A person may cross the line between normal and abnormal at the point that they cannot deal with the demands of everyday life - they fail to function adequately.
For instance, not being able to maintain basic standards of nutrition and hygiene, hold down a job or maintain relationships.
ROSENHAN AND SELIGMAN (1989) proposed further signs of failure to cope
When someone is not coping:
They no longer conform to interpersonal rules e.g maintaining personal space.
They experience severe personal distress.
They behave in a way that is irrational or dangerous.
Example: intellectual disability disorder
Having a very low IQ is a statistical infrequency but diagnosis would not be made on this basis alone. There would have to be clear signs that the person was not able to cope with the demands of everyday living. So intellectual disability disorder is an example of failure to function adequately.
