Bifactor Modeling of the Positive and Negative Syndrome Scale: Generalized Psychosis Spans Schizoaffective, Bipolar, and Schizophrenia Diagnoses

OBJECTIVE

Common genetic variation spans schizophrenia, schizoaffective and bipolar disorders, but historically, these syndromes have been distinguished categorically. A symptom dimension shared across these syndromes, if such a general factor exists, might provide a clearer target for understanding and treating mental illnesses that share core biological bases.

METHOD

We tested the hypothesis that a bifactor model of the Positive and Negative Syndrome Scale (PANSS), containing 1 general factor and 5 specific factors (positive, negative, disorganized, excited, anxiety), explains the cross-diagnostic structure of symptoms better than the traditional 5-factor model, and examined the extent to which a general factor reflects the overall severity of symptoms spanning diagnoses in 5094 total patients with a diagnosis of schizophrenia, schizoaffective, and bipolar disorder.

RESULTS

The bifactor model provided superior fit across diagnoses, and was closer to the "true" model, compared to the traditional 5-factor model (Vuong test; P < .001). The general factor included high loadings on 28 of the 30 PANSS items, omitting symptoms associated with the excitement and anxiety/depression domains. The general factor had highest total loadings on symptoms that are often associated with the positive and disorganization syndromes, but there were also substantial loadings on the negative syndrome thus leading to the interpretation of this factor as reflecting generalized psychosis.

CONCLUSIONS

A bifactor model derived from the PANSS can provide a stronger framework for measuring cross-diagnostic psychopathology than a 5-factor model, and includes a generalized psychosis dimension shared at least across schizophrenia, schizoaffective, and bipolar disorder.

Correlation between the Personal and Social Performance scale (PSP) and the Positive and Negative Syndrome Scale (PANSS) in a Greek sample of patients with schizophrenia

BACKGROUND

Psychosocial dysfunction is one of schizophrenia's core features, often leading to a deprecation of independent living and significant failure to maintain a competent quality of life. Cognitive and occupational performance as well as psychosocial functioning is moreover recognized as determinants of treatment response. Therefore, the elaboration of measures regarding social performance besides scales that assess psychopathology is essential. The Personal and Social Performance (PSP) scale has been found to be as much valid as reliable for assessing social functioning in the acute and stable stage of schizophrenia. The aim of this study was to estimate the correlation between the PSP and Positive and Negative Syndrome Scale (PANSS) (convergent validity) in patients with schizophrenia during routine clinical practice.

METHODS

A longitudinal study with a six-month follow-up is presented. Correlation between the PSP scale and the Positive and Negative Syndrome Scale (PANSS) was conducted in a Greek sample of 2010 patients with schizophrenia in outpatient setting in two successive visits. PANSS and PSP scales were used for the assessment of psychopathological symptoms and social and personal functioning.

RESULTS

The PSP subscales scores were well correlated with each other with Spearman correlation coefficients (r) ranging from 0.56 to 0.76 on both visits in three out of the four main areas, whereas in the category of "disturbing and aggressive behavior" the correlations were lower but still significant. Furthermore, total PSP score showed high association to PANSS total score in the first (r = -0.59) as well as in the second visit (r = -0.50). Regression analysis showed that one point decrease of PANSS's total score is associated with a 0.42 points increase on the PSP scale. PSP and PANSS scales exhibited high convergent validity.

CONCLUSIONS

The PSP could provide additional valuable information in the assessment of schizophrenia related social functioning and treatment response.

Sedentary behavior and psychiatric symptoms in overweight and obese adults with schizophrenia and schizoaffective disorders (WAIST Study)

OBJECTIVE

Examine the association between sedentary behavior and psychiatric symptoms among overweight and obese adults with schizophrenia or schizoaffective disorders (SZO/SA).

DESIGN

Randomized clinical trial; Weight Assessment and Intervention in Schizophrenia Treatment (WAIST) Study: baseline data collected 2005-2008.

SETTING

University of Pittsburgh Medical Center, Pittsburgh, PA, USA.

PARTICIPANTS

Community-dwelling adults diagnosed with SZO/SA, with mild symptom severity [Positive and Negative Syndrome Scale (PANSS)<90], who were interested in losing weight, age 18-70years, BMI>27kg/m(2).

