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Symptoms and Signs of Schizophrenia

Doctor's Notes on Schizophrenia

Schizophrenia is a life-long mental disorder involving a breakdown in the relation between thought, emotion, and behavior, leading to faulty perception, inappropriate actions and feelings, withdrawal from reality and personal relationships into fantasy and delusion, and a sense of mental fragmentation. Signs and symptoms may include disorganized thinking and speech, delusions, hallucinations, abnormal behavior and movements (silly acting to agitation, useless and excessive movements or postures, for example), may neglect personal hygiene, may lack emotions and become socially withdrawn. Suicidal thoughts and behaviors are fairly common with schizophrenia – these constitute an emergency. The disorder is mainly diagnosed in an age range from teens to age 45.

The causes of schizophrenia are unknown. Risk factors for the development or trigger for the disease include family history, having an autoimmune disease, elderly father, pregnancy and birth complications, malnutrition, any toxin or viral infections that effect brain function and taking mind-altering drugs as a teen or young adult.

Medical Author:
Medically Reviewed on 3/11/2019

Schizophrenia Symptoms

Schizophrenia symptoms can drastically affect a person's inner world and experience, leading to outward changes in behavior. Hallucinations or delusions may prompt a person to act in a seemingly strange or bizarre way. For example, a delusion that someone is reading their thoughts may prompt them to get rid of telephones and computers, or to act unusually frightened or suspicious. At other times, a person with schizophrenia may not have any outward appearance of being ill.

People with schizophrenia vary widely in their behavior as they struggle with an illness beyond their control. In active stages, those affected may ramble in illogical sentences or react with uncontrolled anger or fright to a perceived threat. People with schizophrenia may also experience relatively passive phases of the illness in which they seem to lack personality, movement, and emotion (also called a flat affect). People with schizophrenia may alternate in these extremes. Their behavior may or may not be predictable. It is important to be aware, however, that most people with schizophrenia are not prone to act violently -- people with mental illness are actually more likely to be victims of violence than perpetrators.

In order to better understand schizophrenia, the symptoms are often grouped under the following categories:

  • Positive symptoms: hearing voices (auditory hallucinations), suspiciousness, feeling under constant surveillance, delusions, disorganized speech (such as creating and using words without a meaning [neologisms])
  • Negative (or deficit) symptoms: social withdrawal, difficulty in expressing emotions (in extreme cases called blunted affect), difficulty in taking care of themselves, inability to feel pleasure (Negative symptoms cause severe impairment and may be mistaken for laziness or depression in some cases.)
  • Cognitive symptoms: difficulties attending to and processing of information, in understanding the environment, and in remembering simple tasks
  • Affective (or mood) symptoms: most notably depression, accounting for a very high rate of attempted suicide in people suffering from schizophrenia

Helpful definitions in understanding schizophrenia include the following:

  • Psychosis: Psychosis is defined as being detached or disconnected from reality. During this phase, one can experience delusions or prominent hallucinations. People with psychoses are often not able to realize that their experiences or beliefs are not real. Psychosis is a prominent feature of schizophrenia but is not unique to this illness. Other psychotic disorders in the DSM 5 include brief psychotic disorder, schizophreniform disorder, schizoaffective disorder, and delusional disorder.
  • Schizoid personality disorder: a disorder characterized by almost complete lack of interest in social relationships and a restricted range of expression of emotions in interpersonal settings, making a person with this disorder appear cold and aloof
  • Schizotypal personality disorder: This more severe personality disorder is characterized by acute discomfort with close relationships as well as disturbances of perception and abnormal behaviors, making those affected by this disorder seem odd and eccentric because of unusual mannerisms. Recent studies suggest that this disorder shares genetic risk factors with schizophrenia and may be a milder variant of schizophrenia.
  • Hallucinations: A person with schizophrenia may have strong sensations of objects or events that are real only to him or her. These may be in the form of things that they believe strongly that they see, hear, smell, taste, or touch. Hallucinations have no outside source and are sometimes described as "the person's mind playing tricks" on him or her.
  • Illusion: An illusion is a mistaken perception for which there is an actual external stimulus. For example, a visual illusion might be seeing a shadow and misinterpreting it as a person. The words "illusion" and "hallucination" are sometimes confused with each other.
  • Delusion: A person with a delusion has a strong belief about something despite evidence that the belief is false. For instance, a person may listen to a radio and believe the radio is giving a coded message about an impending extraterrestrial invasion. All of the other people who listen to the same radio program would hear, for example, a feature story about road repair work taking place in the area. The recurrent, intrusive, and often false thoughts (obsessions) in obsessive-compulsive disorder can sometimes be mistaken for delusions.
  • Disorganized thinking: Speech or behaviors are unorganized or difficult to understand and flattening or inappropriate emotions. People with disorganized-type schizophrenia may laugh at the changing color of a traffic light or at something not closely related to what they are saying or doing. Their disorganized behavior may disrupt normal activities, such as showering, dressing, and preparing meals.
  • Catatonia is now considered to be a symptom of a psychiatric (for example, schizophrenia, depression, bipolar) or medical condition, rather than a type of schizophrenia. Catatonia is characterized by a marked decrease in how a person reacts to the environment. This can result in severe disturbances of movement and behavior. People with catatonia may keep themselves completely immobile or move all over the place in a purposeless way. They may not say anything for hours (mutism), or they may repeat anything you say (echolalia) or speak senselessly. Untreated catatonia can progress to a life-threatening medical condition.
  • Residual symptoms refer to a past history of at least one episode of schizophrenia, but the person currently has no positive symptoms (delusions, hallucinations, disorganized thinking, speech, or behavior). It may represent a transition between a full-blown episode and complete remission, or it may continue for years without any further psychotic episodes.
  • Symptoms of schizophrenia in children and younger teenagers are less common since this form is not as common as adult-onset schizophrenia. Children with this illness tend to have a more severe course of symptoms, with more cognitive (thinking) problems, more negative symptoms, and more severe social challenges than people with adult-onset schizophrenia.

