Specificity of Incident Diagnostic Outcomes in Patients at Clinical High Risk for Psychosis

It is not well established whether the incident outcomes of the clinical high-risk (CHR) syndrome for psychosis are diagnostically specific for psychosis or whether CHR patients also are at elevated risk for a variety of nonpsychotic disorders. We collected 2 samples (NAPLS-1, PREDICT) that contained CHR patients and a control group who responded to CHR recruitment efforts but did not meet CHR criteria on interview (help-seeking comparison patients [HSC]). Incident diagnostic outcomes were defined as the occurrence of a SIPS-defined psychosis or a structured interview diagnosis from 1 of 3 nonpsychotic Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) groups (anxiety, bipolar, or nonbipolar mood disorder), when no diagnosis in that group was present at baseline. Logistic regression revealed that the CHR vs HSC effect did not vary significantly across study for any emergent diagnostic outcome; data from the 2 studies were therefore combined. CHR (n = 271) vs HSC (n = 171) emergent outcomes were: psychosis 19.6% vs 1.8%, bipolar disorders 1.1% vs 1.2%, nonbipolar mood disorders 4.4% vs 5.3%, and anxiety disorders 5.2% vs 5.3%. The main effect of CHR vs HSC was statistically significant (OR = 13.8, 95% CI 4.2-45.0, df = 1, P < .001) for emergent psychosis but not for any emergent nonpsychotic disorder. Sensitivity analyses confirmed these findings. Within the CHR group emergent psychosis was significantly more likely than each nonpsychotic DSM-IV emergent disorder, and within the HSC group emergent psychosis was significantly less likely than most emergent nonpsychotic disorders. The CHR syndrome is specific as a marker for research on predictors and mechanisms of developing psychosis.

Alcohol confounds relationship between cannabis misuse and psychosis conversion in a high-risk sample

OBJECTIVE

Cannabis use has been examined as a predictor of psychosis in clinical high-risk (CHR) samples, but little is known about the impact of other substances on this relationship.

METHOD

Substance use was assessed in a large sample of CHR participants (N = 370, mean age = 18.3) enrolled in the multisite North American Prodrome Longitudinal Study Phase 1 project. Three hundred and forty-one participants with cannabis use data were divided into groups: No Use (NU, N = 211); Cannabis Use without impairment (CU, N = 63); Cannabis Abuse/Dependence (CA/CD, N = 67). Participants (N = 283) were followed for ≥2 years to determine psychosis conversion.

RESULTS

Alcohol (45.3%) and cannabis (38.1%) were the most common substances. Cannabis use groups did not differ on baseline attenuated positive symptoms. Seventy-nine of 283 participants with cannabis and follow-up data converted to psychosis. Survival analysis revealed significant differences between conversion rates in the CA/CD group compared with the No Use (P = 0.031) and CU group (P = 0.027). CA/CD also significantly predicted psychosis in a regression analysis, but adjusting for alcohol use weakened this relationship.

CONCLUSION

The cannabis misuse and psychosis association was confounded by alcohol use. Non-impairing cannabis use was not related to psychosis. Results highlight the need to control for other substance use, so as to not overstate the cannabis/psychosis connection.

Prodromal Symptom Severity Predicts Accelerated Gray Matter Reduction and Third Ventricle Expansion Among Clinically High Risk Youth Developing Psychotic Disorders

