2024; 22(2): 333-344  https://doi.org/10.9758/cpn.23.1126
Evaluation of the Relationship between Disability and Disease Severity, Cognitive Functions, and Insight in Patients with Schizophrenia
Hatice Ayça Kaloğlu, Şerif Bora Nazlı
Department of Psychiatry, Ankara Etlik City Hospital, Ankara, Turkey
Correspondence to: Hatice Ayça Kaloğlu
Department of Psychiatry, Etlik City Hospital, Halil Sezai Erkut Street, no 5, Yenimahalle, Ankara 06170, Turkey
E-mail: aycakaloglu@gmail.com
ORCID: https://orcid.org/0000-0002-9457-5985
Received: August 18, 2023; Revised: November 27, 2023; Accepted: December 27, 2023; Published online: February 28, 2024.
© The Korean College of Neuropsychopharmacology. All rights reserved.

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Objective: This study aims to examine the clinical characteristics, cognitive functions, and levels of insight, which are thought to be related to disability in schizophrenia patients, and to determine which variable will guide the clinician to predict the disability.
Methods: Participants were 102 individuals with schizophrenia aged 18−60. All participants completed the social functioning scale and the Beck cognitive insight scale. To determine the severity of disability, World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) scale was conducted. Positive and negative syndrome scale, Calgary depression scale for schizophrenia, trail making tests and Stroop test were performed.
Results: The regression analysis indicated that high income, increased education level, and fewer hospitalization variables had significant negative effects (p < 0.05) on the WHODAS overall score, explaining 20.8% of the variance. The duration of trail-making test form A, PANSS total score, and Stroop 3 duration variables had significant positive effects (p < 0.05) on the WHODAS score, explaining 49.3% of the total variance. Increased levels of education, higher income, and higher cognitive insight were found to be associated with less disability. Increased severity of disease and some deterioration in the mental field were found to be related to high disability.
Conclusion: In this research, the predictors of disability in individuals with schizophrenia, level of education, and income are among the predictors of disability, and disease severity seems to be more related to the impairment of cognitive functions. Interventions and treatments that support the psychosocial functionality should be planned rather than symptom-oriented treatment approaches.
Keywords: Schizophrenia; Cognitive functions; Disability evaluation; Stroop test; Trail making test
INTRODUCTION

According to the World Health Organization (WHO), over 21 million individuals worldwide are affected by schizophrenia, which can affect their ability to work, live independently, and develop social communication skills. Therefore, schizophrenia is a significant cause of disability [1]. It is considered among the ten leading causes of disease-related disability around the globe [2].

“Disability,” which includes the sub-dimensions of bodily structure and functions, individual activities, and participation in society, can be roughly defined as “a person’s inability to work due to physical and mental diseases.” Mental disorders cause impaired functionality, but not all mental disorders lead to disability [3-5]. The WHO’s International Classification of Functioning, Disability, and Health–ICF provides a unified and standardized language for defining health, functionality, and disability [6].

Although symptomatic remission was initially the target in the treatment of schizophrenia, the concept of recovery began to be discussed after the 2000s.

Recovery involves the patient’s ability to function normally in all aspects of their life, including work, school, or within the community. Even when the disease is mostly in remission, individuals with schizophrenia can experience deficiencies in their social, professional, and daily activities [7]. While achieving symptomatic remission is a crucial step towards the recovery process, it is insufficient and does not guarantee complete restoration of functionality. Strikingly, it is estimated that at least one-third of individuals with schizophrenia continue to experience complications in adjusting to their psychosocial roles, even if their psychotic symptoms are in remission [8]. Schizophrenia is more than just a clinical entity characterized by delusions, hallucinations, and aggression; it is a disorder that significantly affects many aspects of mental functions. Severe disability can be observed in patients due to its effects on thought structure and process, high cognitive functions, and emotional expression processes. It is known that disability in schizophrenia refers to not only impairments in mental functions but also impairments in various activities and areas of participation [9]. Individuals diagnosed with schizophrenia may experience challenges in family and social relationships, as well as in securing and maintaining employment due to cognitive impairments or perceptual disruptions. Today, the treatment of schizophrenia strives not only for symptom relief but also to provide affected individuals to lead a quality and everyday life within the community with minimal disability despite mental disorders.

