Lecture 2: Neurobiological Risk Factors

Question 1

Twin studies on ASB

Answer 1

• Heritability ranges from 0.4-0.5

- Stable across different measurement e.g. teacher report

Question 2

Different forms of ASB

Answer 2

• Reactive aggression = heritability 0.39 e.g. frustration
• Proactive aggression = heritability 0.50 e.g. instrumental to achieve a goal
• Meta analysis of 103 studies on aggressive ASB (H=0.65) vn non-aggressive (H=0.48) = strong genetic influence
• -> BUT heritability of ASB is strongest for early onset

Question 3

Twin study: violent crime

Answer 3

-Violent crime heritability = 0.54

Question 4

Adoption studies

Answer 4

Mednick et al (1984)

• 14,427 adoptees in Denmark
• Sig positive correlation between adopted and biological parents for convictions of property
• BUT not true with respect to violent crimes

Question 5

Candidate genes: Brunner syndrome

Answer 5

• Brunner et al (1993) noticed 5 family males all antisocial (NOTE FOR GEORGIA: A FEMALE NOTICED THAT THE MALES WERE ANTISOCIAL)
• Analysed urine sampleS
• Identified mutation in warrior gene - MAOA
• Brunner syndrome associated with mutation in MAOA - gene changed glutamine to a termination codon
• MAO-A enzyme degrades amine neurotransmitters
• Theres MAOA-L and MAOA-H
• MAOA-L associated abnormal levels of serotonin –> aggressive behaviour

Question 6

MAOA study - interaction

Answer 6

• Genotyped large sample
• Maltreatment measured in childhood
• Looked at male individual from sample
• Found gene (MAOA-L) X environment interaction (maltreatment)

Question 7

Birth complications

Answer 7

Mednick et al (1959-1961)

• Tested biosocial interaction hypothesis = birth complications combined with maternal rejection predisposes to adult violent crime
• 4269 males from birth
• Complications at age 0
• Early maternal rejection age 1
• Violent crimes at 18
• Birth complications combined with early maternal deprivation increased risk of adult crime
• When only rejected least percentage committed crimes, but small group that did commit performed most violent

Question 8

Mechanisms that can explain interaction between birth complication and social risk - study

Answer 8

• Guinea pig study
• Looked at hypoxia = deprivation of o2 during birth
• Looked at neuronal density
• Ones exposed to hypoxia had reduced neuronal density in cortical and sub cortical structures (hippocampus, cingulate and cortex)
• Reduced grey matter at hippocampus after 7 and 28 days
• Hypoxia = decreased white matter integrity
• Birth complications set in motion structural brain problems

Question 9

Drinking in pregnancy

Answer 9

• Foetal alcohol syndrome (FAS) = exposure to alcohol pre-natally
• 4 features:
  1. Exposure to alcohol during pregnancy
  2. Craniofacial abnormalities
  3. Growth retardation
  4. Central nervous dysfunction (learning disabilities and low IQ)

Question 10

Facial features of children with FAS

Answer 10

• Small head
• Short nose
• Thin upper lip

Question 11

FAS associated with psychiatric disorders study

Answer 11

• Over 5000 studies
• Looked at with psychiatric disorders associated with FAS
• CD = most common (90%)

Question 12

Mechanisms that underlines relationship between FAS and antisocial behaviour

Answer 12

• Impacts corpus callosum
• Damages to hippocampus = impairs learning and memory
• Associated with poor executive functions

Question 13

Structural brain: study of antisocial behaviour

Answer 13

• Glenn and Raine (2014)
• Man with rumpus compressing ventral medial prefrontal cortex
• Was school teacher then acted inappropriately with children
• Operated on –> back to normal
• Tumour came back and behaviour returned

Question 14

Antisocial personality disorder symptoms

Answer 14

• Impulsivity
• Recklessness
• Repeated criminal acts
• Lack of remorse
• Poor decision making

Question 15

Biology of ASPD

Answer 15

• Abnormalities with vmPFC
• Lesions with vmPFC –> changes in behaviour and personality regardless of age

Meta analysis:

• Looking at relationship between grey matter volume and CD
• Subdivided PFC into different regions
• Demonstrated that individuals with CD had grey matter reduction in several regions of PFC, orbit-frontal cortex, dPFC, internal cingulate cortex

Question 16

Relationship between amygdala and antisocial behaviour

Answer 16

• Lower amygdala volume in men associated with childhood aggression, early psychopathic traits, future violence
• Smaller amygdala = greater psychopathic features
• Individuals who committed violent acts = grey matter reduction in amygdala bilaterally

Question 17

Nervous system

Answer 17

• Peripheral and central
• PNS = somatic and autonomic (parasympathetic, sympathetic and visceral)
• Unconsciously
• Physiological arousal

Question 18

Fearlessness theory

Answer 18

• Raine (1993)
• Low HR = marker for low fear
• Low fear can disrupt early fear conditioning
• Facilitates criminal acts

Question 19

Sensation-seeking theory

Answer 19

• Quay (1965) and Eysenk (1997)
• Low resting HR = marker of low autonomic arousal = they seek stimulating behaviour –> antisocial behaviour to increase level of arousal
• Longitudinal study in Finland looking at men = relationship between low RH and violent crime

Question 20

Study in Germany looking at psychopathy

Answer 20

• Performed task with brain scanner
• Every time man with moustache there was painful stimulation on finger
• No moustache = no stimulation
• 2 stages = habituation ethene extinction
• Looked at skin conductance
• Found with psychopaths = disconnection what they were saying and what they felt –> had no ANS response (no sweat)
• Psychopaths = hardly anything happened except bit of activity in amygdala
• Controls = enhanced differential activation in limbic prefrontal circuit during fear acquisition