Classification of schizophrenia
Schizophrenia affects thought processes and the ability to determine reality. Type I is characterised by positive symptoms, with better prognosis for recovery. Type II is characterised by negative symptoms, with poorer prognosis for recovery. Positive symptoms involve displaying behaviours concerning loss of touch with reality, such as hallucinations, where sufferers hear voices in their head, and delusions, false beliefs resistant to confrontation with reality. Negative symptoms involve displaying behaviours concerning disruption of normal emotions and actions, such as speech poverty, characterised by brief replies to questions with minimal elaboration, and avolition, a general lack of energy resulting in loss of goal-directed behaviour. Schizophrenia is diagnosed by reference to classification systems, for example the DSM-V. Diagnosis should be reliable and valid. Reliability refers to the consistency of diagnosis, over time (test—re-test reliability) and by different clinicians (inter-rater reliability). Validity refers to the accuracy of diagnosis, like predictive validity, where diagnosis leads to successful treatment. Co-morbidity concerns the presence of additional disorders simultaneously occurring with schizophrenia, while culture bias refers to the tendency to over-diagnose members of other cultures as suffering from schizophrenia. Gender bias concerns the tendency for diagnostic criteria to be applied differently to males and females, while symptom overlap involves the perception that symptoms of schizophrenia are also symptoms of other mental disorders.
Fig 12.1 David Rosenhan’s classic study brings the validity of schizophrenia diagnosis into question
Rosenhan (1973) assessed the validity of schizophrenia diagnosis using DSM-II. 8 sane volunteers presented themselves at mental hospitals claiming to hear voices. All were admitted and thereafter acted normally. Reactions to them and time taken to be released were recorded. It took between 7 and 52 days for them to be released, diagnosed as ’schizophrenics in remission’. Normal behaviours were perceived as signs of schizophrenia by clinicians, though 35 out of 118 real patients suspected they were imposters. Rosenhan concluded that diagnosis lacked validity, but clinicians protested that people do not usually fake insanity to get admission into hospital. Therefore Rosenhan informed hospitals that an unspecified number of imposters would try to gain admission during a 3-month period. Of 193 patients admitted during this time, 83 aroused suspicions as being imposters. No imposters were sent. This backed up Rosenhan’s claim that diagnosis of schizophrenia lacks validity.
• Beck (1962) reported only a 54 per cent concordance rate between practitioners’ diagnoses, while 43 years later Soderberg (2005) reported a concordance rate of 81 per cent, which suggests reliability of diagnosis has improved over time as diagnostic criteria have been updated.
• Sim et al. (2006) reported that 32 per cent of hospitalised schizophrenics had an additional mental disorder, illustrating the problem that co-morbidity presents in achieving reliable and accurate diagnoses.
• McGovern & Cope (1977) reported that two-thirds of patients detained in Birmingham hospitals were first- and second-generation Afro-Caribbeans, suggesting a cultural bias to over-diagnose schizophrenia in the black population.
• Lewin et al. (1984) found that if clearer diagnostic criteria were applied, the number of female schizophrenia sufferers became much lower, suggesting a gender bias in the original diagnosis.
• Ophoff et al. (2011) found that of 7 gene locations on the genome associated with schizophrenia, 3 of them were additionally associated with bipolar disorder, suggesting a genetic overlap between the 2 disorders.
Evidence generally suggests that reliability of diagnoses has improved as classification systems have been updated.
The high level of certain co-morbid disorders found in schizophrenics suggests that such co-morbidities might actually be sub-types of the disorder.
Females tend to develop schizophrenia on average 4—10 years later than males, and females can develop a later form of post-menopausal schizophrenia, which suggests there are different types of schizophrenia to which males and females are vulnerable.
Being labelled schizophrenic has a long-lasting, negative effect on social relationships, work prospects, self-esteem, etc., which is unfair when diagnoses of schizophrenia have generally low levels of validity.
Schizophrenics with co-morbid conditions are often excluded from research and yet form the majority of sufferers. This suggests that research findings cannot be generalised to the majority of schizophrenic patients.
Research suggests there is a case for different diagnostic considerations when diagnosing males and females. However, this would cast doubts on the validity of schizophrenia as a separate disorder.
Misdiagnosis due to symptom overlap can lead to delays in receiving proper treatment or to even receiving inappropriate treatment. This could lead to further suffering, degeneration of condition and even suicide.
The fact that there is genetic overlap between mental disorders suggests that gene therapies might be developed to simultaneously treat different disorders.