Antisocial Personality Disorder Lecture Notes PDF

Antisocial Personality Disorder FURTHER BIOPSYCHOLOGY AND COGNITION - LEVEL 5 DR LYNNE MARROW  Introductio n In this lecture we will look at: Antisocial personality disorder MAOA gene and aggression Neuroanatomical differences in psychopathology The role of the environment in psychopath...

Antisocial Personality Disorder FURTHER BIOPSYCHOLOGY AND COGNITION - LEVEL 5 DR LYNNE MARROW  Introductio n In this lecture we will look at: Antisocial personality disorder MAOA gene and aggression Neuroanatomical differences in psychopathology The role of the environment in psychopathology Antisocial Personality Disorder DSM-V – Personality Disorders Antisocial Personality Disorder Disorder previously known as both psychopathic and sociopathic personality disorder Diagnosed more frequently in males than females Antisocial Personality Disorder Symptoms include: longstanding pattern (after the age of 15) of disregard for the rights of others failure to conform history of deceitfulness impulsiveness reduced ability to feel empathy irresponsible behaviour lack of remorse for wrongdoings Antisocial Personality Disorder Strongly associated with criminal behaviour Hart and Hare (1997) estimated: 15% of the prison population are psychopaths Psychopaths commit approximately 50% more criminal offences than non-psychopathic criminals (findings relevant to North America) The MAOA Gene Antisocial Personality Disorder Brunner (1993) Approached to determine whether the anti-social behaviour in a group of closely related males could have a genetic basis. Found: Mutation in the monoamine oxidase A (MAOA) gene Located on X chromosome Brunner’s Syndrome The MAOA Gene The gene encodes a protein (MAO–A) that breaks down monoamine molecules serotonin, noradrenaline and dopamine Regulates neurotransmitter signalling at monoaminergic synapses throughout the brain If it doesn’t work properly, there is a build-up of neurotransmitters This leads to changes in mood and behaviour The MAOA Gene Cases et al (1995) Mice lacking the MAO-A protein displayed: Increased serotonin (5-HT) levels Increased noradrenaline levels But negligible change in dopamine levels Suggesting 5-HT and NA are neurotransmitters most affected The MAOA Gene Poor functioning of the MAOA gene in mice is associated with aggression and specific brain abnormalities Pharmacological manipulation of MAO-A replicates these findings when given during a critical developmental window (Cases et al, 1996) The MAOA Gene Ansorge et al (2004) found: Elevated 5-HT during development => with altered emotional behaviour in mice Cases et al (1996) found: Early postnatal depletion of 5-HT, but not of catecholamines, reverses the brain abnormalities in MAOA-deficient animals These findings suggest ways that genes might affect behaviour The MAOA Gene The MAOA gene has several varieties – distinguished by their levels of activity: the low-activity variant; produces less MAOA-L protein. MAOA-H is more active; produces more protein The MAOA Gene Beaver, DeLisi, Vaughn and Barnes (2010) Examined the association between MAOA gene activity and: gang membership weapon use The MAOA Gene Beaver, DeLisi, Vaughn and Barnes (2010) Found: Low MAOA activity alleles conferred an increased risk of joining a gang and using a weapon in a fight for males but not females Male gang members who used weapons in a fight - more likely to have a low MAOA activity allele than those who did not The MAOA Gene McDermott (2009) Asked volunteers to play a game against an anonymous partner who would split a pot of money between them. If they were dissatisfied with their share they could, at a small cost, punish their partner by administering an unpleasantly spicy sauce. The MAOA Gene McDermott (2009) Found: MAOA -L carriers were always slightly more likely to dole out the sauce However, the big difference in aggression between them and others came as a reaction to their partner taking the lion's share of the money Sex Differences Men have greater vulnerability to psychopathy than women, but unlikely that a simple gene ratio accounts for this Sex hormones are likely to play a role in differential sensitivity to MAOA-L gene Oestrogen might be protective against aggression Testosterone, a hormone associated with male aggression, might exacerbate vulnerability to aggression in MAOA-L males. Sex Differences Sjoberg et al, 2008 Assessed men for the MAOA-L gene, levels of testosterone in the CSF and scores on an aggression and anti-social personality disorder scale Found: MAOA-L combined with high CSF testosterone predicted anti-social behaviour Other Differences Structural Differences in the Brain Phineas Gage Damage to Gage’s brain affected both medial prefrontal lobes (Damasio, 1994) Gage demonstrated “acquired sociopathy” Regions of the prefrontal cortex considered important for personality and social behaviour Structural Differences in the Brain Raine et al (1997; 2000) Violent personality-disordered offenders have reduced prefrontal cortex (PFC) grey matter volume and glucose metabolism Budhani, Richell, Blair (2006) Orbitofrontal cortex (OFC) is crucial to successful reversal learning - which is significantly impaired in psychopaths and those with psychopathic traits. Structural Differences in the Brain Other researchers have argued that amygdala dysfunction is central to the deficits seen in psychopathy. Psychopaths have: Significantly reduced amygdala volume - Tiihonen et al (2000) Decreased activity in brain regions modulated by amygdala during facial fear processing - Deeley et al (2006) Performance deficits in tasks sensitive to amygdala damage Structural Differences in the Brain Recently it has been suggested that the social and emotional deficits of psychopaths may reflect an interaction between OFC and amygdala dysfunction The amygdala and OFC are connected by the uncinate fasciculus (UF) Craig et al (2009) found abnormal (low) levels of connectivity in the UF of psychopaths – particularly affecting the right hemisphere Neurodevelopment and Aggression These circuits are involved in social evaluation and decision making ◦ Amygdala sensitive to social cues ◦ Prefrontal cortex mediates responses In MAOA-L men amygdala is unrestrained and therefore hyper-reactive, possibly biasing them towards misattribution of hostile intent Neurodevelopment and Aggression Buckholz and Meyer-Lindenberg (2008) Suggest the MAOA genotype modifies an individual’s “socioaffective scaffold” MAOA-L alters levels of 5-HT and NA during a critical window for the development of corticolimbic circuitry MAOA-L carriers more vulnerable to the influence of adverse early-life experience Picture from Buckholtz and Meyer-Lindenberg (2008) Neurodevelopment and Aggression "On the whole, genetic risk can be conceived as contributing to ‘loading the gun’; however, single genetic variants in isolation from other risk factors will rarely if ever pull the trigger.” Buckholtz and Meyer-Lindenberg (2008)  Further Reading Articles can be found on Blackboard