Cognition refers to perceiving, paying attention, and remembering information correctly. It is an important concept that enables us to identify and interpret social cues and understand what individuals think and feel. Moreover, social cognition is a concept that must be emphasized in determining disability [10]. Although cognitive functions and social cognition have long been overlooked, they are now considered essential attributes of schizophrenia by many authority figures.

This recognition is well-supported because impairment of cognitive functions is present even before the onset of clinical symptoms. Research indicates that cognitive deficits and executive dysfunctions can be used as markers in predicting the level of disability [11-13].

Another critical concept is insight, defined as the capacity to understand an individual’s problems. It is linked to both prognosis and disability in people with schizophrenia and is just as important as cognitive function [14]. Lack of insight affects 50 to 80% of schizophrenia patients [15]. It is related to the clinical course and severity of the disease, more significant psychosocial dysfunction, lower quality of life, increased requirement for involuntary treatments, and greater aggression. On the other hand, good insight is related to better functionality, better social cohesion, better working performance, and ultimately less disability [14]. Several studies emphasized that higher insight will lead to greater treatment adherence and reduce disability [16,17].

Disability in schizophrenia remains quite limited in some patients; thereby, the person can maintain professional and social roles to a large extent. In some patients, disability is so pronounced that the person may need support and care. Understanding the reasons for the vast variations of disability in people with the same diagnosis will be beneficial in developing therapeutic interventions to preserve functionality. This research aims to examine the clinical characteristics, demographic data, cognitive functions, and levels of insight of the patients, which are thought to be related to disability in schizophrenia patients, and to determine which variable will guide the clinician to predict the disability. Identifying the factors that are most associated with a disability will allow the clinician to intervene early at the initial diagnosis, thus preserving functionality as much as possible.

METHODS

Participants

After receiving the approval, with the decision date and number 21 March 2022 and 133/14, of the clinical research ethics committee from Diskapi Yildirim Beyazit Training and Research Hospital, individuals with schizophrenia who applied to our psychiatry clinic between April 2022 and December 2022 and were within the criteria of inclusion in the research, were included in the research. A total of 102 individuals with schizophrenia were included in the research, and these individuals, who were followed up in our clinic and were diagnosed with schizophrenia according to the Diagnostic and Statistical Manual of Mental Disorders 5th edition criteria, sociodemographic form, Beck cognitive insight scale, Social functionality scale, WHO disability scale 2.0, Positive and negative symptom scale (PANSS), Calgary depression scale were applied, and the trail making test A and B, and Stroop TBAG were also applied.

The study included people between the ages of 18 and 60 who had been diagnosed with schizophrenia. Individuals with schizophrenia over the age of 60 were not included in the study due to possible age-related cognitive impairment. Individuals with schizophrenia who had completed at least 8 years of primary school, and were willing to participate and give their consent are included. The study excluded people with mental retardation, history of substance use. Because of, all these situations can affect the applicability and the results of cognitive batteries. Also individuals who were thought to be unable to adapt to neuropsychological tests due to hearing or vision issues are excluded. For optimal application of cognitive tests, there must be no color blindness or hearing loss. For this reason, individuals who needed hearing aids or had color blindness were excluded from the study.

Method

PANSS, insight and functionality scales were administered to individuals diagnosed with schizophrenia, who met the inclusion criteria and volunteered to participate in the study, by an experienced clinician. Then, the cognitive tests (trail making tests and Stroop test) were administered to the participants by the other researcher who had neuropsychological test battery application training.

