Rich-club connectivity and structural connectome organization in youth at clinical high-risk for psychosis and individuals with early illness schizophrenia

Brain dysconnectivity has been posited as a biological marker of schizophrenia. Emerging schizophrenia connectome research has focused on rich-club organization, a tendency for brain hubs to be highly-interconnected but disproportionately vulnerable to dysconnectivity. However, less is known about rich-club organization in individuals at clinical high-risk for psychosis (CHR-P) and how it compares with abnormalities early in schizophrenia (ESZ). Combining diffusion tensor imaging (DTI) and magnetic resonance imaging (MRI), we examined rich-club and global network organization in CHR-P (n = 41) and ESZ (n = 70) relative to healthy controls (HC; n = 74) after accounting for normal aging. To characterize rich-club regions, we examined rich-club MRI morphometry (thickness, surface area). We also examined connectome metric associations with symptom severity, antipsychotic dosage, and in CHR-P specifically, transition to a full-blown psychotic disorder. ESZ had fewer connections among rich-club regions (ps < .024) relative to HC and CHR-P, with this reduction specific to the rich-club even after accounting for other connections in ESZ relative to HC (ps < .048). There was also cortical thinning of rich-club regions in ESZ (ps < .013). In contrast, there was no strong evidence of global network organization differences among the three groups. Although connectome abnormalities were not present in CHR-P overall, CHR-P converters to psychosis (n = 9) had fewer connections among rich-club regions (ps < .037) and greater modularity (ps < .037) compared to CHR-P non-converters (n = 19). Lastly, symptom severity and antipsychotic dosage were not significantly associated with connectome metrics (ps < .012). Findings suggest that rich-club and connectome organization abnormalities are present early in schizophrenia and in CHR-P individuals who subsequently transition to psychosis.

Thalamic dysconnectivity in the psychosis risk syndrome and early illness schizophrenia

BACKGROUND

Schizophrenia (SZ) is associated with thalamic dysconnectivity. Compared to healthy controls (HCs), individuals with SZ have hyperconnectivity with sensory regions, and hypoconnectivity with cerebellar, thalamic, and prefrontal regions. Despite replication of this pattern in chronically ill individuals, less is known about when these abnormalities emerge in the illness course and if they are present prior to illness onset.

METHODS

Resting-state functional magnetic resonance imaging data were collected from psychosis risk syndrome (PRS) youth (n = 45), early illness SZ (ESZ) (n = 74) patients, and HCs (n = 85). Age-adjusted functional connectivity, seeded from the thalamus, was compared among the groups.

RESULTS

Significant effects of group were observed in left and right middle temporal regions, left and right superior temporal regions, left cerebellum, and bilateral thalamus. Compared to HCs, ESZ demonstrated hyperconnectivity to all temporal lobe regions and reduced connectivity with cerebellar, anterior cingulate, and thalamic regions. Compared to HCs, PRS demonstrated hyperconnectivity with the left and right middle temporal regions, and hypoconnectivity with the cerebellar and other thalamic regions. Compared to PRS participants, ESZ participants were hyperconnected to temporal regions, but did not differ from PRS in hypoconnectivity with cerebellar and thalamic regions. Thalamic dysconnectivity was unrelated to positive symptom severity in ESZ or PRS groups.

CONCLUSIONS

PRS individuals demonstrated an intermediate level of thalamic dysconnectivity, whereas ESZ showed a pattern consistent with prior observations in chronic samples. These cross-sectional findings suggest that thalamic dysconnectivity may occur prior to illness onset and become more pronounced in early illness stages.