A recent prospective longitudinal neuroimaging study of 274 prodromal risk syndrome subjects revealed that those who later developed full-blown psychotic symptoms exhibited accelerated gray matter loss and third ventricle expansion around the time of onset of psychosis. Previous studies also indicate that higher levels of unusual thought content during prodromal states are a significant predictor of psychosis in clinically high-risk youth (CHR). However, the relationship between clinical symptoms and changes in neuroanatomical structure has not been previously examined in the North American Prodrome Longitudinal Study (NAPLS) sample at the atlas level. In this report, we investigated whether symptom severity as measured by the Scale of Prodromal Symptoms (SOPS) predicted the accelerated gray matter decline in 274 CHR cases, including 35 who converted to psychosis. Higher levels of unusual thought content (pre-delusional) symptoms at baseline were associated with a steeper rate of gray matter loss in the prefrontal cortex bilaterally among converters. In contrast, there was no association found among non-converters. Steeper gray matter loss seems to be unique to those (CHR) individuals with higher levels of sub-psychotic pre-delusional symptoms that acutely worsen in the ramp-up to full-blown psychosis, and as such may reflect pathophysiological processes driving emergence of psychosis.

Progressive reduction in cortical thickness as psychosis develops: a multisite longitudinal neuroimaging study of youth at elevated clinical risk

BACKGROUND

Individuals at clinical high risk (CHR) who progress to fully psychotic symptoms have been observed to show a steeper rate of cortical gray matter reduction compared with individuals without symptomatic progression and with healthy control subjects. Whether such changes reflect processes associated with the pathophysiology of schizophrenia or exposure to antipsychotic drugs is unknown.

METHODS

In this multisite study, 274 CHR cases, including 35 individuals who converted to psychosis, and 135 healthy comparison subjects were scanned with magnetic resonance imaging at baseline, 12-month follow-up, or the point of conversion for the subjects who developed fully psychotic symptoms.

RESULTS

In a traveling subjects substudy, excellent reliability was observed for measures of cortical thickness and subcortical volumes. Controlling for multiple comparisons throughout the brain, CHR subjects who converted to psychosis showed a steeper rate of gray matter loss in the right superior frontal, middle frontal, and medial orbitofrontal cortical regions as well as a greater rate of expansion of the third ventricle compared with CHR subjects who did not convert to psychosis and healthy control subjects. Differential tissue loss was present in subjects who had not received antipsychotic medications during the interscan interval and was predicted by baseline levels of an aggregate measure of proinflammatory cytokines in plasma.

CONCLUSIONS

These findings demonstrate that the brain changes are not explained by exposure to antipsychotic drugs but likely play a role in psychosis pathophysiology. Given that the cortical changes were more pronounced in subjects with briefer durations of prodromal symptoms, contributing factors may predominantly play a role in acute-onset forms of psychosis.

The content of attenuated psychotic symptoms in those at clinical high risk for psychosis

Recent research has started to focus on identifying individuals who are at clinical high risk of developing psychosis as a means to try and understand the predictors and mechanisms involved in the progress to a full psychotic episode. The aim of the current study was to provide an initial description and prevalence rates of specific content found within attenuated positive symptoms. The Content of Attenuated Positive Symptoms (CAPS) codebook was used by independent raters to determine the presence of content within a sample of written vignettes. Krippendorff's alpha was used to determine inter-rater reliability. Overall, the majority of items fell in or above an acceptable range of reliability. There was heterogeneity present in the types of content endorsed. However, the most commonly endorsed items included being perplexed by reality, increased hypervigilence, being gifted, hearing indistinct and distinct sounds, seeing figures or shadows, something touching the individual, and unpleasant smells. The use of the CAPS codebook is a reliable way to code the content of attenuated positive symptoms. Identifying and monitoring the presence of certain content may provide insight into the presence of other comorbid issues and the potential for future conversion.

Reliability of neuroanatomical measurements in a multisite longitudinal study of youth at risk for psychosis

