3 ~ Biological and Neurological Origins

Neuropsychology and Behavior

• Biopsychology/Biocriminology - genetic and neuropsychological variables that contribute to criminal behavior

• BUT, understanding the social environment = equally as important (cf. Biosocial criminology)

• Self- Regulation - capacity to control and alter one's behavior and emotions

  • See also, "self-control," e.g., aggression in preschool

  • Malleable, not Fixed

    • Parenting styles (i.e., authoritative), monitoring

• Executive function - has to do with a number of behaviors, such as, organize, plan, goal-directed, risk consideration

  • Neurologically based (i.e., not learned) - depends on growth within the prefrontal cortex

    • Does not mature until ~ 25 years of age

  • Studies suggest that deficits in executive function have been linked to antisocial behavior

    • e.g., impulsiveness, risk-taking

Genetics and Antisocial Behavior

• Genetic causes and environmental causes interact with each other

  • "Despite strong resistance in many quarters, there is now little scientific doubt that genes play a significant role in antisocial behavior"

Genetics

• Behavior genetics - role of genes in human behavior relative to the role of the environment (aka genes vs. environment)

  • Often twin and adoption studies

• Molecular genetics - specific genes linked to behavior (i.e., "which genes?")

Behavior Genetics

• Over 100 studies involving a total of more than 77,000 families have examined the relationship between genes and antisocial behavior

  • Differences attributed to:

    • Genetic effects (50%)

    • Shared environmental influences

    • Nonshared environmental influences

Twin Studies

• Conclusion: genes account for 50% of population variation in antisocial (aggressive, violent) behavior

• Genes are not fixed, static - environmental influences can alter the expression of genes

  • e.g., Peer and sibling interactions, child neglect and abuse v. supportive parenting

Twins' Early Development Study (TEDS)

• Ongoing; over 100 pairs of twins

  • All 18+ now

• Began in the 1990s with 14,000 families, 10,000 families are still involved

• Callous-unemotional trait (e.g., lack of empathy/compassion) - very high heritability & little shared environment

Twin Study of Child and Adolescent Development

• Genetics more important in early-onset aggression (i.e. Life-course persistent)

  • Life-course persistent: antisocial behavior begins in early childhood and continues throughout adulthood

• Environment more important in late-onset (i.e. Adolescent-limited)

  • Adolescent-onset: antisocial behavior desist in young adulthood

Adoption Studies

• Some studies found increased risk of conviction if biological parent had conviction history

Summary of Twin/Adoption Research

• Suggests a genetic component/contribution

• Some are born with predisposition, but environment can inhibit or facilitate

• Not direct causation, but may influence susceptibility or resistance to risk factors

Molecular Genetics

• "Which genes predispose to which kinds of antisocial behavior?"

"Warrior Gene"

• Guo and colleagues (200*)

  • MAOA variants in 2,500 American boys in grades 7 to 12

    • "A specific variant of the MAOA gene was a risk factor of violent delinquency, but only when the boys suffered some other stress, such as family issues, low popularity, and failing school

Biological Factors - Psychophysiological Factors

• Psychophysiology - interaction between behavior and ANS (autonomic nervous system)

• Autonomic arousal theory: chronic offenders - low level of autonomic arousal

  • Offenders are involved in criminal behavior to thrill-seek

    • Fearless + stimulation seeking behavior

    • Linked to Amygdala?...

  • "underarousal prompts individuals to commit more antisocial acts as they seek stimulation to raise their arousal levels to an optimal level"

  • Low arousal = less anxiety/fear, more attracted to excitement

Psychophysiology

• Amygdala - brain structure regulating fear & emotional response

  • Linked to psychopathy & callous-unemotional traits

Biological Factors - Temperament

• "Temperament reflects biologically based emotional and behavior al consistency that appear early in life and predict -- often in conjunctions with other factors -- patterns and outcomes in numerous other domains such as psychopathology and personality"

• "Natural" mood disposition

  • Largely genetic/biological

  • Evolving, affected by parenting styles & environment

    • "How we approach and interact with our social environment influences how that environment will interact with us."

• Link between difficult temperament & persistent antisocial behavior

  • Difficult + parental rejection/coercion = especially high risk

  • Difficult also characterized by poor self-regulation/self-control

Biological Factors - Environmental Risk Factors

• Neurotoxins

  • Sufficient research to imply that prolonged exposure can lead to risk factors that elevate chance of criminal behavior

  • Lead

    • Predominantly impacts children living below poverty level

    • Research defines links to:

      • Behavior Problems

      • ADHD

      • Delinquency

      • Criminal activity

  • Manganese

  • Cadmium

    • Appears to be related to:

      • Learning difficulties

      • Low cognitive functioning

  • Mercury

• Drug Exposure

  • Alcohol exposure in utero --> increased aggressive behavior, violence

    • "a large percentage of youth in confinement may suffer from undiagnosed FASD"

  • Fetal Alcohol Spectrum Disorder (FASD): high rate of self-regulation problems and antisocial behavior (including aggression and violence)

  • Other drugs -- links established, but:

    • Less education, less income, more stress, multiple drugs used, and history of antisocial behavior themselves

      • It is hard to pin-point drugs as a main factor, they are a combination of co-factors

        • Effects of drugs vs. other risk factors --> hard to determine

• Traumatic Brain Injury

  • Up to 60% of the incarceration population in the U.S. is believed to have some evidence of TBI in their background." (v. 8.5% general population)

  • General symptoms/outcomes:

    • Uninhibited or impulsive behavior

    • Difficultly controlling anger

    • Strong correlation between TBI and substance abuse

    • Affects ability to predict consequences of actions

    • Affects ability to control emotions

    • Greater risk-taking behaviors

  • Brain Development and Consequences of Injury

    • Frontal Lobe - planning, self-regulation

      • Damage --> personality change (e.g., hostility, poor judgement

  • Frontal Lobe & TBI

    • Increased aggression

    • More likely to use physical intimidation and violence in conflict situations (esp. Impulsive violence where self-regulation is lacking

Hormones and Neurotransmitters

• Hormones - testosterone linked to aggression?

  • Inconclusive, but seems to increases aggression in those already predisposed to aggression

Neurotransmitters

• Chemical messengers

• Serotonin - linked to aggression and violence

  • Deficiencies - disinhibition of aggression?

  • Serotonin deficiency hypothesis of human aggression

    • "Research has consistently suggested that the neurotransmitter serotonin may play the most significant role in aggression and violence."