Validation of ketamine as a pharmacological model of thalamic dysconnectivity across the illness course of schizophrenia

N-methyl-D-aspartate receptor (NMDAR) hypofunction is a leading pathophysiological model of schizophrenia. Resting-state functional magnetic resonance imaging (rsfMRI) studies demonstrate a thalamic dysconnectivity pattern in schizophrenia involving excessive connectivity with sensory regions and deficient connectivity with frontal, cerebellar, and thalamic regions. The NMDAR antagonist ketamine, when administered at sub-anesthetic doses to healthy volunteers, induces transient schizophrenia-like symptoms and alters rsfMRI thalamic connectivity. However, the extent to which ketamine-induced thalamic dysconnectivity resembles schizophrenia thalamic dysconnectivity has not been directly tested. The current double-blind, placebo-controlled study derived an NMDAR hypofunction model of thalamic dysconnectivity from healthy volunteers undergoing ketamine infusions during rsfMRI. To assess whether ketamine-induced thalamic dysconnectivity was mediated by excess glutamate release, we tested whether pre-treatment with lamotrigine, a glutamate release inhibitor, attenuated ketamine's effects. Ketamine produced robust thalamo-cortical hyper-connectivity with sensory and motor regions that was not reduced by lamotrigine pre-treatment. To test whether the ketamine thalamic dysconnectivity pattern resembled the schizophrenia pattern, a whole-brain template representing ketamine's thalamic dysconnectivity effect was correlated with individual participant rsfMRI thalamic dysconnectivity maps, generating "ketamine similarity coefficients" for people with chronic (SZ) and early illness (ESZ) schizophrenia, individuals at clinical high-risk for psychosis (CHR-P), and healthy controls (HC). Similarity coefficients were higher in SZ and ESZ than in HC, with CHR-P showing an intermediate trend. Higher ketamine similarity coefficients correlated with greater hallucination severity in SZ. Thus, NMDAR hypofunction, modeled with ketamine, reproduces the thalamic hyper-connectivity observed in schizophrenia across its illness course, including the CHR-P period preceding psychosis onset, and may contribute to hallucination severity.

Effectiveness of the family-based model of dialectical behavior therapy for both suicidal adolescents and young adults in an academic medical center

BACKGROUND

Dialectical behavior therapy (DBT) is an effective approach to decreasing suicidal behaviors; the adapted, family-based model for adolescents (through 18 years old; DBT-A) also demonstrates efficacy. Data on higher dropout rates based on age, initial research on DBT with young adults in the community, and the theory that underlies DBT suggest that adaptations may also be appropriate for young adults. This study examines the effectiveness of DBT-A, presents preliminary data on delivering DBT-A to young adults (ages 18-26), and compares clinical characteristics, service utilization, and outcomes to adolescent clients (ages 13-17) to guide clinical considerations and future research on implementing DBT-A.

METHODS

Data were collected from a DBT-A clinic and included results from semi-structured diagnostic interviews, chart review, and scores on self-report measures. The Suicide Ideation Questionnaire and Beck Depression Inventory (BDI), given at program entry, after completion of one rotation through the skills modules, and at graduation, were used to evaluate outcomes. Outcomes were benchmarked against prior DBT-A trials. Adolescents' and young adults' clinical characteristics, service utilization, and outcomes were compared.

RESULTS

The effect size observed was smaller than in efficacy trials. Few differences were observed between teens (n = 87) and young adults (n = 45). Young adults were more likely to have participated in intensive services before DBT-A. They participated in fewer family sessions and graduated in fewer months compared to teens.

CONCLUSION

This study supports the use of the family-based model of DBT for suicidal teens and young adults although future research is needed to improve the effectiveness of this model when implemented in real-world settings.

Theta Phase Synchrony Is Sensitive to Corollary Discharge Abnormalities in Early Illness Schizophrenia but Not in the Psychosis Risk Syndrome

BACKGROUND

Prior studies have shown that the auditory N1 event-related potential component elicited by self-generated vocalizations is reduced relative to played back vocalizations, putatively reflecting a corollary discharge mechanism. Schizophrenia patients and psychosis risk syndrome (PRS) youth show deficient N1 suppression during vocalization, consistent with corollary discharge dysfunction. Because N1 is an admixture of theta (4-7 Hz) power and phase synchrony, we examined their contributions to N1 suppression during vocalization, as well as their sensitivity, relative to N1, to corollary discharge dysfunction in schizophrenia and PRS individuals.

