diagnosis/ classification

• sz is a severe mental health disorder in which emotions are so impaired that contact is lost with reality.
• diagnosis and classification

  sz does not have a single defining characteristics. Its a cluster of symptoms.
• diagnosis and classification

  ICD- 2 or more negative symptoms are sufficient for a diagnosis.
• diagnosis and classification

  DSM5- one of the positive symptoms must be present for a diagnosis.
• Positive symptoms are additional experiences beyond those of ordinary existences.
• Hallucinations; these are unusual sensory experiences. Some hallucinations are related to events in the environment whereas others bear no relationship to what the senses are picking up from the environment, e.g voices heard either talking to or commenting on a person, often criticising them. Hallucinations can be experienced in relation to any sense. E.g the person may see distorted facial expressions or occasionally people or animals that are not there. 
• Delusions; aka paranoia. Delusions are irrational beliefs. These can take a range of forms. Common delusions involve being an important historical, political or religious figure, e.g Jesus or napoleon. Delusions also commonly involve being persecuted, perhaps by government or aliens or having super powers. Another class of delusions concerns the body. A person may believe that they are under external control. Delusions can make a person behave in ways that make sense to them but seen bizarre to others. 
• Negative symptoms involve the loss of usual abilities and experiences. 
• Speech poverty; schizophrenia is characterised by changes in patterns of speech. Speech poverty is seen as negative symptoms because the emphasis is on reduction in the amount and quality of speech in schizophrenia. This is sometimes accompanied by a delay in the persons verbal responses during conversations. Nowadays, more emphasis is placed on speech disorganisation in which speech becomes incoherent or the speaker changes topic mid-sentence. This is classified in DSM-5 as a positive symptom of schizophrenia, whilst speech poverty remains a negative symptom. 
• Avolition; sometimes called ‘apathy’, this can be described as finding it difficult to begin or keep up with goal-directed activity, e.g actions performed in order to achieve a result. People with schizophrenia often have sharply reduced motivation to carry out a range of activities. Nancy Andreasen identified three signs of avolition: poor hygiene and grooming, lack of persistence in work or education and lack of energy.
• A strength of diagnosis of sz is its reliability.

  A psychiatric diagnosis is reliable when different diagnosing clinicians reach the same diagnosis for the same individual (inter-rater reliability)and when the same clinicians reaches the same diagnosis for the same individual on two occasions (test-retest reliability). Prior to DSM-5, reliability for sz diagnosis was low but this has now improved. Pairs of interviewers achieved inter-rater reliability= +0.97 and test-retest reliability = +0.92. diagnosis of sz is consistently applied.
• weakness of diagnosis of sz is its validity.

  Ellie Cheniaux et al had two psychiatrists independently assess the same 100 clients using ICD-10 and DSM-5 criteria and found that 68 were diagnosed with sz under the ICD system and 39 under DSM.

  This suggests that sz is either over or under diagnosed according to the diagnostic system. This suggests that criterion validity is low.
• a weakness of sz diagnosis is its co-morbidity with other conditions.

  If conditions occur together a lot of time then this calls into question the validity of their diagnosis and classification because there might actually be a single condition. Sz is commonly diagnosed with other conditions. one review found that about 1/2 of those diagnosed with sz also had a diagnosis of depression or substance abuse. suggests sz may not exist as a distinct condition, and is a problem for diagnosis as some people diagnosed with sz may have unusual cases of depression
• weakness of sz diagnosis is the existence of gender bias.

  Since 1980s, men have been diagnosed with sz more commonly than women. possible explanation for this is that women are less vulnerable than men, perhaps due to genetic factors. It seems more likely that women are undiagnosed because they have closer relationships and hence get support. leads to women with sz often functioning better than men. this under diagnosis is a gender bias and means women may not be receiving treatment and services that might benefit them.
• weakness of sz diagnosis is the existence of culture bias.

  symptoms e.g hearing voices have different meanings in different cultures. In Haiti some people believe that voices are communication from ancestors. British people of African-Caribbean origin are up to 9x likely to receive a diagnosis as white british people, although people living in African-Caribbean countries are not, ruling out a genetic vulnerability. Lead to over interpretation of symptoms in black british people. means British African Caribbean people may be discriminated against by a culturally biased diagnostic system.
• weakness of sz diagnosis is a symptom overlap with other conditions.

  A considerable overlap between symptoms of sz and the symptoms of other conditions. E.g both sz and bipolar disorder involve positive symptoms (delusion) and negative symptoms (avolition). This suggests that in terms of classification sz and bipolar disorder may be two different conditions but variations of a single condition. in terms of diagnosis it means that sz is hard to distinguish from bipolar disorder. symptoms overlap means sz may not exist as a distinct condition and that even if it does its hard to diagnose.