Empirical evaluation of the factorial structure of clinical symptoms in schizophrenia: effects of typical neuroleptics on the brief psychiatric rating scale

Factor analyses of multidimensional symptoms in a large group of patients with major depressive disorder, bipolar disorder, schizoaffective disorder and schizophrenia

BACKGROUND

There is an ongoing discussion about which neurobiological correlates or symptoms separate the major psychoses (i.e. Major Depressive Disorder MDD, Bipolar Disorder BD, and Schizophrenia SZ). Psychopathological factor analyses within one of these disorders have resulted in models including one to five factors. Factor analyses across the major psychoses using a comprehensive set of psychopathological scales in the same patients are lacking. It is further unclear, whether hierarchical or unitarian models better summarize phenomena.

METHOD

Patients (n = 1182) who met DSM-IV criteria for MDD, BD, SZ or schizoaffective disorder were assessed with the SANS, SAPS, HAMA, HAM-D, and YMRS. The sample was split into two and analyzed using explorative and confirmatory factor analyses to extract psychopathological factors independent of diagnosis.

RESULTS

In the exploratory analysis of sample 1 (n = 593) we found 5 factors. The confirmatory analysis using sample 2 (n = 589) confirmed the 5-factor model (χ² = 1287.842, df = 571, p < .0001: CFI = 0.932; RMSEA = 0.033). The 5-factors were depression, negative syndrome, positive formal thought disorder, paranoid-hallucinatory syndrome, and increased appetite. Increased appetite was not related to medication. None of the factors was specific for one diagnosis. Second order factor analysis revealed two higher order factors: negative/affective (I) and positive symptoms (II).

CONCLUSION

This is the first study delineating psychopathological factors in a large group of patients across the spectrum of affective and psychotic disorders. In future neurobiological studies, we should consider transdiagnostic syndromes besides the traditional diagnoses.

Effects of sample size and distributional assumptions on competing models of the factor structure of the PANSS and BPRS

Factor analytic work on the Positive and Negative Syndrome Scale (PANSS) and Brief Psychiatric Rating Scale (BPRS) has yielded varied and conflicting results. The current study explored potential causes of these discrepancies. Prior research has been limited by small sample sizes and an incorrect assumption that the items are normally distributed when in practice responses are highly skewed ordinal variables. Using simulation methodology, we examined the effects of sample size, (in)correctly specifying item distributions, collapsing rarely endorsed response categories, and four factor analytic models. The first is the model of Van Dorn et al., developed using a large integrated data set, specified the item distributions as multinomial, and used cross-validation. The remaining models were developed specifying item distributions as normal: the commonly used pentagonal model of White et al.; the model of Van der Gaag et al. developed using extensive cross-validation methods; and the model of Shafer developed through meta-analysis. Our simulation results indicated that incorrectly assuming normality led to biases in model fit and factor structure, especially for small sample size. Collapsing rarely used response options had negligible effects.

Lack of association between dopaminergic antagonism and negative symptoms in schizophrenia: a positron emission tomography dopamine D2/3 receptor occupancy study

RATIONALE

Several pre-clinical studies suggest that antipsychotic medications cause secondary negative symptoms. However, direct evidence for a relationship among antipsychotic medications, their direct effects on neurotransmitter systems, and negative symptoms in schizophrenia remains controversial.

OBJECTIVE

The objective of this study was to examine the relationship between antipsychotic-related dopamine D_2/3 receptor occupancy and negative symptoms in patients with schizophrenia.

METHODS

Forty-one clinically stable outpatients with schizophrenia participated in this prospective dose reduction positron emission tomography (PET) study. Clinical assessments and [¹¹C]-raclopride PET scans were performed before and after participants underwent gradual dose reduction of their antipsychotic medication by up to 40 % from the baseline dose.

RESULTS

No significant relationship was found between antipsychotic-related dopamine D_2/3 receptor occupancy and negative symptom severity at baseline or follow-up. Similar null findings were found for subdomains of negative symptoms (amotivation and diminished expression). Occupancy was significantly lower following dose reduction; however, negative symptom severity did not change significantly, though a trend toward reduction was noted. Examination of change scores between these two variables revealed no systematic relationship.

