Suicidal thoughts and behaviours in adolescence

Key findings

About Growing Up in Australia

Growing Up in Australia: The Longitudinal Study of Australian Children (LSAC) is an ongoing, nationally representative study that follows the lives of children and their families from all over Australia. In 2004, around 5,000 0-1 year olds (B cohort) and 5,000 4-5 year olds (K cohort) and their families were recruited and have been surveyed every 2 years since. With extensive information on children's physical, socio-emotional, cognitive and behavioural characteristics, development and linked biomarkers, education, health and welfare data, the study has been a unique resource providing evidence for policy makers to identify opportunities for early intervention and prevention strategies.

What do we already know?

Suicidal thoughts and behaviours are a major but preventable public health concern. Suicidal thoughts and behaviours include suicidal ideation (i.e. thoughts about taking one's own life), making a suicide plan and attempting suicide. Suicide attempts are a major cause of injury and death among adolescents and young people worldwide (Clayton et al., 2023; Nock et al., 2008). Recent evidence suggests that while death by suicide is more common among males, females more commonly have non-fatal suicidal thoughts and behaviours (Arya et al., 2024; Australian Institute of Health and Welfare [AIHW], 2023; Qu et al., 2024).

The prevalence of suicidal thoughts and behaviours is worryingly high in Australia, and even higher for young people. According to recent Australian Bureau of Statistics (ABS) data, 3.3% of people aged 16-85 years reported having suicidal thoughts and behaviours in the last 12 months. This figure increases to 4.9% for those aged 16-34 years (ABS, 2020-22; Arya et al., 2024).

Available data on Australian adolescents aged 12-17 years in 2013-14 estimated prevalence of 7.5% for ideation, 5.2% for planning and 2.4% for attempts in the past 12 months, with the prevalence twice as high for males than females (Lawrence et al., 2015). However, there are limited data on the characteristics of suicidal thoughts and behaviours, such as frequency, co-occurrence of ideation, planning and attempt(s), and trajectories over time.

Patterns of suicidal thoughts and behaviours may change with age and developmental stage. These patterns can vary from a one-off instance to persistent episodes. Evidence suggests that the prevalence of suicidal behaviours tends to increase during adolescence, a time of significant social, emotional and biological changes (Miller & Prinstein, 2019). To understand if these thoughts and behaviours are persistent or transient, it is important to examine the distinct patterns and trajectories of suicidal thoughts and behaviours experienced during early and middle adolescence and into early adulthood.

This study builds on earlier research by AIFS that looked at self-harm and suicidal behaviour of young people aged 14-15 years (Daraganova, 2016) and suicidality and help-seeking of young people aged 14-15 years and 16-17 years ( AIFS, 2020).

How will this research build the evidence base?

This research builds on the existing evidence on suicidal thoughts and behaviours by examining prevalence, co-occurrences and trajectories (or 'pathways') from adolescence to early adulthood using a nationally representative sample. We also aim to understand 'who' is most in need of support by looking at the individual, psychological and social factors of those aged 14-19 years who experienced any suicidal thoughts and behaviours. This information is crucial for informing prevention efforts and providing supports.

This work aligns with the National Suicide Prevention Strategy 2025-2035 (National Suicide Prevention Office, 2025), which identifies 2 domains of suicide prevention:

1. prevention of suicidal distress,¹ which can be associated with suicidal thoughts and behaviours
2. support for people experiencing suicidal thoughts and behaviours and those who care for them.

The strategy states that to achieve this objective, it is critical to have available and translated evidence. Our research aims to contribute to this evidence base.

Participant characteristics

In the study sample, there were equal numbers of males and females at ages 14-15, 16-17 and 18-19 years. At all 3 time points, around 18% reported having a single parent, around 10% spoke a language other than English at home and 25% of respondents lived in the highest 20% of advantaged neighbourhoods compared to 15% in the lowest 20%. Around 64% of 14-15 and 16-17 year olds in the sample lived in major cities. This increased to 71% at age 18-19 years. Further details are presented in the supplementary materials Table S1a. These characteristics, except for language at home and living in an advantaged neighbourhood, are similar to the Australian population aged 14-19 years according to Census 2016 (reference to ABS, 2016, supplementary materials Table S1a).

Prevalence of suicidal thoughts and behaviours

Around one-third (34%) of young people ever reported having suicidal thoughts and behaviours by 18-19 years of age, with females (38%) more likely to have than males (31%) (Figure 1).

These findings complement the findings of the 2020-22 National Study of Mental Health and Wellbeing, which showed that younger people had a higher prevalence of suicidal thoughts and behaviours than older age groups and that females had a higher prevalence than males (ABS, 2020-22).