Multisite longitudinal neuroimaging designs are used to identify differential brain structural change associated with onset or progression of disease. The reliability of neuroanatomical measurements over time and across sites is a crucial aspect of power in such studies. Prior work has found that while within-site reliabilities of neuroanatomical measurements are excellent, between-site reliability is generally more modest. Factors that may increase between-site reliability include standardization of scanner platform and sequence parameters and correction for between-scanner variations in gradient nonlinearities. Factors that may improve both between- and within-site reliability include use of registration algorithms that account for individual differences in cortical patterning and shape. In this study 8 healthy volunteers were scanned twice on successive days at 8 sites participating in the North American Prodrome Longitudinal Study (NAPLS). All sites employed 3 Tesla scanners and standardized acquisition parameters. Site accounted for 2 to 30% of the total variance in neuroanatomical measurements. However, site-related variations were trivial (<1%) among sites using the same scanner model and 12-channel coil or when correcting for between-scanner differences in gradient nonlinearity and scaling. Adjusting for individual differences in sulcal-gyral geometries yielded measurements with greater reliabilities than those obtained using an automated approach. Neuroimaging can be performed across multiple sites at the same level of reliability as at a single site, achieving within- and between-site reliabilities of 0.95 or greater for gray matter density in the majority of voxels in the prefrontal and temporal cortical surfaces as well as for the volumes of most subcortical structures.

Is there an association between advanced paternal age and endophenotype deficit levels in schizophrenia?

The children of older fathers have increased risks of developing schizophrenia spectrum disorders, and among those who develop these disorders, those with older fathers present with more severe clinical symptoms. However, the influence of advanced paternal age on other important domains related to schizophrenia, such as quantitative endophenotype deficit levels, remains unknown. This study investigated the associations between paternal age and level of endophenotypic impairment in a well-characterized family-based sample from the Consortium on the Genetics of Schizophrenia (COGS). All families included at least one affected subject and one unaffected sibling. Subjects met criteria for schizophrenia (probands; n = 293) or were unaffected first-degree siblings of those probands (n = 382). Paternal age at the time of subjects’ birth was documented. Subjects completed a comprehensive clinical assessment and a battery of tests that measured 16 endophenotypes. After controlling for covariates, potential paternal age–endophenotype associations were analyzed using one model that included probands alone and a second model that included both probands and unaffected siblings. Endophenotype deficits in the Identical Pairs version of the 4-digit Continuous Performance Test and in the Penn Computerized Neurocognitive Battery verbal memory test showed significant associations with paternal age. However, after correcting for multiple comparisons, no endophenotype was significantly associated with paternal age. These findings suggest that factors other than advanced paternal age at birth may account for endophenotypic deficit levels in schizophrenia.

Logic and justification for dimensional assessment of symptoms and related clinical phenomena in psychosis: relevance to DSM-5

Work on the causes and treatment of schizophrenia and other psychotic disorders has long recognized the heterogeneity of the symptoms that can be displayed by individuals with these illnesses. Further, researchers have increasingly emphasized the ways in which the severity of different symptoms of this illness can vary across individuals, and have provided evidence that the severity of such symptoms can predict other important aspects of the illness, such as the degree of cognitive and/or neurobiological deficits. Additionally, research has increasingly emphasized that the boundaries between nosological entities may not be categorical and that the comorbidity of disorders may reflect impairments in common dimensions of genetic variation, human behavior and neurobiological function. As such, it is critical to focus on a dimensional approach to the assessment of symptoms and clinically relevant phenomena in psychosis, so as to increase attention to and understanding of the causes and consequences of such variation. In the current article, we review the logic and justification for including dimensional assessment of clinical symptoms in the evaluation of psychosis in the Fifth Edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-5).

