Many people afflicted with schizophrenia report having hallucinations (hearing voices in one's head) and/or delusions (erroneous beliefs about being persecuted) while having a schizophrenic episode. Hallucinations and delusions are significantly less common in depressed, ADHD, CD, and selective mutism patients. 

Men tend to develop schizophrenia earlier than women, in that the average age of onset of schizophrenia for men is 18 and the average age of onset for women is 25. Many other psychological disorders come to fruition during the "young adult" period, including antisocial personality disorder and various mood disorders.

A negative symptom is one that dispells attention from a subject. Alternatively, positive symptoms attract attention to a subject. While a lack of emotion is a negative symptom, hallucinations, delusions, and disorganized speech are all positive symptoms.

The main tenet of the neurodevelopmental hypothesis is that schizophrenia is the result of early brain insult during either pre- or perinatal development, which is later expressed in the mature brain. Many have suspected that this insult could be due to environmental factors that mothers endure or are exposed to, as evidenced by the many schizophrenic children born from starving mothers during World War II, or from mothers exposed to toxins. The insult could also be due to genetic inheritance.

Mania (a period of especially high activity and euphoria) is not directly associated with schizophrenia; it is commonly associated with bipolar disorder. The other answer choices are four of the most common symptoms of schizophrenia.

People with schizophrenia perceive things without a stimulation, which are termed hallucinations. These people also suffer delusions, which are mistaken beliefs that are contrary to facts. Their speech is disorganized and can be incoherent.

In obsessive-compulsive disorders, people have obsessions, which are recurrent thoughts, and compulsions, which are recurrent, irrestible actions. People who experience episodes of depression with mania are considered to have bipolar disorder. Antisocial personality disorder describes people who lie, cheat, and steal, and have no sense of responsibility and no guilt about their behavior. Post-traumatic stress disorder occurs when a person who has gone through a significant trauma shows stress symptoms that impair the person's ability to function. 

A delusion of persecution is when a person believes everyone is trying to hurt (persecute) him or her; Lucy's belief about random planes bombing her and strangers plotting to hurt her are two examples of such perceived persecution. 

Positive symptoms are the presence of emotions or behaviors that are usually absent in a healthy patient. Negative symptoms are the absence of emotions or behaviors that are usually present in a healthy patient.

Flat affect is a negative symptom of schizophrenia, since it is a disruption in normal emotional functioning. Delusions, hallucinations, and catatonia are examples of positive symptoms, whereas impaired executive functioning is an example of a cognitive symptom.

While hallucinations, delusions, and incoherent speech are all noted symptoms of schizophrenia- new feelings or behaviors not present in healthy people-, flat affect (a lack of emotional expression and decrease in talkativeness) is a noted negative symptom, something that healthy people have/do that schizophrenia sufferers do not.

The causes of schizophrenia are varied but one of the leading suspected factors is an excess of the chemical dopamine.