A new study has been published Biological psychology Examines the relationship between psychopathic fearlessness and low immune response. According to the new findings, women with high scores in fearful psychopathic behavior have reduced heart rate variability when faced with intense and unexpected stimuli. But this relationship was not found among men.
Previous research has found that people with certain psychopathic traits often have an automatic threshold response to danger. This is related to the fearlessness of psychopathy.
Beyond the startle response, other physiological measures have been associated with psychopathy, such as decreased muscle tension and, in some cases, decreased heart rate. There has also been work combining these various measures into a “threat sensitivity” index, which can be used as a way to measure and study these behaviors.
The new angle in this research is looking at what is called the cardioprotective response (CDR). This is a complex pattern of changes in heart rate that occur in response to a sudden, unexpected threat or shock. CDR, reflected in heart rate and other cardiovascular parameters, is believed to represent the activity of the sympathetic branch of the autonomic nervous system, an organ involved in triggering ‘fight or flight’ responses to perceived threats.
The researchers hypothesized that the CDR might be a useful new measure for studying fearlessness in psychopathy. They were particularly interested in the second level of CDR speed, as it appears to be related to readiness to respond to threats.
The study involved 156 participants (60 men), who completed the Psychopathic Personality Inventory-Revised (PPI-R), a self-reported measure of psychopathic tendencies. This questionnaire examines traits such as social influence, stress avoidance, fearlessness, Machiavellian self-centeredness, rebellious nonconformity, blameworthy extraversion, reckless nonplanning, and prudence.
A protective psychophysiological test measuring CDR was performed in which participants were presented with an unexpected loud white noise stimulus after an 8-minute rest period. They were told that they would participate in a study to record their electrocardiogram in resting conditions, without talking about the upcoming sound. Their heart rate was recorded from 15 seconds up to 80 seconds before taking off.
The study found that males outperformed females in all areas of psychopathy. In addition, males show higher heart rate variability (both increases and decreases) in response to loud noises than females. This was especially true between certain time points after the noise was played.
Heart rate response to loud noise has been linked to some personality traits measured by the PPI-R questionnaire. In particular, women who scored high on ‘fearless dominance’ (comprising traits such as social influence, anxiety buffering and fearlessness) showed lower mean heart rate changes in response to loud noises.
Looking more closely at the components of ‘fearless dominance’, women who scored high on the ‘fearless’ trait showed an increase in heart rate, especially during the protective response called ‘second acceleration’ (where the heart rate goes up after an initial decrease, a process associated with preparing the body to respond to danger). This remained true even when controlling for the influence of other traits due to fearlessness dominance.
This finding is significant because it shows a sex-dependent relationship between fear-related behaviors and immune responses. Heart suggests that response to threat may be a useful way to study fear as seen in psychopathy and to understand how this differs between men and women.
The research team acknowledged a few limitations; First, the study used a self-report measure of psychopathy, which is subject to bias and may not accurately capture all aspects of psychopathy. Additionally, the study used a relatively small sample size, which may limit the generalizability of the findings. Finally, the study did not examine other factors that may influence the relationship between psychopathic fear and CDR, such as childhood illness or other environmental factors.
The study “Low immune response as a physiological correlate of psychopathic fear: Gender differences”, written by V. Branchadell, R. Poy, P. Segarra, P. Ribes-Guardiola and J. Moltó.