Personality Disorders: Causal Factors of ASPD

Biological Factors

Research on the biological factors of Antisocial Personality Disorder (ASPD) has focused on both genetic and psychological factors. The concordance rate of genetic predisposition shows a higher evident rate among identical twins than in fraternal twins for ASPD. Adoption study conclusions are similar, too. When researchers compared criminal records of men who were adopted, the rate of criminality was almost twice as high when the biological father had a criminal record and the adoptive father did not—a clear sign of genetic predisposition.

The clue to genetic predisposition factors of antisocial behaviour in individuals could be the relative absence of anxiety and guilt, which seems to characterize Antisocial Personality Disorder. According to many researchers' beliefs, the psychological basis for the disorder may be a dysfunction in the brain structures governing emotional arousal and behavioral self-control. This can result in impulsive behaviour and a clinically under-aroused state; impairing avoidance learning, causing boredom, and encouraging a search for excitement. According to psychological basis, children and adults alike with antisocial behaviour patterns tend to have lower heart rates, particularly under stress.

MRIs of antisocial individuals have shown subtle neurological deficits in their prefrontal lobes—the seat of executive function; which are planning, reasoning, and behavioral inhibition; such neurological deficits are associated with a reduction of autonomic activity. This supports a long-suspected idea of severely antisocial individuals being wired differently at a neurological level, causing them to respond with less arousal and a greater sense of impulsiveness to pleasurable and unpleasurable stimuli alike.

Psychological & Environmental Factors

According to psychodynamic theorists, antisocial personalities are individuals with no conscience. Psychoanalytic theorists believe that such individuals lack anxiety and guilt because they did not develop an adequate superego. The absence of a well-developed superego causes reduction of the restraints on the identity, resulting in impulsive behaviour. Inadequate identification with appropriate adult figures is thought to cause these individuals' failure to develop a strong superego because these figures weren’t either physically or psychologically available to the child. Supporting this position, the absence of the father from home has a higher related incidence of antisocial symptoms in children, even with socioeconomic status equated.

Cognitive theorists believe that an important feature of antisocial individuals is their consistent failure in thinking about—or to anticipate the long-term negative consequences—of their acts. This results in impulsive behaviour, with thought only of their wants of the moment. From this perspective, the key to preventing these individuals from getting themselves into trouble is to help them develop cognitive control (executive function) necessary to think before acting. Learning through modelling can play an important role too.

Many antisocial personalities come from homes of aggressive and inattentive parents. Such parents become role models for aggressive behaviour and disregard for others' needs. Another important environmental factor is exposure to deviant peers. Antisocial children often learn some of their deviant behaviour from peer groups that help model antisocial behaviour and reinforce it with social approval. When environmental factors are combined with a possible genetic predisposition for antisocial behaviour, it clearly encourages a pattern of deviant behaviour.

According to the learning explanations of some biological theorists, it suggests that individuals with antisocial behaviour lack impulse control. Learning theorists believe that the reason for poor impulse control in these individuals occur due to impaired ability to develop conditioned fear responses when they are punished. This results in a deficit of avoidance learning. Hans Eysenck said a person's ability to develop a conscience depended on that person’s ability to learn fear and inhibitory avoidance responses. Individuals who fail in these aspects will have less ability to inhibit their behaviour.

Clinical studies

In accordance with this hypothesis, Adrian Raine and his co-workers did a 14-year follow-up on males who had been subjected to classical conditioning at the age of 15, in which a soft tone had been used as the conditioned stimulus (CS) and a loud averse tone as the unconditioned stimulus (UCS). Conditioned fear was measured by the participant’s skin conductance response when the CS occurred after a number of pairings with the loud UCS. According to the research findings, the men who accumulated a criminal record by the age of 29 had shown poorer conditioning at the age of 15 than those with no criminal record.

According to further studies, major damage to the grey and white matter in the prefrontal cortex, as well as autonomic deficits, can result in pseudo-psychopathic personality in patients with neurological disorders, but it is not known whether individuals with antisocial personality disorder in the community, with no discernible brain trauma, also have subtle prefrontal deficits.

When prefrontal grey and white matter volumes were assessed using structural magnetic resonance imaging in 21 community volunteers with ASPD; as well as in two control groups which comprised of 34 healthy subjects, 26 subjects with substance dependence, and 21 psychiatric controls. The autonomic activity of (skin conductance and heart rate) was assessed during a social stressor in which the participants gave a videotaped speech of their faults.

The ASPD group showed an 11 percent reduction of prefrontal grey matter volume in the absence of ostensible brain lesions and reduced autonomic activity during the stressor. These deficits were a prediction of group membership independent of psychosocial risk factors. These findings are said to be the first evidence of structural brain deficits in ASPD. This prefrontal structural deficit may underlie the low arousal, poor fear conditioning, lack of conscience, and decision-making deficits known to characterize antisocial behaviour.