|Year : 2016 | Volume
| Issue : 4 | Page : 457-464
A cross-sectional study of cognitive functions and disability in schizophrenia from a tertiary care hospital in North India
Meha Jain1, Shweta Singh2, Pronob Kumar Dalal2, Anil Nischal2, Adarsh Tripathi2, Sujita Kumar Kar2
1 Department of Pediatrics, Integral Institute of Medical Sciences and Research, Lucknow, Uttar Pradesh, India
2 Department of Psychiatry, King George's Medical University, Lucknow, Uttar Pradesh, India
|Date of Web Publication||12-Jul-2016|
Department of Pediatrics, Integral Institute of Medical Sciences and Research, Lucknow - 226 003, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Background: Cognitive functions are important predictors of day to day functioning. Cognitive functions are significantly affected in schizophrenia and various other psychiatric disorders. There are very few Indian studies studying the relationship between cognitive functions and disability. Aims and Objectives: The purpose of the present study was to assess the cognitive functions in stable patients of schizophrenia and compare them with normal controls and also to study the relationship between cognition and disability in these patients. Materials and Methods: Thirty stable patients of schizophrenia attending psychiatry outpatient clinic of a Tertiary Care Hospital of North India were included in the study. Thirty healthy volunteers with no psychiatric illness matched for age, gender, and education were also included cognitive functions were assessed using Brief Assessment of Cognition in Schizophrenia and disability was assessed using WHO Disability Assessment Schedule 2.0 (WHODAS 2.0). Results: Highly significant difference (P < 0.0001) was found between the cognitive functions of the schizophrenia group and healthy control group. The patients of schizophrenia had a maximum disability in the area of life activities followed by participation and cognition. There existed a significant negative correlation between cognition and mobility (r = −0.45, P < 0.05), getting along with people (r = −0.44, P < 0.05), life activities (r = −0.42, P < 0.05), participation (r = −0.39, P ≤ 0.05), and total scores on WHODAS 2.0 (r = −0.48, P ≤ 0.05). Conclusion: Cognitive functions are an important predictor of disability. Cognitive deficits exist even in the stable patients of schizophrenia which is significantly higher than the healthy group.
Keywords: Brief Assessment of Cognition in Schizophrenia, cognitive function, cognitive functions and disability, disability, schizophrenia
|How to cite this article:|
Jain M, Singh S, Dalal PK, Nischal A, Tripathi A, Kar SK. A cross-sectional study of cognitive functions and disability in schizophrenia from a tertiary care hospital in North India. Med J DY Patil Univ 2016;9:457-64
|How to cite this URL:|
Jain M, Singh S, Dalal PK, Nischal A, Tripathi A, Kar SK. A cross-sectional study of cognitive functions and disability in schizophrenia from a tertiary care hospital in North India. Med J DY Patil Univ [serial online] 2016 [cited 2021 Apr 20];9:457-64. Available from: https://www.mjdrdypu.org/text.asp?2016/9/4/457/186056
| Introduction|| |
Schizophrenia is a devastating psychiatric disorder with symptoms broadly characterized as positive symptoms and negative symptoms. The positive symptoms include hallucinations, delusions, and disorganized speech whereas the negative symptoms predominantly describe apathy, avolition, and poverty of speech.
Recently, the focus has shifted to Kraeplin's view of cognitive impairment in patients of schizophrenia as it is a possible causal risk factor for psychosis, representing a third group of symptoms.
Cognitive functions are required to perform in the spheres of personal, social, and occupational activities of everyday life. Broadly, cognition can be divided into two broad categories: Neurocognition and social cognition. The main neurocognitive functions are information processing, attention, executive functions, comprehension, learning, and memory. Social cognition includes those set of cognitive processes involved in interaction with the social world. Cognitive functions are responsible for better day to day functioning and are related to functioning impairment in everyday living skills; hence by improving cognition, patient's functioning in everyday living skills may improve, giving them a better chance of vocational and independent living success. Thus, cognitive functions responsible for mediation of these disabilities are identified and targeted for cognitive remediation; the effectiveness of cognitive remediation to improve functioning will be enhanced.
