The positive/negative symptom distinction in psychoses. A replication and extension of previous findings

An observer-rated strategy for differentiating schizophrenic and manic states in inpatient settings

OBJECTIVES

Differentiating schizophrenia from mania in acutely psychotic patients can be difficult, but is important in determining immediate and subsequent management. Such differentiation is generally addressed by clinical interviews, but an observational approach may assist. This paper therefore describes the development of a relevant observational measure.

METHODS

We developed a provisional list of 49 items (weighting features with suggested specificity to schizophrenia and mania) for independent completion by two nurses and judged its ability to predict diagnosis provided by consultant psychiatrists.

RESULTS

Eighty-seven psychotic patients were recruited, and 173 completed data sets were analysed. We refined the item set to two sets of 10 items that best-differentiated schizophrenia from mania and vice versa. Optimal differentiation was achieved with a score of at least 7 on both the schizophrenia and mania item sets. Difference scores (i.e. schizophrenia items affirmed minus mania items affirmed) were also generated, with a difference score of +1 (i.e. one or more schizophrenia items being affirmed than mania items) showing optimal differentiation (sensitivity 0.67, specificity 0.82) between the two conditions. Evaluating all potential difference scores, we demonstrated that, as difference scores increased, diagnostic accuracy in identifying each condition was very high.

CONCLUSION

Analyses allow the properties of an observational measure (the 20-item Sydney Psychosis Observation Tool) to be described. While a single cut-off difference score was derived with acceptable discriminatory ability, we also established the capacity of varying difference scores to assign both schizophrenia and mania diagnoses with high accuracy.

Loneliness and the psychosis continuum: a meta-analysis on positive psychotic experiences and a meta-analysis on negative psychotic experiences

There is an increase in interest in the relationships between loneliness and psychosis. The notion of psychosis continuum implies that psychotic experiences extend from clinical populations with psychotic disorders to non-clinical populations. This meta-analytic review aimed to examine the respective associations of loneliness with positive and negative psychotic experiences along the psychosis continuum. A systematic database search was conducted and a total of 30 studies were included in the first meta-analysis and 15 studies were included in the second meta-analysis. There was a medium association between loneliness and positive psychotic experiences (r = 0.302, p < 0.001). In particular, the association between loneliness and paranoia was robust (r = 0.448, p < 0.001). The second meta-analysis revealed a medium association between loneliness and negative psychotic experiences (r = 0.347, p < 0.001). The associations between loneliness and both positive and negative psychotic experiences were found to be smaller among clinical than non-clinical samples. The above findings provided evidence for the associations between loneliness and the two core dimensions of psychotic experiences along the phenomenological continuum. Future research should examine the dynamics of these relationships in both clinical and non-clinical samples, preferably using a single-symptom approach.

A Method to Optimize the Response Range While Maintaining Rorschach Comprehensive System Validity

Brief and lengthy Rorschach records have been identified as common problems in protocol administration. Clinicians have debated how to prevent overly short and long records, but they have been reluctant to alter standardized administration for fear of introducing bias. The present study examines a nonintrusive method for constraining responses by prompting for an extra response when only one is offered per card and by removing the card after four responses are given. Among patients who typically produce brief records, consisting of a residential sample of civil and forensic patients with a range of disordered thinking, the alternative administration method demonstrated improved Comprehensive System validity in assessing thought disorder and eliminated the need to readminister the test due to fewer than 14 responses. The findings have clinical implications for protocol administration with thought-disordered populations that typically produce brief records.

Convergent validity and neuropsychological correlates of the schedule for the assessment of negative symptoms (SANS) attention subscale

Cognitive deficits have come to be viewed as a hallmark feature of schizophrenic illness. Although laboratory based assessment of patients' cognitive deficits has been well investigated, few studies to date have examined the utility of clinical ratings of cognitive symptoms using the Schedule for the Assessment of Negative Symptoms (SANS) attention subscale. In this report, we examined the convergence between clinical ratings of cognitive impairment using the SANS attention subscale and performance on a variety of neurocognitive tests designed to measure attentional impairment, as well as other cognitive constructs such as working memory and executive functioning. A total of 56 acute schizophrenic inpatients were clinically rated with the SANS and completed the Continuous Performance Test, Digit Span Distraction Test, Wisconsin Card Sorting Task, and the Trailmaking Test. A series of correlational and regression analyses were conducted to test the concurrent and discriminant validity of the SANS attention subscale. Performance measures of attention, but not working memory or executive functioning, were significantly correlated with and moderately predicted the severity of SANS rated inattention. Additionally, the attention subscale was discriminated from the other SANS negative symptom subscales in predicting a laboratory measure of attentional functioning. The SANS attention subscale demonstrated both concurrent and discriminant validity. These data indicate that attentional dysfunction in schizophrenia can be meaningfully rated and interpreted using the SANS.

