Alize J. Ferrari

Purpose: First Nations people in Australia, New Zealand, Canada and the United States of America (USA) experience high rates of mental and substance-use disorders (MSDs) and face socially determined health inequalities, but this is not always well quantified. This systematic review sought to summarise best-estimates of MSD prevalence and describe related sociodemographic correlates among First Nations adults in these countries. Methods: Relevant studies published between 1980 and 2026 were searched using PubMed, Embase, and PsycINFO following PRISMA guidelines. Epidemiological population surveys producing prevalence estimates and/or sociodemographic correlates of MSDs for representative populations of First Nations peoples were identified. Prevalence data and sociodemographic correlates were extracted and described. Meta-analyses were conducted for MSDs with at least three available estimates. Results: A total of 50 studies from 24 unique population-level representative surveys met inclusion criteria. Surveys from the USA provided the most data (35 studies). Generally, MSD prevalence was lowest in the USA and highest in Australia, with twelve-month rates ranging between 20.9% (18.8–23.1%) and 51.7% (47.3–55.9%) respectively. Mood disorders and anxiety disorders were most prevalent. Sociodemographic variables including sex, socioeconomic factors, and regionality were associated with higher risk of certain MSDs. Conclusion: The prevalence and related sociodemographic correlates of MSDs identified across countries are varied and have implications for risk profiles and treatment needs. Low numbers of studies and heterogeneous data-collection methodologies highlight the need for better quality, representative population level data on MSDs for First Nations peoples.

Purpose: Participation rates in population-based health surveys have been declining for decades, with nonresponse bias being a serious threat to the validity and generalizability of results. The aim of the study was to examine differences between participants and nonparticipants invited to a psychiatric diagnostic interview survey in terms of sociodemographic and health characteristics, and use of health services for mental health problems, including diagnoses. Methods: The study sample for the follow-up psychiatric diagnostic interview was recruited among participants in the fourth survey of the Trøndelag Health Study (HUNT4) in Norway. Information about sociodemographic and health characteristics was gathered from the main survey, while data on health service use was collected by linking records from primary and specialist patient registries with information about participation status. Results: Male sex, younger age, being unmarried, having lower educational attainment, and having lower income were associated with higher odds for nonparticipation. Contact with the primary or specialist health services for mental health problems and hospitalization for a mental disorder more than a year before or after invitation date, were associated with lower odds for nonparticipation, especially for diagnoses indicating affective disorders, anxiety disorders, personality disorders, hyperkinetic disorders or milder mental complaints. Conclusion: Contrary to most prior studies examining nonresponse bias, the results indicate that people who had been in contact with the health services for mental health problems were more inclined to participate in a survey focused on mental disorders. The direction of nonresponse bias should be carefully considered and adjusted for in population-based studies.

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Aims: There is currently little nationally representative diagnostic data available to quantify how many Aboriginal and Torres Strait Islander people may need a mental health service in any given year. Without such information, health service planners must rely on less direct indicators of need such as service utilisation. The aim of this paper is to provide a starting point by estimating the prevalence ratio of 12-month common mental disorders (i.e. mood and anxiety disorders) for Indigenous peoples compared to the general Australian population. Methods: Analysis of the four most recent Australian Indigenous and corresponding general population surveys was undertaken. Kessler-5 summary scores by 10-year age group were computed as weighted percentages with corresponding 95% confidence intervals. A series of meta-analyses were conducted to pool prevalence ratios of Indigenous to general population significant psychological distress by 10-year age groups. The proportion of respondents with self-reported clinician diagnoses of mental disorders was also extracted from the most recent survey iterations. Results: Indigenous Australians are estimated to have between 1.6 and 3.3 times the national prevalence of anxiety and mood disorders. Sensitivity analyses found that the prevalence ratios did not vary across age group or survey wave. Conclusions: To combat the current landscape of inequitable mental health in Australia, priority should be given to populations in need, such as Indigenous Australians. Having a clear idea of the current level of need for mental health services will allow planners to make informed decisions to ensure adequate services are available.

Background: The treatment coverage for major depressive disorder (MDD) is low in many parts of the world despite MDD being a major contributor to disability globally. Most existing reviews of MDD treatment coverage do not account for potential sources of study-level heterogeneity that contribute to variation in reported treatment rates. This study aims to provide a comprehensive review of the evidence and analytically quantify sources of heterogeneity to report updated estimates of MDD treatment coverage and gaps by location and treatment type between 2000 and 2019. Methods and findings: A systematic review of the literature was conducted to identify relevant studies that provided data on treatment rates for MDD between January 1, 2000, and November 26, 2021, from 2 online scholarly databases PubMed and Embase. Cohort and cross-sectional studies were included if treatment rates pertaining to the last 12 months or less were reported directly or if sufficient information was available to calculate this along with 95% uncertainty intervals (UIs). Studies were included if they made use of population-based surveys that were representative of communities, countries, or regions under study. Studies were included if they used established diagnostic criteria to diagnose cases of MDD. Sample and methodological characteristics were extracted from selected studies. Treatment rates were modeled using a Bayesian meta-regression approach and adjusted for select covariates that quantified heterogeneity in the data. These covariates included age, sex, treatment type, location, and choice of MDD assessment tool. A total of 149 studies were included for quantitative analysis. Treatment coverage for health service use ranged from 51% [95% UI 20%, 82%] in high-income locations to 20% [95% UI 1%, 53%] in low- and lower middle-income locations. Treatment coverage for mental health service use ranged from 33% [95% UI 8%, 66%] in high-income locations to 8% [95% UI <1%, 36%] in low- and lower middle-income countries. Minimally adequate treatment (MAT) rates ranged from 23% [95% UI 2%, 55%] in high-income countries to 3% [95% UI <1%, 25%]) in low- and lower middle-income countries. A primary methodological limitation was the lack of sufficient data from low- and lower middle-income countries, which precluded our ability to provide more detailed treatment rate estimates. Conclusions: In this study, we observed that the treatment coverage for MDD continues to be low in many parts of the world and in particular in low- and lower middle-income countries. There is a continued need for routine data collection that will help obtain more accurate estimates of treatment coverage globally.