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:
Psychiatric comorbidities are common among individuals with schizophrenia and may exacerbate both the severity and chronicity of the primary illness. However, the influence of psychiatric comorbidities on the seasonal trends of schizophrenia admissions is not well understood. Using time series data this study aimed to explore the influence of comorbid psychiatric conditions on seasonality and hospital admissions for schizophrenia.
Methods:
Hospital admissions data for schizophrenia patients (ICD-10 F20) and comorbid conditions (F01-F99) from Queensland Health (2010-2015) were linked to climate data obtained from Bureau of Meteorology. A generalized linear regression model with quasi-Poisson distribution assessed the association between psychiatric comorbidities and seasonal admissions, including interaction terms between these conditions and daily mean temperature.
Results:
Approximately 52.65% of schizophrenia patients had comorbid psychiatric conditions, with the highest prevalence (77.5%) in North and Far North Queensland. Drug abuse reduced winter admissions by 4%-13% in Southeast and North and Far North Queensland. Alcoholism reduced winter admissions by 26%-58% in South West and Central Queensland (p < 0.05). Anxiety disorder increased August admissions by 53%, and depression increased July admissions by 6% in South East Queensland. Time series analysis showed that daily admissions decreased by 5%-7% with higher temperatures, except in Central Queensland (p < 0.01). Drug abuse reduced admissions by 12%-72% while anxiety disorder decreased admissions by 6% in South East and 93% in North and Far North Queensland (p <0.05). Depression (20%) and alcoholism (29%) increased hospitalization risk in Central Queensland (p <0.05). Interaction terms revealed that psychiatric comorbidities specially drug abuse and anxiety disorder significantly influenced the effect of temperature on admissions (<0.05).
Conclusion:
Psychiatric comorbidities influenced the seasonal patterns of schizophrenia admissions, with substance abuse and temperature sensitivity playing key roles. These findings suggest that understanding these interactions could help develop targeted interventions, especially in vulnerable regions and seasons.

Background
Within high income countries such as Australia, suicide is known to pattern by occupation or industry, with some groups at higher risk than others. One group at particularly high risk of suicide is construction workers, with male construction workers dying by suicide at a rate up to twice that of other workers. Monitoring suicide rates among construction workers is key to informing both targeted and universal suicide prevention initiatives across Australia.
Methods
We used 21 years of data from the National Coronial Information System to compare suicide mortality among Australian male construction workers relative to other employed males. We calculated age-standardized suicide rates for construction workers and those employed in other occupations, and examined trends for age-groups across six categories (15-24 years; 25-34 years; 35-44 years, 45-54 years; 55-64 years, 65 years+).


Results
The pooled age-standardised rate of suicide among construction workers over 21 years was 25.7 per 100,000, compared to 14.3 per 100,000 for other employed males. Across the 21 years of observation, there was a steady decline in suicide rates among construction workers, while rates among non-construction workers appeared to remain relatively unchanged. The difference between construction workers and non-construction workers was greatest among younger construction workers, with little difference between construction and non-construction workers observed for those over 45 years.

Discussion
While male construction workers remain at higher risk of suicide relative to other workers in Australia, rates of suicide have declined over the 21-year period of investigation. Given that suicide rates among construction workers aged under 45 years appear to drive disparities between construction and non-construction workers, these workers should be a focus of suicide prevention efforts. There remains a need for government, unions, employers, and other industry stakeholders to strive and advocate for a continued decline in suicide rates among this high-risk group.

Background
Young carers provide unpaid care to another person. Despite evidence that this group is at increased risk of poor mental health, little is known about self-harm and suicide among young carers. This study used population representative data to examine self-harming and suicidal behaviours among young carers.

Methods
We used data from Waves 6-8 (2014-2018) of the Longitudinal Study of Australian Children to assess the effect of “core” caregiving activities (e.g. personal care, assistance moving around) on suicidal and self-harming behaviours. Care activities at 16-17 years were classified as core caregiving, non-core caregiving and no caregiving. Five self-harming and suicidal measures, collected at age 18/19 years, were used to form two outcomes: thoughts (of self-harm or suicide, or plan to suicide) and behaviours (self-harm, suicide attempt), operationalised as binary variables. Analyses were carried out using augmented inverse probability treatment weighting (AIPW), adjusting for potential confounders on complete case data. Multiple sets of sensitivity analyses were conducted, including on an imputed dataset.
Results
Core caregiving at age 16/17 was associated with suicidal and self-harming behaviours at age 18/19 compared to those not in a caregiving role, with an average treatment effect (ATE) of 0.07(95%CI0.02, 0.12), equating to a risk ratio of 1.81(95%CI1.16, 2.45). The ATE of core caregiving on thoughts of suicide or self-harm (compared to non-carers) was 0.06(95%CI -0.00, 0.12), equating to a risk ratio of 1.29 (95%CI 0.98, 1.59). No differences were observed between non-core care provision and no care for any outcomes. Sensitivity analyses confirmed main findings.

Discussion
This research provides evidence that intensive forms of caregiving provided by young carers is associated with elevated risks of some suicide and self-harming behaviours. This underscores the crucial need to better identify and support young carers, to mitigate these adverse outcomes.

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.