices in multilevel analysis. The ordinal α coefficients were high, ranging from 0.73 to 0.94 across individual samples, and from 0.84 to 0.91 for the combined sample.

CONCLUSIONS

The results are consistent with the conceptual notion that schizotypal personality is a multifaceted construct and support the validity and utility of SPQ in cross-cultural research. We discuss theoretical and clinical implications of our results for diagnostic systems, psychosis models and cross-national mental health strategies.

Neural correlates of social exchanges during the Prisoner's Dilemma game in depression

BACKGROUND

Depression is a disabling disorder that significantly impacts on the interpersonal functioning of individuals. However, little is known about the neural substrates of such difficulties. In the last few years neuroeconomics, which combines imaging with multiplayer behavioural economic paradigms, has been used to study the neural substrates of normal and abnormal interpersonal interactions.

METHOD

This study used functional magnetic resonance imaging to investigate neural activity in unmedicated depressed participants (n = 25) and matched healthy controls (n = 25). During scanning, participants played a behavioural economic game, the Prisoner's Dilemma. In this game, the participant and a co-player independently choose either to cooperate or not cooperate with each other.

RESULTS

Depressed participants reported higher levels of negative feelings (betrayal, guilt) during the game than did controls. Neural activation was compared between 'imbalanced' events [when one of the players cooperated and the other defected ('CD' and 'DC')] and 'draw' events [when both players either cooperated or defected ('CC' and 'DD')]. Participants preferentially activated the anterior insula and the dorsolateral prefrontal cortex (DLPFC), a region implicated in cognitive control and regulation of emotions. Importantly, compared to controls depressed participants showed reduced activation in the left DLPFC, with the extent of signal reduction correlating with increased self-report feelings of guilt associated with DC outcomes.

CONCLUSIONS

Our findings suggest that depression is associated with reduced activation of the DLPFC during social events that involve unreciprocated cooperation. This abnormality may underlie anomalies in cognitive control and top-down regulation of emotions during challenging social exchanges.

Attention bias toward threat is associated with exaggerated fear expression and impaired extinction in PTSD

BACKGROUND

Post-traumatic stress disorder (PTSD) develops in a minority of traumatized individuals. Attention biases to threat and abnormalities in fear learning and extinction are processes likely to play a critical role in the creation and/or maintenance of PTSD symptomatology. However, the relationship between these processes has not been established, particularly in highly traumatized populations; understanding their interaction can help inform neural network models and treatments for PTSD.

METHOD

Attention biases were measured using a dot probe task modified for use with our population; task stimuli included photographs of angry facial expressions, which are emotionally salient threat signals. A fear-potentiated startle paradigm was employed to measure atypical physiological response during acquisition and extinction phases of fear learning. These measures were administered to a sample of 64 minority (largely African American), highly traumatized individuals with and without PTSD.

RESULTS

Participants with PTSD demonstrated attention biases toward threat; this attentional style was associated with exaggerated startle response during fear learning and early and middle phases of extinction, even after accounting for the effects of trauma exposure.

CONCLUSIONS

Our findings indicate that an attentional bias toward threat is associated with abnormalities in 'fear load' in PTSD, providing seminal evidence for an interaction between these two processes. Future research combining these behavioral and psychophysiological techniques with neuroimaging will be useful toward addressing how one process may modulate the other and understanding whether these phenomena are manifestations of dysfunction within a shared neural network. Ultimately, this may serve to inform PTSD treatments specifically designed to correct these atypical processes.