METHODS

Theta phase and power values were extracted from electroencephalography data acquired from PRS youth (n = 71), early illness schizophrenia patients (ESZ; n = 84), and healthy controls (HCs; n = 103) as they said "ah" (Talk) and then listened to the playback of their vocalizations (Listen). A principal component analysis extracted theta intertrial coherence (ITC; phase consistency) and event-related spectral power, peaking in the N1 latency range. Talk-Listen suppression scores were analyzed.

RESULTS

Talk-Listen suppression was greater for theta ITC (Cohen's d = 1.46) than for N1 in HC (d = 0.63). Both were deficient in ESZ, but only N1 suppression was deficient in PRS. When deprived of variance shared with theta ITC suppression, N1 suppression no longer differentiated ESZ and PRS individuals from HC. Deficits in theta ITC suppression were correlated with delusions (P = .007) in ESZ. Theta power suppression did not differentiate groups.

CONCLUSIONS

Theta ITC-suppression during vocalization is a more sensitive index of corollary discharge-mediated auditory cortical suppression than N1 suppression and is more sensitive to corollary discharge dysfunction in ESZ than in PRS individuals.

Deficient auditory predictive coding during vocalization in the psychosis risk syndrome and in early illness schizophrenia: the final expanded sample

BACKGROUND

During vocalization, efference copy/corollary discharge mechanisms suppress the auditory cortical response to self-generated sounds. Previously, we found attenuated vocalization-related auditory cortical suppression in psychosis and a similar trend in the psychosis risk syndrome. Here, we report data from the final sample of early illness schizophrenia patients (ESZ), individuals at clinical high risk for psychosis (CHR), and healthy controls (HC).

METHODS

Event-related potentials (ERP) were recorded from ESZ (n = 84), CHR (n = 71), and HC (n = 103) participants during a vocalization paradigm. The N1 ERP component was elicited during production (Talk) and playback (Listen) of vocalization. Age effects on N1 suppression (Talk-Listen), Talk N1, and Listen N1 were compared across groups. N1 measures were adjusted for normal aging before testing for group differences.

RESULTS

Both ESZ and CHR groups showed reduced Talk-Listen N1 suppression relative to HC, but did not differ from each other. Listen N1 was reduced in ESZ, but not in CHR, relative to HC. Deficient Talk-Listen N1 suppression was associated with greater unusual thought content in CHR individuals. N1 suppression increased with age in HC (12-36 years), and while CHR individuals showed a similar age-related increase, no such relationship was evident in ESZ.

CONCLUSIONS

Putative efference copy/corollary discharge-mediated auditory cortical suppression during vocalization is deficient in ESZ and precedes psychosis onset, particularly in CHR individuals with greater unusual thought content. Furthermore, this suppression increases from adolescence through early adulthood, likely reflecting the effects of normal brain maturation. This maturation effect is disrupted in ESZ, presumably due to countervailing illness effects.

Childhood trauma and clinical high risk for psychosis

As a risk factor for psychosis, childhood trauma rates are elevated in the clinical-high-risk (CHR) syndrome compared to the general population. However, it is unknown whether trauma is typically experienced in childhood or adolescence/young adulthood, whether it occurred prior to CHR syndrome onset, and how severe trauma relates to presenting symptoms. In this study, we examined the relationship of trauma history to symptoms and functioning in individuals diagnosed with the CHR syndrome on the Structured Interview for Psychosis-Risk Syndromes (N = 103). Trauma, defined as meeting the DSM-IV A1 criterion of actual or threatened death or injury, was assessed by semi-structured interview. A large proportion of CHR participants (61%) reported trauma exposure, including interpersonal trauma, trauma prior to CHR onset, and childhood trauma prior to age 12. Those with a trauma history (versus those without trauma) were rated as having more severe perceptual disturbances, general/affective symptoms and more impairment on the Global Assessment of Functioning Scale. The number of traumatic events correlated with more severe ratings in those three domains. Additionally, the number of interpersonal traumas was correlated with ratings of suspiciousness. Trauma was unrelated to specific measures of social and role functioning. A small proportion of CHR participants were diagnosed with formal PTSD (14%), which was unrelated to symptom severity or functioning. Thus, we demonstrate that trauma exposure is often early in life (before age 12), occurs prior to the onset of the CHR syndrome, and is related to both positive and affective symptoms.