Schizophrenia Causes

The causes of schizophrenia are not known. However, the interplay of genetic, biological, environmental, and psychological factors are all thought to be involved. We do not yet understand all of the causes and other issues involved, but current research is making steady progress toward elucidating and defining the causes of schizophrenia. Schizophrenia, schizotypal personality disorder, and bipolar disorder are thought to share common genetic risk factors.

In biological models of schizophrenia, researchers have investigated hereditary (familial) predisposition, season of birth, infectious agents, allergies, and disturbances in metabolism.

Schizophrenia runs in families (hereditary), and an increasing number of genes have been implicated. First-degree relatives (siblings and children of affected individuals) have an increased risk of schizophrenia, but it is not substantially increased in more distant relatives. However, genetics alone do not cause schizophrenia. For example, the risk of illness in an identical twin of a person with schizophrenia is 40%-50% (for example, genetics accounts for only about half of the risk for schizophrenia). A child of a parent suffering from schizophrenia has a 10% chance of developing the illness. The risk of schizophrenia in the general population is 1% or less.

The current concept is that multiple genes are involved in the development of schizophrenia and that other risk factors such as prenatal (intrauterine), perinatal, and nonspecific stressors are involved in creating a disposition or vulnerability to develop the illness. Neurodevelopment may be affected due to one or more of these factors. Neurotransmitters (chemicals allowing the communication between nerve cells) also play a part in the development of schizophrenia. The list of neurotransmitters under scrutiny is long, but researchers have given special attention to dopamine, serotonin, and glutamate.

Neuroimaging research has also suggested subtle changes in specific brain areas, or in the connections between brain areas, may be involved with schizophrenia. However, none of these findings so far have been consistent enough to be useful in diagnosing or predicting schizophrenia. Functional neuroimaging (for example, functional magnetic resonance imaging [fMRI]) and electroencephalographic (EEG) studies have shown changes in brain function related to schizophrenia. One finding has been that the default mode network (DMN) of the brain is more highly activated in people with schizophrenia and bipolar disorder. The DMN is involved with internally focused tasks (for example, thinking and concentration), and this abnormal activity may be related to symptoms of illness. There is hope that a better understanding of these structural and functional changes in the brain may lead to more accurate diagnosis and better treatments for schizophrenia.

Environmental risk factors, like a history of drug use, particularly early and heavy use of marijuana or abuse of stimulants (for example, amphetamines [speed], or mixed amphetamine salts [Adderall]), have also been associated with the development of schizophrenia.

When a person first develops symptoms of psychosis, it is important for their doctors to investigate all reasonable medical causes for any acute change in someone's mental health or behavior. Sometimes other medical conditions may cause symptoms that resemble schizophrenia, but these conditions have different treatments.

Schizophrenia Symptoms, Types, Causes, Treatment Slideshow

Schizophrenia Symptoms, Types, Causes, Treatment Slideshow

Schizophrenia is a chronic, severe, debilitating mental illness characterized by disordered thoughts, abnormal behaviors, and anti-social behaviors. It is a psychotic disorder, meaning the person with schizophrenia does not identify with reality at times.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.