CONCLUSIONS

Our cross-sectional and longitudinal results failed to find a significant dose-dependent relationship between severity of negative symptoms and antipsychotic-related dopaminergic antagonism in schizophrenia. These findings argue against the notion that antipsychotics necessarily cause secondary negative symptoms. Our results are also in contrast with the behavioral effects of dopaminergic antagonism routinely reported in pre-clinical investigations, suggesting that the role of this variable in the context of chronic treatment and schizophrenia needs to be re-examined.

Antipsychotics and amotivation

Antipsychotic drugs are thought to produce secondary negative symptoms, which can also exacerbate primary negative symptoms. In the present study, we examined whether motivational deficits in particular were related to antipsychotic treatment in patients with schizophrenia in a dose-dependent manner. Five hundred and twenty individuals with schizophrenia who were receiving antipsychotic monotherapy for at least 6 months and followed prospectively were included in the present study. Participants were receiving one of five antipsychotic medications (olanzapine, perphenazine, quetiapine, risperidone, or ziprasidone), and analyses were conducted for patients receiving each drug separately. Analysis of covariance models were constructed to examine the effect of antipsychotic dose on level of motivational impairment, controlling for selected demographic and clinical variables (eg, positive symptoms). Level of motivation, or deficits therein, were evaluated using a derived measure from the Quality of Life Scale, and in addition with scores derived from the Positive and Negative Syndrome Scale. Antipsychotic dose was not related to the level of amotivation for any of the medications examined. Moreover, severity of sedation was not significantly related to the degree of amotivation. One hundred and twenty-one individuals were identified as antipsychotic-free at baseline, and after 6 months of antipsychotic treatment, no change in motivation was found. Chronic treatment with antipsychotics does not necessarily impede or enhance goal-directed motivation in patients with schizophrenia. It is possible that the negative impact of antipsychotics in this regard is overstated; conversely, the present results also indicate that we must look beyond antipsychotics in our efforts to improve motivation.

Sample size requirements for the internal validation of psychiatric scales

The ratio of subjects to variables (N/p), as a rule to calculate the sample size required in internal validity studies on measurement scales, has been recommended without any strict theoretical or empirical basis being provided. The purpose of the present study was to develop a tool to determine sample size for these studies in the field of psychiatry. First, a literature review was carried out to identify the distinctive features of psychiatric scales. Then, two simulation methods were developed to generate data according to: (1) the model for factor structure derived from the literature review and (2) a real dataset. This enabled the study of the quality of solutions obtained from principal component analysis or Exploratory Factor Analysis (EFA) on various sample sizes. Lastly, the influence of sample size on the precision of Cronbach's alpha coefficient was examined. The N/p ratio rule is not upheld by this study: short scales do not allow smaller sample size. As a rule of thumb, if one's aim is to reveal the factor structure, a minimum of 300 subjects is generally acceptable but should be increased when the number of factors within the scale is large, when EFA is used and when the number of items is small.

Neurocognitive abnormalities during comprehension of real-world goal-directed behaviors in schizophrenia

Origins of impaired adaptive functioning in schizophrenia remain poorly understood. Behavioral disorganization may arise from an abnormal reliance on common combinations between concepts stored in semantic memory. Avolition-apathy may be related to deficits in using goal-related requirements to flexibly plan behavior. The authors recorded event-related potentials (ERPs) in 16 patients with medicated schizophrenia and 16 healthy controls in a novel video paradigm presenting congruous or incongruous objects in real-world activities. All incongruous objects were contextually inappropriate, but the incongruous scenes varied in comprehensibility. Psychopathology was assessed with the Scales for the Assessment of Positive and Negative Symptoms (SAPS/SANS) and the Brief Psychiatric Rating Scale. In patients, an N400 ERP, thought to index activity in semantic memory, was abnormally enhanced to less comprehensible incongruous scenes, and larger N400 priming was associated with disorganization severity. A P600 ERP, which may index flexible object-action integration based on goal-related requirements, was abnormally attenuated in patients, and its smaller magnitude was associated with the SANS rating of impersistence at work or school (goal-directed behavior). Thus, distinct neurocognitive abnormalities may underlie disorganization and goal-directed behavior deficits in schizophrenia.