Reduced higher-dimensional resting state fMRI dynamism in clinical high-risk individuals for schizophrenia identified by meta-state analysis

New techniques to investigate functional network connectivity in resting state functional magnetic resonance imaging data have recently emerged. One novel approach, called meta-state analysis, goes beyond the mere cross-correlation of time courses of distinct brain areas and explores temporal dynamism in more detail, allowing for connectivity states to overlap in time and capturing global dynamic behavior. Previous studies have shown that patients with chronic schizophrenia exhibit reduced neural dynamism compared to healthy controls, but it is not known whether these alterations extend to earlier phases of the illness. In this study, we analyzed individuals at clinical high-risk (CHR, n = 53) for developing psychosis, patients in an early stage of schizophrenia (ESZ, n = 58), and healthy controls (HC, n = 70). ESZ individuals exhibit reduced neural dynamism across all domains compared to HC. CHR individuals also show reduced neural dynamism but only in 2 out of 4 domains investigated. Overall, meta-state analysis adds information about dynamic fluidity of functional connectivity.

Deficits in Cortical Suppression During Vocalization are Associated With Structural Abnormalities in the Arcuate Fasciculus in Early Illness Schizophrenia and Clinical High Risk for Psychosis

Self-generated speech produces a smaller N1 amplitude in the auditory-evoked potential than externally generated speech; this phenomenon is known as N1-suppression. Schizophrenia patients show less N1-suppression than healthy controls. This failure to self-suppress may underlie patients' characteristic tendency to misattribute self-generated thoughts and actions to external sources. While the cause of N1-suppression deficits to speech in schizophrenia remains unclear, structural damage to the arcuate fasciculus is a candidate, due to its ostensible role in transmitting the efference copy of the motor plan to speak. Fifty-one patients with early illness schizophrenia (ESZ), 40 individuals at clinical high-risk for psychosis (CHR), and 59 healthy control (HC) participants underwent an electroencephalogram while they spoke and then listened to a recording of their speech. N1-suppression to the spoken sounds was calculated. Participants also underwent a diffusion-tensor imaging (DTI) scan, from which the arcuate fasciculus and pyramidal tract were extracted with deterministic tractography. ESZ patients exhibited significantly less N1-suppression to self-generated speech than HC participants, with CHR participants exhibiting intermediate levels. ESZ patients also exhibited structural abnormalities in the arcuate fasciculus-specifically, reduced fractional anisotropy and increased radial diffusivity-relative to both HC and CHR. There were no between-group differences in the structural integrity of the pyramidal tract. Finally, level of N1-suppression was linearly related to the structural integrity of the arcuate fasciculus, but not the pyramidal tract, across groups. These results suggest that the self-suppression deficits to willed speech consistently observed in schizophrenia patients may be caused, at least in part, by structural damage to the arcuate fasciculus.

Transient Patterns of Functional Dysconnectivity in Clinical High Risk and Early Illness Schizophrenia Individuals Compared with Healthy Controls

Schizophrenia shows abnormal dynamic functional network connectivity (dFNC), but it is unclear whether these abnormalities are present early in the illness course or precede illness onset in individuals at clinical high risk (CHR) for psychosis. We examined dFNC from resting-state functional magnetic resonance imaging data in CHR (n = 53), early illness schizophrenia (ESZ; n = 58), and healthy control (HC; n = 70) individuals. We applied a sliding temporal window approach capturing five distinct dFNC states. In ESZ patients, the likelihood of transitioning from state 4, a state that exhibited greater cortical-subcortical hyperconnectivity and also lacked typically observed anticorrelation between the default mode network and other functional networks, to a hypoconnected state was increased compared with HC and CHR groups. Furthermore, we investigated the interaction of group and state on dFNC. Overall, HC individuals showed significant changes of connectivity between states that were absent or altered in ESZ patients and CHR individuals. Connectivity differences between groups were identified primarily in two out of the five states, in particular, between HC and ESZ groups. In summary, it appears that the interaction effect was mostly driven by (1) dynamic connectivity changes in HC that were abnormal in CHR and ESZ individuals and (2) the fact that dysconnectivity between groups was only present in some states. These findings underscore the likelihood that abnormalities are present not only in static FNC but also in dFNC, in individuals at CHR for schizophrenia.

