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This paper aims at providing an overview of the background, design and initial findings of Psychosis Incident Cohort Outcome Study (PICOS).
PICOS is a large multi-site population-based study on first-episode psychosis (FEP) patients attending public mental health services in the Veneto region (Italy) over a 3-year period. PICOS has a naturalistic longitudinal design and it includes three different modules addressing, respectively, clinical and social variables, genetics and brain imaging. Its primary aims are to characterize FEP patients in terms of clinical, psychological and social presentation, and to investigate the relative weight of clinical, environmental and biological factors (i.e. genetics and brain structure/functioning) in predicting the outcome of FEP.
An in-depth description of the research methodology is given first. Details on recruitment phase and baseline and follow-up evaluations are then provided. Initial findings relating to patients' baseline assessments are also presented. Future planned analyses are outlined.
Both strengths and limitations of PICOS are discussed in the light of issues not addressed in the current literature on FEP. This study aims at making a substantial contribution to research on FEP patients. It is hoped that the research strategies adopted in PICOS will enhance the convergence of methodologies in ongoing and future studies on FEP.
Abnormalities in incentive decision making, typically assessed using the Iowa Gambling Task (IGT), have been reported in both schizophrenia (SZ) and bipolar disorder (BD). We applied the Expectancy–Valence (E–V) model to determine whether motivational, cognitive and response selection component processes of IGT performance are differentially affected in SZ and BD.
Performance on the IGT was assessed in 280 individuals comprising 70 remitted patients with SZ, 70 remitted patients with BD and 140 age-, sex- and IQ-matched healthy individuals. Based on the E–V model, we extracted three parameters, ‘attention to gains or loses’, ‘expectancy learning’ and ‘response consistency’, that respectively reflect motivational, cognitive and response selection influences on IGT performance.
Both patient groups underperformed in the IGT compared to healthy individuals. However, the source of these deficits was diagnosis specific. Associative learning underlying the representation of expectancies was disrupted in SZ whereas BD was associated with increased incentive salience of gains. These findings were not attributable to non-specific effects of sex, IQ, psychopathology or medication.
Our results point to dissociable processes underlying abnormal incentive decision making in BD and SZ that could potentially be mapped to different neural circuits.
The amygdala plays a central role in the fronto-limbic network involved in the processing of emotions. Structural and functional abnormalities of the amygdala have recently been found in schizophrenia, although there are still contradictory results about its reduced or preserved volumes.
In order to address these contradictory findings and to further elucidate the possibly underlying pathophysiological process of the amygdala, we employed structural magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI), exploring amygdalar volume and microstructural changes in 69 patients with schizophrenia and 72 matched healthy subjects, relating these indices to psychopathological measures.
Measuring water diffusivity, the apparent diffusion coefficients (ADCs) for the right amygdala were found to be significantly greater in patients with schizophrenia compared with healthy controls, with a trend for abnormally reduced volumes. Also, significant correlations between mood symptoms and amygdalar volumes were found in schizophrenia.
We therefore provide evidence that schizophrenia is associated with disrupted tissue organization of the right amygdala, despite partially preserved size, which may ultimately lead to abnormal emotional processing in schizophrenia. This result confirms the major role of the amygdala in the pathophysiology of schizophrenia and is discussed with respect to amygdalar structural and functional abnormalities found in patients suffering from this illness.
Several, although not all, of the previous small diffusion-weighted imaging (DWI) studies have shown cortical white-matter disruption in schizophrenia.
To investigate cortical white-matter microstructure with DWI in a large community-based sample of people with schizophrenia.
Sixty-eight people with schizophrenia and 64 healthy controls underwent a session of DWI to obtain the apparent diffusion coefficient (ADC) of white-matter water molecules. Regions of interest were placed in cortical lobes.
Compared with controls, the schizophrenia group had significantly greater ADCs in frontal, temporal and occipital white matter (analysis of covariance, P < 0.05).
Our findings confirm the presence of cortical white-matter microstructure disruption in frontal and temporo-occipital lobes in the largest sample of people with schizophrenia thus for studied with this technique. Future brain imaging studies, together with genetic investigations, should further explore white-matter integrity and genes encoding myelin-related protein expression in people with first-episode schizophrenia and those at high risk of developing the disorder.
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