Executive functions and cognitive deficits in schizophrenia: comparisons between probands, parents and controls in India

BACKGROUND

Cognitive impairment is said to be a core feature of schizophrenia. Executive function is an important cognitive domain.

AIM

This study was undertaken to assess cognitive impairment among Indian patients with schizophrenia (Sz) or schizoaffective disorder (SzA), compared with their parents and unaffected individuals (controls).

SETTINGS AND DESIGN

Executive functions as measured by Trail-making Test (TMT), of patients and their parents were compared with controls. The patients were recruited from the Outpatients' Department (OPD) of a government hospital.

MATERIALS AND METHODS

Patients diagnosed as Sz or SzA (n=172) and their parents (n=196: families n=132, 119 fathers and 77 mothers) participated. We also included 120 persons with no history of psychiatric illness. Cognitive function was assessed with the TMT. The Information Score of the Post Graduate Institute Battery of Brain Dysfunction test, developed in India for Indian subjects was used as a proxy for general fixed knowledge.

STATISTICAL ANALYSIS

Logistic and linear regression was used to compare cognitive deficits of cases, parents and controls.

RESULTS

Cases and their parents took significantly more time than controls on Part B of the TMT. There were no statistically significant differences between cases and parents on any of the TMT parameters. Using regression analysis, the most significant correlates of all TMT parameters among cases were with occurrence of auditory hallucinations and current age.

CONCLUSION

Cases, as well as their parents showed more cognitive impairment than controls on the TMT.

The measurement of psychotic acuity by nursing staff

Accurate evaluation of patients' psychotic state is essential to decrease psychotic symptoms and protect the patient and others. The aim of this paper is to conduct a literature review in order to access the utility, reliability and validity of current rating scales that are purported to measure psychotic acuity of inpatient population. A search of a number of electronic databases was undertaken to retrieve potential articles that focus on the measurement of acute psychosis. We identified some conceptual and theoretical problems when using a scale that is monitoring the progress of discharge and assesses the outcome of treatments. The findings revealed a difficulty in finding a commonly agreed definition of acute psychosis and a problem of obtaining frequent measures, and the frequency of measurement and fluctuation in psychosis. The most dominant scales in assessing psychosis were reviewed: the Global Assessment of Functioning Scale, the Brief Psychiatric Rating Scale and the Positive and Negative Symptom Scale. Several issues related to the scales' inter-rater reliability and construct validity remain unexplored. None of these scales addressed the conceptual and theoretical problems that we identified. A new scale that will measure acuity of symptoms in inpatient settings needs to be created.

The factor structure of clinical symptoms in depressed inpatients with unipolar or bipolar spectrum disorders: a preliminary study

Factor analysis of symptom structure has proven to be a valuable tool to identify dimensions of symptoms in various psychiatric conditions. This study used exploratory and confirmatory factor analysis to examine symptom structures in depressed inpatients with unipolar (n = 718) or bipolar (n = 134) spectrum disorders who were rated at admission with a psychiatric rating scale. No differences in overall symptom severity on the scale were found in the 2 samples, although different factor structures were detected with exploratory analyses. These models were modified in a confirmatory modeling procedure to improve their fit to the data, resulting in models with good, but not perfect, fits. For people with bipolar disorders, a 5-factor model fit best, with depression loading with anxiety symptoms and in people with unipolar disorders, a 4-factor model with depression loading with vegetative symptoms was found. Our results suggest that similar levels of symptom severity may have different underpinnings in the 2 groups and suggest that more comparative studies of symptoms in these 2 conditions may be useful.

The factor structure of clinical symptoms in mixed and manic episodes prior to and after antipsychotic treatment

BACKGROUND

While the factor structure of clinical symptoms in schizophrenia has been examined and provided crucial information about the illness, there is much less information available in bipolar disorder. This study examined the structure of symptoms of bipolar disorder at an unmedicated baseline assessment and after double-blind treatment with ziprasidone, haloperidol, or placebo. We hypothesized, consistent with recent studies of schizophrenia, that the factor structure after treatment would be similar to the structure of untreated symptoms at study baseline.