Instruments for assessment of auditory hallucinations

The study of individual symptoms of schizophrenia, such as auditory hallucinations, can contribute to effective treatment strategies. We review existing instruments for the assessment of characteristics and dimensions of auditory hallucinations in schizophrenia and other psychiatric disorders and describe their psychometric properties and implications for their use in clinical research and practice. In addition, three widely used global measurement scales for symptoms of schizophrenia, each of which contain questions that pertain to hallucinations, are included.

Negative, positive, and disorganized symptom dimensions in schizophrenia, major depression, and bipolar disorder

We compared the factor structure of positive and negative symptoms in schizophrenia (N = 214), major depression (N = 97), and bipolar disorder (N = 58) to determine whether schizophrenia factors would generalize to mood disorders. A study of schizophrenia and mood disorders identified patients whose symptoms were evaluated with the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms. We conducted principal component analyses with orthogonal rotation on the global ratings. The factor structure replicated earlier findings of three factors (negative, positive, and disorganization) in groups with schizophrenia, combined mood disorders, and psychotic symptoms, regardless of diagnosis. An additional negative symptom factor was found in the major depression group. The bipolar group did not have a disorganization factor. Similar symptom factors in schizophrenia and mood disorders suggest a continuity in the major affective and psychotic disorders that appears to reflect the underlying dimension of a psychotic process.

Executive-frontal lobe cognitive dysfunction in schizophrenia: a symptom subtype analysis

Impairment of executive-frontal lobe functioning, affecting the planning, initiation and regulation of goal-directed behavior, is a common cognitive deficit in schizophrenia. However, it is unclear if deficits in these frontal-lobe-mediated abilities are differentially expressed across clinical subgroups. We analyzed executive-frontal abilities in relation to symptom expression in 53 hospitalized schizophrenic patients. Patients were assigned to one of three subgroups based on rank order analysis of Brief Psychiatric Rating Scale factors: Withdrawal-Retardation, Reality Distortion and Conceptual Disorganization. Executive-frontal tests included Visual Search, Verbal Fluency, Verbal Series Attention, Trail Making - Part B, Symbol Digit, Hopkins Verbal Learning, Digit Span, Wisconsin Card Sorting, Stroop Color-Word and Attentional Capacity. The schizophrenia group showed significant deficits relative to healthy control subjects (n = 20) on all tests. Exploratory factor analysis of test scores revealed three factors: (i) Verbal Processing/Memory; (ii) Cognitive Flexibility/Attention; and (iii) Psychomotor Speed/Visual Scanning. The three symptom subgroups were differentially impaired on executive-frontal abilities: Withdrawal-Retardation on psychomotor speed, verbal fluency, working memory, visual search and cognitive flexibility; Conceptual Disorganization on attention; Reality Distortion on verbal memory. The results have implications for syndrome definition, pharmacological intervention and prediction of outcome in schizophrenia.

Meta-analysis of symptom factors in schizophrenia

Factor and correlational analyses have been used to characterize symptom dimensions in schizophrenia, though they have yielded divergent models. This study used meta-analysis of published work to determine the number and composition of symptom dimensions. Principal components analysis of data from 10 empirical studies (pooled n = 896) yielded three factors, 'positive', 'negative' and 'conceptual disorganization'. The findings suggest that a three-factor solution is a relatively stable outcome of studies assessing these symptoms in chronic patients, and that some symptoms (alogia, attentional impairment) are less likely to load uniquely on a single factor.

