Schizophrenia may begin suddenly, over a period of days or weeks, or slowly and gradually, over a period of years.
Although the severity and types of symptoms vary among different individuals with schizophrenia, the symptoms are usually sufficiently severe to interfere with the ability to work, interact with people, and care for oneself.
However, symptoms are sometimes mild at first (called the prodrome). Individuals may simply appear withdrawn, disorganised, or suspicious. Medical professionals may recognise these symptoms as the beginning of schizophrenia, but sometimes medical professionals recognise them only in hindsight.
Schizophrenia is characterised by psychotic symptoms, which include delusions, hallucinations, disorganised thinking and speech, and bizarre and inappropriate behaviour. Psychotic symptoms involve a loss of contact with reality.
In some individuals with schizophrenia, mental (cognitive) function declines, sometimes from the very beginning of the disorder. This cognitive impairment leads to difficulty paying attention, thinking in the abstract, and solving problems.
The severity of cognitive impairment largely determines overall disability in people with schizophrenia. Many individuals with schizophrenia are unemployed and have little or no contact with family members or other people.
Symptoms may be triggered or worsened by stressful life events, such as losing a job or ending a romantic relationship. Drug use, including use of marijuana, may trigger or worsen symptoms as well.
Overall, the symptoms of schizophrenia fall into four major categories:
- Positive symptoms;
- Negative symptoms;
- Disorganisation; and
- Cognitive impairment.
Individuals may have symptoms from any or all categories.
Positive symptoms involve a distortion of normal functions. They include the following:
- These are false beliefs that usually involve a misinterpretation of perceptions or experiences.
- Also, individuals maintain these beliefs despite clear evidence that contradicts them.
- There are many possible types of delusion.
- For example, people with schizophrenia may have persecutory delusions, believing that they are being tormented, followed, tricked, or spied on.
- They may have delusions of reference, believing that passages from books, newspapers, or song lyrics are directed specifically at them.
- They may have delusions of thought withdrawal or thought insertion, believing that others can read their mind, that their thoughts are being transmitted to others, or that thoughts and impulses are being imposed on them by outside forces.
- Delusions in schizophrenia may be bizarre or not.
- Bizarre delusions are clearly implausible and not derived from ordinary life experiences.
- For example, individuals may believe that someone removed their internal organs without leaving a scar.
- Delusions that are not bizarre involve situations that could happen in real life, such as being followed or having a spouse or partner who is unfaithful.
- These involve hearing, seeing, tasting, or physically feeling things that no one else does.
- Hallucinations that are heard (auditory hallucinations) are by far the most common.
- Individuals may hear voices in their head commenting on their behaviour, conversing with one another, or making critical and abusive comments.
Negative symptoms involve a decrease in or loss of normal functions. They include the following:
- Reduced expression of emotions (blunted affect):
- This involves showing little or no emotion. The face may appear immobile.
- Individuals make little or no eye contact.
- Individuals do not use their hands or head to add emotional emphasis as they speak.
- Events that would normally make them laugh or cry produce no response.
- Poverty of speech:
- This refers to a decreased amount of speech.
- Answers to questions may be terse, perhaps one or two words, creating the impression of an inner emptiness.
- This refers to a diminished capacity to experience pleasure.
- Individuals may take little interest in previous activities and spend more time in purposeless activities.
- This refers to a lack of interest in relationships with other people.
These negative symptoms are often associated with a general loss of motivation, sense of purpose, and goals.
Disorganisation involves thought disorders and bizarre behaviour:
- Thought disorder:
- This refers to disorganised thinking, which becomes apparent when speech is rambling or shifts from one topic to another.
- Speech may be mildly disorganised or completely incoherent and incomprehensible.
- Bizarre behaviour:
- This may take the form of childlike silliness, agitation, or inappropriate appearance, hygiene, or conduct.
- Catatonia is an extreme form of bizarre behaviour in which individuals maintain a rigid posture and resist efforts to be moved or, in contrast, move randomly.
Cognitive impairment refers to difficulty concentrating, remembering, organising, planning, and problem solving.
Some individuals are unable to concentrate sufficiently to read, follow the story line of a movie or television show, or follow directions.
Others are unable to ignore distractions or remain focused on a task.
Consequently, work that involves attention to detail, involvement in complicated procedures, decision making, and understanding of social interactions may be impossible.
About 5 to 6% of individuals with schizophrenia commit suicide, about 20% attempt it, and many more have significant thoughts of suicide.
Suicide is the major cause of premature death among people with schizophrenia and is one of the main reasons why schizophrenia reduces average life span by 10 years.
Risk of suicide is increased in young men with schizophrenia, especially if they also have a substance use disorder.
Risk is also increased in individuals who have depressive symptoms or feelings of hopelessness, who are unemployed, or who have just had a psychotic episode or been discharged from the hospital.
Risk of suicide is greatest for individuals who developed schizophrenia late in life and who were functioning well before it developed.
Such individuals remain able to feel grief and anguish.
Thus, they may be more likely to act in despair because they recognise the effects of their disorder.
These individuals are also the ones with the best prognosis for recovery.
Contrary to popular opinion, individuals with schizophrenia have only a slightly increased risk for violent behaviour.
Threats of violence and minor aggressive outbursts are far more common than seriously dangerous behaviour.
A very few severely depressed, isolated, paranoid people attack or murder someone whom they perceive as the single source of their difficulties (for example, an authority, a celebrity, their spouse).
Individuals who are more likely to engage in significant violence include the following:
- Those who abuse drugs or alcohol;
- Those with delusions that they are being persecuted;
- Those whose hallucinations command them to commit violent acts; and/or
- Those who do not take their prescribed drugs.
However, even taking risk factors into account, medical professionals find it difficult to accurately predict whether a given individual with schizophrenia will commit a violent act.