Quality of life in stable schizophrenia: The relative contributions of disorganization and cognitive dysfunction
Introduction
Regarding the factors that influence quality of life (QOL) in patients with schizophrenia, the majority of researchers have primarily focused on psychiatric symptoms, although many other influential predictors have been identified (Eack et al., 2007). Indeed, one factor that has been shown to be consistently negatively associated with QOL is psychopathology (Lambert and Naber, 2004). QOL has been negatively correlated with positive, negative, and general psychopathology, as well as with depressive symptoms; some studies have found a large relationship between these measures (Norman et al., 2000, Fitzgerald et al., 2001, Rocca et al., 2005), while other studies have identified only a small to moderate relationship (Sim et al., 2004, Ritsner et al., 2005). In many of these studies, positive symptoms, such as hallucinations and delusions, were combined with conceptual disorganization to form a positive symptom factor. Over time, several factor-analytic studies (Norman et al., 1997, Meagher et al., 2000) have supported the view that delusions and hallucinations are distinct from positive symptoms, such as formal thought disorders. As a result, disorganization has emerged as a separate domain worthy of consideration. Disorganization was introduced by Liddle (1987) as an important third factor in addition to the positive and negative symptom factors. According to Liddle, schizophrenic symptoms segregated into three syndromes: psychomotor poverty (poverty of speech, lack of spontaneous movement and various aspects of blunting of affect); disorganization (inappropriate affect, poverty of content of speech, and disturbances of the form of thought); and reality distortion (particular types of delusions and hallucinations). Some studies have suggested that disorganization may be a stronger predictor of community function than reality distortion (Norman et al., 1999, Ventura et al., 2009).
Much more attention has been paid to cognitive dysfunction because it may lead to poor community functioning, including social functioning, work performance, and social skills (Bryson and Bell, 2003). Cognitive deficits persist throughout the illness and serve as rate-limiting factors associated with functional recovery (Keefe and Fenton, 2007). Studies investigating the ability of neurocognitive variables to predict QOL in individuals with schizophrenia have yielded conflicting results. However, a recent meta-analysis revealed a markedly different relationship between neurocognition and objective and subjective QOL (Tolman and Kurtz, 2012). Small to moderate relationships (d ≤ 0.55) were found between crystallized verbal ability, working memory verbal list learning, processing speed, and the executive function and objective indices associated with QOL. In contrast, the results revealed either nonsignificant or inverse relationships for the vast majority of neurocognitive measures and measures of subjective QOL.
Concerning the relationships between cognition and symptoms, there is evidence in the literature of strong correlations between performance on neurocognitive tests and negative symptoms (Ventura et al., 2009). Differential relationships between positive symptoms and neurocognitive functioning have been reported. Symptoms of disorganization, when reported as a factor separate from reality distortion, appear to be related to neurocognition and warrant a separate empirical study. A recent meta-analysis demonstrated a small to moderate (r = − 0.23) relationship between disorganization and neurocognition, while the relationship between neurocognition and reality distortion was relatively weak (r = − 0.04). Disorganization was related to all of the domains of cognitive functioning examined, including verbal memory (r = − 0.20), attention/vigilance (r = − 0.25), reasoning and problem solving (r = − 0.24), processing speed (r = − 0.26), visual memory (r = − 0.20), and working memory (r = − 0.20). In contrast, reality distortion showed no such broad association (r values ranging from − 0.01 to − 0.12) (Ventura et al., 2010).
Previous research has linked disorganization to neurocognition and neurocognition to QOL, although in separate studies. The present study was conducted to determine whether the relationship between disorganization and QOL may be mediated by the extent of cognitive deficits in patients with schizophrenia.
Thus, the objectives of the current study were three-fold. First, we investigated the ability of disorganization alone to predict QOL. Given the previous contradictory findings in the literature, we intended for this investigation to be an exploratory analysis and expected that the disorganization would predict a significantly lower QOL. Second, we studied the ability of cognition alone to predict QOL. Given the results of previous studies, we anticipated a role for cognition in the prediction of QOL. Third, we explored the possibility that disorganization continues to predict QOL when cognition is also considered. It was expected that both disorganization and neuropsychological deficits interact to influence QOL, with neuropsychological deficits acting as partial mediators of the relationship between disorganization and QOL.
Section snippets
Participants
This study was conducted at the Department of Neuroscience, Psychiatric Section, and the Department of Mental Health ASL TO1 Molinette-Turin, Italy. Between July 2008 and March 2010, we screened 345 schizophrenia spectrum patients of either gender, aged between 18 and 65 years. A total of 276 consecutive outpatients who met the inclusion criteria and agreed to participate in the study were enrolled. They all fulfilled the formal Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (
Results
The patients in our study had DSM IV-TR schizophrenia diagnoses of the paranoid subtype (n = 158, 57%), disorganized subtype (n = 27, 10%), undifferentiated subtype (n = 57, 21%), or residual subtype (n = 34, 12%). The mean age (± S.D.) of our patients was 40 (± 10.8) years. The mean duration of illness (± S.D.) was 14.2 (± 9.74) years. There were 116 females (42%) and 160 males (58%). Sixty-two percent of patients were treated with second-generation antipsychotics (SGAs), and 38% were treated with
Discussion
The purpose of the present study was to examine the interactions between disorganization and cognition in predicting QOL within a sample of outpatients with stable schizophrenia.