Scales Used

Socio-demographic data form

The form containing patients’ age, gender, education, marital status, working status, monthly income, age of onset, duration of illness, treatment and other information about the disease was prepared by the researchers.

Beck Cognitive Insight Scale

The Beck Cognitive Insight Scale, a Likert-type scale based on the cognitive processes of patients and scored from 0 to 3, was developed by Beck and consists of two main dimensions: “self-expression” and “self-confidence.” It consists of 15 items in total. Increased self-expression means increased cognitive insight. The items in the dimension of self-confidence show cognitive distortions. In other words, if self-confidence scores are high, individuals have some erroneous thoughts. The total score of the scale is calculated by subtracting the “self-confidence” score from the “self-expression” score [18]. The Turkish validity and reliability study of the scale was conducted by Aslan et al. [19].

Social Functioning Scale

The Social Functioning Scale (SFS) evaluates the individual’s social role functions and social behaviors in terms of quantity. It was developed by Birchwood et al. [20] in 1990. It is a self-report scale with separate forms for the patient and the patient’s relative, and its scope has been created using psychosocial intervention programs and the disability assessment scale. The scale consists of seven subscales in total: social engagement/social withdrawal, interpersonal functionality, preliminary social activities, leisure activities, independence-competence, independence-performance, and work/profession. I referred to the unpublished thesis. A high score in SFS indicates a positive trend toward functionality. The reliability coefficient of the scale was found to be between 0.70−0.79 in various studies [21].

WHO Disability Assessment Schedule 2.0 (WHODAS 2.0)

This chart, developed by WHO and aimed to measure disability, produces scores specific to six different areas of functionality (cognition, movement, self-care, getting along, life activities, and participation in society). WHODAS 2.0 provides a mutual measurement for the effect of any health condition on functionality and does not target a specific disease. The scale is ideal for evaluating health and disability levels in general and specific populations. In our research, the extended version consisting of 36 items was used. The 36-item extended version includes the clinician, proxy, and self-report forms. In simple scoring of the scale, items are scored between 0 and 4 and then added together [22,23]. Higher scores in WHODAS isassociated with more disability. The Turkish validity and reliability study of the scale was conducted by Aslan Kunt and Dereboy [24]. The studies suggest that general disability scores approaching or exceeding 1.5 points can be interpreted as an indicator of loss of functionality [24].

Calgary Depression Scale for Schizophrenia

The scale was developed by Addington et al. [25] in 1992 to evaluate depression in schizophrenia patients, and the Turkish validity and reliability study was conducted by Aydemir et al. [26]. It is a Likert-type scale and consists of 9 items. The cutoff score of the scale for Turkish is 11/12 [26].

PANSS

The scale, developed by Kay et al. [27] in 1987, consists of 30 items: 7 belong to the positive syndrome subscale, 7 to the negative syndrome subscale, and 16 to the general psychopathology scale. The Turkish validity and reliability study of the scale was conducted by Kostakoğlu et al. [28] in 1999.

Stroop Test TBAG Form

The test uses color naming instead of reading words to examine the ability to neglect confounding stimuli and measures selective attention. Stroop first developed the test. To perform the test, only one visual feature must be selectively processed while others are blocked. The Stroop test consists of four parts: reading the color names written in black, naming the color of colored squares or dots, reading the color names written in different colors, and naming the colors without reading the words written in color. Different forms of the Stroop test are based on the reading color names printed in different colors. The form is named The Stroop Test TBAG Form as a tribute to the Basic Sciences Research Group (TBAG), which supports tubitak’s bilnot battery project. The Stroop Test TBAG form uses the Victorian coloring system and uses yellow, blue, red, and green colors and color names [29-31]. The Stroop test TBAG form is implemented in 5 sections. The time required to complete each section, the number of errors in performing the task, and the number of corrections are noted. Completion time measures selective attention skills, error count working memory, and task completion time under the influence of disrupting Stroop effect measures cognitive processing speed and the ability to suppress/inhibit inappropriate stimuli [32,33].

