A Prototype Software Framework for Transferable Computational Health Economic Models and Its Early Application in Youth Mental Health.

We are developing an economic model to explore multiple topics in Australian youth mental health policy. To help make that model more readily transferable to other jurisdictions, we developed a software framework for authoring modular computational health economic models (CHEMs) (the software files that implement health economic models). We specified framework user requirements for: a simple programming syntax; a template CHEM module; tools for authoring new CHEM modules; search tools for finding existing CHEM modules; tools for supplying CHEM modules with data; reproducible analysis and reporting tools; and tools to help maintain a CHEM project website. We implemented the framework as six development version code libraries in the programming language R that integrate with online services for software development and research data archiving. We used the framework to author five development version R libraries of CHEM modules focussed on utility mapping in youth mental health. These modules provide tools for variable validation, dataset description, multi-attribute instrument scoring, construction of mapping models, reporting of mapping studies and making out of sample predictions. We assessed these CHEM module libraries as mostly meeting transparency, reusability and updatability criteria that we have previously developed, but requiring more detailed documentation and unit testing of individual modules. Our software framework has potential value as a prototype for future tools to support the development of transferable CHEMs.Code: Visit https://www.ready4-dev.com for more information about how to find, install and apply the prototype software framework.

Nomenclature for psychosis risk in Japan: Survey results from high-risk individuals, caregivers, and mental health professionals.

BACKGROUND: Labeling terms for high-risk state for psychosis, such as 'ultra-high risk' (UHR), 'attenuated psychosis syndrome' (APS), and 'at-risk mental state' (ARMS), have been criticized for their potential to lead to stigma. Hence, mental health service users in Melbourne recently proposed new terms illustrating the at-risk concept ['pre-diagnosis stage' (PDS), 'potential of developing a mental illness' (PDMI), and 'disposition for developing a mental illness' (DDMI)]. We aimed at testing the suitability of these existing and new terms in the clinical settings of early psychiatric intervention in Japan. METHODS: At two centers of early intervention (Toyama and Tokyo), a questionnaire on the understanding and opinion of high-risk terminology was administered to 62 high-risk patients, 44 caregivers, and 64 clinicians. The questionnaire contained the existing and new terms, where the term ARMS was translated into two different Japanese terms ARMS-psychosis and ARMS-kokoro. Participants' opinion on the disclosure of high-risk status was also obtained. RESULTS: ARMS-kokoro was most preferred, least stigmatizing, and best explaining the patients' difficulties for all groups, while UHR and other terms including the Japanese word 'psychosis' (i.e., APS and ARMS-psychosis) were not preferred. New labeling terms were generally not well received. All groups preferred full disclosure of high-risk terms by the psychiatrist with or without the presence of family members. CONCLUSION: The term ARMS-kokoro was commonly accepted as a favorable labeling term for the high-risk state for psychosis in Japan. However, another translation ARMS-psychosis was considered stigmatizing, demonstrating the importance of appropriate translation of high-risk terminology into local languages.

An open label pilot trial of low-dose lithium for young people at ultra-high risk for psychosis.

AIM: Lithium, even at low doses, appears to offer neuroprotection against a wide variety of insults. In this controlled pilot, we examined the safety (i.e., side-effect profile) of lithium in a sample of young people identified at ultra-high risk (UHR) for psychosis. The secondary aim was to explore whether lithium provided a signal of clinical efficacy in reducing transition to psychosis compared with treatment as usual (TAU). METHODS: Young people attending the PACE clinic at Orygen, Melbourne, were prescribed a fixed dose (450 mg) of lithium (n = 25) or received TAU (n = 78). The primary outcome examined side-effects, with transition to psychosis, functioning and measures of psychopathology assessed as secondary outcomes. RESULTS: Participants in both groups were functionally compromised (lithium group GAF = 56.6; monitoring group GAF = 56.9). Side-effect assessment indicated that lithium was well-tolerated. 64% (n = 16) of participants in the lithium group were lithium-adherent to week 12. Few cases transitioned to psychosis across the study period; lithium group 4% (n = 1); monitoring group 7.7% (n = 6). There was no difference in time to transition to psychosis between the groups. No group differences were observed in other functioning and symptom domains, although all outcomes improved over time. CONCLUSIONS: With a side-effect profile either comparable to, or better than UHR antipsychotic trials, lithium might be explored for further research with UHR young people. A definitive larger trial is needed to determine the efficacy of lithium in this cohort.

