Improving prediction of psychosis in youth at clinical high-risk: pre-baseline symptom duration and cortical thinning as moderators of the NAPLS2 risk calculator.

BACKGROUND: Clinical implementation of risk calculator models in the clinical high-risk for psychosis (CHR-P) population has been hindered by heterogeneous risk distributions across study cohorts which could be attributed to pre-ascertainment illness progression. To examine this, we tested whether the duration of attenuated psychotic symptom (APS) worsening prior to baseline moderated performance of the North American prodrome longitudinal study 2 (NAPLS2) risk calculator. We also examined whether rates of cortical thinning, another marker of illness progression, bolstered clinical prediction models. METHODS: Participants from both the NAPLS2 and NAPLS3 samples were classified as either 'long' or 'short' symptom duration based on time since APS increase prior to baseline. The NAPLS2 risk calculator model was applied to each of these groups. In a subset of NAPLS3 participants who completed follow-up magnetic resonance imaging scans, change in cortical thickness was combined with the individual risk score to predict conversion to psychosis. RESULTS: The risk calculator models achieved similar performance across the combined NAPLS2/NAPLS3 sample [area under the curve (AUC) = 0.69], the long duration group (AUC = 0.71), and the short duration group (AUC = 0.71). The shorter duration group was younger and had higher baseline APS than the longer duration group. The addition of cortical thinning improved the prediction of conversion significantly for the short duration group (AUC = 0.84), with a moderate improvement in prediction for the longer duration group (AUC = 0.78). CONCLUSIONS: These results suggest that early illness progression differs among CHR-P patients, is detectable with both clinical and neuroimaging measures, and could play an essential role in the prediction of clinical outcomes.

Accelerated cortical thinning precedes and predicts conversion to psychosis: The NAPLS3 longitudinal study of youth at clinical high-risk.

Progressive grey matter loss has been demonstrated among clinical high-risk (CHR) individuals who convert to psychosis, but it is unknown whether these changes occur prior to psychosis onset. Identifying illness-related neurobiological mechanisms that occur prior to conversion is essential for targeted early intervention. Among participants in the third wave of the North American Prodrome Longitudinal Study (NAPLS3), this report investigated if steeper cortical thinning was observable prior to psychosis onset among CHR individuals who ultimately converted (CHR-C) and assessed the shortest possible time interval in which rates of cortical thinning differ between CHR-C, CHR non-converters (CHR-NC), and health controls (HC). 338 CHR-NC, 42 CHR-C, and 62 HC participants (age 19.3±4.2, 44.8% female, 52.5% racial/ethnic minority) completed up to 5 MRI scans across 8 months. Accelerated thinning among CHR-C compared to CHR-NC and HC was observed in multiple prefrontal, temporal, and parietal cortical regions. CHR-NC also exhibited accelerated cortical thinning compared to HC in several of these areas. Greater percent decrease in cortical thickness was observed among CHR-C compared to other groups across 2.9±1.8 months, on average, in several cortical areas. ROC analyses discriminating CHR-C from CHR-NC by percent thickness change in a left hemisphere region of interest, scanner, age, age2, and sex had an AUC of 0.74, with model predictive power driven primarily by percent thickness change. Findings indicate that accelerated cortical thinning precedes psychosis onset and differentiates CHR-C from CHR-NC and HC across short time intervals. Mechanisms underlying cortical thinning may provide novel treatment targets prior to psychosis onset.

Characterizing sustained social anxiety in individuals at clinical high risk for psychosis: trajectory, risk factors, and functional outcomes.

