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Last Updated: Wednesday, 15 December, 2004, 09:07 GMT
Biological predisposition to violence: facts behind the fiction
All the drama-documentaries in the IF series are based on rigorous journalism and research.

Here are just some facts surrounding the issues of crime, violence and biological predisposition.

Wednesday, 22 December, 2004
2100 GMT

  • More than one million violent crimes (violence against the person, sexual offences and robberies) were recorded in 2003/04 - a 12% increase on the previous year.

  • 10% of all offenders are responsible for over half of all crime. They account for at least 50% of serious convictions.
    (Source: Home Office research - Annex B of Criminal Justice: the way forward Cm 5074, 2001)

  • Experts have linked violent behaviour to environmental factors during childhood. Research shows that poor living conditions in economically deprived areas and poor parenting of young children increase the risk of violent behaviour in adulthood.

  • 70,000 children in the UK are receiving medication for ADHD (Attention Deficit Hyperactivity Disorder).
    (Source: Meidplus UK Data, April 2003)

  • However, it is believed there are many more undiagnosed children - it is estimated as many as 5% of school age children have ADHD and 100,000 children need treatment.

  • 23% of all crime has been attributed to poor or non-existent diagnosis of ADHD in children in care homes.
    (Source: Dale C and Storey L, Nursing Praxis-Care and Treatment of Offenders with a Learning Disability)

  • Court records suggest that ADHD youths are four to five times more likely to be arrested and to have multiple arrests and convictions.
    (Sources: Weiss, G., & Hechtman, L., (1986). Hyperactive children grown up. New York, N.Y.: The Guilford Press; Lambert, N. M. (1988). Adolescent outcomes for hyperactive children. American Psychologist, 43, 786-799; Mannuzza, S., Klein, R.G., Konig, P.H. and Giampino, T.L. (1989) Hyperactive boys almost grown up: IV. Criminality and its relationship to psychiatric status, Archives of General Psychiatry, 46, 1073-1079; Satterfield, J.H., Hoppe, C.M. and Schell, A.M., (1982) A prospective study of delinquency in 110 adolescent boys with attention deficit disorder and 88 normal adolescent boys, American Journal of Psychiatry, 139 (6), 795-798; Satterfield, T., Swanson, J., Schell, A., Lee, F. (1994) Prediction of anti-social behaviour in attention-deficit hyperactivity disorder boys from aggression/defiance scores)

  • Studies using brain imaging (positron emission topography or PET) have shown that a group of murderers had poor functioning of the prefrontal cortex part of the brain - the area believed to control and regulate aggressive behaviour. Some scientists believe therefore that a person with a damaged or poor functioning prefrontal cortex has a tendency to be violent.
    (Source: Brain abnormalities in murderers indicated by positron emission tomography. Raine A, Buchsbaum M, LaCasse L. Biol Psychiatry. September 1997,15;42(6):495-508)

  • Earlier studies had already shown that damage to the brain caused by birth complications have both been linked to violent behaviour.
    (Source: Kandel, E., and Mednick, S.A. 1991. Perinatal complications predict violent offending. Criminology 29(3):519-529.)

  • A 2003 study in Mauritius using brain scans (magnetic resonance imaging or MRI) showed that brain activity could be boosted by an enriched lifestyle (better diet and exercise) in the early years of life, helping to prevent violent behaviour. By 23 years old, subjects were 64% less likely to have criminal records than those who did not have the enriched lifestyle.
    (Source: Effects of Environmental Enrichment at Ages 3-5 Years on Schizotypal Personality and Antisocial Behavior at Ages 17 and 23 Years. Am J Psychiatry 2003 160: 1627-1635)

  • A study of a Dutch family in 1993 was the first to suggest the link between a genetic defect and extreme aggression. Several generations of men in the family had committed violent crimes. The research found that these men all had a genetic mutation that caused low levels of an enzyme called MAO-A.
    (Source: Abnormal behavior associated with a point mutation in the structural gene for monoamine oxidase A. American Association for the Advancement of Science, Vol 262 (5133) 22 October 1993 pp 578-580)

  • However, biological factors alone do not necessarily indicate a predisposition to violence. A study of abused boys in New Zealand found that abused children were more likely to grow up to show anti-social behaviour if they had low levels of MAO-A.
    (Source: Caspi et al., Science, vol. 297, p851 Caspi, A. Moffitt, T.E. et al. 2002. Role of genotype in the cycle of violence in maltreated children. Science 297(Aug. 2):851-854)

  • In 1991, a 64-year-old man was tried for murder. Brain scans showed that he had a cyst pressing on the prefrontal cortex part of the brain and his defence team planned to use this as part of his defence (although the case was never presented after the plea was changed).
    (Source: The Legal Admissibility of Positron Emission Tomography Scans in Criminal Cases: People v. Spyder Cystkopf. Weiss Z. Semin Clin Neuropsychiatry. 1996 Jul;1(3):202-210)

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