Non-psychotic Outcomes in Young People at Ultra-High Risk of Developing a Psychotic Disorder: A Long-Term Follow-up Study.

BACKGROUND: The majority of individuals at ultra-high risk (UHR) for psychosis do not transition to a full threshold psychotic disorder. It is therefore important to understand their longer-term clinical and functional outcomes, particularly given the high prevalence of comorbid mental disorders in this population at baseline. AIMS: This study investigated the prevalence of non-psychotic disorders in the UHR population at entry and long-term follow-up and their association with functional outcomes. Persistence of UHR status was also investigated. STUDY DESIGN: The sample comprised 102 UHR young people from the Personal Assessment and Crisis Evaluation (PACE) Clinic who had not transitioned to psychosis by long-term follow-up (mean = 8.8 years, range = 6.8-12.1 years since baseline). RESULTS: Eighty-eight percent of participants at baseline were diagnosed with at least one mental disorder, the majority of which were mood disorders (78%), anxiety disorders (35%), and substance use disorders (SUDs) (18%). This pattern of disorder prevalence continued at follow-up, though prevalence was reduced, with 52% not meeting criteria for current non-psychotic mental disorder. However, 35% of participants developed a new non-psychotic mental disorder by follow-up. Presence of a continuous non-psychotic mental disorder was associated with poorer functional outcomes at follow-up. 28% of participants still met UHR criteria at follow-up. CONCLUSIONS: The study adds to the evidence base that a substantial proportion of UHR individuals who do not transition to psychosis experience persistent attenuated psychotic symptoms and persistent and incident non-psychotic disorders over the long term. Long-term treatment and re-entry into services is indicated.

The Cost-Effectiveness of a Novel Online Social Therapy to Maintain Treatment Effects From First-Episode Psychosis Services: Results From the Horyzons Randomized Controlled Trial.

BACKGROUND: Digital interventions have potential applications in promoting long-term recovery and improving outcomes in first-episode psychosis (FEP). This study aimed to evaluate the cost-effectiveness of Horyzons, a novel online social therapy to support young people aged 16-27 years following discharge from FEP services, compared with treatment as usual (TAU) from a healthcare sector and a societal perspective. STUDY DESIGN: A cost-effectiveness analysis (CEA), based on the change in social functioning, and a cost-utility analysis (CUA) using quality-adjusted life years were undertaken alongside a randomized controlled trial. Intervention costs were determined from study records; resources used by patients were collected from a resource-use questionnaire and administrative data. Mean costs and outcomes were compared at 18 months and incremental cost-effectiveness ratios were calculated. Uncertainty analysis using bootstrapping and sensitivity analyses was conducted. STUDY RESULTS: The sample included 170 participants: Horyzons intervention group (n = 86) and TAU (n = 84). Total costs were significantly lower in the Horyzons group compared with TAU from both the healthcare sector (-AU$4789.59; P < .001) and the societal perspective (-AU$5131.14; P < .001). In the CEA, Horyzons was dominant, meaning it was less costly and resulted in better social functioning. In the CUA, the Horyzons intervention resulted in fewer costs but also yielded fewer QALYs. However, group differences in outcomes were not statistically significant. When young people engaged more with the platform, costs were shown to decrease and outcomes improved. CONCLUSIONS: The Horyzons intervention offers a cost-effective approach for improving social functioning in young people with FEP after discharge from early intervention services.

The Addition of Fish Oil to Cognitive Behavioral Case Management for Youth Depression: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Clinical Trial.

BACKGROUND: Clinical trials suggest that long-chain omega-3 polyunsaturated fatty acids (n-3 PUFAs) (fish oil) may reduce depressive symptoms in adults with major depressive disorder. Therefore, n-3 PUFAs may be a potential treatment for depression in youth. METHODS: Participants were 15- to-25 year-old individuals with major depressive disorder who sought care in one of three government-funded mental health services for young people in metropolitan Melbourne, Perth, or Sydney, Australia. Participants were randomly assigned in a double-blind, parallel-arm design to receive either fish oil (840 mg of eicosapentaenoic acid and 560 mg of docosahexaenoic acid) or placebo capsules as adjunct to cognitive behavioral case management. All participants were offered 50-minute cognitive behavioral case management sessions every 2 weeks delivered by qualified therapists (treatment as usual) at the study sites during the intervention period. The primary outcome was change in the interviewer-rated Quick Inventory of Depressive Symptomatology, Adolescent Version, score at 12 weeks. Erythrocyte n-3 PUFA levels were assessed pre-post intervention. RESULTS: A total of 233 young people were randomized to the treatment arms: 115 participants to the n-3 PUFA group and 118 to the placebo group. Mean change from baseline in the Quick Inventory of Depressive Symptomatology score was -5.8 in the n-3 PUFA group and -5.6 in the placebo group (mean difference, 0.2; 95% CI, -1.1 to 1.5; p = .75). Erythrocyte PUFA levels were not associated with depression severity at any time point. The incidence and severity of adverse events were similar in the two groups. CONCLUSIONS: This placebo-controlled trial and biomarker analysis found no evidence to support the use of fish oil for treatment in young people with major depressive disorder.

