PT - JOURNAL ARTICLE AU - Bergman, Beverly P AU - Mackay, DF AU - Fear, NT AU - Pell, JP TI - Age at entry to UK military service and long-term mental health AID - 10.1136/bmjmilitary-2021-001786 DP - 2023 Jun 01 TA - BMJ Military Health PG - 212--217 VI - 169 IP - 3 4099 - http://militaryhealth.bmj.com/content/169/3/212.short 4100 - http://militaryhealth.bmj.com/content/169/3/212.full SO - BMJ Mil Health2023 Jun 01; 169 AB - Introduction It has been suggested that ‘junior entry’ to the UK Armed Forces (prior to age 17.5 years) increases the risk of adverse mental health outcomes. We used data from a large cohort of veterans to examine long-term mental health outcomes in veterans by age at entry to the UK Armed Forces, compared with non-veterans.Methods Retrospective cohort study of 78 157 veterans in Scotland, born between 1945 and 1995 and and 252 637 matched non-veterans, with up to 37 years follow-up, using Cox proportional hazard models to examine the association between veteran status and cumulative risk of major mental health disorder, stratified by birth cohort, and age at recruitment for the veterans.Results The risk of mental health disorder in the veterans increased with age at entry, ranging from HR 1.12, 95% CI 1.06 to 1.18, p<0.001 for junior entrants to HR 1.37, 95% CI 1.27 to 1.80, p<0.001 for those aged 20–25 years at entry. The pattern was most marked for veterans born before 1960, and age at recruitment had little impact in recent birth cohorts. Post-traumatic stress disorder accounted for most of the observed differences. Younger age at recruitment was associated with longer service, median 7.4 years (IQR 3.0–14.7) compared with 5.6 years (IQR 2.1–11.7) for entrants aged 20–25 years.Conclusion We found no evidence that early recruitment is associated with adverse impact on long-term mental health. Paradoxically, it was veterans who entered service at age 20–25 years who demonstrated increased risk, although this attenuated in more recent birth cohorts.No data are available. The study remains in progress and data are not currently available for sharing.