So far the studies assessing cognition in India have either used lengthy assessment tools  or have assessed only a particular area of cognition. Brief Assessment of Cognition in Schizophrenia (BACS) is a brief assessment tool which takes around 20 min, measures all the domains of cognition which tend to be impaired in schizophrenia and has been found to be as reliable as lengthy measures of cognition. Indian studies using tools such as BACS are scanty.
Disability is “any restriction or lack (resulting from any impairment) of ability to perform an activity in the manner or within the range considered normal for a human being,” (WHO). Disabilities include poor self-care, inability to manage the tasks of daily living, social withdrawal, poor functioning in affinitive roles, and work incapacity. Disability in schizophrenia is said to be contributed by its positive and negative symptoms, cognitive deficits, and soft neurological signs.
Very few studies in India have assessed the relationship between impaired cognitive function and disability of patients with schizophrenia.,, Evidence are able to find a link between cognitive domains and functioning, but the research has yet to establish an underlying gold-standard cognitive substrate connected to disability and its areas due to which the nature of the relationship between cognitive function and disability is still unclear. Hence, the present study was planned to assess the cognition of schizophrenia using BACS and to study the relationship between cognition and disability.
| Materials and Methods|| |
The aim of the present study was to assess the cognition of schizophrenia using BACS compare them with healthy controls and to study the relationship between cognition and disability in these patients.
The study had been conducted between September 01, 2013 and March 15, 2014, in the Department of Psychiatry, King George's Medical University, Lucknow, India. Written informed consent was obtained from all subjects involved in the study. The study was approved by Institutions Ethics Committee.
A total of 30 case wise patients with schizophrenia and 30 healthy controls were recruited into the study. Subjects between 18 and 45 years with a minimum of 8 years of formal education and willing to give informed consent were included in the study. The patients diagnosed with schizophrenia according to International Classification of Disease Diagnostic Criteria for Research (ICD-10 DCR) criteria, stable on the same medication(s) for at least 3 months and had Positive and Negative Syndrome Scale (PANSS) score of (at the time of assessment) <70, with <4 score in the areas of delusions, hallucinations, grandiosity, suspiciousness/persecution, conceptual disorganization, hostility, and unusual thought content were considered. Those patients fulfilling current or lifetime ICD-10 DCR criteria of any other psychiatric disorder were excluded from the study. Subjects with ICD-10 DCR criteria of current or lifetime psychoactive substance use (except nicotine), a severe physical disorder, neurological disorder or symptoms, with history of receiving electroconvulsive therapy in last 6 months, and currently on medications affecting cognitions such as tricyclic antidepressants, antiepileptics, lithium, and anti-dementia drugs were excluded from the study. All patients were on second generation antipsychotics alone or in combination. Few patients were on trihexyphenidyl for extrapyramidal side effects.
The control group was selected from family members of patients with medical disorder, staff employees, and from healthy volunteers fulfilling the selection criteria. The family members of patients with schizophrenia and other psychiatric disorders were excluded as there is the likelihood of genetic-mediated impairment of cognition. They were group matched for age, gender and education.
All patients with schizophrenia attending adult psychiatry outpatients were screened on selection criteria. Diagnosis of schizophrenia was confirmed as per ICD-10 DCR. Their sociodemographic and historical details were recorded on the semi-structured proforma. Mini International Neuropsychiatric Interview was administered to rule out any other co-morbid psychiatric disorder. Standard progressive matrices (SPM) were administered to assess for current level of intellectual functioning. As in our study protocol, we had excluded individuals with an intellectual disability; SPM was used as a screening tool to rule out intellectual disability. Patients taking benzodiazepines were advised to not to take their medication 8 h prior to the assessment. BACS was applied to assess for cognition and World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) was administered to assess for disability.
For controls, General Health Questionnaire-12 was administered to rule out the presence of any psychiatric disorder. Eligible subjects were selected on the basis of inclusion and exclusion criteria. Consent was taken from the subjects. Their sociodemographic and historical details were recorded on the semi-structured proforma. Same tests as the schizophrenia group were then applied to the control group.
Semi-structured proforma for sociodemographic and clinical details
Specifically designed semi-structured proforma was used to record the sociodemographic data, chief complaints, history of present illness, past history, family history, personal history, premorbid personality, medical history, physical examination, mental status examination, and diagnosis.