Combining Clinical With Cognitive or Magnetic Resonance Imaging Data for Predicting Transition to Psychosis in Ultra High-Risk Patients: Data From the PACE 400 Cohort.

BACKGROUND: Multimodal modeling that combines biological and clinical data shows promise in predicting transition to psychosis in individuals who are at ultra-high risk. Individuals who transition to psychosis are known to have deficits at baseline in cognitive function and reductions in gray matter volume in multiple brain regions identified by magnetic resonance imaging. METHODS: In this study, we used Cox proportional hazards regression models to assess the additive predictive value of each modality-cognition, cortical structure information, and the neuroanatomical measure of brain age gap-to a previously developed clinical model using functioning and duration of symptoms prior to service entry as predictors in the Personal Assessment and Crisis Evaluation (PACE) 400 cohort. The PACE 400 study is a well-characterized cohort of Australian youths who were identified as ultra-high risk of transitioning to psychosis using the Comprehensive Assessment of At Risk Mental States (CAARMS) and followed for up to 18 years; it contains clinical data (from N = 416 participants), cognitive data (n = 213), and magnetic resonance imaging cortical parameters extracted using FreeSurfer (n = 231). RESULTS: The results showed that neuroimaging, brain age gap, and cognition added marginal predictive information to the previously developed clinical model (fraction of new information: neuroimaging 0%-12%, brain age gap 7%, cognition 0%-16%). CONCLUSIONS: In summary, adding a second modality to a clinical risk model predicting the onset of a psychotic disorder in the PACE 400 cohort showed little improvement in the fit of the model for long-term prediction of transition to psychosis.

Network-Based Spreading of Gray Matter Changes Across Different Stages of Psychosis.

Importance: Psychotic illness is associated with anatomically distributed gray matter reductions that can worsen with illness progression, but the mechanisms underlying the specific spatial patterning of these changes is unknown. Objective: To test the hypothesis that brain network architecture constrains cross-sectional and longitudinal gray matter alterations across different stages of psychotic illness and to identify whether certain brain regions act as putative epicenters from which volume loss spreads. Design, Settings, and Participants: This case-control study included 534 individuals from 4 cohorts, spanning early and late stages of psychotic illness. Early-stage cohorts included patients with antipsychotic-naive first-episode psychosis (n = 59) and a group of patients receiving medications within 3 years of psychosis onset (n = 121). Late-stage cohorts comprised 2 independent samples of people with established schizophrenia (n = 136). Each patient group had a corresponding matched control group (n = 218). A sample of healthy adults (n = 356) was used to derive representative structural and functional brain networks for modeling of network-based spreading processes. Longitudinal illness-related and antipsychotic-related gray matter changes over 3 and 12 months were examined using a triple-blind randomized placebo-control magnetic resonance imaging study of the antipsychotic-naive patients. All data were collected between April 29, 2008, and January 15, 2020, and analyses were performed between March 1, 2021, and January 14, 2023. Main Outcomes and Measures: Coordinated deformation models were used to estimate the extent of gray matter volume (GMV) change in each of 332 parcellated areas by the volume changes observed in areas to which they were structurally or functionally coupled. To identify putative epicenters of volume loss, a network diffusion model was used to simulate the spread of pathology from different seed regions. Correlations between estimated and empirical spatial patterns of GMV alterations were used to quantify model performance. Results: Of 534 included individuals, 354 (66.3%) were men, and the mean (SD) age was 28.4 (7.4) years. In both early and late stages of illness, spatial patterns of cross-sectional volume differences between patients and controls were more accurately estimated by coordinated deformation models constrained by structural, rather than functional, network architecture (r range, >0.46 to <0.57; P < .01). The same model also robustly estimated longitudinal volume changes related to illness (r ≥ 0.52; P < .001) and antipsychotic exposure (r ≥ 0.50; P < .004). Network diffusion modeling consistently identified, across all 4 data sets, the anterior hippocampus as a putative epicenter of pathological spread in psychosis. Epicenters of longitudinal GMV loss were apparent in posterior cortex early in the illness and shifted to the prefrontal cortex with illness progression. Conclusion and Relevance: These findings highlight a central role for white matter fibers as conduits for the spread of pathology across different stages of psychotic illness, mirroring findings reported in neurodegenerative conditions. The structural connectome thus represents a fundamental constraint on brain changes in psychosis, regardless of whether these changes are caused by illness or medication. Moreover, the anterior hippocampus represents a putative epicenter of early brain pathology from which dysfunction may spread to affect connected areas.

