Joining the Armed Forces under the age of 18 does not appear to increase the risk of post-traumatic stress disorder (PTSD), two new studies have found.
New research found little evidence that early recruitment had any association with an adverse impact on long-term mental health.
Young people can join the UK Armed Forces at age 16 or 17 as junior entrants or 'juniors' and service at that age mainly focuses on education, physical fitness and trade and skills training.
Deployment is not permitted until people are 18, however, concerns have been raised that juniors are more likely to be channelled into combat roles so are potentially at higher risk of poorer mental health outcomes than those who join at 18 years or older.
Two studies led by researchers from the University of Glasgow and the King's Centre for Military Health Research (KCMHR), at King's College London, found no increased risk of PTSD among people who joined the military as juniors.
However, the University of Glasgow-led study did note an increased risk of mental health issues in veterans who had entered service between the ages of 20 and 25.
The study led by KCMHR found that under-18s who joined after 2003 reported a higher prevalence of alcohol misuse and self-harm.
Lead researcher Dr Beverly Bergman, Honorary Clinical Associate Professor and leader of the Scottish Veterans Health Research Group at the University of Glasgow, explained their study's conclusions.
"Our findings provide no evidence to support the concerns which have been expressed that junior entry to military service, prior to age 17.5 years, is associated with an increased risk of adverse mental health outcomes," she said.
"By contrast, it is entry to service at age 20 and above which carries the highest risk, although the overall effect has reduced in more recent generations of veterans.
"We also found those who enter service as junior entrants are more likely to follow a longer military career and have a lower risk of long-term mental health disorder, than those recruited at older ages.
"Efforts to prevent recruitment in the younger age groups in order to protect mental health are, at best, misplaced and, at worst, may paradoxically result in increased risk to mental health."
The study looked at more than 78,000 veterans in Scotland born between 1945 and 1995, of who more than 28,000 had entered as juniors.
The veterans were compared with 253,000 people who had no record of military service.
Ultimately the study concluded that veterans born more recently were less likely to have any difference in the risk of mental health disorder irrespective of their age at recruitment.
The King's College London-led study used data from the KCMHR military cohort study of UK Armed Forces personnel.
The research compared deployment, pre-service and post-service experiences and mental health outcomes in those who joined service as Junior Entrants and had completed basic training, with those who joined service as Standard Entrants and had completed basic training.
Looking at 4,447 participants, they found the data showed there was no increased risk of PTSD or common mental disorders.
They did however report that under-18s who signed up after 2003 reported higher levels of alcohol misuse and self-harm when compared with those joining over the age of 18.
Professor Nicola Fear, author and co-director of KCMHR at King's College London, said: "Self-harm and increased alcohol use are clear signs of distress and we need to explore why these rates are raised in the younger cohort."
Cover image: British Army.