Clozapine versus quetiapine for people with schizophrenia

BACKGROUND Description of the condition Schizophrenia is a chronic and disabling mental illness which involves a complex set of disturbances associated with abnormalities of brain structure and function, that affects about one per cent of the population (Insel 2010). It is characterised by a combination of positive symptoms (hallucinations, delusions, and thought disorder), negative symptoms (loss of mental energy and efficiency, such as limited emotional expression, apathy, social withdrawal, and poverty of thought and speech), and cognitive impairment (affects executive functioning, verbal memory, and attention) (Owen 2016). Typically, the prodromal phase of schizophrenia emerges in the early adolescent years and patients experience a decline in cognitive and social functioning, which precedes the onset of a first episode of psychosis (where the person's perception of reality is altered significantly and often involves experience of delusions and hallucinations). It is not until the first episode is presented in late adolescence or early adulthood, that a person is referred for specialist consultation (Kahn 2015; Owen 2016). Schizophrenia, like most psychiatric diagnoses, remains a syndromic concept. The use of operational criteria, such as those incorporated in the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) (DSM-V) and the International Classification of Diseases (ICD-10) (ICD-10) of the World Health Organization, have provided a reliable diagnostic approach for clinicians, and they are the classifications that are, in the main, currently being used (Jablensky 2016). Schizophrenia concerns not only the patients themselves, but also their family members who assume their care. It is one of the health problems that contributes most to the global burden of diseases due to the early onset and the frequent chronicity leading not only to individual burden but to high levels of social burden and cost as well (Chong 2016; Marwaha 2004).