FP - Biological explanations of offending behaviour: Genetic and neural

Question 1

Epigenetics

Answer 1

Refers to the material in each cell of the body that acts like a set of ‘switches’ to turn genes on or off.

Question 2

Genetic explanations

Answer 2

The likelihood of behaving in a particular way is determined by a person’s genetic make-up, i.e. it is inherited from parents.

Question 3

Neural explanations

Answer 3

Involve areas of the brain and nervous system and the action of chemical messengers in the brain known as neurotransmitters in controlling behaviour.

Question 4

What do genetic explanations propose?

Answer 4

That one or more genes predispose individuals to criminal behaviour.

Question 5

What do we talk about in genetic explanations of offending behaviour?

Answer 5

Monoamine oxidase A (MAOA)
Cadherin 13 (CDH13)
Diathesis-stress

Question 6

What type of explanation is the genetic and neural approach?

Answer 6

Biological explanation

Question 7

What is the case study for personality change via brain damage?

Explain it

Answer 7

Gage, 1894

Railway worker - catastrophic damage to pre-frontal lobes caused by a metal bolt catapulting through his cheek and up through his eye into his brain (pre-frontal area).

Recovered physically but went from being a sober, quiet family man to a violent drunk.

Pre-frontal lobes keep behaviour in check, moderate impulses.

Question 8

What was Mobley’s claim (he was ‘born to be criminal’) based on?

Answer 8

Research by Han Brunner.

Question 9

What is the key study for genetic explanations and the MAOA gene?

Answer 9

Brunner, 1993

Question 10

What did Brunner (1993) do?

Answer 10

A study of violence in a family with genetic abnormality.

Question 11

What was the aim of Brunner’s (1993) study?

Answer 11

To explain the behaviour of a large family in the Netherlands where the males are affected by a syndrome of borderline mental retardation and abnormals violent behaviour (i.e. impulsive aggression, arson, attempted rape, exhibitionism).

Question 12

What was the method of Brunner et als. (1993) study on a dutch family?

Answer 12

Clinical examination of male family members and comparison with normal family members.

Question 13

What did the clinical examination of the dutch family studied by Brunner include?

Answer 13

Behavioural examination.
Clinical examination.
DNA analysis.

Question 14

What was found in the behaviour examination of the dutch family studied by Brunner?

Answer 14

• Repeated episodes of aggressive and sometimes violent behaviour (often out of proportion to provocation).
• Sleep disturbances and night terrors.
• Inappropriate sexual behaviour towards sisters and female relatives.
• Arson.

Question 15

What was found in the clinical examination of the dutch family studied by Brunner?

Answer 15

• All 9 males mentally retarded (average IQ 85). Only 1 completed primary education (all unaffected males attended school and were employed).
• All females, including carriers, appear normal.

Question 16

What was found in the DNA analysis of the dutch family studied by Brunner?

Answer 16

• Data was collected from the analysis of urine samples over a 24h period.
• All affected males showed genetic mutations in the genes producing MAO-A.

Question 17

What explanation did Brunner give for the aggressive males having genetic mutations in the genes producing MAO-A causing their behaviour?

Answer 17

MAO-A breaks down and removes 3 neurotransmitters; noradrenaline, dopamine and serotonin.

Therefore, lower activity levels of MAO-A will lead to increased levels of these nt (arousal, emotional arousal and sleep).

Question 18

What are the consequences of the affected males in Brunner’s study having lower activity levels of MAO-A?

Answer 18

• Increased serotonin may have caused their criminal behaviours as impulse control is inhibited.
• Low levels of dopamine and noradrenaline have been known to cause spontaneous and irritable aggression in animals so could be responsible for their criminal behaviour.
• Disturbed behaviour may also have been due to arousal seeking behaviour.

Question 19

Briefly explain the case of Stephen Mobley

Answer 19

(1966-2005)

• Convicted murderer executed by the state of Georgia for the 1991 killing of John C. Collins, a 25y/o college student working nights as a Domino’s Pizza store manager.
• On appeal, Mobley’s attorneys advanced a novel argument that Mobley was genetically predisposed to seeking violent solutions to conflict.
• The case was described as “perhaps the most widely cited case in which defence lawyers used genetic factors in the defence of their client”.

Question 20

What studies give evidence for the genetic component that predisposes individuals to criminal behaviour?

Answer 20

Twin studies - Mendick et al. (1984) and Raine (1993).

Question 21

What evidence proposed by Raine shows the role of genetics in criminal behaviour?

Answer 21

Reviewed research on the delinquent behaviour of twins and found 52% concordance for MZ twins compared with 21% for DZ twins.

Question 22

What does the CDH13 gene/Cadherin protein do?

Answer 22

Slows down axon growth when neurons change structure or type - This ‘negative regulation’ helps conserve energy and speed up the change.

Slows down the natural death (apoptosis) of vascular cells around neurons during periods of stress - This is a natural defence mechanism against atherosclerosis and harmful (oxidative) stress. It is in a very low activity state in some types of cancer development, leaving growth mostly unchecked.

Question 23

What study showed evidence for the role of both MAOA and CDH13?

Answer 23

Finnish study by Jari Tiihonen et al. (2015) with 900 offenders.

Question 24

What did the Finnish study by Jari Tiihonen et al. (2015) find and what was concluded?

Answer 24

Evidence of low MAOA activity and also low activity from the CDH13 gene. They estimated that 5-10% of all violent crime in Finland is due to abnormalities in the MAOA and CDH13 genes.

