Experts have identified many classifications of psychological diseases. Some of the most common are mood disorders, which can cause feelings of depression or even extreme euphoria. Anxiety disorders are also considered common psychological diseases; these disorders can cause feelings of anxiety ranging from generalized nervousness to panic attacks to specific phobias. Eating disorders, such as anorexia, can cause dangerous changes in diet and serious risk to physical health. Psychotic disorders, personality disorders, impulse control disorders, and substance abuse disorders are also considered common psychological diseases.
Mood disorders are generally believed to be some of the most common psychological diseases. Mood disorders are usually defined as disorders that cause either abnormally low or abnormally high mood, to the point where the person's normal, healthy functioning becomes impaired and life problems arise. Depression and bipolar disorder are usually counted among these.
Anxiety disorders generally involve debilitating nervousness, anxiety, or fear. Sometimes, these feelings occur in response to a specific stimulus, but in other cases the feelings of worry do not seem to be connected to a particular event or situation. Social phobia, panic disorder and obsessive-compulsive disorder (OCD) are normally considered anxiety disorders.
Eating disorders are another of the more common psychological diseases. Binge eating, bulimia, and anorexia are believed to be the most common eating disorders. These disorders generally affect the patient's relationship to food and can drastically impact her diet. They are usually rooted in deep-seated emotional problems, and may affect a person's perception of her physical appearance or her feelings of self-worth.
Psychotic disorders typically influence patients' perception of reality, making it difficult for them to distinguish what is real from what isn't. People with psychotic psychological diseases may believe odd, and sometimes unrealistic, things even when they are offered solid proof to the contrary. Auditory and visual hallucinations are also common to these disorders. Schizophrenia and delusional disorder are types of psychotic disorders.
Impulse control disorders are psychiatric conditions that generally cause their victims to succumb to irresistible impulses to do things that could be harmful or detrimental. Kleptomania, usually defined by an uncontrollable urge to steal, is considered such a disorder. Other impulse control conditions include trichotillomania, the urge to pull out one's hair, or dermatillomania, the urge to pick at blemishes or wounds on the skin. Substance abuse disorders, such as drug or alcohol addiction, are often grouped into this classification as well.
Personality disorders are probably very common, and some believe that most cases evade diagnosis. Borderline personality disorder, antisocial personality disorder, and narcissistic personality disorder are among these psychological diseases. These disorders typically involve problems with the person's beliefs, worldview, and ways of thinking, which can be difficult to correct.