MEASUREMENTS

Objectively measured sedentary behavior by accelerometry, and psychopathology assessed by PANSS. Participants wore the actigraphs for 7 consecutive days during their waking hours. Sedentary behavior was defined as ≤100 counts per minute during wear-time and excluded sleep and non-wear time.

RESULTS

On average, 81% of the participant's monitoring time or 756min/day was classified as sedentary behavior using accelerometry. No association was observed between sedentary behaviors and PANSS psychiatric symptoms [total (p≥0.75), positive (p≥0.81), negative (p≥0.59) and general psychopathology (p≥0.65) subscales]. No association was observed between sedentary behaviors and age, race, gender and BMI.

CONCLUSION

From a clinical and public health perspective, the amount of time (approximately 13h) and percentage of time (81% excluding non-wear time associated with sleeping) engaged in sedentary behavior among overweight and obese adults in this population is alarming, and points to an urgent need for interventions to decrease sedentary behaviors. The lack of associations between sedentary behavior and psychiatric symptoms may be due to a ceiling effect for sedentary behavior.

Social cognitive impairments and negative symptoms in schizophrenia: are there subtypes with distinct functional correlates?

Social cognitive impairments and negative symptoms are core features of schizophrenia closely associated with impaired community functioning. However, little is known about whether these are independent dimensions of illness and if so, whether individuals with schizophrenia can be meaningfully classified based on these dimensions (SANS) and potentially differentially treated. Five social cognitive measures plus Scale for the Assessment of Negative Symptoms (SANS) and Positive and Negative Syndrome Scale (PANSS) scores in a sample of 77 outpatients produced 2 distinct factors--a social cognitive factor and a negative symptom factor. Factor scores were used in a cluster analysis, which yielded 3 well-defined groupings--a high negative symptom group (HN) and 2 low negative symptom groups, 1 with higher social cognition (HSC) and 1 with low social cognition (LSC). To make these findings more practicable for research and clinical settings, a rule of thumb for categorizing using only the Mayer-Salovey-Caruso Emotional Intelligence Test and PANSS negative component was created and produced 84.4% agreement with the original cluster groups. An additional 63 subjects were added to cross validate the rule of thumb. When samples were combined (N = 140), the HSC group had significantly better quality of life and Global Assessment of Functioning (GAF) scores, higher rates of marriage and more hospitalizations. The LSC group had worse criminal and substance abuse histories. With 2 common assessment instruments, people with schizophrenia can be classified into 3 subgroups that have different barriers to community integration and could potentially benefit from different treatments.

French version validation of the psychotic symptom rating scales (PSYRATS) for outpatients with persistent psychotic symptoms

BACKGROUND

Most scales that assess the presence and severity of psychotic symptoms often measure a broad range of experiences and behaviours, something that restricts the detailed measurement of specific symptoms such as delusions or hallucinations. The Psychotic Symptom Rating Scales (PSYRATS) is a clinical assessment tool that focuses on the detailed measurement of these core symptoms. The goal of this study was to examine the psychometric properties of the French version of the PSYRATS.

METHODS

A sample of 103 outpatients suffering from schizophrenia or schizoaffective disorders and presenting persistent psychotic symptoms over the previous three months was assessed using the PSYRATS. Seventy-five sample participants were also assessed with the Positive And Negative Syndrome Scale (PANSS).

RESULTS

ICCs were superior to .90 for all items of the PSYRATS. Factor analysis replicated the factorial structure of the original version of the delusions scale. Similar to previous replications, the factor structure of the hallucinations scale was partially replicated. Convergent validity indicated that some specific PSYRATS items do not correlate with the PANSS delusions or hallucinations. The distress items of the PSYRATS are negatively correlated with the grandiosity scale of the PANSS.

CONCLUSIONS

The results of this study are limited by the relatively small sample size as well as the selection of participants with persistent symptoms. The French version of the PSYRATS partially replicates previously published results. Differences in factor structure of the hallucinations scale might be explained by greater variability of its elements. The future development of the scale should take into account the presence of grandiosity in order to better capture details of the psychotic experience.