Breaking this down into suicidal ideation, planning and attempts, all 3 were higher for females than males. However, the patterns changed throughout adolescence (Figure 2). For females, the prevalence of ideation, planning and attempt all peaked at 16-17 years of age. For males, they either stabilised at age 16-17 years or, in the case of planning, continued to increase by age 18-19 years.

Figure 2: Prevalence of suicidal ideation, planning and attempt in the last 12 months in 2014, 2016 and 2018

Source: LSAC K cohort, Waves 6, 7 and 8. N (female) = 1,625 (2014); 1,437 (2016) and 1,315 (2018); N (male) = 1,696 (2014); 1,479 (2016) and 1,334 (2018).

Co-occurrence of suicidal ideation, planning and attempt

Understanding the co-occurrence of suicidal ideation, planning and attempts can help inform prevention efforts. Evidence from international studies suggests that suicidal ideation, planning and attempts do not always go together (Nock et al., 2013; Rodway et al., 2020; Romanelli et al., 2022). There can be suicide deaths with no known history of suicidal ideation, intent or self-harm (Rodway et al., 2020). A better understanding of these patterns can help services to provide the best support across the different pathways of suicidal thoughts and behaviours.

Among young people who reported having any suicidal thoughts or behaviours, the prevalence of all 3 elements together increased throughout adolescence for males but decreased for females (although this was off a higher base). For males, the co-occurrence of all 3 elements of suicidal thoughts and behaviours increased from 12% at age 14-15 years to 20% at age 18-19 years. For females, it decreased from 24% at age 14-15 years to 19% at age 18-19 years. See Figure 3a and Figure 3b.

This study also shows that suicide attempts do not always go along with suicidal ideation or planning for males or females. In our sample, males (9%) were more likely than females (6%) to report an attempt alone. The proportion of males who reported a suicide attempt without ideation and planning was highest at age 14-15 years (12%). For females, it was highest at age 16-17 years (9%).

Trajectories of suicidal thoughts and behaviours

Understanding how suicidal thoughts and behaviours develop during the transition from adolescence to adulthood may help in the design of early intervention and prevention strategies.

For this analysis, young people who responded to questions on suicidal thoughts and behaviours at all 3 waves were considered. The characteristics of the young people at age 14-15 years are available in Table S1b. Young people who reported experiencing any of suicidal ideation, planning or attempt at ages 14-15, 16-17 or 18-19 years were classified as having suicidal thoughts and behaviours at that age. Looking at Figure 2, suicidal thoughts and behaviours will, in most cases, show the presence of suicidal ideation, as that is the most common behaviour.

In our study sample, 8 trajectories of suicidal thoughts and behaviours across the 3 ages were seen (Figure 4). These were then put into 5 broad groups (Figure 5):

1. 'No suicidal thoughts and behaviours' at any age (74%)
2. 'Persistent' with suicidal thoughts and behaviours at all ages (3%)
3. 'Improved/decreased' suicidal thoughts and behaviours (7%), consisting of:
   1. suicidal thoughts and behaviours at ages 14-15 but not at ages 16-17 and 18-19 years (early improvement) (5%)
   2. suicidal thoughts and behaviours at ages 14-15 and 16-17 but not at 18-19 years (late improvement) (2%).
4. 'Emerged/increased' suicidal thoughts and behaviours (10%), consisting of:
   1. no suicidal thoughts and behaviours at ages 14-15 but present at ages 16-17 and 18-19 years (emerged early) (4%)
   2. no suicidal thoughts and behaviours at ages 14-15 and 16-17 but present at 18-19 years (emerged late) (6%)
5. 'Variable' with suicidal thoughts and behaviours having upward (5%) and downward triangle (1%) pattern.

Figure 4: Trajectories of suicidal thoughts and behaviours at ages 14-15, 16-17 and 18-19 years

Notes: Unweighted proportions for each trajectory are reported in text above the figure.
Source: LSAC K cohort, Waves 6, 7 and 8; N = 2,220. Sample includes those who responded to the suicidal thoughts and behaviours questions at all 3 waves.

The most common trajectory for young people was to report no form of suicidal thoughts or behaviours across the 3 ages from adolescence to early adulthood. This was higher for males (77%) than females (71%) (Figure 5). The second most common trajectory among both males and females was 'emerged/increased' (10% females and 10% males). This was followed by 'improved/decreased' (8% females and 6% males). Around 7% of females and 6% of males showed no consistent pattern in their suicidal thoughts and behaviour, while 4% of females and 2% of males reported suicidal thoughts and behaviours at all ages.

Characteristics of young people with and without any suicidal thoughts and behaviours

Suicidal thoughts and behaviours in young people are influenced by a wide range of factors. These factors can be broadly classified as individual, psychological and social. Understanding the relationship of suicidal thoughts and behaviours with these factors is crucial in identifying and supporting those at risk.