Definition and description of schizophrenia in the DSM-5

Although dementia praecox or schizophrenia has been considered a unique disease for over a century, its definitions and boundaries have changed over this period and its etiology and pathophysiology remain elusive. Despite changing definitions, DSM-IV schizophrenia is reliably diagnosed, has fair validity and conveys useful clinical information. Therefore, the essence of the broad DSM-IV definition of schizophrenia is retained in DSM-5. The clinical manifestations are extremely diverse, however, with this heterogeneity being poorly explained by the DSM-IV clinical subtypes and course specifiers. Additionally, the boundaries of schizophrenia are imprecisely demarcated from schizoaffective disorder and other diagnostic categories and its special emphasis on Schneiderian "first-rank" symptoms appears misplaced. Changes in the definition of schizophrenia in DSM-5 seek to address these shortcomings and incorporate the new information about the nature of the disorder accumulated over the past two decades. Specific changes in its definition include elimination of the classic subtypes, addition of unique psychopathological dimensions, clarification of cross-sectional and longitudinal course specifiers, elimination of special treatment of Schneiderian 'first-rank symptoms', better delineation of schizophrenia from schizoaffective disorder, and clarification of the relationship of schizophrenia to catatonia. These changes should improve diagnosis and characterization of individuals with schizophrenia and facilitate measurement-based treatment and concurrently provide a more useful platform for research that will elucidate its nature and permit a more precise future delineation of the 'schizophrenias'.

Sexual dimorphisms and prediction of conversion in the NAPLS psychosis prodrome

Sex differences in age at onset, symptomatology, clinical course (see Walker et al., 2002) and functional impairment (Thorup et al., 2007) are well documented in psychosis. The general pattern of findings is that males manifest an earlier onset, more severe symptoms and poorer prognosis than females. Limited studies examining individuals at clinical high-risk (CHR) suggest a similar pattern of sexual dimorphism (Holtzman et al., in review; Corcoran et al., 2011). As part of the North American Prodrome Longitudinal Study (NAPLS), the current study prospectively examined sexual dimorphisms in relationships among CHR symptoms, childhood (premorbid) academic and social functioning, baseline social and role functioning, and conversion to psychosis. Subjects included 276 (113F/163M) CHR NAPLS participants (ages 12-36.8years). All measures/criteria were assessed at baseline except conversion status, assessed at 6-month intervals up to 30months. Results show sex differences in baseline social and role functioning (though not in early childhood adjustment) that predate psychosis onset, with sexually dimorphic patterns in relation to prodromal symptoms. Among male (but not female) CHRs, baseline social functioning and positive prodromal symptoms predicted conversion. These findings help elucidate early course of vulnerability for, and maximally sensitive and specific etiological and prediction models of, psychosis conversion. Findings highlight the importance of considering sexually differentiated predictors of longitudinal course and outcome, in the context of emerging risk profiles. This may optimize efforts at early identification and individually tailored preventive interventions targeting different neurobiological markers/systems and/or cognitive-behavioral approaches. We speculate a contemporary, multidimensional model of psychosis risk that posits a role of sexually dimorphic, genetically linked influences that converge with a modulating role of gonadal hormones (see Walder et al., 2012) across a temporally sensitive neurodevelopmental trajectory towards conferring risk.

Predictive value of thought disorder in new-onset psychosis

OBJECTIVE

This research addresses the relationship of formal thought disorder in the early stages of psychotic illness to the long-term outcome of mental health many years later. The specific topic of concern was to evaluate the prognostic significance of thought disorder on the severity of psychosis over time.

METHODS

Subjects with new-onset psychosis were evaluated on a variety of measures including education, physical health, Brief Psychiatric Rating Scale scores. They were also given the Thought, Language, and Communication Scale to evaluate thought disorder. Subjects were interviewed again at 10 and 20 years to evaluate variations in outcome. Appropriate statistical methods were used to evaluate changes in the level of functioning over time.

RESULTS

Thought disorder was not unique to schizophrenia. Bipolar patients presented with significant positive thought disorder at the onset of psychosis. Overtime positive thought disorder gradually improved in most patients. Negative thought disorder was more persistent, especially in subjects with schizophrenia. Initial psychosis with thought disorder characterized by poverty of content seemed to be associated with poor long-term outcome.

CONCLUSION

Formal thought disorder can predict outcome in some cases of psychosis. Not all types of thought disorder have the same prognostic implication. Positive forms of thought disorder (pressured speech, tangentiality) had no significant predictive value. Negative thought disorder (particularly poverty of speech and poverty of content) tend to predict a chronic, more unrelenting course of illness.

