Depressive Reaction
Most people have blue moods from time to time in their lives. Indeed, when faced with a personal tragedy like the death of a loved one, a normal healthy individual may well undergo a period of depression. A person suffering from the depressive reaction, however, has persistent feelings of worthlessness and pessimism unrelated to event that might depress a normal person. An inability to cope with problem situations is gradually magnified into an inability to cope with anything at all. Attempts to mask the crisis by putting on a "front"--feigning cheerfulness and optimism--give way to episodes of total hopelessness. Suicide is often considered and sometimes attempted. Threats of suicide from a depressed person should always be regarded seriously.
Common physical symptoms accompanying depression are fatigue, loss of appetite, and insomnia.

Dissociative Reaction
The dissociative reaction involves a basic disruption of the patient's personality. The dissociative reaction permits a person to escape from a part of his personality associated with intolerable anxiety. The escape is made in various ways: by forgetfulness or absent-mindedness, dream states (including sleepwalking), amnesia, and--most seriously-- the adoption of multiple personalities, in which the patient behaves like one person at certain times and like an altogether different person at other times.

Schizophrenic Reaction
Schizophrenia, the most common and destructive of the psychotic reactions, is characterized by withdrawal from external reality, inability to think clearly, disturbances in affective reaction (capacity to feel and express emotion), and a retreat into a fantasy life--all of these resulting in a progressive deterioration of the patient's ordinary behavioral patterns.

Simple Schizophrenia
The patient with simple schizophrenia experiences a gradual loss of concern and contact with other people, and a lessening of the motivation needed to perform the routine activities of everyday life. There may be some personality deterioration, but the presence of hallucinations and delusions is rare.

Hebephrenic Schizophrenia
This form of schizophrenia is marked by delusions, hallucinations, and regressed behaviour. Hebephrenics babble and giggle, and often react in inappropriately childish ways. Their silly manner can make them seem happier than other schizophrenics, but this disorder often results in severe personality disintegration--more severe, in fact, than in other types of schizophrenia.

Manic-Depressive Reaction
This disorder, also called an affective reaction, is characterized by two phases--mania and depression. Patients are governed by one phase or another or by the alternation of both.
The manic phase may be mild and bring elation and a general stepping up of all kinds of activity. The patient tends to talk endlessly and in an associative rather than a logical way. If the disorder is more severe, he may act or dress bizarrely; he may be a whirlwind of activity and become so excited and agitated that he forgoes food and sleep and ends up in a state of total collapse.
In a mild depressive phase, the individual feels dull and melancholy, his confidence begins to drain away, and he becomes easily fatigued by daily routines. When the depressive phase is more severe, the patient starts to retreat from reality, gradually entering into a state of withdrawal that is very much like a stupor. At this point he hardly moves or speaks. He may be unable to sleep. Eventually he begins to question his value as a human being and is crushed by feelings of guilt. He may refuse to eat. Symptoms may progress to the point where an attempt at suicide is a real possibility.
Although the manic-depressive psychosis may alternate from one of its phases to the other, one or the other phase is usually dominant for a prolonged period of time. Depression is more often dominant than mania. Manic-depressive patients often recover spontaneously for periods of time, but relapses are fairly common.