Brief assessment of cognition in schizophrenia 
The BACS assesses verbal memory, working memory, motor speed, verbal fluency, attention, and executive function. The BACS is fully portable and is designed to be easily administered by a variety of testers, including nurses, clinicians, psychiatrists, neurologists, social workers, and other mental health personnel. The time required for the testing with the BACS is only approximately 30 min with minimal extra time for scoring and training demands. The BACS has been shown to be reliable, valid and practical. The validated Hindi translation of the BACS was used after personal communication from the developer of BACS. The above mentioned five cognitive domains were assessed by six cognitive tasks and individual z-scores of all six tasks were added up to give rise to the composite score.
WHO Disability Assessment Schedule 2.0 (WHODAS 2.0)
The WHODAS 2.0 captures the level of functioning in six domains of life: Cognition, mobility, self-care, getting along, life activities, and participation. These questions relate to functioning difficulties experienced by the respondent in the six domains of life during the previous 30 days. Test-retest reliability has an intraclass coefficient of 0.69-0.89 at item level; 0.93-0.96 at domain level; and 0.98 at an overall level. In terms of face validity — that is, the indicators that show that the instrument measures what it is intended to measure −64% of the experts agreed that the WHODAS 2.0 content measures disability as defined by the International Classification of Functioning (ICF), Disability and Health ICF. The interview-administered version of WHODAS was used which was translated to Hindi by the examiner.
The data had parametric distribution. It was summarized as mean ± standard deviation. Groups were compared by independent samples Student's t-test. Categorical groups were compared by Chi-square (χ2) test. A two-tailed (α = 2) P< 0.05 was considered statistically significant. Pearson's correlation was applied for seeing the correlation between two variables.
The data were tabulated using Microsoft Excel 2010 software by Microsoft Corpn. Statistical analyses were performed on Statistical Package for Social Sciences (SPSS) version 16.0 by IBM.
| Results|| |
A maximum number of patients was in the age group of 26-35 years (53.33%) with a mean age of 29.87 years. More than two-thirds of the study population were males (83.33%). The majority of the subjects in the schizophrenia group were Hindu (93.3%), unmarried (66.67%), belonged to nuclear family (73.33%), with a rural background (56.67%), and were unemployed (40%). Most of them were either unemployed (40%) or engaged in semi-skilled occupation (30%). Only 20% were doing the skilled job. The schizophrenia group and the control group belonged to a comparable sociodemographic background. The difference in the two groups was not statistically different so these factors may not influence the study outcome measures.
[Table 1] shows the comparison of the study group and the control group on various demographic parameters. As depicted in the [Table 1] the study group and control group had no statistically significant differences on sociodemographic details and hence were comparable.
|Table 1: Sociodemographic details comparing the study group and the control group|
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The mean duration of illness was 6.99 ± 5.01 years in the schizophrenia group. The majority fell in the range of 0-5 years (43.33) of the duration of illness. 33.33% fell in the range of 5-10 years. Though majority fell in the ranges of more than 5 years but more than 50% fell in the range of 0-10 years so the mean duration of illness was 6.99 years.
The mean PANSS score was 8.13 on the positive scale, 11.27 on the negative scale, and 20.37 on the General Psychopathology Scale (GPS).
Comparison of cognition according to BACS scores between the schizophrenia and control groups is shown in [Table 2] and [Figure 1].
|Table 2: Comparison of cognition as per BACS scores between the two groups|
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|Figure 1: Comparison of means on Brief Assessment of Cognition in Schizophrenia of schizophrenia group and control group|
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WHODAS 2.0 was applied to the schizophrenia group and it was seen that the maximum disability was in the area of life activities (20.80 ± 9.68) followed by participation (14.57 ± 6.03) and cognition (10.11 ± 3.84). Disability was not found in the areas of self-care (6.97 ± 2.87), mobility (4.77 ± 1.33), and getting along with people (6.97 ± 2.79).
