Classification of schizophrenia (Schizophrenia Model Answers) (Paper 3 Model Answers)

Discuss reliability and/or validity in relation to the diagnosis and classification of schizophrenia (16 marks)

The concept of reliability in the context of mental health classification systems, such as the ICD or DSM, refers to the consistency of these instruments in assessing and measuring certain aspects, such as the severity of symptoms in schizophrenia. Inter-rater reliability is a measure of agreement between two or more psychiatrists in arriving at the same diagnosis for a patient, typically requiring an 80% agreement for reliability. Test-retest reliability, on the other hand, examines whether the same diagnosis is consistently made by a clinician on separate occasions using the same information.

Validity, in relation to schizophrenia, pertains to how accurately a classification system measures what it claims to measure, specifically the symptoms associated with schizophrenia. Criterion validity is one aspect of validity and focuses on whether different assessment systems yield the same diagnosis for the same patient. However, research by Cheniaux et al suggests that schizophrenia is often over-diagnosed using the ICD and under-diagnosed when utilizing the DSM, highlighting a limitation in their validity.

One limitation of the classification and diagnosis of schizophrenia is culture bias. Studies by Javier Escobar have indicated that physicians, predominantly white, may misinterpret symptoms and exhibit a lack of trust towards black individuals. This can result in over-diagnosis among African Americans, as Western psychiatrists may not understand that certain symptoms, such as auditory hallucinations, may be considered normal in some African cultures. This cultural bias undermines the validity of diagnosis, particularly when relying on the DSM, which is based on American culture.

Gender bias is another limitation in the diagnosis of schizophrenia. Research by Longenecker suggests that men are more likely to be diagnosed than women since the 1980s. This could be attributed to potential genetic vulnerabilities in men, but it may also reflect bias in practitioners' tendency to under-diagnose schizophrenia in women due to their better interpersonal functioning, while over-diagnosing it in men. This gender bias decreases the validity of diagnosis, as it leads to many women being left undiagnosed, which can have detrimental consequences.

Furthermore, the presence of comorbidity poses a challenge to the validity of classifying and diagnosing schizophrenia. Buckley et al found that approximately half of the patients diagnosed with schizophrenia also receive diagnoses of depression (50%) or OCD (23%). This raises questions about the classification system and diagnosis of schizophrenia. It suggests that the co-occurrence of severe depression and schizophrenia may indicate a need for considering them as a single condition, rather than distinct entities. This limitation raises concerns about the validity of classification systems like the ICD and DSM when used to diagnose individuals with schizophrenia.

 

Describe and evaluate the classification and diagnosis of schizophrenia (16 marks)

Classification refers to the process of organising symptoms into distinct categories, while diagnosis involves identifying mental illnesses, such as schizophrenia, based on these symptoms. Two main classification systems are commonly used to assess whether someone has schizophrenia.

The first system is the Diagnostic and Statistical Manual of Mental Disorders (DSM), widely utilized in the United States. According to the DSM criteria, a patient must exhibit two or more negative symptoms (such as speech poverty and avolition) for at least one month to be diagnosed with schizophrenia.

The second system is the International Classification of Diseases (ICD), developed by the World Health Organization and composed of representatives from 193 countries worldwide. The ICD is extensively used in Europe and the United Kingdom. To receive a schizophrenia diagnosis according to the ICD, a patient needs to display at least one severe positive symptom (like delusions or hallucinations) for a minimum of one month.

Schizophrenic symptoms are categorized into two types: positive and negative symptoms. Positive symptoms refer to experiences that occur in addition to normal ones. These include hallucinations (such as hearing voices or seeing nonexistent people or animals) and delusions (irrational beliefs lacking a basis in reality, which may seem bizarre to others but make sense to the individual, like believing they are being monitored by the government or aliens).

On the other hand, negative symptoms manifest as a reduction in normal functioning or a loss of usual abilities and experiences. They involve avolition (difficulty initiating or maintaining goal-directed activities, such as personal hygiene and grooming) and speech poverty (a decrease in the amount and quality of speech, often becoming incoherent and non-fluent).

