Alberto says: Individuals with schizophrenia may experience hallucinations (most reported are hearing voices), delusions (often bizarre or persecutory in nature), and disorganized thinking and speech.
The last may range from loss of train of thought, to sentences only loosely connected in meaning, to speech that is not understandable known as word salad in severe cases.
Social withdrawal, sloppiness of dress and hygiene, and loss of motivation and judgment are all common in schizophrenia.
There is often an observable pattern of emotional difficulty, for example lack of responsiveness. Impairment in social cognition is associated with schizophrenia, as are symptoms of paranoia. Social isolation commonly occurs.
Difficulties in working and long-term memory, attention, executive functioning, and speed of processing also commonly occur.
In one uncommon subtype, the person may be largely mute, remain motionless in bizarre postures, or exhibit purposeless agitation, all signs of catatonia.
About 30 to 50% of people with schizophrenia fail to accept that they have an illness or their recommended treatment. Treatment may have some effect on insight. People with schizophrenia often find facial emotion perception to be difficult.
Schizophrenia is often described in terms of positive and negative (or deficit) symptoms. Positive symptoms are those that most individuals do not normally experience but are present in people with schizophrenia. They can include delusions, disordered thoughts and speech, and tactile, auditory, visual, olfactory and gustatory hallucinations, typically regarded as manifestations of psychosis.
Hallucinations are also typically related to the content of the delusional theme. Positive symptoms generally respond well to medication.
Negative symptoms are deficits of normal emotional responses or of other thought processes, and respond less well to medication.
They commonly include flat expressions or little emotion, poverty of speech, inability to experience pleasure, lack of desire to form relationships, and lack of motivation. Negative symptoms appear to contribute more to poor quality of life, functional ability, and the burden on others than do positive symptoms.
People with greater negative symptoms often have a history of poor adjustment before the onset of illness, and response to medication is often limited.
A combination of genetic and environmental factors play a role in the development of schizophrenia.
People with a family history of schizophrenia who have a transient psychosis have a 20–40% chance of being diagnosed one year later.
The greatest risk for developing schizophrenia is having a first-degree relative with the disease (risk is 6.5%); more than 40% of monozygotic twins of those with schizophrenia are also affected.
Environmental factors associated with the development of schizophrenia include the living environment, drug use and prenatal stressors.
Parenting style seems to have no major effect, although people with supportive parents do better than those with critical or hostile parents.
Childhood trauma, separation from ones families, and being bullied or abused increase the risk of psychosis.
Living in an urban environment during childhood or as an adult has consistently been found to increase the risk of schizophrenia by a factor of two, even after taking into account drug use, ethnic group, and size of social group.
Other factors that play an important role include social isolation and immigration related to social adversity, racial discrimination, family dysfunction, unemployment, and poor housing conditions.
About half of those with schizophrenia use drugs or alcohol excessively. Amphetamine, cocaine, and to a lesser extent alcohol, can result in psychosis that presents very similarly to schizophrenia.
Although it is not generally believed to be a cause of the illness, people with schizophrenia use nicotine at much greater rates than the general population.