BACKGROUND: While comorbidity of clinical high-risk for psychosis (CHR-P) status and social anxiety is well-established, it remains unclear how social anxiety and positive symptoms covary over time in this population. The present study aimed to determine whether there are more than one covariant trajectory of social anxiety and positive symptoms in the North American Prodrome Longitudinal Study cohort (NAPLS 2) and, if so, to test whether the different trajectory subgroups differ in terms of genetic and environmental risk factors for psychotic disorders and general functional outcome. METHODS: In total, 764 CHR individuals were evaluated at baseline for social anxiety and psychosis risk symptom severity and followed up every 6 months for 2 years. Application of group-based multi-trajectory modeling discerned three subgroups based on the covariant trajectories of social anxiety and positive symptoms over 2 years. RESULTS: One of the subgroups showed sustained social anxiety over time despite moderate recovery in positive symptoms, while the other two showed recovery of social anxiety below clinically significant thresholds, along with modest to moderate recovery in positive symptom severity. The trajectory group with sustained social anxiety had poorer long-term global functional outcomes than the other trajectory groups. In addition, compared with the other two trajectory groups, membership in the group with sustained social anxiety was predicted by higher levels of polygenic risk for schizophrenia and environmental stress exposures. CONCLUSIONS: Together, these analyses indicate differential relevance of sustained v. remitting social anxiety symptoms in the CHR-P population, which in turn may carry implications for differential intervention strategies.

Migrant status, clinical symptoms and functional outcome in youth at clinical high risk for psychosis: findings from the NAPLS-3 study.

PURPOSE: Migrant status is a known risk factor for psychosis, but the underlying causes of this vulnerability are poorly understood. Recently, studies have begun to explore whether migrant status predicts transition to psychosis in individuals at clinical high risk (CHR) for psychosis. Results, however, have been inconclusive. The present study assessed the impact of migrant status on clinical symptoms and functional outcome in individuals at CHR for psychosis who took part in the NAPLS-3 study. METHODS: Participants' migrant status was classified as native-born, first-generation, or second-generation migrant. Clinical symptoms were assessed using the Structured Interview for Psychosis-Risk Syndromes (SIPS); functional outcome was measured using the Global Functioning Scales:Social and Role (GF:S; GF:R). Assessments were conducted at baseline, 12-months, 18-months, and 24-months follow-up. Generalized linear mixed models for repeated measures were used to examine changes over time and differences between groups. RESULTS: The overall sample included 710 individuals at CHR for psychosis (54.2% males; Age: M = 18.19; SD = 4.04). A mixed model analysis was conducted, and no significant differences between groups in symptoms or functioning were observed at any time point. Over time, significant improvement in symptoms and functioning was observed within each group. Transition rates did not differ across groups. CONCLUSION: We discuss potential factors that might explain the lack of group differences. Overall, migrants are a heterogeneous population. Discerning the impact of migration from that of neighborhood ethnic density, social disadvantage or socio-economic status of different ethnic groups could help better understand vulnerability and resilience to psychosis.

White matter changes in psychosis risk relate to development and are not impacted by the transition to psychosis.

Subtle alterations in white matter microstructure are observed in youth at clinical high risk (CHR) for psychosis. However, the timing of these changes and their relationships to the emergence of psychosis remain unclear. Here, we track the evolution of white matter abnormalities in a large, longitudinal cohort of CHR individuals comprising the North American Prodrome Longitudinal Study (NAPLS-3). Multi-shell diffusion magnetic resonance imaging data were collected across multiple timepoints (1-5 over 1 year) in 286 subjects (aged 12-32 years): 25 CHR individuals who transitioned to psychosis (CHR-P; 61 scans), 205 CHR subjects with unknown transition outcome after the 1-year follow-up period (CHR-U; 596 scans), and 56 healthy controls (195 scans). Linear mixed effects models were fitted to infer the impact of age and illness-onset on variation in the fractional anisotropy of cellular tissue (FAT) and the volume fraction of extracellular free water (FW). Baseline measures of white matter microstructure did not differentiate between HC, CHR-U and CHR-P individuals. However, age trajectories differed between the three groups in line with a developmental effect: CHR-P and CHR-U groups displayed higher FAT in adolescence, and 4% lower FAT by 30 years of age compared to controls. Furthermore, older CHR-P subjects (20+ years) displayed 4% higher FW in the forceps major (p < 0.05). Prospective analysis in CHR-P did not reveal a significant impact of illness onset on regional FAT or FW, suggesting that transition to psychosis is not marked by dramatic change in white matter microstructure. Instead, clinical high risk for psychosis-regardless of transition outcome-is characterized by subtle age-related white matter changes that occur in tandem with development.

Bullying in clinical high risk for psychosis participants from the NAPLS-3 cohort.

