A 2967-adolescent cohort looked for bushfire harm at 24 months and did not find it

A prospective study of 2967 Australian adolescents has reported that bushfire harm was not a significant predictor of any mental health outcome measured 24 months later [s1]. It is a null result, and it arrives in the same journal that four months earlier published a systematic review concluding that every study it examined found bushfire exposure affecting adolescent mental health [s2].

Both cannot be simply correct, and the gap between them is where the useful information sits.

What the cohort did

The sample was recruited in 2019–2022 at age 13–14 and followed for 24 months [s1]. The exposure of interest was the Black Summer bushfires of 2019–2020. Researchers measured bushfire exposure and bushfire harm separately, and tracked symptoms of depression, anxiety, psychological distress, insomnia and suicidality [s1]. Linear regression models examined effects over time; logistic regression identified predictors [s1].

Of the 2967 participants, 167 — 5.4% — reported bushfire harm [s1].

The paper extends the team's own earlier cross-sectional analysis within the same cohort [s1]. That matters: the design is not a fresh look at a new group of teenagers but a follow-up on adolescents already measured, which is exactly the structure needed to ask whether an early signal persists.

It did not. Bushfire harm was not a significant predictor of any of the mental health outcomes at 24 months [s1]. What did predict 24-month symptoms was baseline symptoms — the strongest association in the analysis [s1]. Participants who were gender or sexuality diverse, who reported adverse childhood experiences, or who had a history of mental health problems carried increased risk of depression, anxiety, distress and insomnia symptoms at follow-up compared with those without those risk factors [s1].

The authors describe the finding as encouraging while stating that its underlying causes are unclear and require further research [s1]. That is an unusually restrained conclusion for a null result, and it is the right one.

What the review found

The systematic review, published in September 2025, followed the PRISMA framework and included 19 studies covering nine separate bushfire events across six countries [s2]. Its summary is consistent: exposure to bushfire is associated with adolescent mental disorders, particularly post-traumatic stress disorder and depressive symptoms [s2].

It also identified which features of an event predict poor outcomes. The consistent predictors were the subjective feeling of threat during the fire, property loss, housing adversity, and injury to oneself or a family member [s2]. And it reported replicated evidence of something more specific: in adolescent populations, subjective or perceived life threat has a greater impact on PTSD symptoms than objective or actual life threat [s2].

All studies in the review showed bushfire exposure affecting adolescent mental health, with some symptoms worsening at follow-up [s2].

Why the two results may not actually conflict

The most obvious explanation is the one the cohort study cannot rule out. The review's most consistent signal is PTSD [s2]. The cohort measured depression, anxiety, psychological distress, insomnia and suicidality [s1] — not PTSD. A study that does not measure the outcome most reliably associated with an exposure will tend not to find that exposure doing much.

The second explanation is exposure intensity. The review's predictors are severe and specific: property loss, housing adversity, injury to a family member, the subjective experience of life threat [s2]. A broadly representative national adolescent cohort in which 5.4% report bushfire harm [s1] is not the same population as a sample recruited from a burnt-out town. Most of the literature in the review comes from communities selected because a fire went through them. The cohort's harmed subgroup is 167 adolescents distributed across a continent, and the severity distribution inside that group is not something the abstract reports.

The third is statistical. A subgroup of 167 within a sample of 2967 [s1] gives limited power to detect a modest effect, particularly after adjustment. "Not a significant predictor" is not the same claim as "no effect", and the paper does not make the stronger claim.

The fourth is the most interesting. Baseline symptoms dominated the 24-month models [s1]. If a teenager's mental health two years out is mostly explained by their mental health at the start, that is a general statement about adolescent psychopathology being stable — and it means a one-off environmental exposure has to be very large to show up above that floor.

What the cohort establishes that the review cannot

The review is built almost entirely from studies of populations chosen after a disaster, which is a design that cannot easily distinguish disaster effects from the characteristics of people who live in disaster-prone places. The cohort begins from a broadly representative sample and asks who within it was harmed [s1]. That is the direction of inference that supports population-level claims, and there is very little of it in this literature.

Its finding about who does carry risk at 24 months — gender and sexuality diverse adolescents, those with adverse childhood experiences, those with prior mental health problems [s1] — is consistent with the general pattern that pre-existing vulnerability, not the acute event, drives long-run outcomes. That pattern has been documented across disaster types for decades, and this study is one more data point rather than a discovery.

What to watch

The honest summary is that Australia now has one prospective cohort saying bushfire harm did not predict adolescent mental health at two years [s1], and one systematic review saying nineteen studies found bushfire exposure did affect adolescent mental health [s2], with the most likely reconciliation being that they measured different outcomes in differently exposed populations.

The test that would settle it is a prospective cohort that measures PTSD alongside depression and anxiety, and that reports results stratified by the severity markers the review identified — property loss, injury, perceived life threat [s2]. Neither paper provides that. As fire seasons lengthen, whether adolescent services should be surged into fire-affected regions or targeted at adolescents with prior symptoms wherever they live is a resource-allocation question that this evidence base cannot yet answer.

Sources

• Longitudinal effects of bushfire harm on adolescent mental health, Australian & New Zealand Journal of Psychiatry, published online 19 January 2026
• Bushfire and adolescent mental health: A systematic review, Australian & New Zealand Journal of Psychiatry, published online 29 September 2025