[Table 3] shows that there exists a significant negative correlation between z-score on BACS and mobility, getting along with people, life activities, participation, and total score on WHODAS 2.0.
|Table 3: Correlations between cognition (BACS Z-score) and disability (WHODAS 2.0 domain scores)|
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[Table 4] shows that there exists a significant negative correlation between z-score on BACS and GPS on PANSS score.
|Table 4: Correlations between cognition (BACS z-score) and other variables|
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[Table 5] shows that there exists a significant positive correlation between total WHODAS 2.0 scores and score on GPS on PANSS score.
|Table 5: Correlations between disability (total WHODAS 2.0 scores) and other variables|
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The correlation analysis revealed a significant and negative correlation between WHODAS 2.0 total score and BACS z-score (r = −0.48, P< 0.05) and positive correlation between WHODAS 2.0 total score and GPS of PANSS score (r = 0.39, P< 0.05). Further, regression analysis revealed that cognition, as measured by BACS, may estimate disability with 20% coefficient of determination (R2 = 0.203, P< 0.05).
| Discussion|| |
The present study assessed the cognitive functions in stable patients of schizophrenia and compared it with healthy controls. This study also attempted to study the relationship between cognitive functions and disability in these patients. Patients and controls had to satisfy rigorous selection criteria for entering the study. They were all matched for age, gender and education status so that the confounding factors for assessment of cognition may be minimized.
The schizophrenia group and the control group belonged to a comparable sociodemographic background. The difference in the two groups was not statistically different so these factors may not influence the study outcome measures.
It was seen that the patients of schizophrenia had persistent cognitive deficits in all the domains, i.e., verbal memory, working memory, motor speed, verbal fluency, attention, and executive function even during the stable phase. When compared with the healthy controls highly significant difference (P< 0.0001) had been found in the cognition of both groups.
Our findings are similar to the findings of other studies that demonstrated the presence of cognitive deficits in patients with schizophrenia on most domains tested, including attention, vigilance, immediate memory, working memory, delayed memory, and executive function.,
In a study, it was found that patients with schizophrenia perform poorly in the areas of processing speed, verbal working memory, and visual working memory.
A study by Srinivasan and Tirupati compared the cognitive functioning of 100 symptomatic subjects with chronic schizophrenia with an equal number of healthy controls and found that people with schizophrenia performed worse on all cognitive tests involving memory, attention, and executive function.
The results suggest that the patients had more disability in the areas of life activities, participation and cognition as compared to self-care, mobility, and getting along with people.
The maximum disability was in the area of life activities. The items on life activities include both household activities and work activities. In this study, most of the patients were unemployed (40%) thus a high score on this item. Furthermore, the informants were able to respond more precisely to the questions on the area of life activities, as it was more objective and less hypothetical. Possibly, loss or lack of gainful activity could have been perceived as more disabling than deficiencies in certain other activities such as communication, self-care, etc.
Thara and Rajkumar found that the 3 years course of disability tended to be stable without any fluctuations and that the highest disability was in the area of occupational functioning.
The next disabling area was participation. The items on participation talk about what the patient thinks about the society's perception of their illness and about the effect of their illness on their family. Most of the patients in the present study were from the rural background (56.67%) where mental illness is still stigmatized, and such persons were perceived differently by the society. Because of this, there were high scores in this area.
Cognition was also found to be disabling to the patients of schizophrenia. It was seen that the patients were finding difficulties in attention and concentration, problem-solving and memory which in turn was causing problems in their day-to-day activities thus a high score in this area.
Disability was not found in the areas of self-care, mobility, and getting along with people. It could be because the patients taken in this study were stable on medications for 3 months and having a total PANSS score of <70 and <4 score: Delusions, hallucinations, grandiosity, suspiciousness/persecution, conceptual disorganization, hostility, and unusual thought content. As the symptoms were minimal, so the patients were able to take care of themselves and perform daily chores but still not be able to go for work and perform difficult tasks.
Relationship between cognitive impairment, disability, and symptomatology
A significant negative correlation was found between z-score on BACS and mobility (r = −0.45, P< 0.05), getting along with people (r = −0.44, P< 0.05), life activities (r = −0.42, P< 0.05), participation (r = −0.39, P ≤ 0.05), and total on WHODAS 2.0 (r = −0.48, P ≤ 0.05). This suggests that decrease in cognitive function would increase the disability in the areas of mobility, getting along with people, life activities and participation, and total disability.
Impairment in the areas of verbal memory, working memory, motor speed, verbal fluency, attention, and executive functioning were related to the impairment of everyday situations such as keeping track of scheduling and planning, problem-solving which in turn causes impairment in life activities. The patients with schizophrenia had deficits in verbal fluency, which causes difficulty in communication thus leading to difficulty in making friends and keeping the friendship.