PURPOSE: Bullying is associated with a heightened risk for poor outcomes, including psychosis. This study aimed to replicate previous findings on bullying prevalence in clinical high-risk (CHR) individuals, to assess the longitudinal course of clinical and functional variables between bullied and non-bullied CHR and the association of bullying with premorbid functioning, clinical outcome, transition to psychosis and risk of violence. METHODS: The sample consisted of 691 CHR participants and 96 healthy controls. Participants reported whether they had experienced bullying and how long it had lasted. Assessments included DSM-5 diagnoses, attenuated psychotic symptoms, negative symptoms, social and role functioning, depression, stress, premorbid functioning, and risk of violence. The bullied and non-bullied CHR groups were compared at baseline and further longitudinally on clinical and functioning variables and transition to psychosis. RESULTS: Bullying was more prevalent among CHR individuals than healthy controls. Bullied CHR had a higher prevalence of PTSD and more severe depression and stress at baseline than non-bullied CHR. There was no impact of bullying on clinical and functional variables over time. Bullying was not related to final clinical status or transition to psychosis. However, bullied participants had poorer premorbid functioning and a greater risk of violence. CONCLUSION: While bullying may not impact the likelihood of CHR individuals to transition to psychosis, it may be a risk factor for development of the at-risk state and may be related to a greater risk of violence. Future studies should consider bullying perpetration among CHR individuals.

Contributions of common genetic variants to risk of schizophrenia among individuals of African and Latino ancestry.

Schizophrenia is a common, chronic and debilitating neuropsychiatric syndrome affecting tens of millions of individuals worldwide. While rare genetic variants play a role in the etiology of schizophrenia, most of the currently explained liability is within common variation, suggesting that variation predating the human diaspora out of Africa harbors a large fraction of the common variant attributable heritability. However, common variant association studies in schizophrenia have concentrated mainly on cohorts of European descent. We describe genome-wide association studies of 6152 cases and 3918 controls of admixed African ancestry, and of 1234 cases and 3090 controls of Latino ancestry, representing the largest such study in these populations to date. Combining results from the samples with African ancestry with summary statistics from the Psychiatric Genomics Consortium (PGC) study of schizophrenia yielded seven newly genome-wide significant loci, and we identified an additional eight loci by incorporating the results from samples with Latino ancestry. Leveraging population differences in patterns of linkage disequilibrium, we achieve improved fine-mapping resolution at 22 previously reported and 4 newly significant loci. Polygenic risk score profiling revealed improved prediction based on trans-ancestry meta-analysis results for admixed African (Nagelkerke's R2 = 0.032; liability R2 = 0.017; P < 10-52), Latino (Nagelkerke's R2 = 0.089; liability R2 = 0.021; P < 10-58), and European individuals (Nagelkerke's R2 = 0.089; liability R2 = 0.037; P < 10-113), further highlighting the advantages of incorporating data from diverse human populations.

The association between migrant status and transition in an ultra-high risk for psychosis population.

PURPOSE: Migrant status is one of the most replicated and robust risk factors for developing a psychotic disorder. This study aimed to determine whether migrant status in people identified as Ultra-High Risk for Psychosis (UHR) was associated with risk of transitioning to a full-threshold psychotic disorder. METHODS: Hazard ratios for the risk of transition were calculated from five large UHR cohorts (n = 2166) and were used to conduct a meta-analysis using the generic inverse-variance method using a random-effects model. RESULTS: 2166 UHR young people, with a mean age of 19.1 years (SD ± 4.5) were included, of whom 221 (10.7%) were first-generation migrants. A total of 357 young people transitioned to psychosis over a median follow-up time of 417 days (I.Q.R.147-756 days), representing 17.0% of the cohort. The risk of transition to a full-threshold disorder was not increased for first-generation migrants, (HR = 1.08, 95% CI 0.62-1.89); however, there was a high level of heterogeneity between studies The hazard ratio for second-generation migrants to transition to a full-threshold psychotic disorder compared to the remainder of the native-born population was 1.03 (95% CI 0.70-1.51). CONCLUSIONS: This meta-analysis did not find a statistically significant association between migrant status and an increased risk for transition to a full-threshold psychotic disorder; however, several methodological issues could explain this finding. Further research should focus on examining the risk of specific migrant groups and also ensuring that migrant populations are adequately represented within UHR clinics.

