University of Gothenburg
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What is schizophrenia, what is the rate of occurrence, what are the causes and symptoms? Maria Unenge Hallerbäck and Tove Lugnegård provide the answers.


Schizophrenia is a severe form of psychotic disorder. Schizophrenia can manifest in different ways and there is much evidence to support that it is not a uniform disorder but rather an umbrella term for several different psychotic conditions.


Tove Lugnegård & Maria Unenge Hallerbäck

Rate of occurrence

The prevalence of schizophrenia in the population is 0.2-0.5%. In Sweden around 35,000 people are estimated to be diagnosed with schizophrenia.


There is a relatively high rate of heredity in cases of schizophrenia, but one has not been able to identify any single gene causing the disorder. It is believed to be many different genes and perhaps even many "small" gene variations that increase the risk of schizophrenia. The risk of being afflicted with schizophrenia later in life is something which develops over the process of the brain's development, all the way from the fetal stage into adult life. Environmental factors such as malnourishment or infections during the fetal stage can cause an increased risk. Cannabis abuse can contribute to schizophrenia. It is not uncommon for people who develop schizophrenia to have had non-specific difficulties in concentration, social interaction and motor control during their formative years.


Schizophrenia often initially appears at a young adult age. Sometimes it is a gradual development in which the person starts to pull away more and more from studies and work and avoids interacting with relatives and friends. The person takes on a changed perception of both themselves and reality. Increased sensitivity to sensory input and strong unexpected emotional outbursts are common, as is a changed sleeping pattern. Sometimes the person's descent into schizophrenia is sudden and without preceding symptoms. The typical symptoms of schizophrenia are hallucinations, delusions, incoherent speech and behaviour, as well as catatonic symptoms, i.e. physical stiffness and getting stuck in certain movements. The hallucinations are often in the form of voice hallucinations. Hearing voices commenting on what one is doing or different voices talking to or arguing with each other are common. Other frequently occurring symptoms include dulled emotions, reduced energy level and becoming increasingly withdrawn.


In the acute phase the aim of the treatment is to reduce the psychotic symptoms as quickly as possible. There are medications that reduce the acute symptoms. In addition, potential causes that may have contributed to triggering the psychosis, e.g. acute mental stress, sleep deprivation, drug abuse, are examined. When the psychotic symptoms have been lessened, treatment focuses on establishing a functional daily life. Follow-up contact is important in order to be able to monitor the person's development and prevent new psychotic breaks.