The study also found that people with either form of extremist view were less likely to be depressed, but that men at risk of depression may experience protection from strong cultural or religious identity.
To investigate the population distribution of extremist views among UK men, the researchers surveyed 3,679 UK men aged 18–34 years in Great Britain, asked a range of questions to determine the level of their support for Britain, including whether they would fight for or against the British Army, and analysed their attitudes, psychiatric morbidity, ethnicity and religion.
The study, published in the British Journal of Psychiatry, found that Pro-British men were more likely to be White, UK born and not religious, while anti-British men were more likely to be Muslim, religious, of Pakistani origin, and from deprived areas.
Lead researcher Professor Jeremy Coid from QMUL's Wolfson Institute of Preventive Medicine said: "Although only a small number of people at the time of study said they would fight against their own country, the important thing is to look out for any shifts in future that might be occurring in these numbers. Then we can ask ourselves, are these divisions in society getting worse, what is causing the trends that we see, and does something need to be done?"
Professor Coid added: "What's fascinating about this study is that it appears that those who are pro-British are remarkably similar to those who are anti-British in aspects of their psychology. Unlike those who are pro or anti-British, it's the ones in the middle with no firm views who seem to be more prone to depression.
"We also find that religion can have an extremely protective effect on mental wellbeing, and people who are religious tend not to be violent or display antisocial behaviour. Individuals who are radicalised and have sympathies towards terrorism are clearly misusing and perverting the word of their religion."
Explore further: Study finds links between depression and risk of developing extremist ideas
J. W. Coid et al. Extremism, religion and psychiatric morbidity in a population-based sample of young men, The British Journal of Psychiatry (2016). DOI: 10.1192/bjp.bp.116.186510