METHODS

Hospitalized patients with manic (n = 363) or mixed (n = 71) bipolar episodes were rated with the Hamilton Depression Rating Scale (HAM-D) and the Mania Rating Scale [(MRS); derived from the Schedule for Affective Disorders and Schizophrenia - Change Bipolar Scale]. After 21 days of double-blind treatment, all patients were again rated with the MRS and HAM-D.

RESULTS

Exploratory orthogonal factor analysis (varimax rotation) including both HAM-D total scores and the MRS items found different five-factor solutions for mixed and manic patients at the unmedicated baseline assessment. Confirmatory modeling indicated that these models, with some modifications, fit the data well. At the endpoint, however, a single-factor solution was found for mixed and manic groups.

IMPLICATIONS

Symptomatology in bipolar disorder is multifactorial in an acute and unmedicated state, with slightly different factor structures for mixed and manic episodes. Following treatment, a single severity dimension is detected. These results suggest that symptom dimensions in mania may be different from those seen in schizophrenia, where different elements of symptoms have been proven to have different functional correlates and treatment response.

A comparison of African-Caribbean and White European young adults' conceptions of schizophrenia symptoms and the diagnostic label

BACKGROUND

Discrepancies in the experiences of different ethnic groups in mental health services exist, such as in the persistently higher rates of schizophrenia diagnosis found among the African-Caribbean population compared to the white European population in the UK. Some hypotheses consider whether this is due to greater stigmatizing attitudes to mental illness in the African-Caribbean community, leading individuals to avoid treatment-seeking and an increased incidence of schizophrenia. This study aimed to investigate recognition and evaluation of schizophrenic symptoms across African-Caribbean and white European individuals.

METHOD

One hundred and twenty eight adult students from London colleges completed a questionnaire assessing stigma beliefs, evaluation of symptoms as mental illness and help-seeking beliefs, in response to symptom vignettes.

RESULTS AND DISCUSSION

African-Caribbean participants indicated less stigmatizing beliefs towards both the symptoms and diagnostic label of schizophrenia compared to the white European participants. White European participants were more likely to label vignettes as implying 'mental illness' and also more likely to recommend professional health treatment. These results are inconsistent with a hypothesis that on average African-Caribbean people stigmatize schizophrenia more than white European people. While white European participants' beliefs were more likely to follow a western model of mental illness, African-Caribbean participants were more likely to have alternative beliefs. The influence of racial discrimination, mental illness knowledge and societal structures are discussed.

The dimensions of clinical and cognitive change in schizophrenia: evidence for independence of improvements

BACKGROUND

As cognitive impairments are related to deficits in everyday functioning in schizophrenia, treatment of these impairments may have the potential to reduce these functional deficits. To determine if treatments truly reduce cognitive impairment, it is important to discriminate direct cognitive effects of treatment from generalized treatment benefits on the multiple clinical dimensions of schizophrenia. Thus, this study used a database from an existing clinical trial and examined the relationships between changes in clinical symptoms and cognitive deficits with several different strategies.

MATERIALS AND METHODS

Two hundred and seventy stable but symptomatic outpatients with schizophrenia entered a study where they were switched from previous treatment to open-label ziprasidone. The present data are from the 6-month endpoint (n=184). Patients were examined at baseline and the 6-month endpoint with ratings of clinical symptoms based on the Positive and Negative Syndrome Scale (PANSS) and a neuropsychological (NP) assessment battery including aspects of cognitive functioning known to be related to functional outcome in schizophrenia.

RESULTS

Changes on the individual PANSS items and NP test scores were examined with two separate principal components analyses, revealing four dimensions of clinical change (psychosis, negative symptoms, affective symptoms, and agitation) and two dimensions of NP improvement. Pearson correlations between changes in the (1) factors derived from the analyses, (2) individual NP items based the four clinical dimensions of change, and (3) the 30 PANSS items and the two NP dimensions of change suggested minimal relationships (largest r=0.15).

IMPLICATIONS

This sample was selected because previous findings suggested that clinical and NP symptoms of schizophrenia significantly improved from baseline after a switch to ziprasidone treatment. While four dimensions of change in clinical symptoms and two dimensions of cognitive improvements were identified, clinical changes, regardless of how they were defined, were not related to NP improvements.

