Gregory P. Strauss

A Review of Reward Processing and Motivational Impairment in Schizophrenia

This article reviews and synthesizes research on reward processing in schizophrenia, which has begun to provide important insights into the cognitive and neural mechanisms associated with motivational impairments. Aberrant cortical-striatal interactions may be involved with multiple reward processing abnormalities, including: (1) dopamine-mediated basal ganglia systems that support reinforcement learning and the ability to predict cues that lead to rewarding outcomes; (2) orbitofrontal cortex-driven deficits in generating, updating, and maintaining value representations; (3) aberrant effort-value computations, which may be mediated by disrupted anterior cingulate cortex and midbrain dopamine functioning; and (4) altered activation of the prefrontal cortex, which is important for generating exploratory behaviors in environments where reward outcomes are uncertain. It will be important for psychosocial interventions targeting negative symptoms to account for abnormalities in each of these reward processes, which may also have important interactions; suggestions for novel behavioral intervention strategies that make use of external cues, reinforcers, and mobile technology are discussed.

Are Negative Symptoms Dimensional or Categorical? Detection and Validation of Deficit Schizophrenia With Taxometric and Latent Variable Mixture Models

Studies have supported the validity of the deficit form of schizophrenia (ie, people with primary and enduring negative symptoms). A test of whether that group is a true taxon-that is, a distinct, discontinuous group-has yet to be conducted and the underlying structure of negative symptoms as categorical or dimensional remains undetermined. The present study examined the latent structure of negative and deficit symptoms to determine if a nonarbitrary boundary distinguishes deficit from nondeficit forms of schizophrenia (ie, whether these symptoms reflect a continuous or categorical variable). Schedule for the Deficit Syndrome ratings of 789 individuals with a psychotic disorder were submitted to taxometric and latent variable mixture analyses to test categorical vs dimensional hypotheses of negative symptoms and deficit schizophrenia. Analytic models favored a taxonic structure of negative symptoms and the validity of the deficit/nondeficit classification scheme. Taxometric classification outperformed clinician-based deficit/nondeficit classification in its association with summer birth, male sex, premorbid adjustment, neurocognition, and psychosocial functioning. Within taxon and complement classes, severity scores remained significant predictors of premorbid adjustment, neurocognition, and psychosocial functioning. Thus, although a categorical approach is validated, a hybrid categorical-dimensional conceptualization of negative symptoms also has validity for the prediction of external variables.

The role of low cognitive effort and negative symptoms in neuropsychological impairment in schizophrenia.

OBJECTIVE Two experiments were conducted to examine whether insufficient effort, negative symptoms (e.g., avolition, anhedonia), and psychological variables (e.g., anhedonia and perception of low cognitive resources) predict generalized neurocognitive impairment in individuals with schizophrenia (SZ). METHOD In Experiment 1, participants included 97 individuals with SZ and 63 healthy controls (CN) who completed the Victoria Symptom Validity Test (VSVT), the MATRICS Consensus Cognitive Battery (MCCB), and self-report anhedonia questionnaires. In Experiment 2, participants included 46 individuals with SZ and 33 CN who completed Greens Word Memory Test (WMT), the MCCB, and self-reports of anhedonia, defeatist performance beliefs, and negative expectancy appraisals. RESULTS RESULTS indicated that a low proportion of individuals with SZ failed effort testing (1.0% Experiment 1; 15.2% Experiment 2); however, global neurocognitive impairment was significantly predicted by low effort and negative symptoms. CONCLUSIONS Findings indicate that low effort does not threaten the validity of neuropsychological test results in the majority of individuals with schizophrenia; however, effort testing may be useful in SZ patients with severe negative symptoms who may be more likely to put forth insufficient effort due to motivational problems. Although the base rate of failure is relatively low, it may be beneficial to screen for insufficient effort in SZ and exclude individuals who fail effort testing from pharmacological or cognitive remediation trials.

