Usually with schizophrenia, the person's inner world and behavior change notably. Behavior changes might include the following:
Depersonalization (a sense of being unreal, hazy and in a dreamlike state), sometimes accompanied by intense anxiety
Loss of appetite
Loss of hygiene
Hallucinations (hearing or seeing things that aren't there)
The sense of being controlled by outside forces
A person with schizophrenia may not have any outward appearance of being ill. In other cases, the illness may be more apparent, causing bizarre behaviors. For example, a person with schizophrenia may wear aluminum foil in the belief that it will stop one's thoughts from being broadcast and protect against malicious waves entering the brain.
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 violence 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.
In order to better understand schizophrenia, the concept of clusters of symptoms is often used. Thus, people with schizophrenia can experience symptoms that may be grouped under the following categories:
Positive symptoms: Hearing voices, suspiciousness, feeling as though they are under constant surveillance, delusions, or making up 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. These symptoms cause severe impairment and are often mistaken for laziness.
Cognitive symptoms: Difficulties attending to and processing of information, understanding the environment, and remembering simple tasks.
Affective (or mood) symptoms: Most notably depression, accounting for a very high rate of attempted suicide in people suffering from schizophrenia. Anxiety can also be present and may be a direct result of the psychosis or come and go during a psychotic episode.