There is no known single cause of schizophrenia. We do not yet understand all of the factors necessary to produce schizophrenia, but experts do agree that the disease is caused by the interaction of genetic and environment factors that lead to abnormalities of brain function³. Many of the symptoms of schizophrenia have been linked to abnormalities in the transfer and processing of information within the brain, and with particular neurotransmitters (dopamine and serotonin) ³. Research indicates that vulnerability to schizophrenia is inherited, the estimated heritability is roughly 80%². There is other evidence that environmental influences may have effects on the brain which increase the chance of developing the disease².

People with schizophrenia may have perceptions of reality that are extremely different from those shared by others. They often suffer terrifying symptoms such as hearing internal voices, or believing that other people are reading their minds, controlling their thoughts, or plotting to harm them. Living in a world distorted by hallucinations and delusions, people with schizophrenia may feel frightened, anxious, and confused. Their speech and behavior can become so disorganized that they may be incomprehensible or frightening to others. Partly because of the unusual realities they experience, people with schizophrenia may exhibit inconsistent behavior.
People with schizophrenia usually experience several types of symptoms listed below¹.
(1) "Positive" symptoms
These are psychological features "added" as a result of the disorder, but not normally seen in healthy people such as hallucinations, delusions, disorganised thinking and agitation.
(2) "Negative" symptoms
These are psychological capabilities, which most people possess, but which people with schizophrenia have lost such as lack of drive, or initiative, social withdrawal, apathy (not caring about anything) and emotional unresponsiveness ('blunting') such as drive and initiative. Other examples of "negative" symptoms include social withdrawal, apathy (not caring about anything), and emotional unresponsiveness ('blunting').
(3) Cognitive symptoms
Patients had poorer performance than healthy controls over a wide range of cognitive functions, such as attention, memory and executive function.
The sudden onset of severe psychotic symptoms is referred to as an acute psychotic episode. The negative symptoms of schizophrenia may be less obvious than the positive symptoms, and may precede, occur along with, or follow the positive psychotic symptoms. During a psychotic episode, people with schizophrenia cannot think logically, and may lose all sense of who they are.
The relative risk for suicide is increased by 12 times, with a lifetime risk of roughly 6.5%¹.

?     There are a number of different 'conventional' antipsychotic medicines that seem to work mainly by reducing the effects of the neurotransmitter dopamine in the brain. They are mainly useful for treating the positive symptoms of schizophrenia. However, they are not always very effective against the negative symptoms of schizophrenia, or mood symptoms (affective symptoms). In addition, some patients may respond poorly or not at all to these medicines. Conventional antipsychotics have a number of unpleasant side effects, and patients may have to take additional medicines to combat these. The side effects may contribute to patients not taking their medication (non-compliance), which can lead to relapse of schizophrenia symptoms¹.
?     A number of new 'atypical' antipsychotic medications for schizophrenia with fewer and less severe side effects than older medications have been introduced in 1980s. The atypical antipsychotic medicines appear to target both serotonin and dopamine, and as a result they seem to have effects on a broader range of symptoms. They are effective in the treatment of psychosis, including hallucinations and delusions, and may also be helpful for treating the negative symptoms of the disease¹.
?     The large majority of people with schizophrenia show substantial improvement when treated with antipsychotic medicines. Discontinuation of medication without physician supervision and guidance may lead to relapse⁴.
?     For more information, please consult psychiatrists or healthcare professionals.
  

 1.  Owen, Sawa and Mortensen, Lancet. 2016 July 2; 388(10039): 86–97.
 2.  Huang YQ et al., Lancet Psychiatry. 2019 Mar;6(3):211-224.
 3.  Millan MJ, et al. Nat Rev Drug Discov. 2016 Jul;15(7):485-515.
 4.  Alvarez-Jimenez et al. Schizophr Res 2012; 139:116–128.