Toward Leveraging Human Connectomic Data in Large Consortia: Generalizability of fMRI-Based Brain Graphs Across Sites, Sessions, and Paradigms.

While graph theoretical modeling has dramatically advanced our understanding of complex brain systems, the feasibility of aggregating connectomic data in large imaging consortia remains unclear. Here, using a battery of cognitive, emotional and resting fMRI paradigms, we investigated the generalizability of functional connectomic measures across sites and sessions. Our results revealed overall fair to excellent reliability for a majority of measures during both rest and tasks, in particular for those quantifying connectivity strength, network segregation and network integration. Processing schemes such as node definition and global signal regression (GSR) significantly affected resulting reliability, with higher reliability detected for the Power atlas (vs. AAL atlas) and data without GSR. While network diagnostics for default-mode and sensori-motor systems were consistently reliable independently of paradigm, those for higher-order cognitive systems were reliable predominantly when challenged by task. In addition, based on our present sample and after accounting for observed reliability, satisfactory statistical power can be achieved in multisite research with sample size of approximately 250 when the effect size is moderate or larger. Our findings provide empirical evidence for the generalizability of brain functional graphs in large consortia, and encourage the aggregation of connectomic measures using multisite and multisession data.

Stress perception following childhood adversity: Unique associations with adversity type and sex.

Childhood adversity is associated with poor mental and physical health outcomes across the life span. Alterations in the hypothalamic-pituitary-adrenal axis are considered a key mechanism underlying these associations, although findings have been mixed. These inconsistencies suggest that other aspects of stress processing may underlie variations in this these associations, and that differences in adversity type, sex, and age may be relevant. The current study investigated the relationship between childhood adversity, stress perception, and morning cortisol, and examined whether differences in adversity type (generalized vs. threat and deprivation), sex, and age had distinct effects on these associations. Salivary cortisol samples, daily hassle stress ratings, and retrospective measures of childhood adversity were collected from a large sample of youth at risk for serious mental illness including psychoses (n = 605, mean age = 19.3). Results indicated that childhood adversity was associated with increased stress perception, which subsequently predicted higher morning cortisol levels; however, these associations were specific to threat exposures in females. These findings highlight the role of stress perception in stress vulnerability following childhood adversity and highlight potential sex differences in the impact of threat exposures.

Clinical and functional characteristics of youth at clinical high-risk for psychosis who do not transition to psychosis.

BACKGROUND: Much of the interest in youth at clinical high risk (CHR) of psychosis has been in understanding conversion. Recent literature has suggested that less than 25% of those who meet established criteria for being at CHR of psychosis go on to develop a psychotic illness. However, little is known about the outcome of those who do not make the transition to psychosis. The aim of this paper was to examine clinical symptoms and functioning in the second North American Prodrome Longitudinal Study (NAPLS 2) of those individuals whose by the end of 2 years in the study had not developed psychosis. METHODS: In NAPLS-2 278 CHR participants completed 2-year follow-ups and had not made the transition to psychosis. At 2-years the sample was divided into three groups - those whose symptoms were in remission, those who were still symptomatic and those whose symptoms had become more severe. RESULTS: There was no difference between those who remitted early in the study compared with those who remitted at one or 2 years. At 2-years, those in remission had fewer symptoms and improved functioning compared with the two symptomatic groups. However, all three groups had poorer social functioning and cognition than healthy controls. CONCLUSIONS: A detailed examination of the clinical and functional outcomes of those who did not make the transition to psychosis did not contribute to predicting who may make the transition or who may have an earlier remission of attenuated psychotic symptoms.

Association of baseline inflammatory markers and the development of negative symptoms in individuals at clinical high risk for psychosis.