Rater evaluations for psychiatric instruments and cultural differences: the positive and negative syndrome scale in China and the United States

This article compares Positive and Negative Syndrome Scale (PANSS) data from Chinese and American inpatients with chronic schizophrenia to show how differences in item ratings may reflect cultural attitudes of raters. The Chinese sample (N = 504) came from Beijing Huilongguan Hospital. The American sample came from 268 PANSS assessments of Clinical Antipsychotic Trials of Intervention Effectiveness subjects hospitalized for 15 days or more to optimize equivalence of the samples. When controlling for age and sex, the Chinese sample scored significantly lower for total score by 25% (p < 0.0001), for the positive subscale by 35% (p < 0.0001), and on the general subscale by 32% (p < 0.0001) but not significantly different on the negative subscale score (+0.26%; p = 0.76). However, the Chinese sample scored 26% higher on the item on poor rapport (p < 0.0001), 10.2% higher on passive social withdrawal (p = 0.003), and most notably 46% higher on the item on lack of judgment and insight (p < 0.0001). These results remain broadly consistent across sex subgroup analyses. Differences seem to be best explained by both cultural differences in patient clinical presentations and varying American and Chinese cultural values affecting rater judgment.

Searching for a consensus five-factor model of the Positive and Negative Syndrome Scale for schizophrenia

Although the developers of the Positive and Negative Syndrome Scale (PANSS) grouped items into three subscales, factor analyses indicate that a five-factor model better characterizes PANSS data. However, lack of consensus on which model to use limits the comparability of PANSS variables across studies. We counted "votes" from published factor analyses to derive consensus models. One of these combined superior fit in our Caucasian sample (n=458, CFI=.970), and in distinct Japanese sample (n=164, CFI=.964), relative to the original three-subscale model, with a sorting of items into factors that was highly consistent across the studies reviewed.

Is the PANSS used correctly? a systematic review

BACKGROUND

The PANSS (Positive and Negative Syndrome Scale) is one of the most important rating instruments for patients with schizophrenia. Nevertheless, there is a long and ongoing debate in the psychiatric community regarding its mathematical properties.All 30 items range from 1 to 7 leading to a minimum total score of 30, implying that the PANSS is an interval scale. For such interval scales straightforward calculation of relative changes is not appropriate. To calculate outcome criteria based on a percent change as, e.g., the widely accepted response criterion, the scale has to be transformed into a ratio scale beforehand. Recent publications have already pointed out the pitfall that ignoring the scale level (interval vs. ratio scale) leads to a set of mathematical problems, potentially resulting in erroneous results concerning the efficacy of the treatment.

METHODS

A Pubmed search based on the PRISMA statement of the highest-ranked psychiatric journals (search terms "PANSS" and "response") was carried out. All articles containing percent changes were included and methods of percent change calculation were analysed.

RESULTS

This systematic literature research shows that the majority of authors (62%) actually appear to use incorrect calculations. In most instances the method of calculation was not described in the manuscript.

CONCLUSIONS

These alarming results underline the need for standardized procedures for PANSS calculations.

Prevalence of celiac disease and gluten sensitivity in the United States clinical antipsychotic trials of intervention effectiveness study population

Celiac disease (CD) and schizophrenia have approximately the same prevalence, but epidemiologic data show higher prevalence of CD among schizophrenia patients. The reason for this higher co-occurrence is not known, but the clinical knowledge about the presence of immunologic markers for CD or gluten intolerance in schizophrenia patients may have implications for treatment. Our goal was to evaluate antibody prevalence to gliadin (AGA), transglutaminase (tTG), and endomysium (EMA) in a group of individuals with schizophrenia and a comparison group. AGA, tTG, and EMA antibodies were assayed in 1401 schizophrenia patients who were part of the Clinical Antipsychotic Trials of Intervention Effectiveness study and 900 controls. Psychopathology in schizophrenia patients was assessed using the Positive and Negative Symptoms Scale (PANSS). Logistic regression was used to assess the difference in the frequency of AGA, immunoglobulin A (IgA), and tTG antibodies, adjusting for age, sex, and race. Linear regression was used to predict PANSS scores from AGA and tTG antibodies adjusting for age, gender, and race. Among schizophrenia patients, 23.1% had moderate to high levels of IgA-AGA compared with 3.1% of the comparison group (χ(2) = 1885, df = 2, P < .001.) Moderate to high levels of tTG antibodies were present in 5.4% of schizophrenia patients vs 0.80% of the comparison group (χ(2) = 392.0, df = 2, P < .001). Adjustments for sex, age, and race had trivial effects on the differences. Regression analyses failed to predict PANSS scores from AGA and tTG antibodies. Persons with schizophrenia have higher than expected titers of antibodies related to CD and gluten sensitivity.