Avolition in schizophrenia is associated with reduced willingness to expend effort for reward on a Progressive Ratio task

The current study examined whether effort-cost computation was associated with negative symptoms of schizophrenia (SZ). Participants included outpatients diagnosed with SZ (n=27) and demographically matched healthy controls (n=32) who completed a Progressive Ratio task that required incrementally greater amounts of physical effort to obtain monetary reward. Breakpoint, the point at which participants was no longer willing to exert effort for a certain reward value, was examined as an index of effort-cost computation. There were no group differences in breakpoint for low, medium, or high value rewards on the Progressive Ratio task. However, lower breakpoint scores were associated with greater severity of avolition and anhedonia symptoms in SZ patients. Findings provide further evidence that impaired effort-cost computation is linked to motivational abnormalities in SZ.

Plasma oxytocin levels predict social cue recognition in individuals with schizophrenia

Lower endogenous levels of the neuropeptide oxytocin may be an important biological predictor of social cognition impairments in schizophrenia (SZ). Prior studies have demonstrated that lower-level social cognitive processes (e.g., facial affect perception) are significantly associated with reduced plasma oxytocin levels in SZ; however, it is unclear whether higher-level social cognition, which requires inferential processes and knowledge not directly presented in the stimulus, is associated with endogenous oxytocin. The current study explored the association between endogenous oxytocin levels and lower- and higher-level social cognition in 40 individuals diagnosed with SZ and 22 demographically matched healthy controls (CN). All participants received the Social Cue Recognition Test (SCRT), which presents participants with videotaped interpersonal vignettes and subsequent true/false questions related to concrete or abstract aspects of social interactions in the vignettes. Results indicated that SZ had significantly higher plasma oxytocin concentrations than CN. SZ and CN did not differ on SCRT hits, but SZ had more false positives and lower sensitivity scores than CN. Higher plasma oxytocin levels were associated with better sensitivity scores for abstract items in CN and fewer false positives for concrete items in individuals with SZ. Findings indicate that endogenous oxytocin levels predict accurate encoding of lower-level socially relevant information in SZ.

Plasma oxytocin levels predict olfactory identification and negative symptoms in individuals with schizophrenia.

Basic neuroscience research provides strong evidence for the role of oxytocin in olfactory processes and social affiliation in rodents. Given prior indication of olfactory impairments that are linked to greater severity of asociality in schizophrenia, we examined the association between plasma oxytocin levels and measures of olfaction and social outcome in a sample of outpatients with schizophrenia (n=39) and demographically matched healthy controls (n=21). Participants completed the 40-item University of Pennsylvania Smell Identification Test (UPSIT), and rated each odor for how positive and how negative it made them feel. Results indicated that individuals with schizophrenia had higher plasma oxytocin levels and lower overall accuracy for UPSIT items than controls. Individuals with schizophrenia also reported experiencing more negative emotionality than controls in response to the olfactory stimuli. Lower plasma oxytocin levels were associated with poorer accuracy for pleasant and unpleasant odors and greater severity of asociality in individuals with schizophrenia. These findings suggest that endogenous oxytocin levels may be an important predictor of olfactory identification deficits and negative symptoms in schizophrenia.

Endogenous oxytocin levels are associated with the perception of emotion in dynamic body expressions in schizophrenia

Lower endogenous oxytocin levels have been associated with impaired social cognition in schizophrenia, particularly facial affect identification. Little is known about the relationship between oxytocin and other forms of emotion perception. In the current study, 41 individuals with schizophrenia (SZ) and 22 demographically matched healthy controls (CN) completed a forced-choice affective body expression classification task. Stimuli included dynamic videos of male and female actors portraying 4 discrete emotions: happiness, sadness, anger, and neutral. Plasma oxytocin levels were determined via radioimmunoassay. Results indicated that SZ had significantly higher plasma oxytocin concentrations than CN. SZ were also less accurate at identifying expressions of happiness and sadness; however, there were no group differences for anger or neutral stimuli. A group×sex interaction was also present, such that female CN were more accurate than male CN, whereas male SZ were more accurate than female SZ. Higher endogenous oxytocin levels were associated with better total recognition in both SZ and CN; this association was specific to females in SZ. Findings indicate that sex plays an important role in identifying emotional expressions in body gestures in SZ, and that individual differences in endogenous oxytocin predict emotion perception accuracy.