Meta-analysis of the brief psychiatric rating scale factor structure

A meta-analysis (N=17,620; k=26) of factor analyses of the Brief Psychiatric Rating Scale (BPRS) was conducted. Analysis of the 12 items from Overall et al.'s (J. E. Overall, L. E. Hollister, & P. Pichot, 1974) 4 subscales found support for his 4 subscales. Analysis of all 18 BPRS items found 4 components similar to those of Overall et al. In a 5-component solution, a 5th activation component emerged but was best supported among samples of schizophrenic patients. The first 4 components appear to form the core of the BPRS factor structure. Results of the meta-analysis suggest 5 subscales (with items in parentheses): Affect (anxiety, guilt, depression, somatic); Positive Symptoms (thought content, conceptual disorganization, hallucinatory behavior, grandiosity); Negative Symptoms (blunted affect, emotional withdrawal, motor retardation); Resistance (hostility, uncooperativeness, suspiciousness); and Activation (excitement, tension, mannerisms-posturing).

Spatial working memory deficit correlates with disorganization symptoms and social functioning in schizophrenia

Both spatial working memory deficit and disorganization symptoms have been considered significant components of schizophrenic impairment involved with the dorsolateral prefrontal cortex. The purpose of the present study was to investigate the relationships among spatial working memory, psychiatric symptoms including disorganization symptoms, and social functioning in schizophrenia. Fifty clinically stable patients with schizophrenia and 34 healthy controls participated in the study. Patients were rated with the Brief Psychiatric Rating Scale and the Rehabilitation Evaluation Hall and Baker. The Advanced Trail Making Test was used to evaluate spatial working memory. Patients demonstrated significantly reduced spatial working memory compared to that of healthy controls. Spatial working memory in patients correlated significantly with social functioning such as self-care skills, community skills and speech disturbance, and with disorganization symptoms. Disorganization symptoms also correlated with these aspects of social functioning. In conclusion it is suggested that both spatial working memory deficit and disorganization symptoms, which are impairments involved with the dorsolateral prefrontal cortex dysfunction, can serve as effective predictors of social functioning.

Stability in schizophrenia symptoms over time: Findings from the Mount Sinai Pilgrim Psychiatric Center Longitudinal Study

This study examined the stability of symptoms of schizophrenia over time, focusing on the stability of symptom structure. Symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS). The sample consisted of 215 chronic patients followed up for as long as 4 years. Exploratory factor analysis identified 6 factors. Several statistical techniques were used to examine the stability of these symptoms, including longitudinal confirmatory factor analysis. Low-to-moderate rank-order stability and high absolute stability of the factors were found, with the structure of the PANSS-assessed symptoms consistent over time. The results demonstrate that despite changes in the severity of symptoms in individual patients with schizophrenia, the factor structure and interrelatedness of symptoms have considerable stability over time.

Dimensions of major psychoses: a confirmatory factor analysis of six competing models

The symptoms of major psychosis aggregate in factors. Models of one to eight dimensions have been reported. In the present study, we tested six competing factor models, based on the psychotic and affective items of the OPCRIT checklist, in a large sample (N = 1294) of patients diagnosed with DSM-IV schizophrenia (n = 460), bipolar disorder (n = 726) and delusional disorder (n = 108). Confirmatory factor analysis was used to test the following models: (1) unique psychotic dimension; (2) positive-manic items, negative-depressive items; (3) model 2 with the addition of a disorganized factor; (4A) positive, negative, depressive and manic dimensions; (4B) model 4A with loss of pleasure (Anhedonia) and loss of energy (Apathy) included among depressive instead of negative symptoms; and (5) same as model 4B except for the addition of a disorganized domain. The four- and five-factor models fit the data much better than simpler ones. Between the two four-factor models, M4B emerged as more appropriate than M4A. The five-factor solution (M5) displayed the best fit. In conclusion, our confirmatory factor analysis in a large sample of psychotic subjects indicated that the symptomatology of major psychoses is composed of the following five factors: mania, positive symptoms, disorganization, depression and negative symptoms.

