Psychological disorder - condition reflecting persistent, harmful abnormalities of the mind. At least 20% of canadian adults suffer psychological disorders each year. Can be associated with the 4 d"s. Diagnostic and statistical manual of mental disorders, 4th edition. Used for the diagnosis and classification of psychological disorders in north america. Axis ii - personality disorders; mental retardation. Axis iv - psychosocial and environmental problems. Axis v - global assessment of functioning. Diathesis-stress - a person may be predisposed for a mental disorder that remains unexpressed until triggered by stress. Views disorders as illnesses caused by a malfunctioning brain. Began with the discovery of the cause of general paresis. Huntington"s disease and loss of cells in the striatum. Involves break from reality in thought processes, emotion, and/or behaviour. Positive symptoms - observable addition of abnormal behaviour. Negative symptoms - elimination or reduction of normal behaviours. No ability to take care of self. Negative symptoms - too little mesocortical dopamine.