Trail-Making Test

The test is a widely used, easily applicable executive function measurement test. Through this test, it is possible to evaluate frontal lobe functions by purging factors such as psychomotor speed and ability. Completing the test requires that the visual monitoring and attention functions are intact. Trail-Making Test (TMT), which measures executive functions such as working memory, complex attention, and planning, is a test that requires visual-spatial processing and motor ability. The test consists of two parts, Trail-making form A and B. Errors are recorded in both A and B sections. TMT’s section A evaluates the processing speed based on visual scanning capability, and section B assesses the ability to change the setup between stimulus sets and track succession. The Turkish validity and reliability study for ages between 20 and 49 was conducted by Turkes et al. and for ages 50 and older by Cangöz et al. in 2007 [34-37].

Statistical Analysis

The research data were analyzed using the SPSS 26 program (IBM Co.). Power analysis was performed to determine the sample size. Descriptive findings in the study are given with numbers, percentages, minimum/maximum values, mean, standard deviation, and median values. Whether or not the data for the variables showed a normal distribution according to the skewness and kurtosis values was examined [38]. Non-parametric analysis methods were applied when there were less than 30 groups among the comparison groups in the different analyses. The Kruskal–Wallis test was applied to compare more than two independent groups, multiple comparison tests were performed when significant differences were found. Relationships between variables were evaluated with Pearson or Spearman correlation tests. The study used hierarchical within-block stepwise multiple regression analysis. In the regression analysis, dummy variables were created for the nominal variables. A pvalue of < 0.05 was considered statistically significant in the analyses.

RESULTS

Table 1 lists the sociodemographic and clinical characteristics of the participants. The results reveal that 55.9% (n = 57) of the patients were male, 73.5% (n = 75) were unemployed, 44.1% (n = 45) had an income of less than 5,000 Turkish liras (TL), and 70.6% (n = 72) were single. The results reveal that the mean age of the patients was 38.82 ± 8.66, the mean education period was 11.31 ± 2.89, the mean duration of illness was 149.09 ± 80.93 months, and the mean number of hospitalizations was 2.04 ± 1.97.

When the descriptive findings of the participants for the research scales were analyzed, the mean PANSS total score was 61.92 ± 12.73, the Calgary mean score was 3.13 ± 1.55, the mean score of the Social Functioning Scale was 110.13 ± 28.68, the WHODAS total score average was 1.53 ± 0.51, and the mean of the Beck cognitive insight composite index score was determined to be 0.73 ± 7.37.

Table 2 lists the correlation analysis findings conducted to determine the relationships between the demographic and clinical characteristics of the patients included in the study and the research scales. The findings reveal that there was a negative correlation (p < 0.05) between the education levels (years) of the patients and the PANSS total score, cognitive functions (trail making A and B duration and error scores, Stroop 1−5 durations, Stroop 3 and 5 error scores) and WHODAS disability total score. The study determined a positive (p < 0.05) relationship between the education period of the patients and the social functioning scale total score and Beck cognitive insight composite index score. There were negative significant (p < 0.05) correlations found between patients’ income and PANSS total score, cognitive functions (trail making A and B durations and error scores, Stroop 1−5 duration scores, Stroop 3 and 4 error scores), and WHODAS disability total score. The study determined a positive (p < 0.05) relationship between the income of the patients and the social functioning scale total score and Beck cognitive insight composite index score.

When the correlations between the scales and tests used in our study were examined, there was a positive significant (p < 0.05) relationship between PANSS total score and WHODAS total disability scores and a negative significant (p < 0.05) relationship between PANSS total score and social functionality scale total score and Beck cognitive insight composite index score. We found negatively significant (p < 0.05) correlations between the PANSS total score, the social functionality scale total score, and the Beck cognitive insight composite index score. The study determined that there were positive and significant (p < 0.05) correlations between cognitive dysfunction (tracing A and B errors and the number of tracing B errors, Stroop 1−5 time, Stroop 3−5 errors) and WHODAS total score. The study found a negative significant (p < 0.05) relationship between the WHODAS total score and the Beck cognitive insight composite index score.