Negative symptoms are common in individuals at clinical high-risk (CHR) for psychosis and are associated with worse functional outcomes. Inflammation may be one mechanism underlying negative symptoms. Inflammatory markers are altered in individuals at CHR and are associated with negative symptoms in patients with schizophrenia. We thus hypothesized that baseline inflammatory markers would predict the development of negative symptoms in individuals at CHR for psychosis. Thirty seven individuals from the North American Prodromal Longitudinal Study who met CHR criteria were included in the study. Inflammatory cytokines, including interferon (IFN)-λ, Interleukin (IL)-1ß, IL-1 receptor antagonist (IL-1RA), IL-4, IL-6, IL-8, IL-10, and tumor necrosis factor (TNF) were measured at baseline. Negative symptoms as measured by the Scale of Prodromal Symptoms, were measured at baseline and six and twelve months. Associations between inflammatory markers and the trajectory of negative symptoms (slope) over the first year of follow-up, were assessed using linear regression models controlling for age, sex, race and depressive symptom severity (as assessed by the Calgary Depression Scale for Schizophrenia). Baseline TNF (beta = 0.361, p = 0.007) and IL-6 (beta = -0.306, p = 0.026) predicted negative symptoms slopes, along with depressive symptom severity at baseline (beta = -0.596, p = 0.000). These findings demonstrate that inflammatory cytokines may underlie the development of negative symptoms in some individuals at CHR for psychosis. TNF predicted the development of negative symptoms independent of baseline depression. Given the heterogeneity of the CHR population, the comorbidity of negative symptoms and depression in this population, and the particular challenges in treating negative symptoms, immune markers could represent potential biomarkers that underlie the development of negative symptoms, representing a potential treatment target.

Potentially important periods of change in the development of social and role functioning in youth at clinical high risk for psychosis.

The developmental course of daily functioning prior to first psychosis-onset remains poorly understood. This study explored age-related periods of change in social and role functioning. The longitudinal study included youth (aged 12-23, mean follow-up years = 1.19) at clinical high risk (CHR) for psychosis (converters [CHR-C], n = 83; nonconverters [CHR-NC], n = 275) and a healthy control group (n = 164). Mixed-model analyses were performed to determine age-related differences in social and role functioning. We limited our analyses to functioning before psychosis conversion; thus, data of CHR-C participants gathered after psychosis onset were excluded. In controls, social and role functioning improved over time. From at least age 12, functioning in CHR was poorer than in controls, and this lag persisted over time. Between ages 15 and 18, social functioning in CHR-C stagnated and diverged from that of CHR-NC, who continued to improve (p = .001). Subsequently, CHR-C lagged behind in improvement between ages 21 and 23, further distinguishing them from CHR-NC (p < .001). A similar period of stagnation was apparent for role functioning, but to a lesser extent (p = .007). The results remained consistent when we accounted for the time to conversion. Our findings suggest that CHR-C start lagging behind CHR-NC in social and role functioning in adolescence, followed by a period of further stagnation in adulthood.

Treatment Precedes Positive Symptoms in North American Adolescent and Young Adult Clinical High Risk Cohort.

Early intervention for psychotic disorders, a growing international priority, typically targets help-seeking populations with emerging psychotic ("positive") symptoms. We assessed the nature of and degree to which treatment of individuals at high risk for psychosis preceded or followed the onset of positive symptoms. The North American Prodrome Longitudinal Study-2 collected psychosocial treatment histories for 745 (98%) of 764 high-risk participants (M age = 18.9, 57% male, 57.5% Caucasian, 19.1% Hispanic) recruited from 8 North American communities. Similar to prior findings, 82% of participants reported psychosocial treatment prior to baseline assessment, albeit with significant variability across sites (71%-96%). Participants first received treatment a median of 1.7 years prior to the onset of a recognizable psychosis-risk syndrome. Only one fourth sought initial treatment in the year following syndrome onset. Although mean sample age differed significantly by site, age at initial treatment (M = 14.1, SD = 5.0) did not. High rates of early treatment prior to syndrome onset make sense in light of known developmental precursors to psychotic disorders but are inconsistent with the low rates of treatment retrospectively reported by first-episode psychosis samples. Findings suggest that psychosis risk studies and clinics may need to more actively recruit and engage symptomatic but non-help-seeking individuals and that community clinicians be better trained to recognize both positive and nonspecific indicators of emerging psychosis. Improved treatments for nonspecific symptoms, as well as the characteristic attenuated positive symptoms, are needed.

Multisite reliability of MR-based functional connectivity.