A confirmatory factor analytic evaluation of the pentagonal PANSS model

The positive and negative syndrome scale (PANSS) is widely used in psychiatric research. Reflecting this common use, considerable attention has been applied to the psychometric properties of this instrument. However, despite the publication of numerous studies and analyses, it remains uncertain how best data from the PANSS should be analysed to best model the symptoms of schizophrenia. A resolution to these concerns seemed to be offered following the publication in 1997 of a large multisite factor analysis that produced the 'pentagonal model', which has subsequently been included in the 2000 revision of the PANSS user manual. However, to date, an independent confirmatory analysis of this model has not yet been published. The aim of this study was to test this model in a new independent sample with confirmatory factor analysis (CFA). Independent confirmation of the fit of the model is required to ensure that its implementation is informed by confirmation of its psychometric properties. CFA was performed in a sample of 347 subjects with schizophrenia. The analysis found that the model had inadequate goodness of fit. The use of the pentagonal model has similar difficulties as earlier models and more research is required to ascertain the optimal method for measuring symptom dimensions in research and clinical settings.

Patterns of symptoms in neuroleptic-naive patients with schizophrenia and related psychotic disorders before and after treatment

A three-factor structure of schizophrenic symptoms has received considerable support, but there are no data on the factor structure of symptoms in neuroleptic-naive patients and how symptoms evolve after the inception of antipsychotic treatment. Seventy neuroleptic-naive patients with schizophrenia or related psychotic disorders were assessed with the Scales for the Assessment of Positive and Negative Symptoms before and after neuroleptic treatment. Ten global ratings of symptoms were subjected to factor analysis at the two time points and the factor solutions compared. A three-factor structure composed of psychotic, disorganization, and negative dimensions was found at the two assessment points. The negative and disorganization factors were highly correlated at each assessment and across assessments. While the symptom composition of the factors at the neuroleptic-naive assessment fitted that described in most previous studies, the composition of the negative and disorganization factors after neuroleptic treatment was somewhat different in that attention and inappropriate affect loaded on the negative factor instead of the disorganization factor. It is concluded that caution is warranted when using the three-factor model of schizophrenic symptoms as it may not be stable at different phases of the illness.

Integrating psychopathological dimensions in functional psychoses: a hierarchical approach

Previous factor analysis studies of psychotic symptomatology have demonstrated three psychopathological dimensions: positive, negative and disorganization. However, few studies have analyzed non-schizophrenic samples and most use a syndrome-level of analysis or only schizophrenic symptom scales. This study examined how many dimensions underlie psychosis, and whether within psychosis there is a hierarchical organization of dimensions.A total of 660 inpatients with an acute psychotic episode were studied. Psychopathology was measured through a wide psychopathological assessment using the Manual for the Assessment and Documentation of Psychopathology (AMDP-system). Principal component factor analysis was carried out on 64 psychopathological symptoms scoring 1 or higher in at least 10% of the sample. A 15-factor solution was obtained which failed to depict a psychosis model on clinical and methodological grounds. Further predetermined factor analyses ranging from 1 to 15 factors were carried out to examine alternative factor solutions. A 10-dimensional model was the best model on clinical, statistical and conceptual grounds. Moreover, the examination of the 1 to 10 dimensional models allowed us to infer a hierarchical model of psychopathological dimensions, which can be represented in the frame of a tree-structure. The model permitted transitions between psychiatric categories and psychopathological dimensions, and it was able to integrate previous factor solutions with different numbers of resulting dimensions.The findings have implications for the design of future studies and for the hierarchical conceptualization of psychopathological dimensions.

How many and which are the psychopathological dimensions in schizophrenia? Issues influencing their ascertainment

During the last two decades, much effort has been made to precisely characterize the symptom dimensions of schizophrenia. A number of dimensional models have been proposed, the most popular of which has been a three-dimensional model consisting of psychotic, negative and disorganizational symptoms. This model, however, has been criticized as too simplistic, and more complex models have been proposed, although to date there has been no consensus as to the number and nature of dimensions necessary to account for the whole range of schizophrenic symptoms. In the present paper, the authors review the main methodological issues which have led to the current confusion about the number of dimensions underlying schizophrenic psychopathology. Among the main issues influencing the delimitation of dimensions are: statistical procedures for determining the number of factors, phase of the illness, level of analysis of symptoms (i.e., symptoms or groups of symptoms), and measurement instrument used. Studies analyzing either a broad range of symptoms or particular symptoms at a finer level have produced a rather complex picture of schizophrenic dimensions. There is evidence supporting the existence of eight major dimensions of psychopathology: psychosis, disorganization, negative, mania, depression, excitement, catatonia and lack of insight. The dimensional structure of symptoms becomes even more complex if one considers that these big dimensions can be further divided into more elementary components. A hierarchical approach for organizing the complex dimensional structure of schizophrenic symptoms is proposed.

