Impact of pre-enlistment antisocial behaviour on behavioural outcomes among UK military personnel

Concern has been raised over alleged increases in antisocial behaviour by military personnel returning from the deployment
in Iraq and Afghanistan. US-based research has shown that post-deployment violence is related not only to combat experience,
but also to pre-enlistment antisocial behaviour (ASB). This study aimed to examine the association between pre-enlistment
ASB and later behavioural outcomes, including aggression, in a large randomly selected UK military cohort.

Baseline data from a cohort study of 10,272 UK military personnel in service at the time of the Iraq war in 2003 were analysed.
The associations between pre-enlistment ASB and a range of socio-demographic and military variables were examined as potential
confounders. Logistic regression analyses were performed to examine the relationship between pre-enlistment ASB and military
behavioural outcomes such as severe alcohol use, violence/aggression and risk-taking behaviour, controlling for confounders.

18.1% were defined as having displayed pre-enlistment ASB. Pre-enlistment ASB was significantly associated with factors such
as younger age, low educational achievement, male gender, non-officer rank, Army personnel, being a regular, increasing time
spent on the deployment and having a combat role. Pre-enlistment ASB was associated with increased risk of negative behavioural
outcomes (severe alcohol misuse, outbursts of anger or irritability, fighting or assaultative behaviour and risk-taking behaviour),
after controlling for confounders, suggesting that such background information may identify individuals who are more vulnerable
to subsequent behavioural disturbance.

The results of this study suggest that those already demonstrating ASB prior to joining the military are more likely to continue
on this trajectory, thus emphasising the importance of considering pre-enlistment behaviour when exploring the aetiology of
aggression in military personnel.