Diverse definitions of the early course of schizophrenia - a targeted literature review

Schizophrenia is a debilitating psychiatric disorder and patients experience significant comorbidity, especially cognitive and psychosocial deficits, already at the onset of disease. Previous research suggests that treatment during the earlier stages of disease reduces disease burden, and that a longer time of untreated psychosis has a negative impact on treatment outcomes. A targeted literature review was conducted to gain insight into the definitions currently used to describe patients with a recent diagnosis of schizophrenia in the early course of disease ('early' schizophrenia). A total of 483 relevant English-language publications of clinical guidelines and studies were identified for inclusion after searches of MEDLINE, MEDLINE In-Process, relevant clinical trial databases and Google for records published between January 2005 and October 2015. The extracted data revealed a wide variety of terminology and definitions used to describe patients with 'early' or 'recent-onset' schizophrenia, with no apparent consensus. The most commonly used criteria to define patients with early schizophrenia included experience of their first episode of schizophrenia or disease duration of less than 1, 2 or 5 years. These varied definitions likely result in substantial disparities of patient populations between studies and variable population heterogeneity. Better agreement on the definition of early schizophrenia could aid interpretation and comparison of studies in this patient population and consensus on definitions should allow for better identification and management of schizophrenia patients in the early course of their disease

Reliability of triggering inhibitory process is a better predictor of impulsivity than SSRT

The ability to control behaviour is thought to rely on adequately suppressing impulsive responses toexternal stimuli. However, the evidence for this relationship between response inhibition ability andimpulse control is weak and inconsistent. This study investigates the relationship between responseinhibition and both self-report and behavioural measures of impulsivity as well as engagement in riskybehaviours in a large community sample (N=174) of healthy adolescents and young adults (15-35yrs). Usinga stop-signal paradigm with a number parity go task, we implemented a novel hierarchical Bayesian modelof response inhibition that estimates stop-signal reaction time (SSRT) as a distribution and also accounts forfailures to react to the stop-signal (i.e., “trigger failure”), and failure to react to the choice stimulus (i.e., “gofailure” or omission errors). In line with previous studies, the model reduced estimates of SSRT by up to100ms compared with traditional non-parametric estimation techniques. Although some relationshipsbetween behavioural and self-report measures of impulsivity with traditionally estimated SSRT weresupported, they did not hold for the model-based SSRT estimates. Instead, the behavioural impulsivitymeasures were found to be related to trigger failure. We suggest that trigger failure is correlated with impulsivity because it indexes higher order processing related to inhibition, whereas SSRT, when estimatedwithout confounding from trigger failure, indexes more automatic inhibitory processes

Electrophysiological, cognitive and clinical profiles of at-risk mental state: The longitudinal minds in transition (MinT) study

The onset of schizophrenia is typically preceded by a prodromal period lasting several years during which sub-threshold symptoms may be identified retrospectively. Clinical interviews are currently used to identify individuals who have an ultra-high risk (UHR) of developing a psychotic illness with a view to provision of interventions that prevent, delay or reduce severity of future mental health issues. The utility of bio-markers as an adjunct in the identification of UHR individuals is not yet established. Several event-related potential measures, especially mismatch-negativity (MMN), have been identified as potential biomarkers for schizophrenia. In this 12-month longitudinal study, demographic, clinical and neuropsychological data were acquired from 102 anti-psychotic naive UHR and 61 healthy controls, of whom 80 UHR and 58 controls provided valid EEG data during a passive auditory task at baseline. Despite widespread differences between UHR and controls on demographic, clinical and neuropsychological measures, MMN and P3a did not differ between these groups. Of 67 UHR at the 12-month follow-up, 7 (10%) had transitioned to a psychotic illness. The statistical power to detect differences between those who did or did not transition was limited by the lower than expected transition rate. ERPs did not predict transition, with trends in the opposite direction to that predicted. In exploratory analysis, the strongest predictors of transition were measures of verbal memory and subjective emotional disturbance