The structure of schizophrenic symptoms: a meta-analytic confirmatory factor analysis

To quantitatively review all presently available evidence about the interrelations between positive and negative schizophrenic symptoms, we created an aggregate matrix of the intercorrelations among schizophrenic symptoms by combining data from 28 independent samples using meta-analytic procedures (net bivariate dfs ranging from 683 to 1657). Using confirmatory factor analyses, we then statistically compared four theoretically derived models of the structure of schizophrenic symptoms. Although a three-factor model (Liddle, 1987) best fit the data, results suggest that either more factors or different symptoms are required to account well for the latent structure underlying schizophrenic symptomatology. The nature of such augmented approaches, the opportunities and constraints inherent to multifactorial models, and the limitations of current instruments are discussed.

Factor structure of symptoms in functional psychoses

Global ratings from the Scale for the Assessment of Positive Symptoms and Scale for the Assessment of Negative Symptoms were subjected to principal-component analysis (PCA) in 80 schizophrenia patients, 76 patients with schizophreniform disorder, 80 patients with schizoaffective and mood disorders, and 78 patients with delusional, brief reactive, and atypical psychoses. The resulting factors were correlated with depressive, manic, and catatonic syndromes, and subjected to a multivariate analysis of variance across DSM-III-R diagnoses. PCAs revealed that psychosis, disorganization, and negative factors were also present in each of the nonschizophrenic groups. The disorganization factor tended to be related to the manic syndrome, and the negative factor to depressive and catatonic syndromes. Overall, the three factors had little diagnostic relevance in functional psychoses, although the negative factor was relatively more characteristic of schizophrenia. The data suggest that positive, negative, and disorganization factors are not specific to schizophrenia; this is consistent with a dimensional view of psychopathology in functional psychoses.

Diagnosis and six-month stability of negative symptoms in psychotic disorders

Negative symptoms were examined in 150 primarily first-admission patients diagnosed with schizophrenia, schizoaffective disorder, psychotic depression, psychotic bipolar disorder, and 'other' psychoses. The analysis focused on patients who were rated on the Scale for the Assessment of Negative Symptoms (SANS) within 45 days of admission and at follow-up 6 months later. Significantly more schizophrenics had moderate to severe negative symptoms at each time point compared with other psychotic patients. The SANS scores were found to be relatively stable over time in all five diagnostic groups. Although the DSM-IV includes alogia, affective flattening, and avolition in the A criterion for schizophrenia, only alogia and affective flattening were found to be specific to this disorder. Our results point to the existence and enduring quality of negative symptoms in the early phase of psychosis and its specificity to schizophrenia even at this early stage.

Are positive and negative symptoms relevant to cross-sectional diagnosis of schizophrenic and schizoaffective patients?

The value of positive and negative symptoms for cross-sectional differential diagnosis was studied in a sample of 103 consecutively admitted patients with schizophrenia and schizoaffective psychoses. A semistructured interview for schizophrenia was used. Subjects were diagnosed by Research Diagnostic Criteria (RDC) and classified as schizophrenic, depressive schizoaffective, and manic schizoaffective disorders. DSM-III-R criteria for schizophrenia were used to assign RDC schizophrenics to two groups: "true" schizophrenic (fulfilling both DSM-III-R and RDC criteria) and schizophreniform (fulfilling RDC but not DSM-III-R criteria). The Scale for the Assessment of Positive Symptoms (SAPS) and Scale for the Assessment of Negative Symptoms (SANS) were used. Our findings showed that both positive and negative symptoms were relevant to differential diagnosis between schizophrenia and other psychotic disorders. However, negative symptoms presented higher significant differences between diagnostic groups than positive symptoms. These results were obtained by global ratings and by scoring on individual symptoms of SAPS and SANS. Treatment with neuroleptic and biperidene drugs did not alter symptomatologic differences between groups that resulted from repeated analyses of covariance. Certain symptoms and clusters of symptoms were found to be of higher severity of higher severity in only one diagnostic group. They were as follows: pressure of speech for manic schizoaffective disorder; guilt for depressive schizoaffective; high scores on negative symptoms for depressive schizoaffective and schizophrenic disorders; inappropriate affect for schizophrenic disorder; and three "psychomotor retardation" symptoms of the affective flattening subscale of SANS (unchanging facial expression, decreased spontaneous movements, and paucity of expressive gestures) for depressive schizoaffective disorder.(ABSTRACT TRUNCATED AT 250 WORDS)

Positive and negative symptom course in chronic community-based patients. A two-year prospective study

BACKGROUND

The long-term symptom profile of chronic out-patients was studied.

