Clinical features

The signs and symptoms of the disorder are most usefully divided into:

positive symptoms: delusions (fixed false beliefs held with tenacity and not understandable in terms of the sociocultural context) and hallucinations (false perceptions which can occur in any sensory modality, but with auditory hallucinations being most common)

negative symptoms: restricted or blunted affect (decreased range of facial expression); paucity of thought content; and apathetic social withdrawal

disorganisation symptoms: formal thought disorder (disorganised thoughts, manifested by disjointed speech); disorganised behaviour; and inappropriate affect (e.g. smiling when discussing a sad event), and

cognitive impairment (see below).

There is no specific laboratory or radiological test for schizophrenia, and none of the signs or symptoms outlined above are pathognomonic. However, the ‘first rank’ symptoms elucidated by Schneider (Box 5.2) have some degree of diagnostic specificity, and are useful to ask for in the clinical interview.

BOX 5.2 Schneider’s ‘first rank’ symptoms of schizophrenia

Delusional perception

There is a normal percept to which an ‘un-understandable’ delusional attribution is given.

Passivity phenomena

This is a series of phenomena where the person experiences their will, actions, affect or bodily (somatic) functions being ‘taken over’ by some alien influence. It is an ‘as if’ phenomenon, such as: ‘It is as though my actions are controlled by a robot; I feel like a puppet on a string.’

Negative symptoms can sometimes be ‘mimicked’ by depression, positive symptoms or the extrapyramidal side effects of antipsychotic medication. It is always important to treat the underlying cause, as shown in Table 5.1.

TABLE 5.1 Primary and secondary negative symptoms, and treatment

		Management
Primary		Use atypical antipsychotic; consider adjunctive treatments; if persistent, consider clozapine
Secondary	To depression	Antidepressant medication (SSRI or mirtazapine)
	To positive symptoms	Optimise treatment of positive symptoms: pharmacological and psychosocial approaches should be explored
	To D2 receptor blockade	Consider atypical antipsychotic; if persistent extrapyramidal side effects on atypical antipsychotic, consider adjunctive anticholinergic agent

(Castle & Buckley 2008, with permission)

Not all signs and symptoms occur in any one individual at any one time: different patients show different features and these might change over the course of the illness. Table 5.2 shows the cardinal features of schizophrenia according to DSM–IVTR and ICD–10. It will be noted that there is considerable overlap between these two constructs: the main difference is that DSM–IVTR requires a 6-month duration: disorders with the characteristic symptoms but shorter duration are labelled schizophreniform disorder.

TABLE 5.2 DSM–IVTR and ICD–10 diagnoses of schizophrenia

DSM–IVTR (synopsis)	ICD–10 (synopsis)
Symptoms (at least 1 month unless successfully treated): • delusions • hallucinations • disorganised speech • disorganised or catatonic behaviour, and • negative symptoms	Symptoms: • at least one of: thought echo, insertion, withdrawal, broadcast • passivity phenomena or delusional perception, and • third person conversing or running commentary hallucinations
At least two symptoms required, unless: • delusions are bizarre, and • hallucinations are third person conversing or running commentary	At least two of: • persistent hallucinations in any modality, with delusions • disorganised speech • catatonia, and • negative symptoms (must be ‘primary’)
Social/occupational dysfunction: • work • interpersonal relations, and • self-care
Duration: 6 months at least	Duration: 1 month at least
Exclusions: • schizoaffective disorder • bipolar disorder • general medical condition, and • substance-induced	Exclusions: • mood disorder • organic brain disease, and • alcohol/drug-related intoxication

(Castle & Buckley 2008, with permission)

Differential diagnosis

Schizoaffective disorder

If there are clear affective and psychotic symptoms which occur at different times over the course of illness, a label of schizoaffective disorder is applied. There is some debate about the validity of this diagnosis and the boundaries are vague.

Delusional disorder

This group of disorders is characterised by well-circumscribed delusions in the absence of prominent hallucinations or negative or disorganisation symptoms. The delusional content is ‘understandable’, such as beliefs about having a disease (also termed monosymptomatic hypochondriacal delusions or delusional disorder, somatic subtype) or having an unfaithful partner (delusional jealousy, or Othello syndrome).

Pervasive developmental disorders

Pervasive developmental disorders (e.g. autism, Asperger’s syndrome (see Ch 16)) are characterised by abnormalities in social interactions, and a restricted and stereotyped range of interests and activities, evident from before 3 years of age.

Axis II disorders

Some of the cluster A DSM–IVTR Axis II (personality) disorders (see Ch 12) could be considered formes fruste of schizophrenia. The most obvious is schizotypal personality disorder, characterised by longstanding eccentricity, social withdrawal and odd beliefs. It is placed on Axis II in DSM–IVTR, but is probably genetically linked to schizophrenia, and sometimes evolves into full-blown schizophrenia.