|Year : 2020 | Volume
| Issue : 2 | Page : 115-123
The relationship between cost of treatment and cognitive deficit in schizophrenia
Michael A Amedu1, Shehu Sale2
1 Department of Psychiatry, Federal Medical Centre, Makurdi, Benue State, Nigeria
2 Department of Psychiatry, Bayero University Kano, Kano, Nigeria
|Date of Submission||04-Mar-2020|
|Date of Decision||07-Mar-2020|
|Date of Acceptance||12-May-2020|
|Date of Web Publication||9-Oct-2020|
Dr. Shehu Sale
Department of Psychiatry, Bayero University Kano, Kano
Source of Support: None, Conflict of Interest: None
Context: Schizophrenia is not only a complex and disabling illness, but also costly. Cognitive impairment is a major determinant of functional outcome of patients. Aims: To determine the relationship between the direct cost of treatment and the cognitive impairment in schizophrenia. Settings and Design: This is a longitudinal study at a tertiary mental health facility in northern Nigeria. Materials and Methods: This study involved 270 patients with schizophrenia aged 15–64 years. Instruments used included Schizophrenia Cognition Rating Scale (SCoRS), the Mini International Neuropsychiatric Interview PLUS and a modified cost of illness (COI) questionnaire. Statistical analysis used: All tests of statistics were carried out at 5% level of probability. Results: A total of 270 participated in this study with a male: female ratio of almost 1. The mean age of participants 33.04 years. Majority were unemployed (51.5%), single (45.6%) and of low socioeconomic class (88.5%). Lower SCoRS for stable patients was significantly associated with higher educational attainment, occupational and marital status, high socioeconomic status and absence of caregiver. SCoRS had a significant correlation with duration of untreated psychosis, COI, age at onset, duration of illness, length of caregiving and number of caregivers. Conclusion: Cognitive impairment experienced by patients with schizophrenia are numerous, not only by the suffering and limitations it imposes on them, but also the enormous cost and burden that comes with caregiving. Efforts geared toward early detection and presentation of schizophrenia patients, and subsidizing cost of drug by government will go a long way in reducing cognitive impairment among patients.
Keywords: Cognitive impairment, cost of treatment, Nigeria, schizophrenia
|How to cite this article:|
Amedu MA, Sale S. The relationship between cost of treatment and cognitive deficit in schizophrenia. Niger J Basic Clin Sci 2020;17:115-23
|How to cite this URL:|
Amedu MA, Sale S. The relationship between cost of treatment and cognitive deficit in schizophrenia. Niger J Basic Clin Sci [serial online] 2020 [cited 2022 Jan 25];17:115-23. Available from: https://www.njbcs.net/text.asp?2020/17/2/115/297610
| Introduction|| |
Schizophrenia is one of the most perplexing, incapacitating and tragic of psychiatric syndromes. It is characterised by perceptual and thought disorders, cognitive impairment and abnormal behaviours, resulting in devastating consequences not only for the individual affected, but for the family and society in general. Despite advances made in the understanding of its pathology, its aetiology remains unknown with no definitive diagnostic tests; hence, diagnosis is clinical, based on operationally defined criteria and specific exclusion criteria.,,
Schizophrenia is associated with a long lasting disability than most other mental disorder. Both the positive and negative symptoms of the disease impede profoundly the capacity to cope with the demands of daily living. Patients with schizophrenia experience particular difficulty in dealing with complex demands of society, especially those that involve social interaction and decoding of social cues. Also, the onset of schizophrenia is usually at a developmental stage when social development is incomplete, educational attainment is truncated, and occupational skills are still rudimentary. The consequences of the intrusion of psychosis at this stage is a severely reduced social skills with an enduring socioeconomic disadvantage.
