Objective
Despite social environmental factors such as deprivation, urbanicity, migration and adversity being established risk factors for psychotic disorders, there is a paucity of knowledge on the influence of social environmental risk factors in the UHR population. Firstly, we aimed to investigate the association between social deprivation and risk of transition and secondly, we aimed to investigate the association between migration status and the risk of transition.
Method
UHR individuals at the Personal Assessment and Crisis Evaluation (PACE) service in Melbourne were included. Social deprivation as assessed according to postal code area of residence was obtained from census data and Cox regression analysis was used to calculate hazard ratios.
Results
A total of 219 UHR individuals were included and over the median follow-up time of 4.8 years, 32 individuals (14.6%) were known to have transitioned to a psychotic disorder. 8.8% of UHR individuals were first generation migrants and 41.9% were second generation migrants. The level of social deprivation was not associated with the risk of transition (p = 0.83). Similarly, first or second generation migrants did not have an increased risk of transition to psychosis (p = 0.84).
Conclusions
Despite being established risk factors for psychotic disorders, social deprivation and migrant status have not been found to increase the risk of transition in a UHR population.
Gadget timed out while loading
Over the last two decades, significant progress has been made in prospectively identifying the symptoms and characteristics of the prodromal phase of psychotic disorders (Yung and Nelson, 2011). This has resulted in the ability to identify individuals at higher risk of psychosis compared to the general population, with over one third of these ‘clinical high risk’ individuals subsequently developing a psychotic disorder within three years (Fusar-Poli et al., 2012). The ultimate purpose in identifying this group is to prevent the first episode of psychosis and a recent meta-analysis has demonstrated provisional success on this front, with the overall effect of diverse interventions, specifically, CBT, omega-3 fatty acids and antipsychotic medications, having a risk reduction of 54% at 12 months with a number needed to treat of 9 (van der Gaag et al., 2013). Further factors that may influence the risk of progression to a psychotic disorder in UHR populations have been identified, specifically low functioning, longer duration of symptoms (Nelson et al., 2013) and unusual thought content such as suspiciousness (Cannon et al., 2008, Ruhrmann et al., 2010 and Thompson et al., 2011). Cognitive deficits, a core feature of schizophrenia, are more prevalent in UHR individuals compared to healthy controls and are associated with a higher risk of transition to psychotic disorders (Bora et al., 2014). Neuroimaging studies have identified that people who are UHR for psychosis show some brain alterations in comparison to healthy controls, but there is a lack of consistent findings as to which of these alterations is associated with transition to psychosis (Wood et al., 2013). Genetics studies may also contribute to predicting those at higher risk of psychotic disorders, with certain genetic variations, such as in neuregulin 1, increasing the risk of transition in the UHR population (Bousman et al., 2013). However, while there appears to be a wide range of factors associated with transition to psychotic disorders in the UHR population, the findings of a number of these factors are yet to be replicated.
Despite the established association between psychotic disorders and social environmental risk factors, such as social deprivation, urbanicity, migrant status and social adversity (Morgan et al., 2008, Kelly et al., 2010 and Kirkbride et al., 2012), there is a paucity of research in this area in the UHR population. In the Netherlands, Dragt et al. found that UHR individuals living in an urban environment or receiving state benefits were more likely to transition to psychosis (Dragt et al., 2011). Furthermore, the study found that ethnicity, birth place, obstetrical complications and employment status were not associated with an increased risk of transition. Velhorst et al. identified that UHR individuals from ethnic minorities presented with more negative symptoms and depression (Velthorst et al., 2009). Adversity in early life, specifically the experience of childhood sexual trauma, has been demonstrated to be associated with an increased risk of transition to psychotic disorders in the UHR population (Thompson et al., 2014).
The continuum model, which proposes that psychosis exists on a continuum throughout the general population, has gained substantial support, with a prevalence of psychotic like experiences in non-clinical general population samples of approximately 5% (van Os et al., 2009). Interestingly, the social environmental risk factors for psychotic disorders, such as ethnicity, social disadvantage, urbanity and low socioeconomic status, are also risk factors for psychotic like experiences in the general population (van Os et al., 2000, Johns et al., 2002, Scott et al., 2006 and Morgan et al., 2009). It appears that the risk factors for psychosis and schizophrenia mirror some of the risk factors for the prevalence of psychotic-like experiences in the general population. This highlights the importance of establishing at what point in the illness trajectory the social environmental factors influence the disorder. Establishing whether social environmental risk factors are associated with transition to a psychotic disorder in the UHR population could lead to valuable insights into the aetiology of psychotic disorders.