Prevalence, time trends, and correlates of major depressive episode and other psychiatric conditions among young people amid major social unrest and COVID-19 in Hong Kong: a representative epidemiological study from 2019 to 2022.

Background: Hong Kong is among the many populations that has experienced the combined impacts of social unrest and the COVID-19 pandemic. Despite concerns about further deteriorations in youth mental health globally, few epidemiological studies have been conducted to examine the prevalence and correlates of major depressive episode (MDE) and other major psychiatric disorders across periods of population-level changes using diagnostic interviews. Methods: We conducted a territory-wide household-based epidemiological study from 2019 to 2022 targeting young people aged 15-24 years. MDE, generalised anxiety disorder (GAD), panic disorder (PD), and bipolar disorder (BD) were assessed using the Composite International Diagnostic Interview-Screening Scales in 3340 young people. Psychotic disorders were assessed by experienced psychiatrists according to the DSM. Help-seeking patterns were also explored. Findings: 16.6% had any mental disorder (13.7% 12-month MDE, 2.3% BD, 2.1% GAD, 1.0% PD, 0.6% psychotic disorder). The prevalence of MDE increased from 13.2% during period 1 (May 2019-June 2020) to 18.1% during period 2 (July-December 2020), followed by 14.0% during period 3 (January-June 2021) and 13.2% during period 4 (July 2021-June 2022). Different stressors uniquely contributed to MDE across periods: social unrest-related stressors during period 1, COVID-19 stressors during period 2, and personal stressors during periods 3-4. Lower resilience, loneliness, frequent nightmares, and childhood adversity were consistently associated with MDE. Compared to other conditions, those with MDE showed the lowest service utilisation rate (16.7%). Perceiving services to "cost too much" and "talked to friends or relatives instead" were among the major reasons for not seeking help. MDE was also significantly associated with poorer functioning and health-related quality of life. Interpretation: MDE can be sensitive to population-level changes, although its persistently elevated prevalence across the study period is of concern. Efforts to mitigate their impacts on youth mental health alongside personal risk factors are needed. Further work is required to increase the availability and acceptability of youth-targeted mental health services. Funding: Food and Health Bureau (HKSAR Government).

Towards a youth mental health paradigm: a perspective and roadmap.

Most mental disorders have a typical onset between 12 and 25 years of age, highlighting the importance of this period for the pathogenesis, diagnosis, and treatment of mental ill-health. This perspective addresses interactions between risk and protective factors and brain development as key pillars accounting for the emergence of psychopathology in youth. Moreover, we propose that novel approaches towards early diagnosis and interventions are required that reflect the evolution of emerging psychopathology, the importance of novel service models, and knowledge exchange between science and practitioners. Taken together, we propose a transformative early intervention paradigm for research and clinical care that could significantly enhance mental health in young people and initiate a shift towards the prevention of severe mental disorders.

Effects of risperidone/paliperidone versus placebo on cognitive functioning over the first 6 months of treatment for psychotic disorder: secondary analysis of a triple-blind randomised clinical trial.