The Role of Trauma and Stressful Life Events among Individuals at Clinical High Risk for Psychosis: A Review

The experience of childhood trauma (CT) and stressful life events (SLEs) is associated with subsequent development of a variety of mental health conditions, including psychotic illness. Recent research identifying adolescents and young adults at clinical high risk (CHR) for psychosis allows for prospective evaluation of the impact of trauma and adverse life events on psychosis onset and other outcomes, addressing etiological questions that cannot be answered in studies of fully psychotic or non-clinical populations. This article provides a comprehensive review of the current emerging literature on trauma and adverse life events in the CHR population. Up to 80% of CHR youth endorse a lifetime history of childhood traumatic events and victimization (e.g., bullying). Several studies have shown that the experience of CT predicts psychosis onset among CHR individuals, while the literature on the influence of recent SLEs (e.g., death of a loved one) remains inconclusive. Multiple models have been proposed to explain the link between trauma and psychosis, including the stress-vulnerability and stress-sensitivity hypotheses, with emphases on both cognitive processes and neurobiological mechanisms (e.g., the hypothalamic-pituitary-adrenal axis). Despite the preponderance of CHR individuals who endorse either CT or SLEs, no clinical trials have been conducted evaluating interventions for trauma in CHR youth to date. Furthermore, the current process of formal identification and assessment of trauma, SLEs, and their impact on CHR youth is inconsistent in research and clinical practice. Recommendations for improving trauma assessment, treatment, and future research directions in the CHR field are provided.

Modeling the role of negative symptoms in determining social functioning in individuals at clinical high risk of psychosis

A priority for improving outcome in individuals at clinical high risk (CHR) is enhancing our understanding of predictors of psychosis as well as psychosocial functioning. Social functioning, in particular, is a unique indicator of risk as well as an important outcome in itself. Negative symptoms are a significant determinant of social functioning in CHR individuals; yet, it is unclear which specific negative symptoms drive functional outcome and how these symptoms function relative to other predictors, such as neurocognition and mood/anxiety symptoms. In a sample of 85 CHR individuals, we examined whether a two-factor negative symptom structure that is found in schizophrenia (experiential vs expressive symptoms) would be replicated in a CHR sample; and tested the degree to which specific negative symptoms predict social functioning, relative to neurocognition and mood/anxiety symptoms, which are known to predict functioning. The two-factor negative symptom solution was replicated in this CHR sample. Negative symptom severity was found to be uniquely predictive of social functioning, above and beyond depression/anxiety and neurocognition. Experiential symptoms were more strongly associated with social functioning, relative to expression symptoms. In addition, experiential symptoms mediated the relationship between expressive negative symptoms and social functioning. These results suggest that experiences of motivational impairment are more important in determining social functioning, relative to affective flattening and alogia, in CHR individuals, thereby informing the development of more precise therapeutic targets. Developing novel interventions that stimulate goal-directed behavior and reinforce rewarding experiences in social contexts are recommended.

Symptom assessment in early psychosis: the use of well-established rating scales in clinical high-risk and recent-onset populations

Symptom assessment in early psychosis research typically relies on scales validated in chronic schizophrenia samples. Our goal was to inform investigators who are selecting symptom scales for early psychosis research. We described measure characteristics, baseline scores, and scale inter-relationships in clinical-high-risk (CHR) and recent-onset psychotic disorder (RO) samples using the Positive and Negative Syndrome Scale, Brief Psychiatric Rating Scale, Scale for the Assessment of Positive Symptoms, and Scale for the Assessment of Negative Symptoms; for the CHR group only, we included the Scale of Prodromal Symptoms. For investigators selecting symptom measures in intervention or longitudinal studies, we also examined the relationship of symptom scales with psychosocial functioning. In both samples, symptom subscales in the same domain, across measures, were moderately to highly intercorrelated. Within all measures, positive symptoms were not correlated with negative symptoms, but disorganized symptoms overlapped with both positive and negative symptoms. Functioning was significantly related to negative and disorganized, but not positive, symptoms in both samples on most measures. Findings suggest strong overlap in symptom severity ratings among the most common scales. In recent-onset samples, each has strengths and weaknesses. In CHR samples, they appear to add little information above and beyond the SOPS.

