The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 19 No. 8 • December 2017

Serotonin and Callous Boys

Unsurprisingly, psychopathic men start out as psychopathic boys. A recent paper (Moul, 2013) studied levels of serotonin in serum or saliva looking for either the amount of serotonin or the single nucleotide polymorphisms (variants) of the enzymes that convert the nutrient tryptophan to serotonin. The purpose of the study was to see how serotonin was involved in the behavior of “antisocial” boys who had high levels of callousness (lack of emotions).

The researchers were specifically interested in “Oppositional Defiant Disorder” (ODD) and “Conduct Disorder” (CD), two of the myriad categories of emotional/social dysfunction in the professional DSM. Both of these disorders were said to include behaviors such as arguing with adults (tsk tsk), spitefulness, aggression toward others, breaking rules, and having no respect for the property of others. Psychopaths who don’t have a criminal record (called “successful psychopaths” in a book about psychopaths (Haycock, 2014, pg. 167)) are said to “share a key feature with their criminal cousins; they are never concerned about your best interests.”


  • Haycock DA. MURDEROUS MINDS (Pegasus Books, 2014).

A subgroup of ODD and CD is a callous-unemotional (CU) group (Moul, 2013). People with high levels of CU are regarded as psychopaths, with “specific patterns of neural dysfunction, specifically with regards to the amygdala.” The amygdala is importantly involved in fear and aggression. Indeed, the CU traits include a “poor conditioned fear response” and “reduced ability to recognise fear.”

A model of amygdala function, the DAAM (Differential Amygdala Activation Model) has been developed to attempt to portray mechanisms for the “subtle and emotional deficits” exhibited by those (mostly males) with CU. The DAAM model posits that reduced serotonin neurotransmission may be “integral” to the pattern of amygdala activation seen in CU. In support of this, a paper was described (Moul, 2013) which found that “... acute administration of a serotonin selective reuptake inhibitor (SSRI) and ingestion of tryptophan (the natural precursor of serotonin) improved recognition of both fear and happiness.” Moreover, “[g]enes encoding the serotonin 2a receptor (HTR2A) and tryptophan hydroxylase 1 (TPH1) have been associated with antisocial personality disorder (ASPD) in adult males. Curiously, another paper described in Moul, 2013 showed that “aggressive children with low-prolactin responses to fenfluramine challenge” had a strong family history of aggressive and antisocial traits. Here is another example of the overlap you see so frequently in brain systems: prolactin is intimately involved in sexual intercourse, with a large pulse of prolactin following immediately after ORGASM.

As the authors (Moul, 2013) caution: their sample included only boys and, thus, no conclusions (on the basis of this study) can be made concerning the relationship of serotonin and CU in girls.


  • Moul et al. An exploration of the serotonin system in antisocial boys with high levels of callous-unemotional traits.
  • PLoS ONE.
  • 8(2):e56619 (2013).

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