MAOA gene

Question 1

Who conducted research into twin studies to find an association between aggression and genetics?

Answer 1

Coccaro et al.

Question 2

What did Coccaro et al. find?

Answer 2

Studied adult male twins for aggressive behaviour:
direct assault:
- MZ = 50%
- DZ = 19%
verbal aggression:
- MZ = 28%
- DZ = 7%

Question 3

Who conducted research into adoption studies to find an association between aggression and genetics?

Answer 3

Rhee and Waldman

Question 4

What type of study did Rhee and Waldman carry out?

Answer 4

A meta-analysis of 51 adoption studies.

Question 5

What did Rhee and Waldman find?

Answer 5

They found that genetic influences accounted for 41% of the variance in aggression.

Question 6

What is MAOA?

Answer 6

An enzyme that deactivates neurotransmitters, especially serotonin.

Question 7

What determines the production of MAOA?

Answer 7

MAOA gene.

Question 8

What would happen if there was a dysfunction in the MAOA gene?

Answer 8

May lead to abnormal activity of the MAOA enzyme, which in turn effects levels of serotonin in the brain.

Question 9

What MAOA gene variant is known as the ‘warrior gene’?

Answer 9

Leads to low MAOA activity in areas of the brain and has been associated with various forms of aggressive behaviour.

Question 10

Name 2 psychologists who conducted research into the ‘warrior gene’s association with aggression.

Answer 10

Brunner

Stuart

Question 11

What was Brunner’s study?

Answer 11

• Brunner studied 28 male members of a large Dutch family who were repeatedly involved in impulsively aggressive violent criminal behaviours such as rape, attempted murder and physical assault.

Question 12

What did Brunner find?

Answer 12

Researchers found that these men had abnormally low levels of MAOA in their brains.

Question 13

What did Stuart study?

Answer 13

Studied 97 mn who had been involved in inflicting intimate partner violence.

Question 14

What did Stuart find?

Answer 14

Men with the low-activity MAOA gene were found to be the most violent perpetrators of intimate partner violence.

Question 15

Who conducted research into gene-environment interactions?

Answer 15

Frazzetto et al.

Question 16

What did Frazzetto et al. find?

Answer 16

Found an association between higher levels of anti-social aggression and the low activity MAOA gene variant in adult males BUT this was only the case in those who had experienced significant trauma during the 1st 15 years of life.
Those who had not experience such childhood trauma did not have particularly high levels of aggression as adults, even if they possessed the low-activity MAOA variant.

Question 17

State 3 negatives of the genetic explanation for aggression.

Answer 17

Isolating genetic factors:
- gene-environment interactions
- McDermott - laboratory-based money allocation game, low-activity MAOA gene participants only behaved aggressively when they were provoked.
Multiple gene influences:
- Stuart et al. discovered that IPV in men was also associated with the serotonin transporter gene.
Measuring aggression:
- varying data gathering techniques (self report, direct observation etc)
- Rhee and Waldman: genetic factors had greater influence on aggression in self-report techniques than parent or teacher reports.
- hard to draw valid conclusions.