Biological explanations Genetic and neural Flashcards
Concordance
% chance someone will have a disorder if someone related to them also has it
Twin study- Lange
10/13 MZ- 2/17 DZ had a co twin in prison and were in prison themselves
Twin Study- Christianson
3500 twin pairs in denmark, 35% concordance MZ, 13% in DZ for offending
Issues with twin studies
Should be 100% concordance if purely genetic
Shate similar environments
poor DNA tests so observational classification
Adoption Study- Mednick
13,000 Danish male adoptees compared to parents with convictions. Neither parent- 13%, Bio parent- 20%, bio and adoptive- 24.5%.
Limitations of adoption studies particularly mednick
Male sample, no control over time before adoption
Candidate genes- Tihonen
MAOA-L, low levels implicated with aggression
CDH-13, linked to substance abuse and ADD
900 pps, those with both gene variants went on to offend.
Diathesis stress model
Caspi et al- 500 boys, low MAOA-L, only those who had also been maltreated showed APD.
The prefrontal cortex
Raine- people with APD had 11% less grey matter in prefrontal cortex than controls.
What did Raine say were the predictors to become an offender
Low resting HR, birth defects, mother smoke or drank in pregnancy, poor functioning in the front areas of the brain. People with a reduced amygdla are 4x more likely to offend
Neural process
Amygdala processes information, frontal lobes make decisions, serotonin link the two, low MAOA-L means low serotonin so frontal lobes do not inhibit amygdala.
Crocket et al support for neural processes
Manipulated serotonin, fMRI showed low serotonin worsened communication between the amygdala and the frontal lobes when exposed to emotional images
Mirror neurons
Fire when you watch someone do an action
They form the basis for empathy, automatic response
People with APD may be able to turn it off.
