Mental illness broadly denotes maladaptive patterns of behavior and thought that interfere with functioning. Mental illness can restrict freedom, making one live a more routine, constricted and unfulfilling life. Mental illness often impairs autonomy, making one overly reliant on others. Mental illness often impairs the ability to work, making one financially dependent on public assistance or family members. Finally, mental illness sometimes impairs the ability to relate to others, making marriage and socializing difficult. In all cases, and by definition, a mental illness becomes diagnosable when it interferes with life and functioning. So, for example, some people check; check to see if the stove is off or the door is locked. Some people do this a number of times in a day; perhaps they can’t leave the house until they have checked the stove three times. Still, this falls in the bounds of normality; in other words, it is not diagnosable pathology. On the other hand, when the checking behavior becomes so pronounced that the person is not only checking before leaving, but leaving work to check the stove, then the checking behavior becomes clinically significant, meaning that it now is a symptom which can contribute to diagnosis. This checking behavior might indicate obsessive compulsive disorder, an anxiety disorder in which obsessive thoughts (such as anxiety about the house burning down) are only assuaged by compulsive behaviors (such as checking the stove). When work and life become disrupted by thought and behavior, normality transitions to pathology.
All known mental disorders are described and organized in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders. This compendium of mental pathology follows the medical model, grouping signs and symptoms into recognizable patterns. These patterns are referred to as disorders or syndromes. Diagnoses are comprehensively recorded using a five axis system: