What causes Antisocial Personality Disorder? Unit 1 – Making sense of other people Topic 3 – Development of personality

Lesson objectives By the end of the lesson you will be able to: Describe the biological causes of Antisocial Personality Disorder. Describe and evaluate a study by Raine of the biological causes of Antisocial Personality Disorder.

Key Terms Amygdala – Part of the brain involved in emotion. Grey Matter (Cerebral Cortex) – The outer layer of the brain. Prefrontal cortex – The very front of the brain. It’s involved in social and moral behaviour and controls aggression.

Recap… What is meant by APD?

Biological causes of APD. Some researchers believe that brain abnormalities are the main cause of APD. The Amygdala and the prefrontal cortex that are associated with APD.

The Brain Amygdala – Part of the limbic system and is in the temporal lobe. It’s involved with memory, emotion and fear. Grey matter – Outer layer of the brain. This area is involved in muscle control, sensory perceptions, memory and speech. Prefrontal cortex – Located at the front and is involved in expressing personality and appropriate social behaviour.

The Brain and APD. The amygdala is responsible for learning from negative consequences of our actions. It also responds to fearful and sad facial expressions. We therefore learn to avoid activities we see causing distress. The amygdala is affected in APD people. This means they don’t learn to avoid these harmful behaviours/situations. This is because they are not affected by distress shown in others. Reduction of grey matter in the prefrontal cortex has also be associated with APD. This area is where we learn to feel guilt etc. People with APD are less likely to behave morally or feel remorse for wrong doing.

Raine et al. (2000) Aim – To support the theory that abnormalities in the prefrontal cortex cause APD. Method – Magnetic resonance imaging (MRI) was used to study 21 men with APD and a control of 34 healthy men. The subjects were volunteers. Results – The APD group had 11% reduction in prefrontal grey matter compared with the control group. Conclusion – APD is caused by a reduction in grey matter.

Evaluation. The study supports the biological explanation of APD. Raine and colleagues only studies males so can’t relate the findings to women. Participants were volunteers so not representative of all people. Behaviours linked to one area of the brain often results from a deficit elsewhere in the brain. The cause of APD could be more complex than the study suggest.

Practical Implications Research into APD had implications for the prevention and treatment of the disorder; If you can’t decide the cause you cant treat or prevent it. If it has a biological cause it can’t be prevented. Medication has been ineffective when used. If APD has a situational cause then reducing childhood problems should lower risk of developing APD. Some groups could be overlooked. Children in stable homes can also develop APD. Difficult to treat as the characteristics make the patients difficult to work with. i.e. they don’t believe that they need to change, they lie about their behaviours.