The brief negative symptom scale: validation of the German translation and convergent validity with self-rated anhedonia and observer-rated apathy

BackgroundNegative symptoms are considered core symptoms of schizophrenia. The Brief Negative Symptom Scale (BNSS) was developed to measure this symptomatic dimension according to a current consensus definition. The present study examined the psychometric properties of the German version of the BNSS. To expand former findings on convergent validity, we employed the Temporal Experience Pleasure Scale (TEPS), a hedonic self-report that distinguishes between consummatory and anticipatory pleasure. Additionally, we addressed convergent validity with observer-rated assessment of apathy with the Apathy Evaluation Scale (AES), which was completed by the patient’s primary nurse.MethodsData were collected from 75 in- and outpatients from the Psychiatric Hospital, University Zurich diagnosed with either schizophrenia or schizoaffective disorder. We assessed convergent and discriminant validity, internal consistency and inter-rater reliability.ResultsWe largely replicated the findings of the original version showing good psychometric properties of the BNSS. In addition, the primary nurses evaluation correlated moderately with interview-based clinician rating. BNSS anhedonia items showed good convergent validity with the TEPS.ConclusionsOverall, the German BNSS shows good psychometric properties comparable to the original English version. Convergent validity extends beyond interview-based assessments of negative symptoms to self-rated anhedonia and observer-rated apathy.

EMOTION REGULATION ABNORMALITIES IN SCHIZOPHRENIA: DIRECTED ATTENTION STRATEGIES FAIL TO DECREASE THE NEUROPHYSIOLOGICAL RESPONSE TO UNPLEASANT STIMULI

Previous research provides evidence that individuals with schizophrenia (SZ) have emotion regulation abnormalities, particularly when attempting to use reappraisal to decrease negative emotion. The current study extended this literature by examining the effectiveness of a different form of emotion regulation, directed attention, which has been shown to be effective at reducing negative emotion in healthy individuals. Participants included outpatients with SZ (n = 28) and healthy controls (CN: n = 25), who viewed unpleasant and neutral images during separate event-related potential and eye-movement tasks. Trials included both passive viewing and directed attention segments. During directed attention, gaze was directed toward highly arousing aspects of an unpleasant image, less arousing aspects of an unpleasant image, or a nonarousing aspect of a neutral image. The late positive potential (LPP) event-related potential component indexed emotion regulation success. Directing attention to nonarousing aspects of unpleasant images decreased the LPP in CN; however, SZ showed similar LPP amplitude when attention was directed toward more or less arousing aspects of unpleasant scenes. Eye tracking indicated that SZ were more likely than CN to attend to arousing portions of unpleasant scenes when attention was directed toward less arousing scene regions. Furthermore, pupilary data suggested that SZ patients failed to engage effortful cognitive processes needed to inhibit the prepotent response of attending to arousing aspects of unpleasant scenes when attention was directed toward nonarousing scene regions. Findings add to the growing literature indicating that individuals with SZ display emotion regulation abnormalities and provide novel evidence that dysfunctional emotion-attention interactions and generalized cognitive control deficits are associated with ineffective use of directed attention strategies to regulate negative emotion. (PsycINFO Database Record

Negative symptoms in bipolar disorder and schizophrenia: A psychometric evaluation of the brief negative symptom scale across diagnostic categories

Past studies have demonstrated that the Brief Negative Symptom Scale (BNSS) has excellent psychometric properties in patients with schizophrenia. In the current study, we extended this literature by examining psychometric properties of the BNSS in outpatients diagnosed with bipolar disorder (n=46), outpatients with schizophrenia (n=50), and healthy controls (n=27). Participants completed neuropsychological testing and a clinical interview designed to assess negative, positive, disorganized, mood, and general psychiatric symptoms. Results indicated differences among the 3 groups in the severity of all BNSS items, with SZ and BD scoring higher than CN; however, SZ and BD only differed on blunted affect and alogia items, not anhedonia, avolition, or asociality. BD patients with a history of psychosis did not differ from those without a history of psychosis on negative symptom severity. The BNSS had excellent internal consistency in SZ, BD, and CN groups. Good convergent and discriminant validity was apparent in SZ and BD groups, as indicated by relationships between the BNSS and other clinical rating scales. These findings support the validity of the BNSS in broadly defined serious mental illness populations.