The relationship between the social functioning scale, which is based on the patient’s subjective reporting, between disability and insight was examined. The study found a positive and significant (p < 0.05) relationship between the social functioning scale total score and the Beck cognitive insight composite index score. The WHODAS total score and the social functioning scale total score were found to be negatively correlated (p < 0.05).

Table 3 lists the hierarchical regression analysis findings conducted to determine the effect of demographic and clinical characteristics and research scales on patients’ WHODAS total scores. The variables related to the duration of education, income, and number of hospitalizations with the stepwise method in the first block, and the variables related to the research scales with the stepwise method in the second block (PANSS total score, Calgary score, trail-making test A duration, trail-making test B duration, Stroop 1−5 durations, social functioning scale total score, Beck cognitive insight composite index score) were included in the regression model. Dummy variables were created to include the income variable in the analysis. While creating the dummy variable, the “1−5,000 TL” group was used as the reference group.

In the first block of the regression analysis, income of 10,001 TL and above (β = −0.300) and education period (β = −0.200) variables had negatively significant (p < 0.05) effects on the WHODAS total score; furthermore, the number of hospitalizations (β = 0.200) variable was found to have a positive (p < 0.05) effect on the WHODAS total score. The study determined that the variables of 10,001 TL and above, number of hospitalizations, and duration of education related to income explained 20.8% of the variance in the WHODAS total score.

In the second block of the regression analysis, the study found that the variables of trail-making test A Duration (β = 0.232), PANSS total score (β = 0.384), and Stroop 3 duration (β = 0.223) had positive and significant (p < 0.05) effects on the WHODAS total score. We determined that the variables of trail-making test A duration, PANSS total score, and Stroop 3 duration contributed 28.5% to explaining the variance in the WHODAS total score, and the total explained variance was 49.3%.

DISCUSSION

Understanding the factors that predict disability in schizophrenia is essential for the prognosis of the disease. Identification of disability factors in the early stages of the disease and appropriate interventions may enable the reduction of disability. Regression analysis revealed that high income, increased education level, and fewer hospitalization variables had significant negative effects (p < 0.05) on the WHODAS total score, explaining 20.8% of the variance. Moreover, the duration of trail-making test form A, PANSS total score, and Stroop 3 duration variables had significant positive effects (p < 0.05) on the WHODAS total score, explaining 49.3% of the variance. It was determined that there was a significant and negative (p < 0.05) relationship between the Beck Cognitive Insight Scale combined index score and WHODAS. Results suggested that higher levels of education, income, and cognitive insight were associated with less disability. In contrast, increased disease severity, cognitive deterioration, and more frequent hospitalization were linked with higher disability.

A previous research by Chen et al. [39] also found that low education level was associated with lower ability, consistent with our research. In the same research, unemployment was also found to be associated with more disability. In our research, the low income level of the patients was found to be associated with more disabilities. The low-income level is likely due to the patient not having a regular job; in this sense, our finding is consistent with the literature.

Our research has revealed that higher-income patients tend to have better social functionality, cognitive insight, and cognitive capacity. This is because, with higher income, individuals can access healthcare services more efficiently and receive more regular treatment. Further-more, our research has shown that higher levels of education are associated with better cognitive test performance, improved social functioning, and higher cognitive insight. This is consistent with previous studies that have also suggested a positive correlation between education levels and social functioning in schizophrenia patients [40].