Cognition and schizophrenia
Cognitive impairment is a well-documented feature of schizophrenia and represents a major impediment to the functional recovery of patients. This increased awareness has come to form an important developmental landmark in the understanding of the schizophrenia psychopathology. It is considered to be the prime driver of significant disabilities in occupational, social and economic functioning in patients and hence, important in prognostication as well as being an important target for pharmacological and psychosocial treatment trials. It is one of the most critical determinants of quality of life and a better predictor of level of function than the severity of psychotic symptoms in patients.,
Patients with schizophrenia perform one to two standard deviations (SDs) below healthy controls on various neurocognitive tests. The cognitive dysfunction is typically in the domains of attention, executive function, working and episodic memory. The neurocognitive deficits are present prior to the initiation of antipsychotic treatment and are not caused by psychotic symptoms in majority of patients who are able to complete neurocognitive testing; in some patients, the deficits correlate with measurable brain dysfunction more than any other aspect of the illness.
Studies have shown a relationship between cost of treatment of schizophrenia and cognitive impairment, though most of these studies are from developed countries. In a systematic literature review on the economic considerations of cognition and functional outcomes among patients with schizophrenia, Furiak et al. analysed articles published over a 15 year period (1999–2013) on direct cost, indirect cost and quality of life as it relates to cognitive impairment and interventions for cognitive deficits among patients with schizophrenia. Only 4 of the 43 studies focused on direct cost of cognitive remediation therapy, while 24 of these concentrated on the indirect costs associated with cognitive impairment. All four studies on direct cost and cognition were from the UK. Their findings show that 2 of the studies on direct cost and cognitive impairment found a significant relationship between higher cognition scores and lower total costs (85% of which are direct cost) while the remaining found no relationship. A more robust relationship was found between indirect cost and cognitive impairment as therapies which improve cognition were also found to reduce the indirect cost among schizophrenia patients.
In a different study, Taylor and Abrams used various neuropsychological tasks to assess 62 schizophrenia patients and 42 normal controls. They assessed neurological soft signs, aphasia screening test, tachistoscopic stimulation, auditory threshold determinations, and items from the Mini-Mental State, Halstead-Reitan Neuropsychological Test Battery and the Luria-Nebraska Neuropsychological Battery. Their findings showed that up to 75% of patients with schizophrenia had moderate to severe cognitive dysfunction while none of the control showed more a mild deficit. These differences were not a function of age, sex, handedness, or drug administration.
Psychosocial treatments have become a major cornerstone in the care of persons with schizophrenia. They include a wide range of interventions designed to help people with schizophrenia, improve their functioning and quality of life by enabling them to acquire the skills and supports needed to be successful in usual adult roles and in the environments of their choice. Psychosocial occupational therapists use a holistic approach and varied activities to increase individuals' repertoire of social and self-care skills, work behaviours and leisure activities, stress management, social skills training, exercise and vocational exploration. Current approaches to schizophrenia treatment include a multifaceted approach aimed not only at ameliorating symptoms, but also at improving impairments in other domains and helping patients achieve normative adult roles. Psychosocial treatments emphasise increasing independence rather than reliance on professionals, community integration rather than isolation in segregated settings for persons with disabilities, patient preferences rather than professional goals and building on patient strengths rather than focusing on their deficits.,
The need for early treatment of patients with schizophrenia has been reiterated by many studies as prolonged duration of untreated schizophrenia is associated with poor prognosis. The study by Bottlender et al. in Germany, on the impact of duration of untreated psychosis (DUP) prior to first psychiatric admission on the 15-year outcome showed that a longer DUP was associated with more pronounced negative, positive and general psychopathological symptoms as well as a lower global functioning 15 years after the first psychiatric admission, even after effects of other factors, possibly related to the long-term outcome, were controlled for. They underscore the importance of establishing health service programs for early detection and treatment of schizophrenic patients to shorten the DUP and consequently improve the course and outcome of schizophrenic patients.