Question 25

What is the CDH13 gene believed to be like in criminals?

Answer 25

High activity of CDH13 interrupts the building and strengthening of some neural networks during their development.

Question 26

How does the diathesis-stress model link in with the CDH13 gene?

Answer 26

Childhood stress/trauma might methylate (epigenetics; “switch off”) this gene.

Some networks might end up less well developed or well connected.

Question 27

What is a possible reason why genes can be switched on or off (diathesis-stress model)?

Answer 27

Maltreatment in childhood

Question 28

What did Caspi et al. (2002) use to study diathesis-stress in terms of childhood maltreatment and criminal behaviour and what did they find?

Answer 28

• Used data from the longitudinal Dunedin study (in New Zealand) that has followed about 1000 people from when they were babies in the 1970s.
• Caspi et al. assessed anti-social behaviour at age 26 and found that 12% of those men with low MAOA genes had experienced maltreatment when they were babies but were responsible for 44% of violent convictions.

Question 29

What is the link between head injury and criminal behaviour?

Answer 29

Criminals report having had some head injury - in general 8.5% of the US population have had a brain injury compared to 60% in US prisons (Harmon, 2012).

Therefore brain differences may be due to nurture - or they may be inherited (nature).

Question 30

What did Raines 2009 study (neural explanations) involve?

Answer 30

Comparing 27 psychopaths to 32 non-psychopaths.

Question 31

What did Raines 2009 study (neural explanations) find?

Answer 31

Psychopaths had an 18% volume reduction in the amygdala and thinning of the cortex.

Raine et al. also found an 11% reduction in grey matter of the PFC in people with antisocial personality disorder (APD) compared to controls.

Question 32

What did Raine (2004) do?

Answer 32

Cited 71 brain imaging studies showing that murderers, psychopaths and violent individuals have reduced functioning in the PFC.

Lowered activity in this area is associated with impulsiveness and loss of control.

Question 33

What is the PFC involved in?

Answer 33

Regulating emotion and controlling moral behaviour in general.

Question 34

What is the limbic system?

Answer 34

A set of subcortical structures, such as the thalamus and the amygdalae, that are linked to emotion and motivation.

Question 35

What did Raine et al. (1997) study and find?

Answer 35

Studied murderers who were found not guilty by reason of insanity (NGRI).

Compared with matched controls, they found abnormal asymmetries in the limbic system of the murderers, especially in the amygdala - there was reduced activity of the left and increased activity on the right.

Question 36

What are mirror neurons?

Answer 36

A type of brain cell that fires when you do an action, and also when you simply watch someone else doing the same action.

They help us understand and interpret the actions of others.

Question 37

What does APD stand for?

Answer 37

Antisocial personality disorder.

Question 38

What is empathy like in people with APD?

Answer 38

Sporadic

Question 39

What research is there into APD?

Answer 39

Keysers et al. (2011)

• When APD’s asked to empathise, they did.
• Mirror neurons activated.

In a normal brain, empathy is always “on”.

Question 40

What does MAOA control?

Answer 40

Monoamines - NT (serotonin, noradrenaline and dopamine).

Question 41

What chromosome is MAOA on?

Answer 41

X-chromosome

Question 42

What is significant about MAOA being on the X chromosome?

Answer 42

You only need 1 functioning copy - women inherit 2, but men can inherit dysfunction from the mother alone so are at increased risk of having their defect.

Question 43

Explain what the adoption studies done by Mendick et al. (1984) found about criminal behaviour

Answer 43

• 14427 Danish adoptees.
• 13.5% were criminal with no criminal parents.
• 14.7% were criminal with at least 1 criminal adoptive parent.
• 20% were criminal with at least 1 criminal biological parent.
• 24.5% were criminal with at least 1 criminal adoptive parent and 1 criminal biological parent (additive effect shows diathesis stress).

Question 44

What do researcher suggest about the link between serotonin and criminal behaviour?

Answer 44

E.g. Seo et al., 2008

Low levels of the NT serotonin may predispose individuals to impulsive aggression and criminal behaviour.

Low levels mean a lack of inhibition, by the PFC, of impulsive aggressive urges.

Dopamine hyperactivity may enhance this effect.

Question 45

What do researcher suggest about the link between noradrenaline and criminal behaviour?

Answer 45

Both very high and very low levels of this NT have been associated with aggression, violence and criminality (Wright et al., 2015).

High levels of noradrenaline are associated with activation of the sympathetic nervous system and the fight-or-flight response, and thus are linked to aggression.

Noradrenaline also helps people react to perceived threats, so low levels would reduce this ability.

Question 46

Give supporting evidence for Brunner’s studies on MAO-A (and the role of genetics and NT in criminal behaviour in general)

Answer 46

Virkkunen et al. (1994) - Violent criminals whose violence was compulsive had lower levels of serotonin than violent criminals whose crime was planned.

Beggard et al. (2003) - Serotonergic dysfunction linked to criminal behaviour.

Question 47

Explain evidence by Virkkunen et al. (1994) into the role of genetics and NT in criminal behaviour

Answer 47

Violent criminals whose violence was compulsive had lower levels of serotonin than violent criminals whose crime was planned.

Question 48

Explain evidence by Beggard et al. (2003) into the role of genetics and NT in criminal behaviour

Answer 48

Serotonergic dysfunction linked to criminal behaviour.