A pilot study exploring the effects of a 12-week t'ai chi intervention on somatic symptoms of depression in patients with heart failure

BACKGROUND

Patients with chronic heart failure (HF) and with elevated depression symptoms are at greater risk of morbidity and mortality. Somatic symptoms of depression are particularly prevalent in HF and are related to worse disease prognosis. T'ai chi practice is related to increased emotional well-being in various clinical populations; however, relatively little is known about t'ai chi's effects on somatic versus cognitive symptom dimensions of depression in HF.

PURPOSE

The objective of the study was to measure whether a t'ai chi intervention effectively reduces somatic and/or cognitive symptoms of depression in patients with HF.

METHODS

Patients with HF were assigned to either t'ai chi training (n=16) or a usual-care group (n=12). At baseline and after the 12-week intervention period, participants were evaluated for changes in depressive symptoms using Beck Depression Inventory (BDI) total scores (BDI-t) and subcategorized scores of BDI-somatic (BDI-s) and BDI-cognitive (BDI-c), and for symptoms of fatigue using the Multidimensional Fatigue Symptom Inventory-Short Form.

RESULTS

Patients with HF in the t'ai chi group compared to the usual-care group had reduced BDI-s (p≤0.017), but not BDI-c (p=0.50) scores from pre- to postintervention. Although t'ai chi did not significantly reduce fatigue, changes in physical fatigue (p≤0.05) were independently associated with changes in BDI-t scores.

CONCLUSIONS

T'ai chi practice reduced somatic symptoms of depression, which have been linked to worse prognosis in HF. Reductions in fatigue appear to explain some but not all of the reductions in somatic symptoms of depression.

Covariance modeling of MRI brain volumes in memory circuitry in schizophrenia: Sex differences are critical

Women have consistently demonstrated better verbal memory on tests that evaluate immediate and delayed free recall. In patients with schizophrenia, these verbal memory processes are relatively more preserved in women than men. However an understanding of the brain anatomy of the female advantage for verbal memory is still unclear. 29 females and 59 males with schizophrenia made comparable to 21 female and 27 male healthy volunteers were scanned using structural magnetic resonance imaging (sMRI) in order to assess volumes of regions across the entire brain. Sex differences within and between groups in the covariance structure of memory circuitry regions were evaluated using a novel approach to covariance analysis (the Box M Test). Brain areas of interest included the prefrontal cortex (PFC), inferior parietal lobule (iPAR), anterior cingulate gyrus (ACG), parahippocampus, and hippocampus (HIPP). Results showed significant differences in the covariance matrices of females and males with schizophrenia compared with their healthy counterparts, in particular the relationships between iPAR-PFC, iPAR-ACG, and HIPP-PFC. Sex differences in the iPAR-PFC relationship were significantly associated with sex differences in verbal memory performance. In control women, but not in men ACG volume correlated strongly with memory performance. In schizophrenia, ACG volume was reduced in females, but not in men, relative to controls. Findings suggest that the relationship between iPAR and PFC is particularly important for understanding the relative preservation of verbal memory processing in females with schizophrenia and may compensate for ACG volume reductions. These results illustrate the utility of a unique covariance structure modeling approach that yields important new knowledge for understanding the nature of schizophrenia.

"Attenuated psychotic symptoms syndrome" as a risk syndrome of psychosis, diagnosis in DSM-V: The debate