Despite advancements in the fields of psychopharmacology, social and behavioural therapy for the treatment of schizophrenia, lots of patients go untreated, evidenced by the long pathways to care and the long DUP.,
Few studies in the developed and developing worlds have looked at the relationship between the cost of treatment and cognitive impairment among patients with schizophrenia. Findings from such studies will help spur and project efforts geared at reducing long DUP and pathway to care which is believed to negatively affect cognition among patients with schizophrenia. Also, policy makers will want to know which treatment modalities have more beneficial effect on cognition and at a more affordable cost.
We therefore hypothesised that there is no relationship between direct cost of treatment of schizophrenia and cognitive impairment in schizophrenia and there is no relationship between Duration of Untreated Schizophrenia (DUP) and cognitive deficits among patients with schizophrenia.
Based on the above hypothesis, the study then aimed at finding the relationship between cost of treatment of schizophrenia, severity of cognitive deficit and DUP among patients with schizophrenia in Northern Nigeria.
The objectives were to:
- Estimate the cost of treatment of schizophrenia among in-patients and out-patients at the Ahmadu Bello University Teaching Hospital, Zaria
- Examine the relationship between sociodemographic variables and severity of cognitive deficit of schizophrenia
- Assess the relationship between severity of cognitive deficit of schizophrenia and caregiver burden
- Examine the relationship between DUP and severity of cognitive deficit in schizophrenia.
This study is part of a larger study which sought to assess the cost of treatment of schizophrenia, DUP, cognitive impairment in schizophrenia and caregiver burden from a tertiary institution in northern Nigeria.
This study was carried out at Ahmadu Bello University Teaching Hospital, a tertiary hospital located in Shika-Zaria of Kaduna State in Nigeria about 267 km from Abuja, the nation's federal capital and about 75 km from Kaduna, the state capital. The hospital extends its specialist care to patients from neighbouring states, including the Federal Capital Territory, Abuja. During this study, the psychiatry department had three consultant psychiatrists, six senior registrars and seven registrars. The male and female psychiatric wards with sixteen bed spaces each and the psychiatric clinics (which held twice a week) were used for this study.
these included (a) male and female patients aged 15 years and above with a diagnosis of Schizophrenia (taking into consideration the typical epidemiological age of onset for schizophrenia in male patients) admitted into the psychiatric wards or attending the psychiatric clinic of the hospital. There were two patient groups: group I, patients diagnosed with schizophrenia (either first presentation or a relapse) and receiving acute phase treatment;, Group II, patients diagnosed with schizophrenia who had been stable in the preceding 6 months and were on maintenance treatment., All patients were assessed twice: at the beginning and end of a 4 weeks interval. (b) Caregiver (s) of patient with schizophrenia. The caregiver was any person (relative or paid help) who lived with or frequently visited the patient and was knowledgeable about the patient's daytime and nighttime behaviours. Most of the interviews with the caregivers were conducted in the absence of the patients to facilitate an open discussion that may be difficult with the patient present.
It should be noted that not all stable patients were accompanied by a caregiver. Where there are more than one caregiver per participant, a single key informant fulfilling the requisite criterion B above is recruited, even though the total number of caregivers is noted.
| Materials and Methods|| |
these included inpatients/outpatient diagnosed with schizophrenia; age 15 years and above; caregiver(s) of patients diagnosed with schizophrenia (as defined in B above) who accompany patients to the hospital.
these included patients with history of stroke, head injury or intellectual disability despite meeting the requisite criteria for schizophrenia previously; patients with delirium despite previous diagnosis of schizophrenia.
This was a longitudinal comparative study.
Instruments used for the study
This was designed to obtain sociodemographic data about the study participants such as age, gender, occupation, marital status, level of education, socioeconomic status (SES). There is no consensus on the conceptual meaning and measurement of SES however, for the purpose of this study a modification of Kuppuswamy SES Scale as revised by Guru Raj et al. was adapted for use. This took into cognizance the educational level of participants, the occupational status, income, place of residence, number of dependents and ownership of property of value. The SES was then classified into high, middle and low socioeconomic class based on the total score obtained thus: a score of 26–29 = upper class; 11–25 = middle class; <15 = lower class. At the time of this study the US$ = N190; The minimum wage was N18,000.
