Brain disorders, Abnormalities and Crime

There are some rare cases of brain injuries being identified as the cause of criminality, such as the case of the railway worker Phineas Gage, whose personality changed after a major brain injury.

After his accident, in which an iron rod entered his skull and pierced his brain (specifically his frontal lobe), he changed from being a generally pleasant man to being much more impatient and rude to those around him. Based on theories of how the brain works, this is due to the damage to his frontal lobe that is responsible for personality expression and moderating social behaviour (among other things).

A more modern Canadian study (McIsaac et al, 2016) found that people who had suffered serious head injuries are twice as likely to end up in prison (0.5% compared to 0.2%). 

Female prisoners were even more likely to have survived traumatic brain injuries.

For women with these injuries, the risk of winding up in a Canadian federal prison was 2.76 times higher than it was for uninjured women.

A recent study conducted by the University of Glasgow and published in the Journal of Violent and Aggressive Behaviour looked into the ‘Neurodevelopmental and psychosocial risk factors in serial killers and mass murderers’.

Out of the 239 ‘eligible’ killers used in the study, 28% were found to have had ‘definite, highly probable or possible‘ Autism Spectrum Disorder (to compare, 1 in 100 people in the UK have ASD), 21% had suffered a ‘definite or suspected’ head injury, whilst 55% of those with ASD and/or a head injury had experienced psychosocial stressors such as significant traumatic events during childhood (i.e. violent or sexual abuse, death of a close family member, parental divorce etc).

Suffered a fractured skull after a motorcycle accident at age 17, which left him unconscious for seven days. Two years later he groped a woman on a fire escape, she subsequently punched him causing him to fall two floors and suffer further injuries to his head.

Fred, along with wife Rosemary West would go on to commit at least 12 murders between the 1960-80s

Some brain diseases have been linked with criminal or anti-social behaviour. For example, in the 1920s, epidemics of encephalitis lethargica among children were linked to destructiveness, impulsiveness, arson and abnormal sexual behaviour.

Other brain diseases, including senile dementia, Huntington’s chorea (stops part of the brain working over time) and brain tumours have been linked to various types of deviant or anti-social behaviour.

Brainwave activity is measured by an electroencephalograph (EEG). Some studies show EEG readings among ‘clearly insane’ murderers and psychopathic criminals.

A positron emission tomography (PET) scan is an imaging test that helps reveal how your tissues and organs are functioning. A PET scan uses a radioactive drug (tracer) to show this activity.

Raine et al (1994) used PET scans to study the living brains of impulsive killers. Damage was found in the pre-frontal cortex in the brains of the criminals, the part of the brain that controls impulsive behaviour.