Background: The COVID-19 pandemic and associated public health restrictions in Australia had significant impacts on young people’s mental health. Recent studies indicate that young people’s mental health has improved since the height of the pandemic. Yet, there is limited evidence on individual trajectories of young people’s mental health before, during and after the pandemic, and what might predict such trajectories. The Longitudinal Study of Australian Children (LSAC), a long running prospective cohort study, is now able to shed light on these trajectories.

Methods: Data collected in 2018 (before), 2020-21 (during) and 2023-24 (post pandemic) on symptoms of anxiety and depression in young people aged 19-24 years in two nationally representative cohorts from LSAC will be analysed. Trajectories of anxiety and depression will be identified using appropriate growth models. Multinomial or binomial regressions will be used to investigate the associations between pre-pandemic exposures and trajectories of mental health.

Results: Trajectories of young Australian’s mental health over the last 7 years will be presented and stratified by participant gender and state of residence. In line with positive epidemiology and strengths-based approaches, associations between several pre-pandemic exposures (e.g., social support, social skills, parenting warmth, parent and peer attachment) and mental health trajectories will also be reported.

Conclusion: Findings will provide a nuanced understanding of the current mental health of young Australians following the COVID-19 pandemic. Findings can also help to identify priority groups of young people who may benefit from targeted mental health care now and potentially in the face of future global challenges.

Background: Young carers - unpaid carers under 25 years- show a higher prevalence of suicidal behaviour than the general youth population. Understanding their risk of suicide is central for determining the need for targeted suicide prevention support in this group. However, no quantitative research interrogating the distribution of suicide deaths among young carers and their non-caring peers exists. This analysis seeks to quantify trends in suicide risk among young people aged 15-24 years according to caring status between 2012-2020, and compare whether these trends in suicide risk differ by caring status.

Methods: We linked data from the Australian Census of population and Housing in 2011 to mortality data from the Australian States and Territories Registrars of Births, Deaths and Marriages from 2011 to 2020 and followed 2,000,955 young people for 9.4 years. We used a joint point regression analysis to examine suicide trends between 2012-2020 and compare whether these trends differed by caring status.

Results: The total suicide rate was larger among young carers (Rate: 16.9; 95%CI: 14.5, 19.7) than among their non-caring peers (Rate: 12.9; 95%CI: 12.4, 13.5). The Average Annual Percentage Change (AAPC) indicated that suicide rates among young carers increased by 11.7% (95%CI: 5.41, 19.9) between 2012 and 2020, as compared to a 7% annual increase among non-carers (95%CI: 3.40, 10.9). The comparison between the two groups showed a difference of 4.82% in the annual rate of change, indicating that the suicide rate among carers increased at a significantly higher rate than that of non-carers.

Conclusion: Our findings highlight important inequalities in the suicide trends between young carers and their non-caring peers. Causally focused research is needed to understand whether these differences could be attributed to caregiving. Interventions are needed to address the increasing rate of suicide among young carers.

Background: It has been estimated that about 30% of homes have mould and dampness. The effect of damp housing on respiratory health has been well-established. However, the mental health toll of living in damp housing is less well described. The aim of this study was to ascertain the overall effect of damp housing on mental health, and to examine whether a householder's respiratory health modifies any association.
Methods: We analysed data from the British Household Panel Survey (BHPS) and the UK Household Longitudinal Study (UKHLS). Multivariable fixed effects models, adjusted for demographic, housing, and health factors, were used to test associations between damp housing exposure and mental health. A binary measure indicating poor mental health was derived from the 12-point General Health Questionnaire, with a cutoff of 3 or more indicating poor mental health. The analysis was stratified by presence of a respiratory condition, and modification of the effect of damp on mental health by respiratory condition was tested.
Results: In the BHPS, exposure to damp housing was associated with increased odds of poor mental health (Odds Ratio (OR) = 1.08 [95% CI: 1.04, 1.13], p<0.01). When the analysis was stratified by respiratory condition, the OR in the respiratory condition group was significantly higher (OR = 1.28 [95% CI: 1.15, 1.43], p<0.01) compared with the no respiratory condition group (OR = 1.05 [95% CI: 1.01, 1.10], p = 0.02). This effect modification was supported in models testing for an interaction (Interaction Term OR = 1.14 [95% CI: 1.22], p = 0.02). This evidence of association was supported in the UKHLS data.
Conclusions: Exposure to damp housing increased the odds of poor mental health, particularly for people with respiratory conditions. More research is required to further investigate mediators and strategies that can mitigate the risks for this vulnerable group.