A structured cost of illness (COI) questionnaire adapted from the Centers for Disease Control and Prevention, U. S. Department of Health and Human Services, was designed and used to assess direct cost (e.g., cost of drugs, transportation, investigations, etc.). A prevalence based approach using a “bottom-up” (micro) costing was adopted (which identifies and values resources used).
Schizophrenia Cognition Rating Scale
His scale focuses on cognitive impairment among patients with schizophrenia as well as the degree to which it affects their day-to-day functioning. Each item is completed using a four point scale with higher scores reflecting a greater degree of impairment. For participants who are illiterate, items related to reading would be rated not applicable. The instrument has an informant segment which is completed within a week of interview with the patient. This segment is omitted for participants not accompanied by a caregiver.
The Mini International Neuropsychiatric Interview PLUS
This is a more detailed edition of the Mini International Neuropsychiatric Interview (MINI) designed as a brief structured interview for the major Axis I psychiatric disorders in the ICD-10 and Diagnostic and Statistical Manual of Mental Disorders-IV. It requires Yes or No answers. Studies have shown high validity and reliability scores when compared with the Structured clinical interview for DSM-IV patient edition (SCID-P)and Composite international diagnostic interview (CIDI) but can be administered in a much shorter time (mean time 18.7 ± 11.6). The instrument requires brief training for clinicians but more extensive training for lay interviewers. It has been used in Nigeria by Adewuya et al. The MINI PLUS was administered to patients only the section related to schizophrenia.
Patients' case files were also assessed for other information that could not be got from the patients or their caregivers such as their other medical history, drug history, types of investigations carried out, treatment being given etc.
All patients with psychotic symptoms were assessed and those fulfilling the ICD-10 diagnostic criteria for schizophrenia were recruited into the study following due consent. It was not possible to get all the necessary information from the first visit for out-patients. In-patients were visited at least twice to obtain the necessary information. All costs of treatment accruing during a month's period were considered.
Sample size determination
This was calculated using the formula for comparison of two means:
Where: n = required minimum sample size of each group; μ1–μ0= Difference between the means (for acute and stable patients) for the two comparison group. This represents the difference in mean cost that we would like to detect between acute and stable patients and is set at the naira equivalence of a dollar (which was also the level of the poverty line) = N190; σ1,σ0 = SDs for acute and stable patients (this was based on the study by Suleiman etal.).
Hence, σ1 = 532.5; σ0 = 343.2; u = one sided percentage point of the normal distribution corresponding to 100% – the power. With power = 90%, (100%–90%) =10%; hence u = 1.28; v= percentage of the normal distribution corresponding to the required (two sided) significance level. At significance level of 5%, v = 1.96.
= 116.707283 ⩭ 120. This represents the size of a group (if the two groups were to be of equal size). Considering that the prevalence and incidence of schizophrenia differs (which will reflect in the sample size for the acute and stable patients), it was desired to recruit twice as many stable patients as the acute patients. This was then calculated based on the formula:
Small group size = fn and f = (c + 1)/(2c).
Where n = number required for equal-sized groups = 120; f = adjustment factor = (2 + 1)/(2 × 2) =4/6= ¾; cfn = number of larger group; c = ratio of larger to smaller group = 2.
Hence, fn = 3/4 × 120 = 90 (size of smaller group i.e., acute schizophrenia patients); Number of larger group = cfn = 2 × 90 = 180 (number of stable schizophrenia patients).
Total sample size = 90 + 180 = 270.
Participants who met the requisite inclusion criteria were recruited consecutively until the desired sample size was reached.
The costs of registration and admissions were confirmed from the office of the Deputy Chairman, Medical Advisory Committee, while costs of drugs were obtained from the hospital pharmacy. The costs of investigations were obtained from the various laboratories involved; however, cost of consultation was not factored into the estimation as patients were not charged for consultation. The cost of transportation was obtained from the various transport stations, motor parks and companies (considering the distances covered by patients and caregivers).