Schizophrenia is a common disorder, affecting approximately 1 out of every 100 people, with a typical onset during adolescence and early adulthood. The personal and societal costs of schizophrenia are extremely high. Prevention of schizophrenia, would offer substantial benefits to patients, their family members, and the community at large. The prodromal phase of schizophrenia has been recognized since the 19th century. At-risk individuals for psychosis and schizophrenia are the subjects who can provide information for intervention prior to development of frank psychosis. This approach is currently being investigated. The question remains, however, whether it can be a diagnostic category by itself. The proposal for including the risk syndrome is one of the recommendations by the working group on schizophrenia and psychotic disorders for the forthcoming DSM-V. There are differing views in academia regarding this proposal. Prior to becoming fully psychotic, a consistent literature demonstrates that patients generally had suffered from accelerating attenuated symptoms and distress. It is important that the prodromal phase be accurately recognized in order to accomplish the goal of prevention. We can then purposefully engage in early intervention aiming toward prevention. A recent strong resurgent interest in this area stems largely from two developments: First, the identification of the neurobiological deficit processes associated with the severity and chronicity of schizophrenia, and second, the development of reliable criteria for diagnosis. Although the general at-risk construct appears to offer great potential to advance both the treatment and research dealing with psychotic illnesses, it seems premature to many researchers to include the syndrome as an established entity in the text of the new DSM-V. It would be far more appropriate to include this proposed syndrome in the appendix and evaluate the many contemporary issues in future studies. The main issues involved in this discussion are the clinical validity of the syndrome, concern about stigma and unnecessary treatment, and need for responding to patients' distress in addition to the ethical dilemma. In this review we examine the issue of inclusion of the risk syndrome as a diagnosis.

Treatment history in the psychosis prodrome: characteristics of the North American Prodrome Longitudinal Study Cohort

AIM

Early identification and better characterization of the prodromal phase of psychotic illness can lead to targeted treatment and, perhaps, prevention of many of the devastating effects of a first psychotic episode. The primary aim of this manuscript is to describe the treatment histories of a large cohort of individuals who entered into one of seven prodromal research programs in a North American Prodrome Longitudinal Study consortium.

METHODS

Treatment histories from 372 clinical high-risk subjects are described along with demographic, symptom, diagnostic and functional variables that may have contributed to treatment decisions for this group of individuals.

RESULTS

Of all subjects included, 82.1% had received psychosocial and/or pharmacologic treatment prior to entry. Psychosocial interventions were more common in the attenuated psychotic syndrome prodromal sample, especially those with more negative, disorganized or general symptoms and more impaired functioning. Psychotropic medication had been administered to individuals with a history of Axis I disorders.

CONCLUSIONS

Given the many potential clinical presentations, treatments and ethical issues connected with the psychosis-risk syndrome, it is not surprising that clinicians administered a broad range of interventions to study participants prior to their entry into the various research programs. Those individuals with milder and non-specific symptoms were more likely to have received psychosocial treatments, whereas those with more severe symptoms received pharmacologic intervention. Clinical treatment research is needed that addresses the complexities of these psychosis-risk states and helps to specify appropriate treatment at different stages of the psychosis prodrome.

Distinct genetic influences on cortical surface area and cortical thickness

Neuroimaging studies examining the effects of aging and neuropsychiatric disorders on the cerebral cortex have largely been based on measures of cortical volume. Given that cortical volume is a product of thickness and surface area, it is plausible that measures of volume capture at least 2 distinct sets of genetic influences. The present study aims to examine the genetic relationships between measures of cortical surface area and thickness. Participants were men in the Vietnam Era Twin Study of Aging (110 monozygotic pairs and 92 dizygotic pairs). Mean age was 55.8 years (range: 51-59). Bivariate twin analyses were utilized in order to estimate the heritability of cortical surface area and thickness, as well as their degree of genetic overlap. Total cortical surface area and average cortical thickness were both highly heritable (0.89 and 0.81, respectively) but were essentially unrelated genetically (genetic correlation = 0.08). This pattern was similar at the lobar and regional levels of analysis. These results demonstrate that cortical volume measures combine at least 2 distinct sources of genetic influences. We conclude that using volume in a genetically informative study, or as an endophenotype for a disorder, may confound the underlying genetic architecture of brain structure.