The increase in the total score of PANSS leads to a decrease in the social functioning and cognitive insight scores while increasing the WHODAS score. This means more severe disability is associated with lower insight and social functioning and more severe disability. In a previous study to predict disability, negative symptoms, low level of insight, and low compliance with the treatment were found to explain 54.2% of the variance in disability [14]. In 1-year monitoring research with patients who had their first onset of psychosis, the level of insight and negative symptoms (especially social isolation) were found to be the most significant indicators of prognosis for functionality [41]. Contrary to the current studies [14,42], which found that negative symptoms were more predictive in predicting disability, our research found that disability increases as the total score of PANSS increases.

Moreover, our research found that as the severity of the disease determined by PANSS increased, social functionality and cognitive insight scores decreased. Several studies in the literature, consistent with our findings, have shown an inverse relationship between psychopathology and insight. Insight decreases as the severity of the disease increases [43-45].

In our research, the increase in the Beck cognitive insight score was found to be correlated with higher social functionality. Both high social functioning and increased insight were associated with lower disability. The relationship between schizophrenia and cognitive insight is a subject that has been studied extensively in recent years. Insight is crucial in determining functional outcomes in schizophrenia [46]. Beck et al. [47] suggest that insight plays a crucial role in improving patients’ compliance with antipsychotic medication, increasing their perception of the need for the medication. On the other hand, the lack of insight is often related to poor compliance with medication, worse therapeutic relationships, increased chances of recurrence, and worse outcomes.

Insight not only affects the prognosis negatively by disrupting compliance with treatment and may impair recovery, as insufficient awareness of the disease will prevent attitudes of the individual, such as hope and effort, required for recovery. Deficient insight is known to cause aggravation of the clinical course of the disease, more psychosocial dysfunction, lower quality of life, and more aggression [48,49]. Numerous studies support the notion that higher insight is related to less disability and better functionality, consistent with our research findings [15-17]. Some researchers have found that diminished insight due to schizophrenia is associated with impaired executive functions [50], while some researchers argue that both cognitive impairment and social cognition factors can affect insight [51]. In our research, consistent with previous studies, increased cognitive insight was associated with lower disability and higher social functionality.

Our research has revealed that impairment in cognitive functions was associated with more significant disability. This relationship is shown both by the completion and error counts of the trail-making forms A and B and by the completion time of the five factors of the Stroop test and the number of errors made. In this context, it can be concluded that deterioration in many metacognitive functions such as selective attention, cognitive processing speed, completing the task under disruptive influence, suppressing inappropriate stimuli, visual scanning, switching sets, and tracking succession affect impairment. In our research, although the relationship between the duration of completion of the trail-making test form A and the duration of Stroop test 3 with disability seemed more significant, it was seen that the deterioration correlated with disability in all cognitive tests.

Repeated studies have shown that cognitive functions are an essential determinant of psychosocial functioning in patients with schizophrenia [1]. In research, cognitive dysfunctions and negative symptoms were found to be the most consistent predictors of disability [52]. The increase in patients’ psychosocial functioning is associated with cognitive symptoms rather than improvement of psychotic symptoms [53-56]. It has been reported that improving cognitive functions increases the psychosocial functionality and autonomy of the patient [45]. Deterioration in executive functions has been found to predict functionality in patients with chronic schizophrenia in remission [57]. During the 10-month follow-up of 127 schizophrenia patients, assessments of cognitive functions were found to predict patients’ functioning at home, at school, or in their work lives [58]. Evidence supports higher independent living and occupational performance in patients with preserved executive functions [59]. Consistent with the literature, this study has shown that better cognitive functions are associated with less disability and loss of functionality.

As in our study, executive dysfunction has been previously shown to be associated with low cognitive insight [60]. More cognitive impairments have been reported to be associated with poor functionality and insight [61]. Some researchers argue that the relationship between executive functions and patient insight may be due to standard neurobiological foundations [62].