Ethical clearance was obtained from the Ethics and Scientific Committee of the Ahmadu Bello University Teaching Hospital. A written and signed consent form of the subjects or their relative or next of kin was obtained before conducting the interview. In the process of carrying out this study, the patients and their caregivers were given due priority in terms of prompt management in the wards and at the clinics. Patients' convenience was of prime consideration taking into cognizance the length of the interview per participant.
The diagnosis of schizophrenia was based on fulfilling the criteria in the WHO's Tenth Revision of the International Classification of Disease and Related Health Problems, (ICD-10).
The data obtained from the study were analysed using the IBM SPSS Statistics for Windows, version 20 (IBM Corp., Armonk, N.Y., USA). Relevant descriptive statistics were used for continuous and categorical variables and frequency distributions generated as appropriate. Test of normality for all continuous variables was assessed using the Kolmogorov–Smirnov test. The non-parametric equivalents of the corresponding relevant test statistic were then employed. These included the Mann–Whitney U-test, Kruskal–Wallis test and Spearman's correlation. All tests of statistics were carried out at 5% level of probability (except where otherwise specified). A prevalence-based approach was adopted whereby all costs within the most recent year for which data were available, were measured regardless of date of onset of illness. Costs of treatments were estimated using the formula for determining cost of treatment for any illness thus:
COI = number of episodes × (direct cost per episode + indirect cost per episode).
Direct cost per episode = direct outpatient cost + direct inpatient cost + direct home-care cost.
Indirect cost per episode = value of production × (production lost because of illness + production lost because of care giving).
| Results|| |
Sociodemographic characteristics of the participants
This is as shown in [Table 1]. A total of 270 subjects participated in this study of schizophrenia cohorts with 66.7% of them receiving acute phase treatment. All participants approached consented to participate in the study. The sex ratio of participants was approximately 1:1 with 48.1% of the participants being males. The mean age of participants was found to be 33.04 (±9.74) years, however mean age at onset (AAO) of illness was 25.87 (±8.13) years.
|Table 1: Sociodemographic characteristics of participants with schizophrenia|
Click here to view
Most of the participants are single (45.6%) with majority of these singles being males (78.05%). Few of the subjects fall in the high socioeconomic class (2.6%), while 51.5% are unemployed. Majority of the participants (84.8%) were Muslims.
The relationship between the participants' sociodemographic variables and Schizophrenia Cognition Rating Scale (SCoRS) is shown in [Table 2]. This analysis was carried out only on stable patients to control for the influence of acute symptoms on cognitive impairment. The relationship showed a statistically significant relationship between the variables and SCoRS except for sex (P = 0.623).
|Table 2: Relationship between sociodemographic variables and schizophrenia cognition rating scale (n=180)|
Click here to view
The correlates of SCoRS are shown in [Table 3]. It revealed a statistically significant relationship with DUP (P < 0.001), COI (P = 0.048), AAO (P = 0.02), DOI (P = 0.001), length of caregiving (P < 0.001) and number of caregivers (P < 0.001). There was a negative correlation between AAO and age with SCoRS; however, the relationship with age failed to reach statistical significance.
Mean monthly direct cost per acute patient is N25,398.19 (SD: ±24,600.05; 95% confidence interval [CI]: 20,245.81–30,550.57), while the This was calculated using the formulmaean monthly cost per stable patient was N3087.21 (SD: ±1930.40; 95% CI: 2803.28–3371.13).
[Table 4] illustrates a Multiple Regression analysis to evaluate the predictors of severity of cognitive impairment as measured using SCoRS. This was found to be statistically significant for DUP (P < 0.001), number of caregivers (P = 0.008) and length of caregiving (P < 0.016), with DUP having a stronger predictive value than number of caregivers and length of caregiving.
|Table 4: Multiple regression model: Predictors of severity of cognitive impairment using Schizophrenia cognition rating scalea|
Click here to view
| Discussion|| |
Sociodemographic characteristics of participants
The male to female ratio was 0.9:1. Several community and hospital based studies have shown an almost 1:1 male: female ratio in the prevalence of schizophrenia.,, This is because the incidence and prevalence of schizophrenia in both males and females is approximately the same even though the mean age of onset is earlier in males., The mean age of participants is 33.04 (±9.74) years. This can be attributed to either delayed presentation or chronic nature of schizophrenia., It is noteworthy here that the mean age at onset of schizophrenia was found to be 25.87 (±8.14) years, a reflection of the duration of untreated or treated schizophrenia in this study.