Background
This study aimed to investigate the association between increasing ambient temperature and child mental health disorders in a contemporary cohort, and project rates up to 2099.
Method
A case cross-over time series study was conducted based on data from mental health-related hospital admission and ED records in New South Wales, Australia from 2001-2022. The study used daily average temperature from ERA5 data, and projected temperatures under three scenarios of greenhouse-gas emissions from 1980-2099. Conditional logistic regression with an embedded lag-distributed non-linear regression model was used to examine the association. The relative risk (RR) was determined by comparing the risk at extreme heat (99th percentile) with the reference (minimum morbidity temperature). A backward Attributable Fraction (AF) estimated current burden of extreme heat on mental health admissions, and then admission was projected up to 2099.
Results
A total of 719,375 mental health-related hospital admissions were identified. Extreme heat was associated with 1.26-fold (95%CI 1.10-1.43) increased risk of mental health admissions. Stronger associations were found for depressive disorders, psychiatric, anxiety, obsessive-compulsive disorders, and attention-deficit/disruptive disorders with RR ranging between 1.48-1.97. Specific sub- groups including females, children aged 0-11 and young adults aged 18-24 years, those in recent epochs (2011-2015, 2016-22), residing in major cities were at increased risk. About 7.11% of mental health admissions were attributable to extreme heat statewide (95%eCI 4.45-9.80). Compared to the historical 1980-2009 period, under low and medium emission scenario, AF of mental health admissions due to heat are projected to increase by 2.1% and 2.6%. Under high emissions, the AF would increase by 7.1% in 2090s (95%eCI 1.9-14.6).
Conclusion
This study found extreme heat was associated with increased risk of mental disorders hospital admission among children and young adults. Findings support effective climate policies to reduce greenhouse gas emissions and deploying adaption strategies to manage global warming.

Background
Self-rated health (SRH) is a subjective indicator of overall health based on a single questionnaire item. Previous evidence found that it is a strong predictor of mortality, although the underlying mechanism is poorly understood. Epigenetic age is an objective, emerging biomarker of health, estimated using DNA methylation data at hundreds of sites across the genome. This study aimed to assess the overlap and interaction between SRH and epigenetic ageing in predicting mortality risk.
Methods
We used DNA methylation data from 1059 participants in the Melbourne Collaborative Cohort Study (mean age: 69 years) to calculate three age-adjusted measures of epigenetic ageing: GrimAge, PhenoAge, and DunedinPACE. SRH was assessed using a five-category questionnaire item (“excellent, very good, good, fair, poor”). Cox models were used to assess the associations of SRH, epigenetic ageing, and their interaction, with all-cause mortality over up to 17 years of follow-up (Ndeaths=345).
Results
The association of SRH with mortality per category increase was HR=1.29; 95%CI: 1.14-1.46. The association was slightly attenuated after adjusting for all three epigenetic ageing measures (HR=1.25, 95%CI: 1.10-1.41). A strong gradient was observed in the association of GrimAge (Pinteraction=0.006) and DunedinPACE (Pinteraction=0.002) with mortality across worsening SRH strata. For example, the association between DunedinPACE and mortality in participants with “excellent” SRH was HR=1.02, 95%CI: 0.73-1.43 and for “fair/poor” HR=1.72, 95%CI: 1.35-2.20.
Conclusion
SRH and epigenetic ageing were synergistic risk factors of mortality in our study. These findings suggest that consideration of subjective and objective factors may improve general health assessment, which has implications for the ongoing development of molecular markers of ageing.