Recent years have witnessed an increasing number of multisite MRI functional connectivity (fcMRI) studies. While multisite studies provide an efficient way to accelerate data collection and increase sample sizes, especially for rare clinical populations, any effects of site or MRI scanner could ultimately limit power and weaken results. Little data exists on the stability of functional connectivity measurements across sites and sessions. In this study, we assess the influence of site and session on resting state functional connectivity measurements in a healthy cohort of traveling subjects (8 subjects scanned twice at each of 8 sites) scanned as part of the North American Prodrome Longitudinal Study (NAPLS). Reliability was investigated in three types of connectivity analyses: (1) seed-based connectivity with posterior cingulate cortex (PCC), right motor cortex (RMC), and left thalamus (LT) as seeds; (2) the intrinsic connectivity distribution (ICD), a voxel-wise connectivity measure; and (3) matrix connectivity, a whole-brain, atlas-based approach to assessing connectivity between nodes. Contributions to variability in connectivity due to subject, site, and day-of-scan were quantified and used to assess between-session (test-retest) reliability in accordance with Generalizability Theory. Overall, no major site, scanner manufacturer, or day-of-scan effects were found for the univariate connectivity analyses; instead, subject effects dominated relative to the other measured factors. However, summaries of voxel-wise connectivity were found to be sensitive to site and scanner manufacturer effects. For all connectivity measures, although subject variance was three times the site variance, the residual represented 60-80% of the variance, indicating that connectivity differed greatly from scan to scan independent of any of the measured factors (i.e., subject, site, and day-of-scan). Thus, for a single 5min scan, reliability across connectivity measures was poor (ICC=0.07-0.17), but increased with increasing scan duration (ICC=0.21-0.36 at 25min). The limited effects of site and scanner manufacturer support the use of multisite studies, such as NAPLS, as a viable means of collecting data on rare populations and increasing power in univariate functional connectivity studies. However, the results indicate that aggregation of fcMRI data across longer scan durations is necessary to increase the reliability of connectivity estimates at the single-subject level.

Early traumatic experiences, perceived discrimination and conversion to psychosis in those at clinical high risk for psychosis.

PURPOSE: There is evidence to suggest that both early traumatic experiences and perceived discrimination are associated with later onset of psychosis. Less is known about the impact these two factors may have on conversion to psychosis in those who are at clinical high risk (CHR) of developing psychosis. The purpose of this study was to determine if trauma and perceived discrimination were predictors of conversion to psychosis. METHODS: The sample consisted of 764 individuals who were at CHR of developing psychosis and 280 healthy controls. All participants were assessed on past trauma, bullying and perceived discrimination. RESULTS: Individuals at CHR reported significantly more trauma, bullying and perceived discrimination than healthy controls. Only perceived discrimination was a predictor of later conversion to psychosis. CONCLUSIONS: Given that CHR individuals are reporting increased rates of trauma and perceived discrimination, these should be routinely assessed, with the possibility of offering interventions aimed at ameliorating the impact of past traumas as well as improving self-esteem and coping strategies in an attempt to reduce perceived discrimination.

Core Schemas in Youth at Clinical High Risk for Psychosis.

BACKGROUND: Schema Theory proposes that the development of maladaptive schemas are based on a combination of memories, emotions and cognitions regarding oneself and one's relationship to others. A cognitive model of psychosis suggests that schemas are crucial to the development and persistence of psychosis. Little is known about the impact that schemas may have on those considered to be at clinical high risk (CHR) of developing psychosis. AIMS: To investigate schemas over time in a large sample of CHR individuals and healthy controls. METHOD: Sample included 765 CHR participants and 280 healthy controls. Schemas were assessed at baseline, 6 and 12 months using the Brief Core Schema Scale (BCSS). Baseline schemas were compared to 2-year clinical outcome. RESULTS: CHR participants evidenced stable and more maladaptive schemas over time compared to controls. Schemas at initial contact did not vary amongst the different clinical outcome groups at 2 years although all CHR outcome groups evidenced significantly worse schemas than healthy controls. Although there were no differences on baseline schemas between those who later transitioned to psychosis compared to those who did not, those who transitioned to psychosis had more maladaptive negative self-schemas at the time of transition. Associations between negative schemas were positively correlated with earlier abuse and bullying. CONCLUSIONS: These findings demonstrate a need for interventions that aim to improve maladaptive schemas among the CHR population. Therapies targeting self-esteem, as well as schema therapy may be important work for future studies.

Reliability of an fMRI paradigm for emotional processing in a multisite longitudinal study.