Similar to our study, in a study conducted by Escobedo-Aedo et al. [63], evaluating the general functionality level, disability, and their predictors in 77 schizophrenia patients, being younger, working, better pre-morbid adjustment, lower disease severity, better cognitive performance, higher cognitive and clinical insight levels were associated with higher functionality level and less disability in schizophrenia patients. The relationship between the deterioration in cognitive functions and the deterioration in psychosocial functionality is also demonstrated in our study. Cognitive impairment, also present at the onset of the disease, may directly affect functionality. Also, insight may remain diminished in the patient due to impairments in higher cognitive functions such as executive functions and judgment. Since diminished insight will cause diminished adherence to treatment, it can be stated that cognitive impairment indirectly causes deterioration and disability in psychosocial functioning. It still needs to be fully understood in which area the deficiency and deterioration trigger the deterioration in other areas. Further research is required in this area.

Our study found no significant relationship between patients’ self-reported social functionality measurements and predicting their disability. In the literature, some studies found that subjective functionality reporting is the strongest predictor in assessing disability [64]. Moreover, recent evidence has begun to show that not only neurocognitive processes but also social cognition are associated with disability due to schizophrenia. A recent study has shown that different impairments in neurocognition and social cognition predict different areas of functionality in patients with schizophrenia [65]. A previous study aimed to identify the predictors of disability due to schizophrenia found that cognitive performance affected functionality through social cognition and insight. Social cognition has been shown to affect functionality through negative symptoms. As a result, it was concluded that both cognitive functions and social cognition negatively affect the patient’s functionality by causing a deterioration in negative symptoms and insight [42]. This may be attributed to the SFS being a quantitative self-report scale.

Current studies in the literature examining disability in patients with schizophrenia have focused on regional clinical methods or therapeutic assistance. Our study is one of the very few studies that evaluates all clinical and demographic characteristics of individuals with schizophrenia, aims to determine therapeutic treatments and insight levels separately, and which features are more effective in the treatment of disability. In this context, we can emphasize the superiority of our study in examining disability in schizophrenia patients. Another superiority and dissimilarity of our study is the use of WHODAS, a relatively new and comprehensive scale in the assessment of disability in patients with schizophrenia. The most comprehensive form of the WHODAS disability scale was used.

Taken together, this study evaluated the predictors of disability in individuals with schizophrenia; level of education and income are among the predictors of disability, and disease severity seems to be more related to the impairment of cognitive functions. To reduce disability in individuals with schizophrenia, clinicians need to address the issue from a broader perspective, and treatments that support the psychosocial functionality of patients should be planned rather than symptom-oriented treatment approaches. The interventions to be made before the deterioration of functionality will undoubtedly prevent the development of disability. In this context, estimating which symptoms predict disability and identifying more risky patient groups for the development of disability at an early stage may be of critical benefit for early intervention.

Limitations and Recommendation for Further Studies

Our research has some limitations. One of these limitations is that research is needed on the social cognitions of the participants in our study. There has previously been a comprehensive study by Oh et al. [66] on the important role of social cognition in predicting functioning in individuals with schizophrenia. Also, no classification was made according to the antipsychotic groups and antipsychotic doses used by the patients, and the possible effects of drug groups on cognitive functions were not examined. There are also difficulties arising from the nature of cognitive functions and neuropsychological tests. Since cognitive functions involve the interaction of various functions simultaneously, it is impossible to isolate a single cognitive component. None of the neuropsycholo-gical tests that were used in our study are unique tests developed for use in schizophrenia patients. New neuropsychological tests with high sensitivity for people with schizophrenia allow cognitive functions to be examined in a more isolated way, and studies evaluating the social cognition component can lead to more accurate results.

In this area, there is a need for studies with larger samples and more specific neuropsychological tests that will also address the social cognitive disorders of the disease. It should be kept in mind that early intervention in disability is a very critical point in terms of the prognosis of the disease.

Funding

None.

Conflicts of Interest

No potential conflict of interest relevant to this article was reported.