This study finds majority of the participants to be single (45.6%). Schizophrenia is known to be negatively associated with fertility and marriage. This has been attributed to the negative effects of social stigma,, and social cognitive deficits associated with schizophrenia which impairs their ability to detect and respond appropriately to social cues, resulting in alienation and maintenance of social distance. Most of the participants in this study were unemployed. The occurrence of schizophrenia during adolescence and early adulthood means that the attainment of academic and occupational skills are truncated. The cognitive deficits associated with the illness contributes immensely to the difficulties encountered in trying to achieve academic prowess and vocational competence., This further contributes indirectly to the cost of schizophrenia as many patients are not gainfully employed.
Mean monthly and annual costs of treatment of schizophrenia
The mean direct cost of treatment for acute phase schizophrenia is N7762.67 at 1$ = N195 exchange rate. This is closer to the estimate of N 9882 by Amoo and Ogunlesi which was the mean direct estimate incurred per admission. This study however estimated its mean direct estimate per month rather than per admission which varies considerably among patients. The mean monthly estimate by Suleiman et al. was N491; however, their study was at a time when the naira equivalent of the dollar was N82.
The relationship between sociodemographic variable and schizophrenia cognition rating scale
This study failed to detect a significant association between age of participants and SCoRS scores. This can be attributed to the fact that the age here does not give any additional information about the nature, timing of presentation and severity of illness. The participants are a heterogeneous group in terms of age extending between 15 and 64 years. This is in contrast to the AAO which in this study has a significant relationship with SCoRS (P = 0.020). Studies have demonstrated a poor outcome for patients with early onset psychosis,, and have been attributed to the truncation in acquisition of education, work and social skills necessary for adult independent living. Other factors include delayed presentation and treatment which is prevalent in many countries, increased risk of comorbidities and sometimes poor response to treatment.
Research findings of the relationship between DUP and cognitive impairment in patients with schizophrenia have been mixed. While some studies found a significant relationship, others failed to detect a convincing association. This study finds a statistically significant relationship between DUP and SCoRS scores. Cognitive impairment among patients with schizophrenia is known to underlie their functional outcome. There continues to be the compelling debate about the neurotoxic effect of psychosis to brain which in turn affects the brain functioning. This is despite failure to detect statistically significant findings of progressive deterioration in brain pathology of structural imaging studies.
Studies have shown the effect of cognitive impairment on economic implications of treatment for schizophrenia. Severe cognitive impairment as indicated by higher SCoRS scores frequently imply more dependency on caregiver(s) and more cost implications as found in this study [Table 3]. Some authors have even encouraged the use of combination of drugs and cognitive remediation therapy to favour a better outcome than either treatment alone. This implies more cost and is important to health planners, policy makers and health financiers.
Predictors of schizophrenia cognition rating scale
These were found to be DUP, Number of Caregivers and Length of Caregiving with DUP being a better predictor of impaired cognition in schizophrenia than number of caregivers and length of caregiving. The number of caregivers and length of caregiving is a reflection of symptoms severity and the ongoing need for care (NB, this analysis was carried out on stable patients to control for acute symptoms while assessing for cognitive impairment). These, in turn, are a reflection of the severity of functional impairment of the patients which is attributed to cognitive impairment.