Sensory-gating deficit of the N100 mid-latency auditory evoked potential in medicated schizophrenia patients

The clinical and neuro-cognitive correlates of the P50 and N100 auditory evoked responses gating deficits in schizophrenia have thus far eluded identification. Based on our prior results, we hypothesized that, in addition to the P50, gating of the N100 is significantly decreased in schizophrenia and that this deficit correlates with the negative symptoms dimension of schizophrenia. Amplitudes and gating measures of the P50 and N100 were compared between stable out-patients (N=45) (mainly on atypical antipsychotics) with chronic schizophrenia and age- and gender-matched healthy controls (N=49) and the clinical correlates examined. All subjects underwent the paired-stimulus paradigm in 3 or 4 different days. Data from day one and the mean of all days (MOAD) were examined. P50 and N100 amplitudes and gating measures were correlated with PANSS and Wisconsin Card Sorting Test data. Utilizing day one data, no amplitude or gating measures were significantly different between the groups. Utilizing MOAD data, both P50 and N100 gating were significantly decreased in schizophrenia patients. The N100 gating deficit correlated with the negative-symptoms cluster and measures of frontal lobe dysfunction. The data suggest a correlation between N100 gating deficit and the negative-cognitive deficits dimensions of schizophrenia. Data also suggest that improving the signal to noise ratio (MOAD data) increases the sensitivity for detecting gating abnormalities and assessing their clinical correlates.

A systematic method for estimating individual responses to treatment with antipsychotics in CATIE

OBJECTIVE

In addition to comparing drug treatment groups, the wealth of genetic and clinical data collected in the Clinical Antipsychotic Trials of Intervention Effectiveness study offers tremendous opportunities to study individual differences in response to treatment with antipsychotics. A major challenge, however, is how to estimate the individual responses to treatments. For this purpose, we propose a systematic method that condenses all information collected during the trials in an optimal, empirical fashion.

METHODS

Our method comprises three steps. First, we test how to best model treatment effects over time. Next, we screen many covariates to select those that will further improve the precision of the individual treatment effect estimates which, for example, improves power to detect predictors of individual treatment response. Third, Best Linear Unbiased Predictors (BLUPs) of the random effects are used to estimate for each individual a treatment effect based on the model empirically indicated to best fit the data. We illustrate our method for the Positive and Negative Syndrome Scale (PANSS).

RESULTS

A model assuming it takes on average about 30 days for a treatment to exert an effect that will then remain about the same for the rest of the trial showed the best fit to the data. Of all screened covariates, only two improved the precision of the individual treatment effect estimates. Finally, correlations between drug effects and PANSS scales suggested that in CATIE it cannot be recommended to simply combine treatment effects across drugs (e.g. to study common drug mechanisms), but it is sensible to study how a given drug affects multiple symptom dimensions.

CONCLUSIONS

We demonstrate that treatment effects can be estimated in a way that condenses all information collected in an optimal, empirical fashion. We expect the proposed method to be valuable for other clinical outcomes in CATIE and potentially other clinical trials.

Negative symptoms are associated with less alcohol use, craving, and "high" in alcohol dependent patients with schizophrenia

BACKGROUND

Alcohol use disorders (AUDs) frequently co-occur with and exacerbate schizophrenia, yet the specific relationships between schizophrenia symptoms and alcohol use remain unclear.

METHODS

PANSS scores were correlated with measures of alcohol and other substance use in patients with schizophrenia-spectrum disorders and AUDs entering a trial of monitored naltrexone treatment. Data were analyzed from the first 80 participants; 55% had schizophrenia and 45% had schizoaffective disorder. All had AUDs; 95% had alcohol dependence and 5% alcohol abuse; 34% also had cannabis abuse/dependence and 31% cocaine abuse/dependence.

RESULTS

PANSS Negative scores were inversely correlated with Addiction Severity Index alcohol composite scores, alcohol craving, quality of alcohol "high" (euphoria), and with frequency of cannabis use. An exploratory analysis indicated that the negative symptoms that may most strongly correlate with less alcohol use, craving and/or euphoria were passive/apathetic social withdrawal, blunted affect, difficulty in abstract thinking, and stereotyped thinking. Higher PANSS Composite scores, indicating the predominance of positive over negative PANSS symptoms, correlated with more alcohol craving and cannabis use. Higher PANSS General scores were associated with more alcohol craving.

