Multimorbidity and vulnerability among those living with psychosis in Indigenous populations in Cape York and the Torres Strait

Abstract

Objective: Previous research has found an alarmingly high rate of psychosis in Indigenous1 patients from remote communities of Cape York and the Torres Strait with the treated prevalence of psychosis four times higher than that found for the Australian population. This study assesses comorbid illness and risk factors among this same cohort of psychosis patients. Methods: Data were collated from a clinical database that contains complete psychiatric records from 1992 to 2015, extracted for all Indigenous patients who received treatment for a psychotic disorder from the Remote Area Mental Health Service. Descriptive analysis and logistic regression models explored differences across subgroups of ethnicity and sex, and relationships between co-morbid disorders and risk factors. All multivariate models included variables of age, year of birth, sex and ethnicity. Results: Sixty per cent of participants ( n = 256) experienced a comorbid mental or substance use disorder. Forty-five per cent ( n = 192) of participants experienced a physical comorbidity. The most frequent physical health outcomes were injury (29%, n = 93), diabetes (18%, n = 58) and cardiovascular disease (21%, n = 68). Risk factors considered to play a potential biological or neurodevelopmental role in the development of psychosis were approximately three times more likely in Aboriginal (odds ratio = 3.2; 95% confidence interval = [2.0, 4.9]) versus Torres Strait Islander patients, and those born after 1980 (odds ratio = 2.5; 95% confidence interval = [1.6, 3.9]) versus those born prior to 1980. Environmental or contextual factors were associated with significantly greater risk among Aboriginal (odds ratio = 3.8; 95% confidence interval = [2.4, 6.0]) compared with Torres Strait Islander patients. Conclusion: Our data expose the perinatal and early environment of Indigenous children who later developed a psychotic disorder. As risk factors for schizophrenia may be cumulative and interactive, both with each other and with critical periods of neurodevelopmental vulnerability, our results suggest possible causes for the increasing prevalence of psychotic disorders between 1992 and 2015.

Factors that contribute to urban–rural gradients in risk of schizophrenia: Comparing Danish and Western Australian registers

“…Similarly, New Zealand data show that the incidence of schizophrenia is twice as high among Indigenous Māori people compared to non-Māori (Tapsell et al, 2018). Recently, Charlson et al (2021) supplemented findings from their earlier paper (Gynther et al, 2019) with new data showing high rates in the same sample for a range of biological, neurodevelopmental, environmental and contextual factors implicated in psychosis vulnerability and onset. It is highly probable that these findings extend beyond remote Northern Queensland and that, irrespective of level of urbanicity, Aboriginal people are much more likely than non-Aboriginal Australians to be exposed to a range of environmental risk factors for schizophrenia such as obstetric complications, social adversity and psychosocial stress, trauma and abuse (Zubrick et al, 2004), all of which have been associated with an increased risk of schizophrenia (Cannon et al, 2002;Morgan and Gayer-Anderson, 2016;Selten et al, 2017;Wicks et al, 2005).…”

Suicides in Aboriginal and non-Aboriginal people following hospital admission for suicidal ideation and self-harm: A retrospective cohort data linkage study from the Northern Territory

“…On the contrary, psychotic symptoms and illness in Aboriginal people are more likely to be associated with acute and episodic responses to situational crises and interpersonal conflict (Parker and Milroy, 2003). Furthermore, substance misuse, especially involving alcohol, is known to be a particularly prevalent comorbid condition and predisposing influence of psychotic illness in Aboriginal people (Charlson et al, 2021) that points to contexts of social disadvantage and dysfunction that may also exacerbate the risk of suicidal behaviour (Hunter, 2013). This is partly supported by the high prevalence of comorbid substance misuse and substance-induced psychosis within the category of severe mental illness diagnoses observed in the Aboriginal cohort in this study (see Supplementary Table 1).…”