Diminished emotion expressivity but not experience in men and women with schizophrenia

Prior studies indicate that men with schizophrenia are less outwardly expressive but report similar emotion experience as healthy people. However, it is unclear whether women with schizophrenia show this same disconnect between expressivity and experience. Men (n = 24) and women (n = 25) with schizophrenia or schizoaffective disorder and women without schizophrenia (n = 25) viewed emotionally evocative film clips and were video recorded to assess facial expressivity. Participants also reported their emotion experience after each clip. Men and women with schizophrenia did not significantly differ from one another in the frequency of facial expressions, but both groups exhibited fewer expressions than women without schizophrenia. People with schizophrenia also reported lower levels of trait expressivity compared with women without schizophrenia. Overall, people with schizophrenia did not differ from controls on self-reported emotion experience with one exception: Women with schizophrenia reported more unpleasant emotion than controls. These results indicate that both women and men with schizophrenia exhibit fewer outward expressions but experience comparable emotion experience as people without schizophrenia.

Functions of non-suicidal self-injury in adolescents and young adults with Borderline Personality Disorder symptoms

Rates of deliberate non-suicidal self-injury (NSSI) increase during adolescence and young adulthood, particularly in clinical samples, making these important developmental stages for understanding the functions of NSSI. Borderline Personality Disorder (BPD) symptoms also begin to emerge in adolescence, though little research has examined relationships between BPD symptoms and the functions of NSSI in youth, the primary goal of the present study. Adolescents and young adults recruited from an outpatient psychotherapy clinic (N=36) endorsed a range of NSSI functions on the Inventory of Statements about Self-Injury (Klonsky and Glenn, 2009). Participants engaged in NSSI to serve intrapersonal functions (e.g., regulate affect, punish oneself) more frequently than interpersonal functions (e.g., bond with peers, establish autonomy). As predicted, linear regression analyses indicated that BPD affective dysregulation symptoms were associated with the intrapersonal but not the interpersonal functions of NSSI. In contrast, BPD interpersonal dysfunction symptoms were differentially associated with the interpersonal rather than intrapersonal functions of NSSI. These preliminary data indicate that clusters of BPD symptoms show unique relationships with functions of NSSI in treatment-seeking adolescents and young adults, relationships that can be used to target specific functions of NSSI in treatment planning.

Symptom dimensions and functional impairment in early psychosis: more to the story than just negative symptoms

Functional impairment is a defining feature of psychotic disorders and usually appears well before their onset. Negative symptoms play a prominent role in the impaired functioning of individuals with schizophrenia and those at clinical-high-risk (CHR) for psychosis. Despite high rates of depression and anxiety in early psychosis, few studies have examined the contribution of these symptoms to functioning in the putative 'prodrome.' In the current study, we tested the hypotheses that 1) worse negative and disorganized, but not positive, symptoms would be significantly related to impaired social and role functioning in two cohorts of CHR individuals (combined N=98) and a separate sample of individuals with recent-onset (RO) psychotic disorders (N=88); and 2) worse anxiety and depression would be significantly related to impaired functioning in both samples, above and beyond the contributions of negative and disorganized symptoms. Findings largely supported our hypotheses that more severe negative and disorganized symptoms were related to poorer social and role functioning in both samples. Anxiety and depression severity were significantly related to poorer functioning in both samples. In addition, depression, but not anxiety, predicted poorer global and social functioning above and beyond that explained by negative symptoms in the CHR sample. These results suggest the need for phase-specific treatment in early psychosis, with a focus on symptom dimensions to improve functional outcomes for CHR individuals.

