The Diathesis-Stress Model of Schizophrenia
Additive Nature: The model assumes that diathesis and stress add together. A person with a high genetic vulnerability requires very little environmental stress to trigger the disorder, whereas someone with low vulnerability would require extreme levels of stress.
Neurodevelopmental Factors: Early life trauma (such as child abuse) is now considered a form of diathesis because it can permanently alter the developing brain's HPA axis, making the individual more reactive to stress later in life.
Protective Factors: The model also implies that positive environments can act as buffers. Even with a high genetic predisposition, a supportive, low-stress environment may prevent the threshold from ever being reached.
| Feature | Meehl's Original Model | Modern Interactionist Model |
|---|---|---|
| Diathesis Source | Single 'schizogene' | Polygenic risk + early trauma |
| Stress Source | Psychogenic (Family/Mother) | Biological (Drugs) + Social (Urbanization) |
| Requirement | Gene is mandatory | Multiple pathways to vulnerability |
| Treatment Focus | Primarily biological | Holistic (Bio-Psycho-Social) |
Combined Therapy: Because the cause is multi-faceted, treatment is most effective when it addresses both biological and environmental factors. This typically involves combining antipsychotic medication with psychological interventions like CBT or Family Therapy.
Synergy Effect: Research indicates that patients receiving combined treatments show lower relapse rates and better social functioning than those receiving medication alone. This supports the model's premise that the disorder is not just a 'broken brain' but a response to environment.
Preventative Measures: By identifying high-risk individuals (those with a known family history), interventions can focus on stress reduction and avoiding triggers (like drug use) to prevent the onset of the first psychotic episode.
Identify the Interaction: When analyzing a case study, always look for two components: the internal vulnerability (e.g., family history) and the external trigger (e.g., moving to a new city).
Avoid Determinism: Never state that a gene 'causes' schizophrenia in this model. Instead, use phrases like 'increases susceptibility' or 'lowers the threshold for onset.'
Check for Modernity: If an exam question asks about the 'modern' model, ensure you mention that diathesis can be non-genetic (e.g., birth complications) and stress can be biological (e.g., cannabis).