Increasing knife crime: Aggressive Adolescents or Traumatized Teenagers?

Georgia Harvey
Masters student at King's College London studying Child and Adolescent Mental Health. Georgia's research to date has predominantly focused on young people, more specifically regarding; trauma, self-harm, suicidal ideation and the impact of social media. With experience working in mental health in both the public and private sector.

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According to the Office for National Statistics, in 2018, almost 43,000 knife related offences were reported to the police across England and Wales, excluding Manchester (Allen et al., 2019). That is almost 118 incidents a day; 1 in 5 of these offenders were aged only 10-17 years old. So why are there reportedly so many young people carrying knives? Well, let me introduce you to one hypothesis explaining these figures, which focuses on trauma and anxiety.

Symptoms of trauma or anxiety can be triggered following exposure to a traumatic event. This is applicable to those who are direct victims, witnesses or even those who have experienced trauma vicariously-second hand trauma to people who hear about it or see it in another person. One example of this would be an individual involved in a road traffic accident. Following this, an individual may experience passenger anxiety, a behavioural symptom. This behaviour is commonly reinforced by thoughts such as “If I get in a car, I could die”, which can lead to the safety behaviour of avoiding commutes in a car. In cognitive behavioural therapy (CBT), this thought would be identified as a thinking error and the aim of treatment would be to challenge this thought in order to decrease and hopefully eradicate the safety behaviour.

Arguably, the thought “somebody is going to stab me” illustrates this same pattern of a thinking. In other words perhaps it too can be a “thinking error”. This view can even lead to the controversial “safety behaviour” of carrying a knife.  Alternatively, this fear of being stabbed can lead to avoidance with regard to certain locations and or avoiding contact with friends. This can further exacerbate poor mental health (Foster, Hooper, Knuiman & Giles-Corti, 2016). This mental health risk is emphasised in a recent longitudinal study of over 2,200 children. It was found that developing a mental health condition was twice as likely amongst trauma-exposed young people, compared to non-traumatised participants (Lewis et al., 2019).

Of course, there are other confounding factors which can result in a young person holding a knife and this is not an article to justify the behaviour. It is essential to understand the influence of a young person’s mental health, in order to provide effective assessment and treatment options to reduce consequent negative behaviours. Currently, too few young people with post-traumatic stress disorder (PTSD) access mental health treatment (Lewis et al., 2019), highlighting a need to improve screening and provision amongst those subject directly or vicariously to trauma, such as knife crime.

This knowledge can also be applied to anti-knife campaigns which have displayed anxiety provoking adverts. For example, North Yorkshire police previously promoted the slogan “the blood on your hands could easily be your own” (Op Sceptre: Week of action against knife crime, 2018). I would argue that to a young person, with a thinking error, this information may simply support their belief that they will be stabbed, particularly if they live in a high-crime community.

The acknowledgement of a young person’s environment, their ‘context’, is also crucial in mental health treatment. It may be deemed more appropriate to target the traumatic memories, before targeting attempts to change their environment. Such an approach could favour treatments such as eye movement desensitisation and reprocessing (EMDR), in the first stage of support over the commonly prescribed CBT.

There is no excuse for criminality. But we know that the factors that drive young people into violence can sometimes be a sign of underlying mental health problems. We also know that an environment soaked in violence provides fertile soil for criminality, mental ill health and further trauma. Instead of targeting so much resource and energy on the surface phenomena like the behaviour, lets focus much more on providing support and treatment. This could reduce anxiety and trauma symptoms and reduce the normalisation of knife carrying amongst some young people. This approach was adopted in Scotland’s Violence Reducing Unit in 2005, which identified stabbings as a public health and policing issue. Since this introduction, it has been reported that within 10 years, homicides which were mainly from sharp instruments, had more than halved (O’Hare, P, 2019). Thus, highlighting the evidence-based benefits of a mental health approach towards knife crime, in addition to a law enforcement approach.

Conflict of interest statement: No conflicts declared.


Knife crime in England and Wales – Number SN4304, 30 September 2019 – Grahame Allen Lukas Audickas, Philip Loft, Alexander Bellis – House of Commons library

Op Sceptre: Week of action against knife crime. (2018).

Allen, G., Audickas, L., Loft, P., & Bellis, A. (2019). Knife crime in England and Wales. House of Commons Library.

Foster, S., Hooper, P., Knuiman, M., & Giles-Corti, B. (2016). Does heightened fear of crime lead to poorer mental health in new suburbs, or vice versa?. Social Science & Medicine, 168, 30-34. doi: 10.1016/j.socscimed.2016.09.004

Lewis, S., Arseneault, L., Caspi, A., Fisher, H., Matthews, T., & Moffitt, T. et al. (2019). The epidemiology of trauma and post-traumatic stress disorder in a representative cohort of young people in England and Wales. The Lancet Psychiatry, 6(3), 247-256. doi: 10.1016/s2215-0366(19)30031-8

 O’Hare, P. (2019). How Scotland stemmed the tide of knife crime.


Thank you for your blog. All the boys I have seen who carried knives told me pragmatically “you have to, if you live round here”. Of the three that come to mind, all suffered with an anxiety disorder and had low self esteem. I wonder what would be a more useful anti knife slogan and whether many of them would see the police as people who are out there to support them.

Hi Georgia,

I am currently a PhD student at Manchester Metropolitan University undertaking research focused on violent knife crime in adolescene and young adulthood. I’m interested in your perspective on this issue and wonder if you would like to discuss with me via email?

Has any research been completed identifying the percentage not enabled to participate in learning simply because functionally illiterate increasing the probability of “approval deprivation”, performance anxiety, stress related ‘text avoidance strategies’ escalating from “cant-do, wont do” to fight or flight responses deemed a misbehaviour / anti-social ?

2000,000 in the UK escape edcuation pre-16 to be labeled NEET’s post 16 and at a predictably higher risk of offending yet, 80% drop off Police radar between their 25th and 6th birthdays having exclaimed at 15 they were “gonna play hard and die young” only to wake-up on their B’day gobsmacked where the last ten years have gone and with 30 just around the corner what are they gonna do now, what are they gonna do now ?

Of course, in a “them and us” society if. no one give a frig about ‘us’ then, why should they give one about “them” in an Hourglass Economy of Haves and Have-nots mainly, differentiated by those who have been enabled to be fluent readers and participate in life-long learning and those who have-not.

Not exactly rocket science or counter intuitive for those excluded from socio-economic participation would present as Maverick socially excluded yet, still seeking to belong to some sub-culture where, some degree of “approval” may be found amongst their peers if not parents, community or society in general mafginalised from in affect self-harming.

Hello, thank you for reading my blog. It’s great to hear the mentioned points applied to real life scenarios. I think anti-knife slogans alone may prove ineffective or confusing for these young people, without the combination of mentoring. But to answer your question, maybe an anti-knife slogan “Think about ALL of the times you’ve left your house without a knife. Let us help you, by leaving it at home”. or “When going out, you need your shoes to leave. Don’t take the knife, and breathe”. The first phrase portrays an image of police support, whilst the second reinforces the techniques of breathing exercises amongst those with anxiety. It really is the small changes which can help towards a large recovery.

Knife crime is a great worry, and an issue in Bristol, in the South West. I am very interested in the work being done in parts of the US, where ACEs (adverse childhood experiences) are used as a starting point for young people to begin to understand the root of their behaviour or mental health issues, so that they have a chance to make a change themselves.

There is an inspiring video called ‘Paper Tigers’, about ‘Lincoln Alternative School’, where all students are screened for ACEs and taught about their impact on brain development. The video concluded with some hopeful statistics showing a dramatic decrease in anti-social behaviour, drug abuse, mental health issues, amongst others. Students are taught overtly about resilience, and how to develop it, and great importance is given to positive relationships with key adults in school. There is hope!

I work in a young person secure setting as a psychologist, and was wondering if we could chat about the difficulty of embedding such ideas with staff who are not familiar with trauma responses?

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