The characteristics of young people with and without any suicidal thoughts and behaviours at 14-19 years of age are presented in Figures 6a to 6d (detailed results are available in supplementary materials Table S2a and S2b). The characteristics of the young people by the 5 trajectories are available in supplementary materials Table S3.

Personal and economic characteristics

Compared to those who reported no suicidal thoughts and behaviours at any age, within the group who had experienced suicidal thoughts and behaviours at least once (see Figure 6a), a greater proportion reported:

• living in a single-parent household at age 14-15 years (19% vs 15%)
• experiencing their biological parents' separation between ages 4-5 years and 14-15 years (24% vs 17%)
• being attracted to the same sex (9% vs 2%)
• experiencing financial stress frequently or always (24% vs 14%) between ages 4-5 and 14-15 years.

Disability and mental health status

Compared to those who reported no suicidal thoughts and behaviours at any age, within the group who reported experiencing suicidal thoughts and behaviours at least once (see Figure 6b), there was a higher proportion who reported at age 14-15 years living with:

• a current medical condition(s) or disability (7% vs 3%)
• depressive symptoms (50% vs 15%)
• elevated levels of anxiety (48% vs 17%).

Drug, alcohol and cigarettes use

Compared to those who reported no suicidal thoughts and behaviours at any age, within the group who reported experiencing suicidal thoughts and behaviours at least once, there was a greater proportion who reported at age 14-15 years (see Figure 6c):

• ever using drugs (11% vs 4%)
• having 10 or more alcoholic drinks (20% vs 10%)
• smoking cigarettes (more than just a few puffs) (7% vs 2%).

Experience of bullying

Compared to those who reported no suicidal thoughts and behaviours at any age, within the group who reported experiencing suicidal thoughts and behaviours at least once, there was a greater proportion who reported at age 14-15 years (see Figure 6d):

• being bullied by someone in the past 12 months (76% vs 56%)
• bullying someone (52% vs 35%) in the past 12 months.

Relevance for policy and practice

Need to understand why the pathways of suicidal thoughts and behaviours are different for young males and females

Evidence from past research suggests that females have a higher risk of suicidal thoughts and related behaviours compared to males (Biswas et al., 2020; Franklin et al., 2017; Goodday et al., 2019; Wong et al., 2023). Similarly, findings from this study found a higher proportion of females than males reporting suicidal thoughts and behaviours.

We observed that suicide ideation, planning and attempts peak at different ages for males and females. Previous studies suggest that sex differences during the pubertal processes and developmental periods could be associated with suicide-related behaviour (Boeninger et al., 2010; Ho et al., 2022). Improving our understanding of what is contributing to the differences in suicidal thoughts and behaviours for young males and females is needed to facilitate effective preventive strategies.

Individual, psychological and social factors need to be considered in the design of effective suicide prevention efforts

This study shows the complex patterns of co-occurrence of suicidal ideation, planning and attempts. It shows that pathways of suicidal thoughts and behaviours are not linear from ideation to planning to attempt, and that suicide ideation cannot always predict a suicide attempt. Therefore, designing prevention strategies based on the co-occurrence of suicidal ideation, planning and attempts is challenging.

According to the National Suicide Prevention Strategy 2025-2035, there is a need to better incorporate personal risk factors and key social determinants in the approach to preventing suicide. In this study we identified several individual, psychological and social factors of suicidal thought and behaviours. These findings are consistent with a recent study that emphasises the need to understand the complex interplay of biological, psychological, societal and cultural factors associated with suicidal thoughts and behaviours (Qu et al., 2024).

Potential of Growing Up in Australia: The Longitudinal Study of Australian Children (LSAC)

In this snapshot we described the prevalence and trajectories of suicidal thoughts and behaviours throughout adolescence. In addition, we described the characteristics of young people with and without suicidal thoughts and behaviours. This evidence is important to inform policy makers about the nature of suicidal distress for Australian adolescents.

Building on this evidence, we intend to do a future snapshot to explore modifiable factors such as family support, peer relationships, school climate and health service use during adolescence. We will look at the effect of these factors in reducing the risk of having suicidal thoughts and behaviours.

References

Arya, V., Burgess, P., Diminic, S., Harris, M. G., Slade, T., Sunderland, M. et al. (2024). Suicidal ideation, suicide plans and suicide attempts among Australian adults: Findings from the 2020-2022 National Study of Mental Health and Wellbeing. Australian & New Zealand Journal of Psychiatry, 00048674241256753.

Australian Bureau of Statistics (ABS). (2020-22). National Study of Mental Health and Wellbeing. ABS. www.abs.gov.au/statistics/health/mental-health/national-study-mental-health-and-wellbeing/2020-2022.

