Outline and evaluate the diathesis-stress model of schizophrenia

The Diathesis Stress model of schizophrenia is part of the interactionist approach that see’s schizophrenia developing due to an interaction between the biological (diathesis) and the environmental (stress) influences. Research using family studies have suggested a genetic vulnerability is inherited and this varies from those with a high vulnerability to a low vulnerability. The Diathesis Stress model of schizophrenia assumes that the development of schizophrenia is determined by this vulnerability but also the environmental stresses they experience within their lives that triggers this vulnerability to cause schizophrenia. Relatively minor stresses may cause sz for individuals who are highly vulnerable while major stressful life events may cause the disorder in those with low vulnerability. This approach pre-supposes additivity i.e. that diathesis and stress combine together to produce schizophrenia.

Twin studies into schizophrenia have provided a strong case for a genetic component being involved and people having a genetic vulnerability for the disorder. The identical twin of a schizophrenia sufferer has been found to be at a much greater risk of developing sz themselves when compared to siblings or fraternal twins. Adoptive relatives have also been found to be at much lower risk than biological relatives (Tienari et al 2004). In 50% of cases where an identical twin has been diagnosed with schizophrenia, the other twin never meets the diagnostic criteria to be diagnosed with sz themselves. The fact that identical twins who share the same genetic DNA do not share the disorder presents a strong case for environmental factors also playing a role in triggering biological vulnerabilities as the diathesis-stress model proposes.

The diathesis Stress model also proposes psychological triggers such as family dysfunction, substance abuse and critical life events are all environmental triggers that can cause sz in those most genetically vulnerable. Critical life events cause stresses and psychological trauma and research by Varese (2012) found that children who experienced severe trauma before the age of 16 were 3 times more likely to develop sz when they were older compared to the general population.

As the interactionist approach acknowledges both biological and psychological factors play a role, treatment is therefore based on both. This model may combine antipsychotic medication with psychological therapies such as CBT to relieve psychological symptoms. The effectiveness of treatments is dependent on factors such as cost, relapse rates, degree of side effects as well as symptom reduction. The combination of treatments will vary dependent on the patients individual circumstances; e.g. family therapy may only be appropriate when patients have problems with dysfunctional family relationships. Antipsychotics are usually initially given to reduce symptoms to a manageable level so psychological treatments can then have a greater effect.