Auditory cortex responsiveness during talking and listening: early illness schizophrenia and patients at clinical high-risk for psychosis

OBJECTIVE

The corollary discharge mechanism is theorized to dampen sensations resulting from our own actions and distinguish them from environmental events. Deficits in this mechanism in schizophrenia may contribute to misperceptions of self-generated sensations as originating from external stimuli. We previously found attenuated speech-related suppression of auditory cortex in chronic patients, consistent with such deficits. Whether this abnormality precedes psychosis onset, emerges early in the illness, and/or progressively worsens with illness chronicity, is unknown.

METHODS

Event-related potentials (ERPs) were recorded from schizophrenia patients (SZ; n = 75) and age-matched healthy controls (HC; n = 77). A subsample of early illness schizophrenia patients (ESZ; n = 39) was compared with patients at clinical high-risk for psychosis (CHR; n = 35) and to a subgroup of age-matched HC (n = 36) during a Talk-Listen paradigm. The N1 ERP component was elicited by vocalizations as subjects talked (Talk) and heard them played back (Listen).

RESULTS

As shown previously, SZ showed attenuated speech-related N1 suppression relative to HC. This was also observed in ESZ. N1 suppression values in CHR were intermediate to HC and ESZ and not statistically distinguishable from either comparison group. Age-corrected N1 Talk-Listen difference z scores were not correlated with illness duration in the full SZ sample.

CONCLUSIONS

Putative dysfunction of the corollary discharge mechanism during speech is evident early in the illness and is stable over its course. The intermediate effects in CHR patients may reflect the heterogeneity of this group, requiring longitudinal follow-up data to address if speech-related N1 suppression abnormalities are a risk marker for conversion to psychosis.

Perceptual asymmetries in schizophrenia: subtype differences in left hemisphere dominance for dichotic fused words

OBJECTIVE

Dichotic listening techniques have been used to study hemispheric dominance for language in schizophrenia. The authors' goal was to compare subjects with paranoid and undifferentiated subtypes of schizophrenia.

METHOD

The Fused Rhymed Words Test was used to compare perceptual asymmetries in 16 patients with paranoid schizophrenia, 28 patients with undifferentiated schizophrenia, and 29 healthy comparison subjects.

RESULTS

Patients with paranoid schizophrenia had the largest left hemisphere advantage and patients with undifferentiated schizophrenia had the smallest. The asymmetry of healthy subjects was intermediate. Hemisphere advantage varied as a function of gender only in the patients with undifferentiated schizophrenia.

CONCLUSIONS

The findings support the hypotheses that undifferentiated schizophrenia is associated with underactivation of left hemisphere resources for verbal processing and that paranoid schizophrenia is characterized by preserved left hemisphere processing.

Event-related brain potentials (ERPs) in schizophrenia for tonal and phonetic oddball tasks

BACKGROUND

Prior studies using simple target detection ("oddball") tasks with pure tones have reported asymmetric reduction of the P3 event-related potential (ERP). This study investigated the time course and topography of ERPs recorded during both tonal and phonetic oddball tasks.

METHODS

Event-related potentials of 66 patients (14 unmedicated) diagnosed with schizophrenia (n = 46) or schizoaffective disorder (n = 20) and 32 healthy adults were recorded from 30 scalp electrodes during two oddball tasks using consonant-vowel syllables or complex tones. Overlapping ERP components were identified and measured by covariance-based principal components analysis.

RESULTS

Schizophrenic patients showed marked, task-independent reductions of early negative potentials (N1, N2) but not reduced P3 amplitude or abnormal P3 asymmetry. Task-related hemispheric asymmetries of the N2/P3 complex were similar in healthy adults and schizophrenic patients. Poorer task performance in patients was related to ERP amplitudes, but could not account for reductions of early negativities.

CONCLUSIONS

The findings suggest that both patients and control subjects activated lateralized cortical networks required for pitch (right frontotemporal) and phoneme (left parietotemporal) discrimination. Task-independent reductions of negativities between 80 and 280 msec after stimulus onset suggest a deficit of automatic stimulus classification in schizophrenia, which may be partly compensated by later effortful processing.

Competitors become allies in MRI joint venture

In spite of what first seemed like insurmountable hurdles, two competing Denver hospitals have joined together in an innovative plan to provide magnetic resonance imaging (MRI) services. Their alliance may be a model for other hospitals in the same type of competitive environment.