A psychological disorder is difficult to define. There is no consensus on the definition of a psychological disorder. A psychological disorder definition should include the following four characteristics:

1. Personal distress
   The disorder must result in personal distress.
2. Disability
   The disorder must result in an impairment in some important area of life.
3. Violation

A correct diagnosis will allow the clinician to describe base rates, causes and treatment. Reliability and validity are the cornerstones of any diagnostic or assessment procedure. Reliability refers to the consistency of measurement. Validity refers to measuring what you want to measure. Alternate form reliability refers to the extent to which scores on two forms of the test

Clinical profile major depressive disorder:

Obsessive-compulsive and related disorders are defined by repetitive thoughts and behaviours that are so extreme that they interfere with everyday life. Obsessions are repetitive thoughts and urges. Compulsions are repetitive behaviours or mental acts. Compulsions are often not seen as pleasurable by the patient. OCD begins before age 10 or in late adolescence/early adulthood.

Clinical profile

Psychosis is a disruption in the experience of reality or disruption of reality testing. Hallucinations are perception-like experiences which occur without an external stimulus and the most common hallucinations are auditory hallucinations. It is not uncommon, as children tend to experience audio-visual hallucinations but this tends to stop at the age of 12 or 13. Delusions are fixed

Eating disorders are not very stable. There is a lot of movement between the disorders. People with anorexia nervosa choose a thin figure as their ideal and overestimate their own body size, but are fairly accurate at reporting their weight. Maintaining thinness is strongly linked to self-esteem in anorexia nervosa.

There are several biological consequences of anorexia

Whether the behaviour is seen as problematic depends on culture. Externalizing disorders are characterised by more outward-directed behaviours. Internalizing disorders are characterised by more inward-focused experiences and behaviours.

There are three sub-types of ADHD:

1. Predominantly inattentive
2. Predominantly hyperactive-impulsive
3. Combined

People with ADHD tend to have problems getting along with peers

Personality refers to a combination of unique traits expressed in thoughts, behaviours, feelings and interpersonal functioning. It is relatively stable over time and over situations. Personality disorders are pervasive, persistent and pathological. It can be assessed using semi-structured interviews (1), file research (2), using observations (3) and using heteroanamnesis, asking someone close to the