Family-based association analysis of a statistically derived quantitative traits for ADHD reveal an association in DRD4 with inattentive symptoms in ADHD individuals

The objective of this study was to determine whether single nucleotide polymorphisms (SNPs) within candidate genes for ADHD are associated with quantitative phenotypes generated from inattentive and hyperactive-impulsive symptoms. One hundred forty-three SNPs were genotyped in and around five ADHD candidate genes. A highly heritable quantitative phenotype was generated at each SNP by weighting inattentive and hyperactive-impulsive symptoms. Once these phenotypes were generated, a screening procedure was used to select and test the five SNP/phenotype combinations with the greatest power to detect an association for each candidate gene. Adjacent SNPs in the promoter region of DRD4, hCV26775267 and hCV26775266, were associated with the quantitative phenotypes generated from the ADHD symptoms (corrected P-values = 0.012 for both SNPs). The correlations between the ADHD symptoms and quantitative phenotype revealed that inattentive symptoms had a strong influence on the generated phenotype. Subsequent family-based association test-principal components (FBAT-PC) analyses using inattentive symptoms only also had significant associations. SNPs in the promoter region of DRD4 are associated with the phenotypes generated from ADHD symptoms. The strong correlation of the inattentive symptoms with these quantitative phenotypes and the subsequent FBAT-PC analyses suggest this region is primarily associated with inattentive symptoms. This analysis adds to previous findings by suggesting that variants at these loci may be specifically associated with inattentive symptoms.

Posttraumatic stress disorder; combat exposure; and nicotine dependence, alcohol dependence, and major depression in male twins

Combat exposure is associated with increased risk of psychiatric and substance use disorders in veterans. However, it is not known whether combat exposure independently increases risk for these disorders or whether this association is accounted for by genetic vulnerability common to posttraumatic stress disorder (PTSD). This article tests competing explanations for the association of combat exposure and PTSD with nicotine dependence (ND), alcohol dependence (AD), and major depression (MD). Data were obtained from 6099 members of the Vietnam Era Twin Registry, a national registry of male-male twin pairs who served in the military during the Vietnam era. Twin models were fit to estimate the genetic and environmental variance common and specific to Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition, lifetime diagnoses of PTSD, combat trauma, and 3 comorbid conditions: ND, AD, and MD. Variance specific to ND, AD, and MD was due to genetic factors (48%, 36%, and 12%, respectively) and unique environmental factors (36%, 42%, and 58%, respectively). After accounting for variance common to PTSD, no residual genetic and environmental variance overlapped between combat and ND, combat and AD, and combat and MD. Combat exposure is not independently associated with lifetime ND, AD, and MD. The association of combat exposure with these 3 disorders is due to genetic and unique environmental contributions in common with PTSD. These findings suggest comorbid PTSD may represent a genetically mediated vulnerability to psychopathology after trauma.

Prediction of psychosis in youth at high clinical risk: a multisite longitudinal study in North America

CONTEXT

Early detection and prospective evaluation of individuals who will develop schizophrenia or other psychotic disorders are critical to efforts to isolate mechanisms underlying psychosis onset and to the testing of preventive interventions, but existing risk prediction approaches have achieved only modest predictive accuracy.

OBJECTIVES

To determine the risk of conversion to psychosis and to evaluate a set of prediction algorithms maximizing positive predictive power in a clinical high-risk sample.

DESIGN, SETTING, AND PARTICIPANTS

Longitudinal study with a 2 1/2-year follow-up of 291 prospectively identified treatment-seeking patients meeting Structured Interview for Prodromal Syndromes criteria. The patients were recruited and underwent evaluation across 8 clinical research centers as part of the North American Prodrome Longitudinal Study.

MAIN OUTCOME MEASURE

Time to conversion to a fully psychotic form of mental illness.

RESULTS

The risk of conversion to psychosis was 35%, with a decelerating rate of transition during the 2 1/2-year follow-up. Five features assessed at baseline contributed uniquely to the prediction of psychosis: a genetic risk for schizophrenia with recent deterioration in functioning, higher levels of unusual thought content, higher levels of suspicion/paranoia, greater social impairment, and a history of substance abuse. Prediction algorithms combining 2 or 3 of these variables resulted in dramatic increases in positive predictive power (ie, 68%-80%) compared with the prodromal criteria alone.