CONCLUSIONS

These findings extend previous reports of the association of negative schizophrenia symptoms with less alcohol and substance use to patients with AUDs and indicate that this relationship also includes less alcohol craving and less alcohol euphoria. The findings may also provide some initial evidence that specific negative symptoms may be keys to these relationships.

Psychopathological characteristics and treatment response of first episode compared with multiple episode schizophrenic disorders

OBJECTIVE

The aim was to investigate the hypothesis that patients with first episode schizophrenic disorders have a more favorable treatment response than those with multiple episodes.

METHOD

A total of 400 inpatients from an ongoing multi-centre, follow-up program who fulfilled ICD-10 criteria for schizophrenic disorders (F2) were assessed at admission to and discharge from hospital using the Positive and Negative Syndrome Scale (PANSS).

RESULTS

At admission, first episode patients (n = 121) showed higher levels of positive symptoms (PANSS positive subscore) and lower ones of negative symptoms (PANSS negative subscore) than multiple episode patients (n = 279), whereas the global disease severity (PANSS total score) was comparable. Analyses of covariance revealed that treatment response (adjusted symptom levels at discharge) was more favorable in first-episode patients, with respect to both positive and negative symptoms.

CONCLUSION

The results are compatible with the hypothesis that treatment response becomes less favorable during the course of schizophrenic illness. This finding might be associated with progressive neurobiological alterations.

The structure of negative symptoms within schizophrenia: implications for assessment

This review examines the structural validity of negative symptoms focusing on 2 questions: (1) Do negative symptoms represent a domain separate from other symptoms in schizophrenia? and (2) Within negative symptoms, is there a structure that suggests multidimensionality? Results from exploratory and confirmatory factor analytic studies are examined to address these questions. Across studies and symptom instruments, negative symptoms appear to consistently emerge as a factor separate from other dimensions of the illness in schizophrenia. Whether 2-, 3-, or 5-factor models are identified, negative symptoms consistently load on a factor separate from positive symptoms, affective symptoms of depression or anxiety, and symptoms of disorganization. Focusing on negative symptoms themselves, factor analytic findings suggest that this construct is multidimensional with at least 2 factors (involving diminished expression and anhedonia-asociality). Although these factors were replicable, serious limitations were noted in this literature. Thus, 2- (or even 3- or 5-) factor models of negative symptoms should not be considered definitive, but rather all converge to support the general conclusion of the multidimensionality of negative symptoms. The later findings indicate the importance of employing assessments that provide adequate coverage of the broad domain of negative symptoms. Importantly, caution is noted in the interpretability of findings based on existing instruments, and implications for future assessment are discussed.

Recent advances in the genetics of schizophrenia

The genetic etiology of schizophrenia, a common and debilitating psychiatric disorder, is supported by a wealth of data. Review of the current findings suggests that considerable progress has been made in recent years, with a number of chromosomal regions consistently implicated by linkage analysis. Three groups have shown linkage to 1q21-22 using similar models, with HLOD scores of 6.5, 3.2, and 2.4. Other replicated loci include 13q32 that has been implicated by two independent groups with significant HLOD scores (4.42) or NPL values (4.18), and 5pl4.1-13.1, 5q21-33, 8p2l-22, and 10p11-15, each of which have been reported as suggestive by at least three separate groups. Different studies have also replicated evidence for a modest number of candidate genes that were not ascertained through linkage. Of these, the greatest support exists for the DRD3 (3q13.3), HTR2A (13q14.2), and CHRNA7 (15q13-q14) genes. The refinement of phenotypes, the use of endophenotypes, reduction of heterogeneity, and extensive genetic mapping have all contributed to this progress. The rapid expansion of information from the human genome project will likely further accelerate this progress and assist in the discovery of susceptibility genes for schizophrenia. A greater understanding of disease mechanisms and the application of pharmacogenetics should also lead to improvements in therapeutic interventions.

Validity and reliability of the Polish version of the Positive and Negative Syndrome Scale (PANSS)

This study presents the results of a training course on using the Positive and Negative Syndrome Scale (PANSS) for the assessment of mental status. The agreements between ratings produced by 418 physicians (psychiatrists) were evaluated and compared with standard ratings. In this way it was possible to supplement some of the listed symptoms with comments, which may help to increase agreement between results obtained through raters' assessments and standard ratings.