Author Contributions

Conceptualization: Hatice Ayça Kaloğlu. Data acquisition: Hatice Ayça Kaloğlu, Şerif Bora Nazlı. Formal analysis: Hatice Ayça Kaloğlu, Şerif Bora Nazlı. Supervision: Şerif Bora Nazlı. Writing—original draft: Hatice Ayça Kaloğlu. Writing—review & editing: Hatice Ayça Kaloğlu, Şerif Bora Nazlı.

Tables

Sociodemografic variables and clinical characteristics of the participants

Sociodemografic variables and clinical characteristics Value
Sex Female 45 (44.1)
Male 57 (55.9)
Working status Employed 24 (23.5)
Unemployed 75 (73.5)
Retired 3 (2.9)
Monthly income 1−5,000 TL 45 (44.1)
5,001−10,000 TL 35 (34.3)
Over 10,000 TL 22 (21.6)
Marital status Married 26 (25.5)
Single 72 (70.6)
Divorced 4 (3.9)
Age (yr) 38.82 ± 8.66
Education (yr) 11.31 ± 2.89

Values are presented as number (%) or mean ± standard deviation.

TL, Turkish liras.

Correlation analysis findings between demographic and clinical characteristics and research scales

Variables Education (yr) Income The duration of illness Number of hospitalization
PANSS total score r −0.305 −0.391 0.064 0.293
p 0.002* 0.000* 0.520 0.003*
TMT-A duration r −0.263 −0.333 0.030 0.103
p 0.008* 0.001* 0.764 0.304
TMT-A error r −0.290 −0.233 −0.093 0.070
p 0.003* 0.018* 0.350 0.486
TMT-B duration r −0.298 −0.283 −0.001 0.130
p 0.002* 0.004* 0.994 0.192
TMT-B error r −0.302 −0.212 −0.027 0.079
p 0.002* 0.033* 0.788 0.432
Stroop 1 duration r −0.331 −0.279 −0.069 −0.097
p 0.001* 0.004* 0.492 0.330
Stroop 2 duration r −0.229 −0.281 −0.073 −0.076
p 0.020* 0.004* 0.465 0.448
p 0.782 0.297 0.489 0.689
Stroop 3 duration r −0.301 −0.294 −0.045 0.082
p 0.002* 0.003* 0.651 0.413
Stroop 3 error r −0.219 −0.227 −0.047 0.030
p 0.027* 0.022* 0.639 0.762
Stroop 4 duration r −0.350 −0.334 0.002 0.123
p 0.000* 0.001* 0.986 0.219
Stroop 5 duration r −0.276 −0.249 0.003 0.007
p 0.005* 0.011* 0.977 0.941
Stroop 5 error r −0.267 −0.165 −0.012 0.175
p 0.007* 0.097 0.902 0.079
Social functioning scale r 0.247 0.407 0.012 −0.168
p 0.012* 0.000* 0.902 0.092
WHODAS total score r −0.298 −0.317 0.078 0.212
p 0.002* 0.001* 0.436 0.033*
Beck cognitive insight score r 0.281 0.216 −0.021 −0.038
p 0.004* 0.030* 0.832 0.705

PANSS, positive and negative syndrome scale; TMT, Trail-Making Test; WHODAS, World Health Organization Disability Assessment Schedule 2.0.

*p < 0.05 was considered statistically significant.

Results of regression analysis

Variables β R R2 F pvalue
Monthly income (10,001 TL or more)a −0.300* 0.456 0.208 8.584 < 0.001
Number of hospitalization 0.200*
Education (yr) −0.200*
Trail-making A duration 0.232* 0.702 0.493 15.412 < 0.001
PANSS total score 0.384*
Stroop 3 duration 0.223*

PANSS, positive and negative syndrome scale; WHODAS, World Health Organization Disability Assessment Schedule 2.0; TL, Turkish liras.

β: standardized regression coefficient a measure for linear regression models. R: a statistical measure that evaluate the performance of the model in regression analysis. R2: a measure for linear regression models.

aReference: 1−5,000 TL.

The dependent variable: WHODAS total score.

*p < 0.05

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