METHOD

242 out-patients receiving neuroleptic medications (109 with schizophrenia and 133 non-schizophrenics), were studied for positive (SAPS) and negative (SANS) symptoms at baseline and at 24 months to investigate whether these symptom groups changed over outpatient maintenance treatment.

RESULTS

Overall and within groups, negative symptoms decreased and positive symptoms increased. While the sums of the SANS scores for the schizophrenic patients were initially higher, their mean SANS score dropped more over time (P < 0.001), to show no difference from non-schizophrenics at follow-up. Positive symptoms increased in both groups, although schizophrenics were higher at both times; sub-scales within the SANS showed different patterns of change.

CONCLUSION

Support is found for a multidimensional view of both positive and negative symptoms and for a reconsideration of the notion of 'progressive downward course' in schizophrenia.

Course of patients diagnosed as having schizophrenia during first episode occurring under age 18 years

Of 118 child and adolescent schizophrenic patients (ICD-9: 295.x; mean onset age 16.0 years), 97 (82.2%) could be completely investigated at follow-up (mean interval 7.4 years; mean age 23.1 years). At follow-up 30% of the patients were semi-dependent or dependent, 72% still required psychiatric treatment, 44% were at least moderately impaired with regard to educational/occupational functions and 58% with regard to social functions; 73% had experienced at least one further schizophrenic episode. Comparison with schizophrenia beginning in adulthood showed that the impairment in social function was much greater in the younger group of patients. These results support the belief that schizophrenic psychoses starting in adolescence have a worse outcome than those beginning in adulthood. The most efficient indicators for a worse outcome were long duration of inpatient treatment at first admission, a high number of symptoms and low social competence at discharge.

[Positive and negative symptoms in schizophrenia: a current overview]

The purpose of this article is to summarize the results of studies examining the validity of the positive and negative sub-types of schizophrenia as proposed by Crow. The authors summarized Crow's model's predictions in the form of 12 research questions and examined whether its predictions were confirmed. The following predictions are generally confirmed by the data collected: (i) it is possible to measure negative symptoms with accuracy; (ii) the negative symptoms predict a deterioration; (iii) the negative symptoms are generally correlated with overall cognitive deficits; (iv) each dimension appears to have distinct neurobiological substrata. However, several elements of the Crow model are not supported by the data collected. Among the necessary modifications, the most important are as follows: (i) it appears more productive to conceive of the negative symptoms as distinct dimensions, rather than distinct diseases; (ii) at least three dimensions exist for describing the symptoms of schizophrenia; (iii) the negative symptoms are not necessarily intrinsic to the schizophrenic process, and they may be due to other causes; (iv) the negative symptoms are not necessarily irreversible, and can be improved under ataractics; (v) the positive symptoms, in particular those relating to disorganization, can also be correlated with cognitive deficits.

Evaluation and interpretation of symptom structures in patients with schizophrenia

Seventy Japanese DSM-III-R schizophrenic patients were assessed for 30 clinical symptoms using the Positive and Negative Syndrome Scale (PANSS) of Kay et al. Principal component analysis was applied to the full item set of this scale and disclosed 5 orthogonal independent symptom groups: negative, hostile/excited, thought-disordered, delusional/hallucinatory and depressive components. Our results provided further support of the contention that more than 2 (i.e., positive and negative) dimensions are required to account for structures of the schizophrenic symptoms.

Three clinical syndromes of schizophrenia in untreated subjects: relation to brain glucose activity measured by positron emission tomography (PET)

A number of studies of chronically ill, medicated patients have found that the clinical symptoms of schizophrenia segregate into three syndromes which can be labelled poverty, disorganization, and reality distortion. It has been previously found that each of these syndromes is associated with a specific pattern of perfusion (rCBF) in paralimbic and association cortex and in related subcortical nuclei. We replicated the symptom factors in 20 untreated subjects. Utilizing positron emission tomography with 18-F-fluorodeoxyglucose as a tracer for glucose metabolism, we reconstructed a map of the entire cortical activity from 16 to 20 tomographic slices. Each of the three syndromes was associated with a different pattern of regional glucose metabolism. Findings in common with previous studies were an association of poverty with left cortical metabolic activity in prefrontal and superior parietal areas, reality distortion with left temporal activity, and disorganization with left inferior parietal lobule. This is the first report of an association between regional metabolic activity and clinical syndromes in untreated patients, strengthening previous models of distributed neural networks in this disorder.