Schmitter-Edgecombe et al., 2012 in their study found that individuals with mild cognitive impairment show deficits in everyday living. In another study by Velligan et al., 1997, they found that measures if cognitive functioning accounted for more than 40% variances in activities of daily living. Cognitive functioning correlates with work outcomes such as employment status and work duration as found in studies.,
It was also seen that there was no significant relationship between cognition on BACS and cognition on WHODAS 2.0. This indicates that there exists a difference in subjective and objective assessment of cognition. Leifker et al., also reported that when everyday functioning is rated by an observer clinician, the correlations with cognition are higher than when patients self-report their functioning. In another study, using a self-report instrument for assessment of disability in patients with schizophrenia, the World Health Organization Disability Assessment Schedule, found that clinician ratings of symptoms, cognitive performance scores, and performance on the UCSD Performance-Based Skills Assessment were all generally unrelated to self-reported disability.
It was also seen that there exists a significant negative correlation between z-score on BACS and scores on GPS on PANSS score (r = −0.37, P ≤ 0.05). This suggests that with an increase in score on GPS there will be a decrease in cognition. GPS includes items on depression, anxiety, tension, poor attention, insight, abstract thinking, etc., which results in low motivation and energy thus resulting in low scores on cognition.
A significant positive correlation between total WHODAS 2.0 scores and GPS on PANSS score (r = 0.39, P ≤ 0.05) was found in the study. This suggests that with an increase in score on GPS there will be an increase in disability. An increase in score on GPS shows an increase in symptomatology which will in turn cause impairment in household and work activities, self-care, and cognition thus leading to increase in disability.
Chaudhury et al., 2006, in their study, measured the relation of disability on the Indian Disability Evaluation Assessment Scale (IDEAS) to the severity of illness as measured by PANSS score. It was seen that there is a strong positive correlation with IDEAS global score (IDEAS-GS) on all the three components of the PANSS score. The correlation between the general psychopathology scores and IDEAS-GS was also highly significant (r = 0.518, P< 0.01).
The correlation analysis had revealed a significant and negative correlation between Disability Assessment Schedule (DAS) total score and BACS z-score (r = −0.48, P< 0.05) and positive correlation between DAS total score and score on GPS of PANSS score (r = 0.39, P< 0.05). This suggests that with a decrease in cognition there will be an increase in disability and with an increase in score on GPS there will be an increase in disability. Further, regression analysis revealed that cognition, as measured by BACS, may estimate disability with 20% coefficient of determination.
Cognition is one of the basic requirements for an individual's functioning. It further implies that remediation for cognitive function in schizophrenia can lead to improvements, not only in cognition and symptoms but also in disability. Intervention studies, primarily of cognitive remediation, also have shown that some executive and memory improvements are associated with subsequent daily functioning.,
The treatment goal is to improve the overall functioning of patients with schizophrenia. It is, therefore, important to study the complex relationship of disability with psychopathology and cognitive functions. By understanding which cognitive function influences which domain of disability, focused cognitive remediation therapy can be designed to target a particular function. As cognitive function was found to be significantly associated with disability, improvement in cognitive function could lead to a reduction in disability.
The study had a small sample size which was because of constraints of time and stringent selection criteria. The study is a cross-sectional study. To further clarify the relationship between cognition and disability longitudinal studies are needed. Antipsychotics and drugs like trihexyphenidyl are known to affect cognition, but it is unethical to keep the patient without drug or not to treat the side effects of antipsychotics. Hence medications were continued. It is another limitation of the study.
The patients included were stable having a PANSS score of <70 and were stable on regular medications. This group represents only a part of all schizophrenia cases in the community, making it difficult to generalize results to the population.
Despite above limitations, the present study has strengths when compared to many other studies in this area. The selection criteria were stringent which ensured exclusion of those who would have possible reasons for their cognitive deficits other than the illness. The age, gender, and education matching was done. Many confounding factors such as age, gender, significant physical illness, other psychiatric disorders, substance use, and medications affecting cognition were taken care of thus enabling the maximum attribution the results to the illness. The tools used in were also standardized having well-established norms, reliability, and validity.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]