One limitation of the classification and diagnosis of schizophrenia is the presence of cultural bias. Studies by Javier Escobar indicate that physicians, predominantly from white backgrounds, tend to over-interpret symptoms and exhibit mistrust toward Black individuals, resulting in a higher likelihood of diagnosis. This bias arises from a lack of understanding by Western psychiatrists that certain positive symptoms, such as auditory hallucinations, may be culturally normative in some African cultures. Such cultural bias can lead to over-diagnosis if psychiatrists fail to consider the individual's cultural background, particularly when employing a diagnostic tool like the DSM, which is rooted in American culture. Consequently, the validity of the classification system is diminished.

Another limitation pertains to gender bias in diagnosis. Research by Longenecker indicates that since the 1980s, men have been more likely to receive a diagnosis of schizophrenia compared to women. This discrepancy may be attributed to men's potentially greater genetic vulnerability to schizophrenia. However, it could also indicate gender bias, as practitioners may tend to under-diagnose schizophrenia in women due to their better interpersonal functioning while over-diagnosing it in men. This gender bias decreases the validity of the diagnosis and leaves many women undiagnosed, which can have detrimental effects.

Furthermore, co-morbidity poses a challenge to the validity of the classification and diagnosis of schizophrenia. Studies by Peter Buckley et al reveal that approximately half of the patients diagnosed with schizophrenia also receive diagnoses of depression (50%) or obsessive-compulsive disorder (23%). This raises questions regarding both the accuracy of the diagnosis itself and the classification system. If a significant number of schizophrenic patients are also diagnosed with depression, it suggests that psychiatrists can distinguish between the two conditions. From a classification perspective, severe depression and schizophrenia may share similarities to the extent that they could be considered a single condition. This weakness challenges the validity of classification systems like the ICD or DSM, which are employed for diagnosing individuals with schizophrenia.

 

To what extent are the DSM5 and ICD10 reliable and valid measures of mental illness? ( 16 marks) 

Model Answer

The reliability and validity of the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition) and ICD-10 (International Classification of Diseases, 10th Revision) as measures of mental illness have been subjects of debate and scrutiny within the field of psychology. Here, we will discuss the extent to which these diagnostic manuals are considered reliable and valid measures.

Reliability refers to the consistency and stability of the diagnostic criteria used in these manuals. It assesses whether different clinicians or researchers would arrive at the same diagnosis when using the manuals. The DSM-5 has made efforts to improve reliability by providing more detailed diagnostic criteria and utilizing structured interviews, aiming to enhance consistency in diagnostic decision-making. Similarly, the ICD-10 also aims to enhance reliability by providing specific diagnostic guidelines.

One way to assess reliability is through inter-rater reliability, which measures the degree of agreement between different clinicians or researchers when using the diagnostic criteria. Studies examining inter-rater reliability for both the DSM-5 and ICD-10 have shown varying results. Some disorders, such as major depressive disorder, have demonstrated good inter-rater reliability, while others, such as personality disorders, have shown lower levels of agreement. Overall, while improvements have been made, there is still room for enhancing reliability in certain diagnostic categories.

Validity, on the other hand, refers to the accuracy and meaningfulness of the diagnoses made using these manuals. It assesses whether the diagnoses correspond to the actual presence or absence of mental disorders and whether they have predictive or clinical utility. Validity is essential to ensure that the diagnoses made are meaningful and reflect the underlying psychological conditions.

Criterion validity is one way to assess the diagnostic validity of the manuals. It involves comparing the diagnoses made using the manuals with other established measures or assessments to determine if they align. Studies examining criterion validity have generally shown mixed results, with some disorders demonstrating good concordance with external measures, while others have shown lower levels of agreement.

Another aspect of validity is construct validity, which evaluates whether the diagnostic categories in the manuals reflect the underlying theoretical constructs of mental disorders. This can be challenging, as mental disorders are complex and multifaceted. The DSM-5 and ICD-10 have faced criticism for relying on descriptive criteria rather than considering underlying mechanisms or etiology. Critics argue that this approach may lead to overdiagnosis, medicalisation of normal behavior, and the potential for comorbidity between disorders.

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