Positive and negative symptoms in the psychoses. Re-analysis of published SAPS and SANS global ratings

The validity of the simple dichotomy between positive and negative symptoms was examined by reanalysing the results of published studies using global ratings from Andreasen's SAPS and SANS. Global ratings from our own sample of 114 diagnostically heterogenous psychotic patients were also analysed. In none of the studies was a simple positive-negative dichotomy an adequate representation of symptom structure. The most commonly occurring structure consisted of three independent groups: Hallucinations/Delusions, Positive Thought Disorder and Negative Symptoms. These findings applied to both manic and schizophrenic groups of patients. An important implication of these results for future studies is that combining positive symptoms into a single scale is inappropriate because possibly differential relationships between Hallucinations/Delusions and Thought Disorder and a variety of external measures may be obscured by such a means of data reduction.

Visual controlled information processing resources and formal thought disorder in schizophrenia and mania

Visual selective attentional performance under low and high processing load conditions was examined in patients with schizophrenia (n = 20), or bipolar affective disorder-manic type (n = 21) and a group of normal control subjects (n = 18). Although schizophrenic patients demonstrated significantly more impaired cognitive performance than normal controls, bipolar patients were found to be as deviant as the schizophrenic patients on almost all of the performance variables. Positive thought disorder under high processing load demands was moderately correlated with schizophrenic patients' response processing ability. In contrast, negative thought disorder ratings were found to be moderately associated with reaction time performance during high processing demands for both patient groups. These findings are discussed with regard to the relationship between selective attention, visual-motor controlled information processing deficits, and thought disorder in psychosis.

Empirical assessment of the factorial structure of clinical symptoms in schizophrenia: negative symptoms

The factor structure of the Scale for the Assessment of Negative Symptoms (SANS) was examined in a confirmatory factor analysis that used the LISREL procedure. Four models of negative symptom factors were tested in 130 hospitalized schizophrenic patients. A three-factor model of diminished expression, social dysfunction, and disorganization generated by the authors yielded a superior fit to the data relative to the two-factor model of Liddle (1987b) and a unifactorial severity model. A four-factor model based on the original subscale formulation of the SANS failed to fit the data.

Empirical assessment of the factorial structure of clinical symptoms in schizophrenic patients: formal thought disorder

Male schizophrenic patients (n = 142) were examined with a clinical assessment of their language dysfunctions with the Scale for the Assessment of Thought, Language, and Communication (TLC). Confirmatory factor analyses were conducted to test the relative fit of several differential theoretical models of the factorial structure of thought disorders. The models examined were positive-negative thought disorder, a three-factor model based on the results of an earlier exploratory factor analysis, and a simpler verbal productivity-disconnection model that can be extracted from other exploratory analyses and empirical studies. The positive-negative thought disorder model failed to fit the data, while the three-factor model fit the data, but no better than the simpler verbal productivity-disconnection model.

Are there more than two syndromes in schizophrenia? A critique of the positive-negative dichotomy

A sample of 115 DSM-III-R schizophrenics was studied by means of the SANS and SAPS. A factor analysis from the nine subscales and two symptoms (inappropriate affect and poverty of content) and a review of the previous factor analyses suggest that schizophrenic symptoms cannot be appropriately classified into positive and negative syndromes. The low internal consistency of the SAPS suggests that the positive symptoms are not a homogeneous syndrome. Our results fit better with Liddle's model of three syndromes (negative, delusion-hallucination and disorganisation syndromes). It is argued that we are far from a valid classification of schizophrenic symptoms and the positive-negative dichotomy appears to be an oversimplification.