| Conclusion|| |
Cognitive impairment has a multifaceted implication for patients with schizophrenia and their caregivers. This study finds a significant relationship between severity of cognitive impairment with AAO, DUP, DUI, COI, educational level occupational status, socioeconomic status, number of caregivers and length of caregiving with DUP being a better predictor of cognitive impairment among patients with schizophrenia. The implication of these findings is the need for a more holistic approach that is geared towards public enlightenment about the nature of schizophrenia which will encourage early detection, presentation and treatment. There is also a need to subsidize cost of treatment for schizophrenia considering the chronic nature of the illness, the enormity of the cost involved and the finding of a preponderance of low SES among victims. This in turn will help reduce frequent relapse that is due financial duress. More of government awareness and intervention can bring about training of more specialists involve the treatment, rehabilitation and reintegration of patients into the society.
The cost estimates obtained in this study are very modest considering the non-inclusion of components of indirect cost which are significantly influenced by severity of functional impairment.
The implication of the effect of cognitive impairment on indirect cost as well as the effect of early treatment and cognitive remediation therapy on long-term functional outcomes of patients with schizophrenia need to be explored by future studies.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Tamminga CA. Schizophrenia and other psychotic disorders: Introduction and overview. In: Sadock BJ, Sadock VA, Ruiz P, editors. Kaplan & Sadock's Comprehensive Textbook of Psychiatry. 9th ed., Vol. 1. Ch. 12. Philadelphia: Lippincott Williams & Wilkins; 2009. p. 1432.
Lewis S, Escalona PR, Keith SJ. Schizophrenia and other psychotic disorders: Phenomenology of schizophrenia. In: Sadock BJ, Sadock VA, Ruiz P, editors. Kaplan & Sadock's Comprehensive Textbook of Psychiatry. 9th ed., Vol 1. Ch. 12. Philadelphia: Lippincott Williams & Wilkins; 2009. p. 1433.
Gelder M, Harrison P, Cowen P. Schizophrenia. Shorter Oxford Textbook of Psychiatry. 5th ed., Ch. 12. Oxford, United Kingdom: Oxford University Press; 2006.
Semple D, Smyth R. Psychiatric Assessment in, Oxford Handbook of Psychiatry. 3rd ed., Philadelphia Oxford, United Kingdom: Oxford University Press; 2013.
Jablensky A. Schizophrenia and other Psychotic Dosorders: World Burden of Schizophrenia. In: Sadock BJ, Sadock VA, Ruiz, P, editors. Kaplan & Sadock's Comprehensive Textbook of Psychiatry. 9th ed. Vol. 1. Ch. 12. Philadelphia; Lippincott Williams & Wilkins; 2009. p. 1451.
Sadock BJ, Sadock VA. Schizophrenia. Kaplan and Sadock's Synopsis of Psychiatry: Behavioral Science/Clinical Psychiatry. 10th ed. Philadelphia 2007.
Barch DM, Ceaser A. Cognition in schizophrenia: Core psychological and neural mechanisms. Trends Cogn Sci 2012;16:27-34.
Keefe RS, Eesley CE. Neurocognition in Schizophrenia; Schizophrenia and Other Psychotic Disorders. Kaplan and Sadock's Comprehensive Textbook of Psychiatry. 9th ed. Philadelphia: Lippincott Williams & Wilkins; 2009.
Furiak N, Duhig A, Myers J, Pitts A, Hass S, Klein R. Economic considerations of cognition and functional outcomes in patients with schizophrenia: A systematic literature review. Schizophr Res Cogn 2014;1:e27-33.
Taylor MA, Abrams R. Cognitive impairment in schizophrenia. Am J Psychiatry 1984;141:196-201.
Tenhula WN, Bellack AS, Drake RE. Schizophrenia: Psychosocial approaches. In: Sadock BJ, Sadock VA, Ruiz P, editors. Kaplan and Sadock's Comprehensive Textbook of Psychiatry. 9th ed., Vol. 1, Ch. 12. Philadelphia: Lippincott Williams & Wilkins; 2009. p. 13.
Kane JM, Stroup TS, Marder SR. Schizophrenia: Pharmacological Treatment. In: Kaplan. Ch. 12.12. Philadelphia: Lippincott Williams & Wilkins; 2009.