First, as hypothesized, disorganization was negatively related to QOL. In the literature, there is evidence that disorganization is the most reliable predictor of a variety of outcome indicators (Heslegrave et al., 1997, Norman et al., 1999, Smith et al., 1999, Ventura et al., 2009). Recently, Ventura et al. (2010)
Role of the funding source
This study was supported by research grant 2006–2167 by the Compagnia di San Paolo, Torino, Italy and by a research grant by the Fondazione Cassa di Risparmio di Savigliano, Savigliano, Torino, Italy.
Contributors
MS, GR and PR designed the study and wrote the protocol. BC, FC, MG and CM carried out the patient clinical assessment and recruitment, data collection and analysis. CM and MS wrote the first draft of the manuscript. All authors contributed to and have approved the final manuscript.
Conflict of interest
We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.
We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us.
We confirm that we
Acknowledgments
This study was supported by the research grant 2006–2167 by Compagnia di San Paolo, Torino, Italy and by a research grant by the Fondazione Cassa di Risparmio di Savigliano, Savigliano, Torino, Italy.
References (56)
- et al.
Cognitive patterns in subtypes of schizophrenia
Eur. Psychiatry
(2002) - et al.
Impairments of executive/attentional functions in schizophrenia with primary and secondary negative symptoms
(2005) - et al.
Clinician-rated function and patient-rated quality of life in schizophrenia: implications of their correspondence for psychopathology and side effects
Prog. Neuropsychopharmacol. Biol. Psychiatry
(2010) - et al.
Identification of clinically meaningful relationships among cognition, functionality, and symptoms in subjects with schizophrenia or schizoaffective disorder
Schizophr. Res.
(2013) - et al.
Association of symptomatology and cognitive deficits to functional capacity in schizophrenia
Schizophr. Res.
(2008) - et al.
Depressive and negative symptoms in schizophrenia: different effects on clinical features
Compr. Psychiatry
(2005) - et al.
Subjective quality of life in first episode schizophrenia spectrum disorders with comorbid depression
Psychiatry Res.
(2004) - et al.
The five-factor model of the Positive and Negative Syndrome Scale II: a ten-fold cross-validation of a revised model
Schizophr. Res.
(2006) - et al.
The functional significance of symptomatology and cognitive function in schizophrenia
Schizophr. Res.
(1997) - et al.
Symptoms as mediators of the relationship between neurocognition and functional outcome in schizophrenia: a meta-analysis
Schizophr. Res.
(2009)
Disorganization and reality distortion in schizophrenia: a meta-analysis of the relationship between positive symptoms and neurocognitive deficits
Schizophr. Res.
Neurocognitive and social functioning in schizophrenia
Schizophr. Bull.
Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR)
Measuring quality of life in patients with schizophrenia
Pharmacoeconomics
The moderator–mediator variable distinction in social psychological research: conceptual, strategic, and statistical considerations
J. Personal. Soc. Psychol.
Predictors of competitive employment among patients with schizophrenia
Curr. Opin. Psychiatry
Determinants of real-world functional performance in schizophrenia subjects: correlations with cognition, functional capacity, and symptoms
Am. J. Psychiatry
Initial and final work performance in schizophrenia: cognitive and symptom predictors
J. Nerv. Ment. Dis.
The architecture of cognitive control in schizophrenia
Brain
Quality of life in schizophrenia: a comparison of instruments
Schizophr. Bull.
California Verbal Learning Test (CVLT) Manual
Psychiatric symptoms and quality of life in schizophrenia: a meta-analysis
Schizophr. Bull.
Quality of life for persons living with schizophrenia: more than just symptoms
Psychiatry Rehabil. J.
Structured Clinical Interview for DSM-IV Disorders (SCID)
Subject and observer-rated quality of life in schizophrenia
Acta Psychiatr. Scand.
Neurocognitive deficits and functional outcome in schizophrenia: are we measuring the “right stuff”?
Schizophr. Bull.
ECDEU Assessment Manual for Psychopharmacology. Revised
Wisconsin Card Sorting Test manual
Cited by (20)
A new schizophrenia screening instrument based on evaluating the patient's writing
2024, Schizophrenia ResearchStructural and Functional Brain Patterns Predict Formal Thought Disorder's Severity and Its Persistence in Recent-Onset Psychosis: Results From the PRONIA Study
2023, Biological Psychiatry: Cognitive Neuroscience and NeuroimagingAdult ADHD, executive function, depressive/anxiety symptoms, and quality of life: A serial two-mediator model
2021, Journal of Affective DisordersCitation Excerpt :There have been similar studies on other mental disorders. Sigaudo et al. (2014) investigated that verbal memory measured by neuropsychological tests as a mediator between disorganization symptoms of schizophrenia and QoL. Another study found that perception of cognitive problems mediated the relationship between post-traumatic stress disorder and functional outcomes (Samuelson et al., 2017).
The effect of bilateral high frequency repetitive transcranial magnetic stimulation on cognitive functions in schizophrenia
2020, Schizophrenia Research: CognitionCitation Excerpt :Attention is a set of functions that provides recognition of the stimulus (detection), selectively focusing on the stimulus (selective attention), pursuing of attention on the stimulus (sustained attention) and transferring of the stimulus for more advanced processes, and is critically important in information processing (Soysal et al., 2008). Working memory which can be defined as the ability to store and manipulate information online, is a process that underlies several dimensions of cognitive functions such as language comprehension, learning and reasoning (Barr et al., 2013; Sigaudo et al., 2014). Executive functions refer to a set of cognitive processes including attentional control, inhibitory control, working memory, and cognitive flexibility, as well as reasoning, problem solving, and planning that are necessary for the cognitive control of behavior.
Formal thought disorder is related to aberrations in language-related white matter tracts in patients with schizophrenia
2018, Psychiatry Research - Neuroimaging