Introduction
Disability associated with mental illness is a major contributor to the global burden of disease. The present study looks at some aspects of disability and quality of life attributable to various six common mental disorders: dementia, schizophrenia, major depression, bipolar affective disorder, generalized anxiety disorder and obsessive-compulsive disorder.
The objectives of this study were to evaluate disability in dementia, schizophrenia, major depressive disorder, bipolar affective disorder, generalized anxiety disorder and obsessive compulsive disorder, and to compare the degree of disability with the severity of illness and quality of life among various disorders.
Methods
Adult patients (≥ 18 years) using services of a major mental health hospital in Al Qassim, between January–June 2008, who were diagnosed as per ICD-10 criteria of mental and behavioral disorders, were included in the study. Patients with mental retardation, chronic debilitating illness, substance abuse disorder, psychiatric co-morbidity and organic brain disease other than dementia were excluded.
The tools used in this study included Mini Mental State Examination (MMSE) for dementia, Positive and Negative Symptoms Scale (PANSS) for schizophrenia, Hamilton’s Rating Scale (HAM) for depression and anxiety, Young Mania Rating Scale (YMRS) and HAM for bipolar affective disorders (BAD) and Yale Brown Obsessive Scale (Y-BOCS) for obsessive compulsive disorder. The measurement of quality of life was carried out using SF-36 questionnaire. Disability was measured using the World Health Organization Disability Assessment Schedule (version 2.0) (WHO/ DAS II). Data were analyzed using the Statistical Package for the Social Sciences (SPSS, 2002). Patients were counseled to be a part of the study and written consent was obtained from them or their responsible persons.
Results
Out of a total of 196 patients, 109 were male and 87 female. These included 24 patients (12.2%) with diagnosis of dementia; 52 (26.5%) with schizophrenia; 32 (16.3%) with major depressive disorder (MDD); 18 (9.2%) with bipolar affective disorder; 43 (21.9%) with generalized anxiety disorder (GAD); and 27 (13.8%) with obsessive compulsive disorder (OCD). A majority of patients in all diagnostic groups except GAD were male. Patients suffering from dementia or schizophrenia had extreme disability as per the WHO/DAS II (70.8% and 51.9%), followed by BAD (16.3%) and MDD (9.2%). GAD and OCD patients had no proportion of patients with extreme disability. Comparison of disability in various disorders indicates that dementia is the most disabling of the mental disorders, followed by schizophrenia. MDD and BAD disorders are the next two disability causing disorders in order of their degree of disability caused. GAD and OCD disorders cause the least amount of disability. Dementia, schizophrenia, MDD and BAD showed low quality of life especially in the mental component summary of the SF-36 but GAD and OCD showed better quality of life. Correlation tests showed a correlation between disorder disability as measured by WHO/DAS II and the quality of life as measured by SF-36 for each disorder. Correlation between illness severity, disability and quality of life are as follows: a) dementia: relation of MMSE scores to cognitive deterioration is negative. The same is reflected in the correlation tests between MMSE scores and WHO/DAS II as well as between MMSE scores and SF-36. The correlation appeared strong on the WHO/DAS II and with The SF-36; b) schizophrenia: strong positive correlation with WHO/DAS II on all three components of the PANSS scale was shown, and similar results were obtained on SF-36; c) major depressive disorder (MDD): highly significant positive correlation with WHO/DAS II and between WHO/DAS II and the SF-36; d) bipolar disorder (BAD): severity of BAD and disability measurement tools revealed a positive correlation on the WHO/DAS II as well as the SF-36; e) generalized anxiety disorder (GAD): correlation tests showed a positive correlation between the severity of anxiety as measured on the Hamilton anxiety rating scale and both WHO/DAS II and the SF-36. This correlation was more significant in WHO/DAS II than in SF-36; f) obsessive-compulsive disorder (OCD): severity of illness measured with Y-BOCS has a significant positive correlation with disability but compulsions tend to have a weak negative correlation with disability scores; the correlation between disability and total Y-BOCS score, though positive, was not statistically significant.
Discussion
Our findings indicate that significant amount of disability occur in a varying proportion of patients in all the disorders under study. The degree of disability tends to correlate with the severity of the disorder as reflected in the rating scales and with the quality of life. This is a replication of studies done earlier. Dementia and schizophrenia were the most causes of disability. This finding is in agreement with Chaudhury, et al., 2006, who found schizophrenia and dementia are the two major disability causing disorders among their seven studied psychiatric disorders. Both BAD and MDD have been implicated in causing disability in several studies. Recent population study found that MDD and BAD to be the two major disability-related disorders. Disability by the WHO/DAS II scale in patients with GAD and OCD; were 51.2% and 59.3% respectively, with only 4.7% of GAD has severe disability. Both disorders are affecting all areas of dysfunction except self care and life activities and they do not need to be admitted in the hospital. Previous studies, were similarly able to show the disabling propensity of OCD. Unlike Olfson et al., (1997) study which failed to correlate GAD with disability, Kessler et al., (1999), had demonstrated that GAD is independently associated with greater dysfunction. The findings from other studies of a strong independent association between mental disorders and disability and decreased quality of life was replicated in our study.