Australian Institute of Family Studies. (2020). Suicidality and help seeking in Australian young people. Melbourne: AIFS. aifs.gov.au/resources/short-articles/suicidality-and-help-seeking-australian-young-people

Australian Institute of Health and Welfare (AIHW). (2023). Suicide & self-harm monitoring. AIHW. 
www.aihw.gov.au/suicide-self-harm-monitoring/data/suicide-self-harm-monitoring-data

Biswas, T., Scott, J. G., Munir, K., Renzaho, A. M., Rawal, L. B., Baxter, J. et al. (2020). Global variation in the prevalence of suicidal ideation, anxiety and their correlates among adolescents: A population based study of 82 countries. eClinicalMedicine, 24.

Boeninger, D. K., Masyn, K. E., Feldman, B. J., & Conger, R. D. (2010). Sex differences in developmental trends of suicide ideation, plans, and attempts among European American adolescents. Suicide and Life-Threatening Behavior, 40(5), 451-464.

Clayton, M. G., Pollak, O. H., & Prinstein, M. J. (2023). Why suicide? Suicide propinquity and adolescent risk for suicidal thoughts and behaviors. Clinical Child and family Psychology Review, 26(4), 904-918.

Daraganova, G. (2016). Self-harm and suicidal behaviour of young people aged 14-15 years old. In Australian Institute of Family Studies (Ed.). Longitudinal Study of Australian Children Annual Statistical Report (pp. 119-144). Melbourne: AIFS.

Franklin, J. C., Ribeiro, J. D., Fox, K. R., Bentley, K. H., Kleiman, E. M., Huang, X. et al. (2017). Risk factors for suicidal thoughts and behaviors: A meta-analysis of 50 years of research. Psychological Bulletin, 143(2), 187.

Goodday, S. M., Bondy, S., Sutradhar, R., Brown, H. K., & Rhodes, A. (2019). The cumulative incidence of self-reported suicide-related thoughts and attempts in young Canadians. The Canadian Journal of Psychiatry, 64(2), 107-115.

Ho, T. C., Gifuni, A. J., & Gotlib, I. H. (2022). Psychobiological risk factors for suicidal thoughts and behaviors in adolescence: A consideration of the role of puberty. Molecular Psychiatry, 27(1), 606-623.

Lawrence, D., Johnson, S., Hafekost, J., Boterhoven de Haan, K., Sawyer, M., Ainley, J. et al. (2015). The mental health of children and adolescents: Report on the second Australian Child and Adolescent Survey of Mental Health and Wellbeing. Canberra: Department of Health.

Miller, A. B., & Prinstein, M. J. (2019). Adolescent suicide as a failure of acute stress-response systems. Annual Review of Clinical Psychology, 15(1), 425-450.

Nock, M. K., Borges, G., Bromet, E. J., Cha, C. B., Kessler, R. C., & Lee, S. (2008). Suicide and suicidal behavior. Epidemiologic Reviews, 30(1), 133.

Nock, M. K., Green, J. G., Hwang, I., McLaughlin, K. A., Sampson, N. A., Zaslavsky, A. M.et al. (2013). Prevalence, correlates, and treatment of lifetime suicidal behavior among adolescents: results from the National Comorbidity Survey Replication Adolescent Supplement. JAMA Psychiatry, 70(3), 300-310.

Qu, D., Zhu, A., & Chen, R. (2024). Addressing the gender paradox: Effective suicide prevention strategies for women. Cell Reports Medicine, 5(6).

Rodway, C., Tham, S.-G., Turnbull, P., Kapur, N., & Appleby, L. (2020). Suicide in children and young people: Can it happen without warning? Journal of Affective Disorders, 275, 307-310.

Romanelli, M., Sheftall, A. H., Irsheid, S. B., Lindsey, M. A., & Grogan, T. M. (2022). Factors associated with distinct patterns of suicidal thoughts, suicide plans, and suicide attempts among US adolescents. Prevention Science, 1-12.

Wong, S. M., Ip, C. H., Hui, C. L., Suen, Y., Wong, C. S., Chang, W. et al. (2023). Prevalence and correlates of suicidal behaviours in a representative epidemiological youth sample in Hong Kong: The significance of suicide-related rumination, family functioning, and ongoing population-level stressors. Psychological Medicine, 53(10), 4603-4613.

Further details

For technical details of this research, including descriptions of measures, detailed results and bibliography.

About the Growing Up in Australia snapshot series

Growing Up in Australia snapshots are brief and accessible summaries of policy-relevant research findings from Growing Up in Australia: The Longitudinal Study of Australian Children (LSAC). Other snapshots in this series are also available.