MCMI-II personality disorders in recent-onset bipolar disorders

This study investigated the personality disorders of 21 recent-onset Bipolar Disorder patients using the revised Million Clinical Multiaxial Inventory (MCMI-II; Millon, 1987). Personality disorder assessments, conducted after patients' clinical symptoms had settled, indicated that 17 patients received at least one MCMI-II personality disorder diagnosis with a trend toward multiple diagnoses. Narcissistic, Antisocial, and Histrionic personality disorders were diagnosed most frequently and were the scales most elevated. Schizoid and Compulsive personality disorders were the scales least elevated. Diagnostic concordance between the MCMI-II and the Structured Interview for DSM-III Personality (SIDP; Pfohl, Stangl, & Zimmerman, 1983) was poor; the MCMI-II made more multiple diagnoses. Implications of the discrepancies between these instruments and suggestions for future research are discussed.

Formal thought disorder in schizophrenia: a factor analytic study

The Thought, Language and Communication Scale (TLC) was studied in a sample composed of 115 DSM-III-R schizophrenic patients admitted to an acute inpatient unit. A principal component analysis with varimax rotation was performed to explore the possibility of the existence of syndromes within the formal thought disturbances. Seven factors were found to have eigen values greater than 1 and five showed appropriate internal consistency. The first factor, or disorganization factor, was close to the Scale for the Assessment of Positive Symptoms (SAPS) formal thought disturbance subscale. The second, or negative factor (perseveration, poverty of speech and content), was moderately correlated with poor premorbid functioning and poor response to neuroleptic treatment. The third and fourth factors were, respectively, formed by stilted speech plus word approximations, and neologisms plus clanging. The fifth factor (distractibility and blocking), as well as the first two factors, were correlated to the Scale for the Assessment of Negative Symptoms (SANS) attention subscale.

Positive and negative symptoms of schizophrenia. Their course and relationship over time

Recent approaches to subtyping schizophrenia have made use of the concepts of positive and negative symptoms. It is sometimes assumed that positive and negative symptoms are distributed discontinuously or inversely. Many of the studies that have examined this concept are cross-sectional. This research examines the relationships among positive and negative symptoms in a sample of 41 DSM III diagnosed schizophrenics. Using the SANS and the SAPS, symptoms are assessed, first, in the acute phase of the illness and then, 6 months later, in a period of relative remission. Results showed that positive and negative symptoms were not inversely related at either phase of the illness. Secondly, in comparison to positive symptoms, negative symptoms were highly intercorrelated at both times. Thirdly, the presence of negative symptoms in the acute phase was highly predictive of the presence of negative symptoms at follow-up. Implications for the longitudinal course of symptoms in schizophrenia are discussed.

The distinction of positive and negative symptoms. The failure of a two-dimensional model

The distinction of positive and negative symptoms in describing schizophrenic patients has become popular. It presupposes that symptoms cluster in two dimensions, fitting together not only theoretically but empirically. Factor analysis of three published studies of 93, 62 and 52 schizophrenic patients and a large pooled sample showed that more than two distinct dimensions are required to categorise symptoms in schizophrenia. This result is consistent across methods and samples, and with previous literature. The added dimensionality resulted from a splitting of the positive symptom domain into more distinct factors.

Smooth pursuit eye tracking dysfunction and negative symptoms in schizophrenia

This study examined the hypothesis that negative symptoms are associated with abnormalities of smooth pursuit in schizophrenic patients. The pursuit eye movements of 25 subjects with schizophrenia and 25 matched normal control subjects were recorded using an infrared eye tracking system and quantified using the log of signal-to-noise ratio (1n S/N). The severity of negative symptoms within the schizophrenic group was rated using the Scale for the Assessment of Negative Symptoms. Previous findings of pursuit abnormalities among schizophrenic patients as a group were replicated. There was, however, no significant association between the eye tracking dysfunction and the severity of negative symptoms.

The positive/negative symptom distinction in schizophrenia. Validity and etiological relevance

This paper presents an overview of the literature on the positive/negative symptom distinction in schizophrenia, and explores the implications of the findings for etiological models. Despite the diversity in methodology and focus, certain consistencies emerge from the research. Most important are findings that negative symptoms show a stronger relation with premorbid dysfunction than positive symptoms, and are more predictive of concordance for schizophrenia in monozygotic twins. Thus it appears that negative symptom ratings partially tap some long-standing characteristics of the individual. Moreover, these characteristics appear to be influenced by genetic factors. The implications of the findings for models of the etiology of positive and negative symptoms are discussed.