Psychological Disorders

About this unit

This unit introduces how psychologists decide when behaviour becomes abnormal, how disorders are classified and what factors cause them. It then describes major groups of disorders: anxiety and related disorders, mood disorders, schizophrenia, neurodevelopmental disorders, and behavioural and substance-related disorders. Understanding these helps reduce stigma and supports early identification and help-seeking.

Key ideas

• The four Ds of abnormality: deviance, distress, dysfunction and danger.
• Classification systems: DSM (American Psychiatric Association) and ICD (World Health Organization).
• Biological, psychological and socio-cultural factors; the diathesis-stress model.
• Anxiety, obsessive-compulsive, trauma-related, somatic symptom and dissociative disorders.
• Depressive and bipolar disorders; warning signs of suicide.
• Schizophrenia symptoms (positive, negative, psychomotor); ADHD and autism spectrum disorder.
• Conduct problems, eating disorders and substance-related disorders.

How to prepare

• Learn each disorder's key symptoms with a short example, as case-based questions are common.
• Memorise which neurotransmitter is linked with which disorder.
• Use correct, respectful terms and avoid everyday labels like "mad".