Ventral Striatal Dysfunction and Symptom Expression in Individuals With Schizotypal Personality Traits and Early Psychosis

Abstract

Striatal abnormalities play a crucial role in the pathophysiology of schizophrenia. Growing evidence suggests an association between aberrant striatal activity during reward anticipation and symptom dimensions in schizophrenia. However, it is not clear whether this holds across the psychosis continuum. The aim of the present study was to investigate alterations of ventral striatal activation during reward anticipation and its relationship to symptom expression in persons with schizotypal personality traits (SPT) and first-episode psychosis. Twenty-six individuals with high SPT, 26 patients with non-affective first-episode psychosis (including 13 with brief psychotic disorder (FEP-BPD) and 13 with first-episode schizophrenia [FEP-SZ]) and 25 healthy controls underwent event-related functional magnetic resonance imaging while performing a variant of the Monetary Incentive Delay task. Ventral striatal activation was positively correlated with total symptom severity, in particular with levels of positive symptoms. This association was observed across the psychosis continuum and within each subgroup. Patients with FEP-SZ showed the strongest elevation of striatal activation during reward anticipation, although symptom levels did not differ between groups in the psychosis continuum. While our results provide evidence that variance in striatal activation is mainly explained by dimensional symptom expression, patients with schizophrenia show an additional dysregulation of striatal activation. Trans-diagnostic approaches are promising in order to disentangle dimensional and categorical neural mechanisms in the psychosis continuum.

Keywords: negative symptoms; neuroimaging; positive symptoms; psychosis continuum; reward processing; schizophrenia.

© The Author(s) 2016. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Figures

Fig. 1.

Symptom dimensions in the psychosis continuum. (A) Simplified model of the psychosis continuum and its putative separation into subgroups. Subgroups investigated in the present study are outlined with a red rectangle. (B) Symptom dimensions in psychosis adapted from Kapur and van Os.

Fig. 2.

At the beginning of each trial, 1 of 3 different cues was presented for 0.75 second. The cue indicated the maximum possible amount participants could gain in that trial, ie, high-reward condition 0 to 2 Swiss Francs (CHF), low-reward condition 0 to 0.40 CHF, or neutral condition 0 CHF (1 CHF = 1.08 US$). After a delay the participants had to identify an outlier from 3 presented circles and press a button as fast as possible. Immediately after the button press, participants were notified about the money won.

Fig. 3.

(A) and (B) illustrate the ventral striatum (VS) region of interest (ROI) from which the mean contrast signal for the contrast anticipation of high reward vs no reward was extracted. (C) Columns in bar graphs reflect mean contrast signal for reward anticipation in the right VS, separately for each group. Error bars depict ± 1 SEM.

Fig. 4.

Correlation plots for Positive and Negative Syndrome Scale (PANSS) positive factor (A) and PANSS total score (B) with mean contrast signal in the right ventral striatum (VS) across the psychosis continuum. Correlation plots for PANSS positive factor (C) and PANSS total score (D) with mean contrast signal in the right VS for each group within the psychosis continuum separately; first-episode schizophrenia (FEP-SZ) (n = 13), patients with brief psychotic disorders (FEP-BPD) (n = 13), and schizotypal personality traits (SPT) (n = 26). Correlation between VS activation and PANSS Positive Factor in FEP-SZ: Spearman correlation (rs) = .50, P = .082, in FEP-BPD: rs = .65, P = .016, and in SPT: rs = .33, P = .101. Correlation between VS activation and PANSS Total Score in FEP-SZ: rs = .60, P = .029, in FEP-BPD: rs = .65, P = .016, and in SPT: rs = .02, P = .923. * Indicates significant correlations.