The drivers of cognitive change following first-episode psychosis remain poorly understood. Evidence regarding the role of antipsychotic medication is primarily based on naturalistic studies or clinical trials without a placebo arm, making it difficult to disentangle illness from medication effects. A secondary analysis of a randomised, triple-blind, placebo-controlled trial, where antipsychotic-naive patients with first-episode psychotic disorder were allocated to receive risperidone/paliperidone or matched placebo plus intensive psychosocial therapy for 6 months was conducted. A healthy control group was also recruited. A cognitive battery was administered at baseline and 6 months. Intention-to-treat analysis involved 76 patients (antipsychotic medication group: 37; 18.6Mage [2.9] years; 21 women; placebo group: 39; 18.3Mage [2.7]; 22 women); and 42 healthy controls (19.2Mage [3.0] years; 28 women). Cognitive performance predominantly remained stable (working memory, verbal fluency) or improved (attention, processing speed, cognitive control), with no group-by-time interaction evident. However, a significant group-by-time interaction was observed for immediate recall (p = 0.023), verbal learning (p = 0.024) and delayed recall (p = 0.005). The medication group declined whereas the placebo group improved on each measure (immediate recall: p = 0.024; ηp2 = 0.062; verbal learning: p = 0.015; ηp2 = 0.072 both medium effects; delayed recall: p = 0.001; ηp2 = 0.123 large effect). The rate of change for the placebo and healthy control groups was similar. Per protocol analysis (placebo n = 16, medication n = 11) produced similar findings. Risperidone/paliperidone may worsen verbal learning and memory in the early months of psychosis treatment. Replication of this finding and examination of various antipsychotic agents are needed in confirmatory trials. Antipsychotic effects should be considered in longitudinal studies of cognition in psychosis.Trial registration: Australian New Zealand Clinical Trials Registry ( http://www.anzctr.org.au/ ; ACTRN12607000608460).

A Sequential Adaptive Intervention Strategy Targeting Remission and Functional Recovery in Young People at Ultrahigh Risk of Psychosis: The Staged Treatment in Early Psychosis (STEP) Sequential Multiple Assignment Randomized Trial.

Importance: Clinical trials have not established the optimal type, sequence, and duration of interventions for people at ultrahigh risk of psychosis. Objective: To determine the effectiveness of a sequential and adaptive intervention strategy for individuals at ultrahigh risk of psychosis. Design, Setting, and Participants: The Staged Treatment in Early Psychosis (STEP) sequential multiple assignment randomized trial took place within the clinical program at Orygen, Melbourne, Australia. Individuals aged 12 to 25 years who were seeking treatment and met criteria for ultrahigh risk of psychosis according to the Comprehensive Assessment of At-Risk Mental States were recruited between April 2016 and January 2019. Of 1343 individuals considered, 342 were recruited. Interventions: Step 1: 6 weeks of support and problem solving (SPS); step 2: 20 weeks of cognitive-behavioral case management (CBCM) vs SPS; and step 3: 26 weeks of CBCM with fluoxetine vs CBCM with placebo with an embedded fast-fail option of ω-3 fatty acids or low-dose antipsychotic medication. Individuals who did not remit progressed through these steps; those who remitted received SPS or monitoring for up to 12 months. Main Outcomes and Measures: Global Functioning: Social and Role scales (primary outcome), Brief Psychiatric Rating Scale, Scale for the Assessment of Negative Symptoms, Montgomery-Åsberg Depression Rating Scale, quality of life, transition to psychosis, and remission and relapse rates. Results: The sample comprised 342 participants (198 female; mean [SD] age, 17.7 [3.1] years). Remission rates, reflecting sustained symptomatic and functional improvement, were 8.5%, 10.3%, and 11.4% at steps 1, 2, and 3, respectively. A total of 27.2% met remission criteria at any step. Relapse rates among those who remitted did not significantly differ between SPS and monitoring (step 1: 65.1% vs 58.3%; step 2: 37.7% vs 47.5%). There was no significant difference in functioning, symptoms, and transition rates between SPS and CBCM and between CBCM with fluoxetine and CBCM with placebo. Twelve-month transition rates to psychosis were 13.5% (entire sample), 3.3% (those who ever remitted), and 17.4% (those with no remission). Conclusions and Relevance: In this sequential multiple assignment randomized trial, transition rates to psychosis were moderate, and remission rates were lower than expected, partly reflecting the ambitious criteria set and challenges with real-world treatment fidelity and adherence. While all groups showed mild to moderate functional and symptomatic improvement, this was typically short of remission. While further adaptive trials that address these challenges are needed, findings confirm substantial and sustained morbidity and reveal relatively poor responsiveness to existing treatments. Trial Registration: ClinicalTrials.gov Identifier: NCT02751632.

Development of the PSYCHS: Positive SYmptoms and Diagnostic Criteria for the CAARMS Harmonized with the SIPS.

