Key terms: • Positive symptoms of schizophrenia are additional
• Classification of mental disorder: The process of organising symptoms into categories based on which experiences beyond those of ordinary existence. They include
symptoms frequently cluster together. hallucinations and delusions.
• Schizophrenia: A severe mental disorder where contact with reality and insight are impaired, an • Hallucinations: These are unusual sensory experiences. Some
example of psychosis. hallucinations are related to events in the environment
• Positive symptoms of schizophrenia: Atypical symptoms experienced in addition to normal whereas others bear no relationship to what the senses are
experiences. They include hallucinations and delusions. picking up from the environment, for example, voices heard
• Hallucinations: A positive symptom of schizophrenia. They are sensory experiences that have either either talking to or commenting on a person, often criticising
no basis in reality or are distorted perceptions of things that are there. them. Hallucinations can be experienced in relation to any
• Delusions: A positive symptom of schizophrenia. They involve beliefs that have no basis in reality, sense. The person may, for example, see distorted facial
for example, a person believes that they are someone else or that they are the victim of a expressions or occasionally people or animals that are not
conspiracy. there.
• Negative symptoms of schizophrenia: Atypical experiences that represent the loss of a usual • Delusions: Also known as paranoia, delusions are irrational
experience such as a loss of clear thinking or a loss of motivation. beliefs. These can take a range of forms. Common delusions
• Speech poverty: A negative symptom of schizophrenia. It involves reduced frequency and quality of involve being an important historical, political or religious
speech. figure, such as Jesus or Napoleon. Delusions also commonly
• Avolition: A negative symptom of schizophrenia. It involves loss of motivation to carry out tasks involve being persecuted, perhaps by government or aliens or
and results in lowered activity levels. of having superpowers. Another class of delusions concerns
• Co-morbidity: The occurrence of t wo disorders or conditions together, for example a person has both the body. A person may believe that they are under external
schizophrenia and a personality disorder. Where t wo conditions are frequently diagnosed together it control. Delusions can make a person behave in ways that
calls into question the validity of classifying the t wo disorders separately. make sense to them but seem bizarre to others.
• Symptom overlap: Occurs when t wo or more conditions share symptoms. Where conditions share
many symptoms this calls into question the validity of classifying the t wo disorders separately. Negative symptoms
• Negative symptoms of schizophrenia involve the loss of usual
• Schizophrenia is a serious mental disorder experienced by about 1% of the world population. It is abilities and experiences. Examples include speech poverty
more commonly diagnosed in men, city-dwellers and lower socioeconomic groups. The symptoms of and avolition.
schizophrenia can interfere severely with everyday tasks, so that many people with schizophrenia • Speech poverty: Schizophrenia is characterised by changes in
end up homeless or hospitalised. patterns of speech. Speech poverty is seen as a negative
symptom because the emphasis is on reduction in the amount
Diagnosis and classification and quality of speech in schizophrenia. This is sometimes
• Diagnosis and classification are interlinked. According to the medical approach, in order to diagnose a accompanied by a delay in the person's verbal responses
specific disorder, we need to distinguish one disorder from another. We do this by identifying clusters during conversation. Nowadays, however, more emphasis is
of symptoms that occur together and classifying this as one disorder. Diagnosis is then possible by placed on speech disorganisation in which speech becomes
identifying symptoms and deciding what disorder a person has (e.g. OCD, schizophrenia etc.). incoherent or the speaker changes topic mid-sentence. This is
• The t wo major systems for the classification of mental disorder, are the World Health Organisation's classified in DSM-5 as a positive symptom of schizophrenia,
International Classification of Disease (ICD-10, version 11 has been published but won't be used for whilst speech poverty remains a negative symptom.
diagnosis until 2022) and the American Psychiatric Association's Diagnostic and Statistical Manual • Avolition: Sometimes called 'apathy, this can be described as
edition 5 (DSM-5). These differ slightly in their classification of schizophrenia. For example, in the finding it difficult to begin or keep up with goal-directed
DSM-5 system one of the so-called positive symptoms must be present for diagnosis whereas t wo or activity, i.e. actions performed in order to achieve a result.
more negative symptoms are sufficient under ICD. People with schizophrenia often have sharply reduced
• Previous editions of ICD and DSM recognised subtypes of schizophrenia (e.g. paranoid schizophrenia motivation to carry out a range of activities. Nancy
involved mainly powerful hallucinations and delusions). Andreasen (1982) identified three signs of avolition: poor
• Both DSM-5 and ICD-10 have dropped subtypes because they tended to be inconsistent e.g. someone hygiene and grooming, lack of persistence in work or
with a diagnosis of paranoid schizophrenia would not necessarily show the same symptoms a few education and lack of energy.
years later.