Aetiology of Psychiatric Disorders

• Predisposing factors: Determine a person‟s vulnerability to psychological distress.  Causes include:
  • Genetic endowment (eg strong genetic component in psychosis) 
  • Environment in utero ® minor damage to CNS 
  • Personality: combination of genetic, uterine development, childhood experiences (physical, psychological, social), adolescence. Particular personalities are prone to certain disorders. Eg early obsessional traits may ® obsessive-compulsive disorders

• Precipitating Factors: Factors that occur shortly before the onset of the disorders and are likely to have caused it. Eg: 
  • Physical: hypothyroidism, drugs, drugs of abuse, head injury (either direct disturbance or due to associated stress)
  • Psychological: eg loss of self-esteem owing to relationship or financial catastrophe
  • Social: eg moving house, changing job, family disturbance

• Perpetuating factors: Factors that prolong the course of the disorder: eg secondary demoralisation

• Psychiatric aspects of physical illness: 
  • Most common psychiatric illnesses in physical illness are mood disorders and acute organic mental disorders 
  • Occurs in one of three ways:
    • Psychological distress can precipitate mental illness
    • Physical distress can cause psychological ill-health (as can the medicines for physical disease) 
    • Physical and psychological disorders may exist simultaneously and independently (especially in the elderly) 
  • Pain: a common medical symptom. Can cause (eg head, neck, lower back, abdomen, genitalia) or arise from psychological disturbance (eg facial pain – antidepressant therapy can be effective).