Categories of Mental Disorders:

• Mental retardation - subnormal intellectual functioning that originates during the period in which the individual is developing;
• Organic brain syndromes disorders - a case wherein there is impairment of brain tissue functions.
• Mental disorders - a case that is believed to be caused by emotional stress.

Mental disorders that is believed to be caused by emotional problems / stress (psychogenic):

• Psychotic Disorders. In this kind of mental disorder the patient usually loses contact with reality and the person also experiences delusions and hallucinations. Example of hallucination is a person seeing something that doesn't exist and hearing voices when no one is talking.
• Schizophrenia is one of the most common psychotic problems. Most people think that a schizophrenic person has "split personality", this is idea probably developed from the fact that episodes of the illness may be separated by periods of normal behavior. Psychiatrist believed there is an organic basis for schizophrenia that is it is only partly caused by emotional stress or it may be hereditary or it may also be caused by viral infection. Types of schizophrenia ranges from behavior of excitement to aggressiveness and withdrawal to stupor.

• Mood Disorders. This disorder is characterized by disturbance in mood. In manic depression there may be fluctuations between periods of deep depression and extreme happiness. In major depressive disorder, a person has strong feelings of sadness and there may be a loss of interest in engaging in all activities, depression can last for at least two weeks. Mood disorders are sometimes caused by toxic substances like prohibited drugs or various medical conditions.

• Anxiety and Panic Disorders. Is an irrational or illogical worry not based on fact. This disorder may already be present from an early age or may begin suddenly after a triggering event. This mental disorder is characterized by anxiety, low self-esteem, and withdrawal from others. In panic disorders, there are recurrent attacks of intense apprehension, fear, or terror. This disorder is usually accompanied by agoraphobia, the fear of being in public places.

• Obsessive-Compulsive Disorder. Obsession is a persistent thoughts and impulses that are experienced at some time during the disturbance, example is thinking that one's hand are contaminated with germs and Compulsion is a repetitive mental acts that the person feels driven to perform in response to an obsession example is repeatedly washing one's hands.
• Post-traumatic stress disorders. An anxiety disorder in which a person repeatedly re-experiences an extremely traumatic event. People with this disorder have persistent frightening thoughts and memories of their ordeal and feel emotionally detached especially with people they were once close to
• Somatoform Disorders. In this disorder a person experiences physical symptoms caused by psychological factors, but does not actually have a physical disease. In order to meet the criteria for a somatoform disorder, the physical symptoms must be serious enough to interfere with the patient's employment or relationships, and must have symptoms that are not under the patient's voluntary control.Sometimes confused with somatoform disorders are psychosomatic disorders, in which a person actually has a physical disease worsened or partially caused by psychological factors.
• Dissociative Disorders. Mental illnesses that involve disruptions of memory, awareness, identity and perception that normally operates smoothly. The disruption may be sudden or gradual, acute or chronic.

Dissociative Amnesia is an inability to recall important personal information usually of traumatic and stressful events.

Dissociative Identity Disorder also called as "multiple personality disorder", is the presence of two or more distinct personalities that dominate an individual's behavior at different times, it is accompanied by dissociative amnesia.

• Personality Disorders. Are chronic psychological disorders which can greatly affect a person's life. These disorders are characterized by a persistent pattern of markedly unusual behavior and ways of thinking. During times of increased stress personality disorder will gain strength and begin to seriously interfere with the person's emotional and psychological functioning.

Antisocial personality disorder is a pattern of mental behavior wherein a person disregards and violates the rights of others. This disorder often brings a person into conflict with society as a consequence of a pattern of behavior that is unethical.

Borderline personality disorder a person with this disorder often experiences a repetitive pattern of disorganization and instability in self-image and close personal relationships. A person with this disorder is often intelligent, warm, friendly and competent. They can maintain this appearance for years until their defense structure crumbles because of very stressful situation like death or breakup.