The genetic and biological basis of psychopathy

The criminal mind is strongly influenced by certain biological factors.

We often talk about the actions, behavioral style, and way of interacting with people that people who could be described as psychopaths have. Despite that, there is a question that is even more disturbing than all these issues: what are psychopaths like behind closed doors? What are the peculiarities of their own body that make them predisposed to psychopathy?

Attempting to answer these questions is, at bottom, to address research on the biological basis of psychopathy..

Let us begin, then, by talking about what we know about its genetic characteristics.

Genetic findings on psychopathy

The strongest evidence in favor of genetics tends to come from twin and adoption studies. According to these studies, the heritability of antisocial behavior in children or adolescents is estimated at 30-44%. is estimated at 30-44%..

In adult criminal subjects, there is a concordance of 69% for monozygotic twins (one same ovule, therefore almost identical genetic load) and 0.33% for dizygotic twins (two ovules), which gives conclusive evidence that there is a weight of genetics in criminal behavior over environment. Numerous studies support these results.

It has also been shown that the Y chromosome chromosome would be involved in aggressiveness, thus attributing to a greater aggressiveness in men than in women, in general.

The MAO-A gene

The MAO-A gene gene is to date the only clear example of how a specific mutation can alter behavior.

can alter behavior. This gene was found to be altered in people suffering from a psychopathic disorder and, in addition, in children abused as infants.

In other words, the alteration of this gene predisposes to violent behavior. Conversely, people who are born with high concentrations of this gene are less likely to develop antisocial problems, people who have high concentrations of this gene from birth are less likely to develop antisocial problems..

What is interesting about this finding is that it could help explain why not all victims of abuse when they grow up do the same to other people, for example.

Neuroanatomical findings

In the late 1990s a study was conducted in which the brain activity of 41 normal subjects and 41 murderers was compared. It was found that criminals had less activity in the prefrontal region (the human region par excellence), which would translate into:

• NeurologicallyNeurologically: loss of inhibition of regions such as the amygdala, responsible (among others) for the regulation of aggressive feelings.

• BehaviorallyRisk-taking, irresponsible, rule-breaking, violent, impulsive behaviors...

• SociallyLack of empathy for other people.

Neurochemical findings

Numerous experiments have shown the crucial role of serotonin as a modulator of aggressive behavior, the relationship being as follows: the less serotonin, the more aggressive behavior is reinforced.. Therefore, it would be easy to conclude that people suffering from this disorder could have altered serotonergic pathways.

In the same way that noradrenaline, dopamine, GABA and nitric oxide would be involved in impulsive and violent behaviors, although with less relevance.

Neuroendocrine findings

In the hormonal field, the ones for which we have the most conclusive evidence are insulin and testosterone. Certain studies show that if we have a low level of glucose, and therefore insulin in our blood, we are more predisposed to violent and impulsive behaviors.

In the case of testosterone, we have multiple studies comparing criminals and healthy people, where they show that the amount of free testosterone in the Blood is increased in the former.. In addition, several investigations indicate that women with higher testosterone levels are more sexually active, competitive, masculine and alcohol consumers compared to women with lower testosterone levels.

Psychophysiological findings

Cleckley (1976) proposed that psychopaths may have the ability to understand the literal (denotative) meaning of language, but not its emotional (connotative) meaning. They would therefore have an emotional deficit.

Psychopaths, in addition, would have altered emotional reactivity since, compared to normal people, in situations where they should feel anxiety and fear, they do not feel it.

Likewise, they also present an absence of startle reaction to the exposure of visually unpleasant content, and very sharp and shrill beeps.

Based on all these data, it was proposed that psychopaths have a weak inhibitory brain system and a strong activation system.and a strong activation system. This would explain their impulsivity and lack of ability to think about future consequences.

By way of conclusion...

Antisocial personality disorder is characterized by a lack of empathy and remorse for the violation of others' rights and social norms, high impulsivity and aggressiveness... They are subjects who will do whatever it takes, regardless of the consequences, to achieve their purposes and personal benefits.

But is a psychopath made or born? The answer is... a combination of both. A marginal environment, where the person is born neglected, with violence, mistreatment, abandonment... has a crucial influence. However, it has been demonstrated by numerous studies, that there is more genetic weight.

A clear proof of this would be obtained through the question... why are there people who become abusers in the face of abuse, while others do not? This answer would be given by the amount of mao-A gene gene that the person has at its base. This could also provide an answer to many other situations in which there are people who succumb to the situation and commit violent acts, while others refuse to do so.

We therefore conclude, a clear and evident brain biological role in antisocial personality disorder and a gene-environment interaction (with more genetic relevance). interaction (with more genetic relevance).

Bibliographical references:

• Caspi,A., McClay, J.; Moffitt,T., Mill,J. and Martin,J. (2002). Role of genotype in the cycle of violence in maltreated children. American Association for the Advancement of Science. 297 (5582): 851-854.
• Garrido, V. (2003). Psicópatas y otros delincuentes violentos. Valencia: Tirant lo Blanch.
• Ros, S., Peris, M.D. and Gracia, R. (2003) Impulsividad. Barcelona: Ars Medica.
• American Psychiatric Association, APA (2002). DSM-IV-TR. Diagnostic and statistical manual of mental disorders. Revised text. Barcelona: Masson.
• Francisco, J. (2000). Bases biológicas de las psicopatologías. Madrid: Psicología Pirámide.
• World Health Organization (1998). ICD-10. Mental and behavioral disorders. Multiaxial version for adults. Geneva: WHO.
• Pelegrín, C. and Tirapu, J. (2003). Neurobiological basis of aggression. Intersalud. Retrieved from: http://hdl.handle.net/10401/2411