Bottlender R, Sato T, Jäger M, Wegener U, Wittmann J, Strauss A, et al.
The impact of the duration of untreated psychosis prior to first psychiatric admission on the 15-year outcome in schizophrenia. Schizophr Res 2003;62:37-44.
Gureje O, Acha RA, Odejide OA. Pathways to psychiatric care in Ibadan, Nigeria. Trop Geogr Med 1995;47:125-9.
Large M, Farooq S, Nielssen O, Slade T. Relationship between gross domestic product and duration of untreated psychosis in low- and middle-income countries. Br J Psychiatry 2008;193:272-8.
Guru Raj MS, Shilpa S, Maheswaran R. Revised socioeconomic status scale for urban and rural India – Revision for 2015.
Centers for Disease Control and Prevention (CDC), U.S. Department of Health & Human Services. Available from: http://www.cdc.gov
. [Last accessed on 2013 Feb 25].
Keefe RS, Poe M, Walker TM, Kang JW, Harvey PD. The Schizophrenia Cognition Rating Scale: An interview-based assessment and its relationship to cognition, real-world functioning, and functional capacity. Am J Psychiatry 2006;163:426-32.
Sheehan DV, Lecrubier Y, Sheehan KH, Amorim PA, Janavas J, Weiller E, et al
. The mini-international neuropsychiatric interview (M.I.N.I.): The development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. J Clin Psychiatry 1995;59 Suppl 20:22-3.
Adewuya AO, Afolabi MO, Ola BO, Ogundele OA, Ajibare AO, Oladipo BF, et al
. Relationships between depression and quality of life in persons with HIV infection in Nigeria. Int J Psychiatry Med 2008;38:43-51.
World Health Organization. International Classification of Disease and Related Health Problems. 10th
ed. Geneva: World Health Organization; 1992.
Kirkwood BR, Sterne JA. Essential Medical Statistics. 2nd
ed., Ch. 35. Massachusetts, USA: Blackwell Sc. Ltd. 2005.
Suleiman TG, Ohaeri JU, Lawal RA, Haruna AY, Orija OB. Financial cost of treating out-patients with schizophrenia in Nigeria. Br J Psychiatry 1997;171:364-8.
Gureje O, Lasebikan VP, Ephraim-Oluwanuga O, Olley BO, Kola L Community study of knowledge of and attitude to mental illness in Nigeria. Br J Psychiatry 2005;186:436-41.
Adewuya AO, Makanjuola RO. Social distance towards people with mental illness in Southwestern Nigeria. Aust NZ J Psychiatry 2008;42:389-95.
Goldberg TE, Green MF. Neurocognitive functioning in patients with schizophrenia: An overview. Neuropsychopharmacology: The Fifth Generation of Progress. Ch. 48. USA: American College of Neuropsychopharmacology; 2002.
Amoo GI, Ogunlesi AO. Financial cost of treating Nigerian in-patient with schizophrenia. Afr J Med Sci 2005;34:15-23.
Sikich L. Early onset psychotic disorders. In: Sadock BJ, Sadock VA, Ruiz P, editors. Kaplan & Sadock's Comprehensive Textbook of Psychiatry. 9th
ed., Vol. 2. Ch. 50. Philadelphia: Lippincott Williams and Wilkins; 2009. p. 3701.
Anderson KK, Voineskos A, Mulsant BH, George TP, Mckenzie KJ. The role of untreated psychosis in neurodegeneration: A review of hypothesized mechanisms of neurotoxicity in first-episode psychosis. Can J Psychiatry 2014;59:513-7.
Michalopoulou PG, Lewis SW, Wykes T, Jaeger J, Kapur S. Treating impaired cognition in schizophrenia: The case for combining cognitive-enhancing drugs with cognitive remediation. Eur Neuropsychopharmacol 2013;23:790-8.
[Table 1], [Table 2], [Table 3], [Table 4]