Dimensional structure of psychotic symptoms: an item-level analysis of SAPS and SANS symptoms in psychotic disorders

The factor structure of psychotic symptoms as assessed by means of the Scales for the Assessment of Positive and Negative Symptoms (SAPS and SANS) was examined in a sample of 660 psychotic inpatients. Analyses were conducted at item-level. Principal-component analysis (PCA) was used to extract factors, the OBLIMIN procedure to rotate factors, and the eigen value greater-than-one criterion to determine the number of factors. PCA resulted in 11 interpretable factors explaining 64% of the total variance: poverty of affect/speech, thought disorder/inappropriate affect, bizarre delusions, social dysfunction, other delusions, paranoid delusions, bizarre behavior, nonauditory hallucinations, auditory hallucinations, manic thought disorder, and attention. Many of the factors were significantly intercorrelated. A second-order PCA resulted in four second-order factors, the first three roughly corresponding to the well-known psychosis, disorganization and negative dimensions. It is concluded that the factor structure of psychotic symptoms is more complex than is generally acknowledged, and that the dimensions of psychosis, disorganization and negative represent second-order dimensions. The subscale composition of the SAPS and SANS was not supported.

Independent frontal-system deficits in schizophrenia: cognitive, clinical, and adaptive implications

This study examined whether frontal-system impairments in schizophrenia occur independently of one another and whether they have distinct implications for information processing, symptom severity, and adaptive functioning. We assessed 26 medication-free schizophrenic outpatients and 18 normal control subjects on eight frontally mediated tasks, semantic information processing, IQ, the BPRS, and long-term psychosocial adaptation. Schizophrenic subjects showed three types of deficits, which were uncorrelated with one another: (1) Executive dysfunction (inflexible problem solving) was related to decreased use of expectancy during controlled semantic priming, lower intelligence, more severe negative symptoms and stereotyped mannerisms. (2) Disinhibition of responses (to irrelevant stimuli) was associated with increased automatic priming, a trend for more severe hallucinations, and was unrelated to intelligence. (3) Motor dyscoordination (inaccurate, dysfluent motor sequencing) was not related to semantic processing, intelligence, or symptoms. Furthermore, all three impairments were unrelated to generalized slowness, age, sex, illness length, or pre-washout neuroleptic dose. Two deficits accounted for aspects of long-term psychosocial adaptation, even after statistical correction for IQ: Executive dysfunction was associated with younger illness onset, poor purposefulness and planning, impaired social relations, and lower global functioning. Motor dyscoordination was associated with poor treatment outcome and restricted educational advancement. Furthermore, executive and motor deficits interacted significantly; subjects who had both deficits showed the least favorable treatment outcome. These findings are neither consistent with generalized impairment nor with a unitary 'frontal syndrome' in schizophrenia. They provide preliminary evidence for at least three frontal-system deficits (dorsolateral, orbital, and premotor), which are dissociable from one another, can occur without general intellectual impairment, and have distinct implications for long-term adaptive functioning.

Attentional and eye tracking deficits correlate with negative symptoms in schizophrenia

Thirty patients with a DSM-III-R diagnosis of schizophrenia were assessed for severity of schizophrenic symptoms using the Brief Psychiatric Rating Scale (BPRS) and were tested on a Continuous Performance Test (CPT) and a smooth pursuit eye tracking task. Negative symptoms were significantly correlated with eye tracking impairment (r = 0.43, p < 0.01) and CPT deficits (r = 0.67, p < 0.001), but performance on neither task was correlated with positive symptoms. CPT performance and eye tracking performance were modestly correlated with each other (r = 0.39, p < 0.01) and CPT performance was found to be a stronger predictor of negative symptoms than eye tracking performance. These data indicate that neurocognitive markers of vulnerability to schizophrenia are associated with negative rather than positive symptoms.