CONCLUSIONS

These findings demonstrate that prospective ascertainment of individuals at risk for psychosis is feasible, with a level of predictive accuracy comparable to that in other areas of preventive medicine. They provide a benchmark for the rate and shape of the psychosis risk function against which standardized preventive intervention programs can be compared.

Evidence for an Association of the Dopamine D5 Receptor Gene on Age at Onset of Attention Deficit Hyperactivity Disorder

The purpose of this study was to determine whether the single nucleotide polymorphisms (SNPs) within candidate genes for attention deficit hyperactivity disorder (ADHD) are associated with the age at onset for ADHD. One hundred and forty-three SNPs were genotyped across five candidate genes (DRD5, SLC6A3, HTR1B, SNAP25, DRD4) for ADHD in 229 families with at least one affected offspring. SNPs with the highest estimated power to detect an association with age at onset were selected for each candidate gene, using a power-based screening procedure that does not compromise the nominal significance level. A time-to-onset analysis for family-based samples was performed on these SNPs to determine if an association exists with age at onset for ADHD. Seven consecutive SNPs surrounding the D5 dopamine receptor gene (DRD5), were associated with the age at onset for ADHD; FDR adjusted q-values ranged from 0.008 to 0.023. This analysis indicates that individuals with the risk genotype develop ADHD earlier than individuals with any other genotype. A haplotype analysis across the 6 significant SNPs that were in linkage disequilibrium with one another, CTCATA, was also found to be significant (p-value = 0.02). We did not observe significant associations with age at onset for the other candidate loci tested. Although definitive conclusions await independent replication, these results suggest that a variant in DRD5 may affect age at onset for ADHD.

North American Prodrome Longitudinal Study: a collaborative multisite approach to prodromal schizophrenia research

This article presents the rationale, design, and preliminary findings of the North American Prodrome Longitudinal Study (NAPLS), a collaborative, multisite investigation into the earliest phase of psychotic illness. We describe how 8 independently conceived research projects were integrated methodologically, how diagnostic reliability was achieved across sites on the Structured Interview for Prodromal Syndromes, and how baseline and follow-up data were aggregated for 888 at risk and comparison subjects. Data are presented describing the demographic, academic/work, and diagnostic characteristics of 3 relevant subgroups: persons at heightened clinical risk for psychosis, help-seeking comparison subjects, and nonpsychiatric controls. The NAPLS data set will be used to explore a series of questions related to prodromal psychosis, including the descriptive phenomenology of currently accepted diagnostic criteria, conversion rates over a 30-month period, predictors of psychosis onset and functional disability, and the impact of early treatment on the course of prodromal symptoms.

Nicotine dependence subtypes: association with smoking history, diagnostic criteria and psychiatric disorders in 5440 regular smokers from the Vietnam Era Twin Registry

Studies suggest empirically derived subtypes of nicotine dependence exist in young adult populations with short smoking careers. It is not known if classes of dependence exist in middle aged smokers with longer smoking careers and whether these classes reflect quantitative or qualitative differences. It is not known if psychiatric disorders are associated with classes of nicotine dependence. Nicotine dependence symptoms were obtained from a 1992 administration of the Diagnostic Interview Schedule. Latent Class Analyses (LCA) was computed using data from 5440 members of the Vietnam Era Twin Registry. LCA was used to derive significantly different classes of nicotine dependence, which were assessed for their association with smoking history, nicotine dependence, and other psychiatric disorders. The LCA model which best fit the data was a 4 class solution characterized by severity. Age onset of regular smoking decreased with more severe classes. Cigarette consumption, failed cessation and psychiatric disorders were associated with more severe classes. Empirically derived subtypes of nicotine dependence are mostly characterized by increasing severity. Suggestions for refinement of nicotine dependence diagnostic criteria are discussed.