Aim: To harmonize two ascertainment and severity rating instruments commonly used for the clinical high risk syndrome for psychosis (CHR-P): the Structured Interview for Psychosis-risk Syndromes (SIPS) and the Comprehensive Assessment of At-Risk Mental States (CAARMS). Methods: The initial workshop is described in the companion report from Addington et al. After the workshop, lead experts for each instrument continued harmonizing attenuated positive symptoms and criteria for psychosis and CHR-P through an intensive series of joint videoconferences. Results: Full harmonization was achieved for attenuated positive symptom ratings and psychosis criteria, and partial harmonization for CHR-P criteria. The semi-structured interview, named P ositive SY mptoms and Diagnostic Criteria for the C AARMS H armonized with the S IPS (PSYCHS), generates CHR-P criteria and severity scores for both CAARMS and SIPS. Conclusion: Using the PSYCHS for CHR-P ascertainment, conversion determination, and attenuated positive symptom severity rating will help in comparing findings across studies and in meta-analyses.

Understanding the complexity, patterns, and correlates of alcohol and other substance use among young people seeking help for mental ill-health.

PURPOSE: Use of alcohol and other substances is a multifaceted issue impacting young people across multiple life domains. This paper aims to elucidate patterns of substance use and associated demographic and clinical factors among young people seeking treatment for their mental health. METHODS: Young people (12-25 years old) were recruited from five youth-specific primary mental health ("headspace") services in Australia. Self-reported substance use and harms in the past 3 months were measured using WHO-ASSIST. Network analyses were conducted to evaluate interrelationships between use and harms associated with different substances. Subgroups were then identified based on whether participants reported using high centrality substances, and associated demographic and clinical factors were assessed with multinomial logistic regression. RESULTS: 1107 youth participated. 70% reported use of at least one substance in the past 3 months, with around 30% of those reporting related health, social, legal or financial problems. Network analysis highlighted substantial interconnections between use and harm indicators for all substances, with amphetamine-type stimulants (ATS) and cannabis being high central substances. Higher levels of substance use and harms were reported in subgroups with ATS or cannabis use and different risk factors were associated with these subgroups. CONCLUSIONS: Findings highlight the importance of screening for substance use in youth primary mental healthcare settings, offering a key opportunity for early intervention. Clinicians should be aware of the inner connections of use and harms of different drugs and the role of cannabis and amphetamine use as a marker for more substance use profiles.

Prevalence and Correlates of Tobacco Use in Young People Presenting to Australian Primary Mental Health Services.

INTRODUCTION: In Australian youth primary mental health settings it is unclear as to the rates and correlates of tobacco use at service entry. AIMS AND METHODS: We aimed to delineate the prevalence and correlates of recent tobacco use (eg, cigarettes, chewing tobacco, cigars, etc) in the past 3 months in young people at their first presentation to primary mental health services as a function of age. Cross-sectional self-report measures were collected using a tablet device from young people presenting to one of five Australian primary mental health (headspace) services. Logistic regression assessed correlates of past 3-month tobacco use in adolescents (12-17 years) and young adults (18-25 years). RESULTS: Regular (at least monthly) tobacco use in the past 3 months was found in 23.4% (n = 247, N = 1055) of the sample. Increasing age (odds ratio [OR] =1.47 per year; 95% confidence interval [CI]: 1.15 to 1.89), male sex (OR = 1.98; 95% CI: 1.02 to 3.83), being in a relationship (OR = 1.96; 95% CI: 1.01 to 3.82), and poorer functioning (OR = 0.95 per unit Social and Occupational Functioning Assessment Scale increase; 95% CI: 0.91 to 0.99) predicted regular tobacco use in adolescents, but not in young adults. Living in a regional location (OR = 2.10; 95% CI: 1.40 to 3.13) and not studying (OR = 0.47; 95% CI: 0.31 to 0.73) predicted tobacco use in young adults. Having a diagnosed mental illness other than depression and/or anxiety predicted tobacco use in both groups (adolescents OR = 2.49; 95% CI: 1.26 to 4.94; young adults OR = 1.80; 95% CI: 1.13 to 2.89). CONCLUSIONS: Nearly a quarter of young people with mental illness are using tobacco, supporting the need for early intervention approaches. Adapting treatment targets by age could improve the impact of interventions in adolescents versus young adults. Poor functioning and lack of engagement in education were associated with tobacco use in both age groups, respectively; however, more research is needed to determine the direction of these relationships. IMPLICATIONS: Young people with mental illness have a high prevalence of recent tobacco use and this is evident when they first present to youth primary mental health services. Youth-oriented mental health settings may provide a unique window for tobacco use prevention and early intervention to reduce smoking in people with mental illness, a priority population. Age-specific targeted approaches might be needed in adolescents and young adults.