Mental health problems do not discriminate and it’s not pretty.
Working as a Mental Health Support Worker in London, I see first-hand the devastating impact that psychotic disorders have on those affected. Huge variability in the incidence rates worldwide have been reported (Jongsma et al, 2018) and it seems that psychosis can affect anyone, but who is most at risk?
Accurate incidence rates of psychosis can help us develop more effective mental health services, but most research focuses heavily on schizophrenia and does not encompass the variability of psychotic disorders. Castillejos et al (2018) aimed to rectify this by carrying out the first systematic review on incidence rates of psychotic disorders, looking at diagnostic groups separately to examine the effect of gender, urbanity, immigration and socioeconomic level.
This systematic review considered various different categories of psychotic disorder separately, to provide information that can inform the development of better mental health services.
Methods
A systematic review was conducted searching five electronic databases for relevant original data published between 2000 and 2015.
Inclusion criteria
- Population-based incidence studies of any psychotic disorder (excluding people living in institutions or prisons)
- ≥30 year difference between the lower and upper age included in each study, in order to obtain a wide age range
- Study with original data
- Published 2000-2015 (a previous systematic review was published in 2001)
Incidence rates were calculated and results were combined to see the association with gender, urbanicity, immigration and socioeconomic level according to different psychotic diagnostic categories. Diagnoses included for analysis: non-affective psychoses, schizophrenia, affective psychoses and substance-use disorder.
Results
- Final sample of 33 articles from 13 different countries included for review
- Majority of studies were based on individuals making first contact with health or social services (26) and the remaining were based on those who had their first admission to hospital (7)
- Non-affective psychoses had a higher overall incidence rate than affective psychoses (22.5 per 100,000 persons and 7.13 per 100,000 persons, respectively)
- High variability in rates of non-affective psychoses (10-69 per 100,000 persons) and schizophrenia (4-62 per 100,000 persons) and overall, great variability between studies.
Gender
Generally, rates of psychotic disorders were higher in men than in women, but affective psychoses were the exception, with higher rates in women than men.
Urbanicity
Incidence rates of affective psychosis, non-affective psychosis and schizophrenia were all higher in urban areas when compared to rural areas.
Immigration
Incidence rates for non-affective psychosis, affective psychosis and schizophrenia were all higher in immigrants when compared to natives.
Socio-economic level
Living in a deprived area was associated with higher rates of affective and non-affective psychoses compared to living in a non-deprived area.
Incidence rates were higher for non-affective versus affective psychosis.
Conclusion
In this review, researchers demonstrated the significant variability presented in the incidence rates of psychotic disorders worldwide.
Incidence rates were higher:
- For men versus women in non-affective psychoses
- For women versus men in affective psychoses
- In urban areas versus rural areas
- In immigrants versus natives.
Incidence rates were higher for men than for women in non-affective psychoses and lower than women in affective psychoses.
Strengths and limitations
This is the only systematic review analysing diagnostic groups separately when looking at rates of psychotic disorders worldwide and certain intervening factors. Encompassing the variability of psychotic disorders is important, to guide future interventions to do the same.
Although most studies included were middle to high quality, how valid are the findings from this review? Considering only published articles were included and the small sample size, it seems that several relevant studies might have been excluded from this review. Chances of publication bias are high.
Also, great methodological variability and small sample size raises concerns about whether it was suitable to combine the data included in this review. The reviewers admit that the association between socio-economic level and psychosis is non-conclusive as a result. But what about the other factors? Analysis on gender included 20 citations, immigration had 14 and urbanicity only eight.
Finally, the incidence rates from this review were biased, including studies only on clinical populations and mostly in developed countries, which can be problematic considering that incidence rates help plan and develop services. What about those who don’t seek help for their psychotic experiences?
Biases in this review towards developed countries and clinical populations make it difficult to generalise these findings.
Implications for practice
Findings from reviews like this can have important clinical implications. They should be applied in practice within mental health services so that clinicians are mindful of these risk factors when assessing and diagnosing, and interventions are tailored to meet the needs of service users and patients. Ultimately, the aim is to ensure early intervention, reducing costly and unpleasant hospital admissions.
International efforts to improve mental health and wellbeing should consider policies to improve access to mental health services for immigrants living in urban areas, especially considering the evidence that immigrants often under-utilise mental health services (Sarría-Santamera et al, 2016). Organisations that guide the development of mental health policies, such as the World Health Organization, should utilise the findings from reviews like this in their policy-making decisions.
As a Mental Health Support Worker, I’m sure I speak on behalf of many, when I say that there’s a need for the development of effective, psychosocial interventions to support those living in the community with a psychotic disorder. Future reviews looking at risk factors associated with incidence rates of psychosis should ensure diagnostic groups are looked at separately. As with other disorders, research needs to encompass the variability of psychotic disorders. However, much larger samples and the inclusion of developing countries should be considered in future and there also seems a serious lack of research on substance-induced psychosis, so this should also be considered in future.
Psychosis incidence rates were higher in urban versus rural areas and higher in immigrants. These findings stress the importance for cities to improve access to mental health services for immigrants.
Conflicts of interest
No conflicts of interest.
King’s MSc in Mental Health Studies
This blog has been written by a student on the Mental Health Studies MSc at King’s College London. A full list of blogs by King’s MSc students from can be found here, and you can follow the Mental Health Studies MSc team on Twitter.
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Links
Primary paper
Castillejos MC, Martín-Pérez C, Moreno-Küstner B. A systematic review and meta-analysis of the incidence of psychotic disorders: the distribution of rates and the influence of gender, urbanicity, immigration and socio-economic level. Psychological Medicine https://doi.org/10.1017/S0033291718000235
Other references
Jongsma HE, Gayer-Anderson C, Lasalvia A, et al. (2018) Treated incidence of psychotic disorders in the multinational EU-GEI study [published online December 6, 2017]. JAMA Psychiatry. doi:10.1001 /jamapsychiatry.2017.3554
Sarría-Santamera, A., Hijas-Gómez, A. I., Carmona, R., & Gimeno-Feliú, L. A. (2016). A systematic review of the use of health services by immigrants and native populations. Public health reviews, 37(1), 28.
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