Multisite neuroimaging studies can facilitate the investigation of brain-related changes in many contexts, including patient groups that are relatively rare in the general population. Though multisite studies have characterized the reliability of brain activation during working memory and motor functional magnetic resonance imaging tasks, emotion processing tasks, pertinent to many clinical populations, remain less explored. A traveling participants study was conducted with eight healthy volunteers scanned twice on consecutive days at each of the eight North American Longitudinal Prodrome Study sites. Tests derived from generalizability theory showed excellent reliability in the amygdala ( Eρ2 = 0.82), inferior frontal gyrus (IFG; Eρ2 = 0.83), anterior cingulate cortex (ACC; Eρ2 = 0.76), insula ( Eρ2 = 0.85), and fusiform gyrus ( Eρ2 = 0.91) for maximum activation and fair to excellent reliability in the amygdala ( Eρ2 = 0.44), IFG ( Eρ2 = 0.48), ACC ( Eρ2 = 0.55), insula ( Eρ2 = 0.42), and fusiform gyrus ( Eρ2 = 0.83) for mean activation across sites and test days. For the amygdala, habituation ( Eρ2 = 0.71) was more stable than mean activation. In a second investigation, data from 111 healthy individuals across sites were aggregated in a voxelwise, quantitative meta-analysis. When compared with a mixed effects model controlling for site, both approaches identified robust activation in regions consistent with expected results based on prior single-site research. Overall, regions central to emotion processing showed strong reliability in the traveling participants study and robust activation in the aggregation study. These results support the reliability of blood oxygen level-dependent signal in emotion processing areas across different sites and scanners and may inform future efforts to increase efficiency and enhance knowledge of rare conditions in the population through multisite neuroimaging paradigms.

Evaluating the impact of cannabis use on thalamic connectivity in youth at clinical high risk of psychosis.

BACKGROUND: Disruptions in thalamic functional connectivity have been observed in people with schizophrenia and in youth at clinical high risk (CHR) of psychosis. However, the impact of environmental risk factors for psychosis on thalamic dysconnectivity is poorly understood. We tested whether thalamic dysconnectivity is related to patterns of cannabis use in a CHR sample. METHODS: 162 CHR and 105 control participants were assessed on cannabis use severity, frequency, and age at onset of first use as part of the North American Prodrome Longitudinal Study and completed resting-state fMRI scans. Whole-brain thalamic functional connectivity maps were generated using individual subjects' anatomically defined thalamic seeds. RESULTS: Thalamic connectivity did not significantly correlate with current cannabis use severity or frequency in either CHR or controls. In CHR cannabis users, a significant correlation emerged between attenuated thalamic connectivity with left sensory/motor cortex and a younger age at onset of cannabis use. CHR who used cannabis before age 15 did not differ on thalamic connectivity as compared to CHR who used after age 15 or CHR who were cannabis naïve. No group differences in thalamic connectivity emerged when comparing CHR separated by moderate/high use frequency, low-frequency or cannabis naïve. CONCLUSIONS: Although a younger age at onset of cannabis use may be associated with disrupted thalamo-cortical coupling, cannabis use does not appear to be an identifying characteristic for thalamic connectivity in CHR with moderate/high use frequency compared to low-frequency users or CHR who are cannabis naïve.

North American Prodrome Longitudinal Study (NAPLS 2): The Prodromal Symptoms.

In studies describing the long-term follow-up up of youth at clinical high risk (CHR) of psychosis, little attention has been given to details of specific prodromal symptoms. In this paper, we describe the prodromal symptoms of 764 CHR participants recruited in the multi-site North American Prodrome Longitudinal Study (NAPLS). Symptoms were rated on the Scale of Prodromal Symptoms (SOPS) at baseline and 6-, 12-, 18-, and 24-month follow-ups. Clinical outcome at the 2-year assessment was categorized as psychotic, prodromal progression, symptomatic or in remission. Most of the CHR sample (92%) met criteria for the attenuated positive symptoms syndrome (APSS). Significant improvements in SOPS symptoms were observed over time. Unusual thought content, disorganized communication, and overall ratings on disorganized symptoms differentiated those who transitioned to psychosis from the other clinical outcome groups. Suspiciousness and total positive symptoms differentiated those in remission from the other clinical outcome groups.