Taking risks to feel excitement has distinctive personality associations, but is weakly detected in genes.
A post by Liisi Ausmees
People engage in various forms of risk-taking, ranging from reckless driving to investing in cryptocurrencies. Frey and colleagues (2017) showed that although all risk-taking domains share something in common, they are nevertheless psychologically different. For instance, while alcohol consumption and smoking occur mainly because of problems with controlling inhibitory processes, recreational risk-taking is probably triggered by a desire for thrill and adventure. In our research, we focused on risk-taking behaviour that is specifically oriented towards feeling excitement.
We are all undeniably different in how much excitement we need in our lives, and whether we are willing to venture past the limits of safety. Our research team, led by Anu Realo, strived to examine in depth the detailed personality profile and the possible genetic associations of such excitement-oriented risk-taking. We approached this topic by examining a group of extreme risk-takers: individuals who had completed at least one solo parachute jump (hereinafter called skydivers). Solo skydiving is an objectively observable real-world behaviour, which is usually undertaken for the sake of excitement and preceded by careful consideration of risks. As such, it is an excellent indicator of risky excitement-seeking.
We started by exploring the personality and genetic data of 298 Estonian skydivers aged between 16 to 69 years (35% women). Skydivers were demographically matched to 298 control individuals who were similar to them in terms of age, gender, and educational background. Data about controls were obtained from the Estonian Biobank. Subsequently, we also extended our analyses to a larger population-based dataset of the Estonian Biobank (more on this shortly). All the methodological and statistical details of the study are available here. Our research had two aims: to find a set of personality characteristics, which are most strongly associated with risky excitement-seeking behaviour, more specifically to skydiving, and to see whether genetic variation contributes to differences in risky excitement-seeking tendencies. Below I will elaborate on the most relevant findings.
Detailed personality profile of skydivers
At the level of the Five-Factor Model personality domains, skydivers were significantly more extraverted and open to experience, and less neurotic and agreeable than control subjects. The narrower facet level painted a more interesting picture — in addition to being greater excitement-seekers (a facet of Extraversion), skydivers were also more active (also a facet of Extraversion) as well as open to different actions and values (facets of Openness to Experience). Skydivers were also less anxious and vulnerable (facets of Neuroticism) than demographically similar controls. Skydivers were not significantly more impulsive than the control subjects, but they did have lower deliberation scores (a facet of Conscientiousness), which refers to doing things on the spur of the moment. So perhaps skydivers are spontaneous without being impulsive?
Still, not every person who is emotionally stable, open, active and enjoys excitement, performs a parachute jump. To really get to the bottom of which specific personality characteristics are related to skydiving, we examined the personality associations of skydiving at the lowest level of measurement — personality questionnaire items, also known as “nuances”. We combined the eight most relevant markers of skydiving into a single weighted score, which we named the Skydiving Personality Markers score. ‘Weighted’ means that the personality items most strongly associated with skydiving carried the most weight in the poly-item score. A similar method of aggregating the weighted effects of personality items or facets into a composite variable has been used by, for example, Mõttus and colleagues (2017). The strongest markers of skydiving were in our research enjoying risky situations and, interestingly, being able to resist cravings. Other, a bit “lighter” markers in this score were doing things just for “kick”, letting imagination fly, being liberal in moral principles, not feeling helpless and needing a lot of help, not planning before travel, and not thinking that more attention should be paid to human needs.
We decided to put this new score to the test. First, we examined whether the Skydiving Personality Markers score helps to distinguish skydivers from each other in terms of engaging in different risky activities. We saw that skydivers with higher scores of Skydiving Personality Markers indeed had somewhat higher probabilities of having smoked, taken drugs, and participated in other extreme sports besides skydiving. Also, skydivers with the higher personality markers score had done more parachute jumps and had a higher probability of having experienced skydiving-related injuries. Interestingly, both indicators — the total number of parachute jumps and experiencing skydiving-related injuries — were unrelated to the excitement-seeking facet scale of Extraversion, which is a widely used risk-taking measure within the Five-Factor Model framework. This might be the case because the majority of items in the excitement-seeking facet scale describe different non-risky stimulating activities. Although both scores include the item ‘enjoying risky situations’, its weight is considerably larger in the Skydiving Personality Markers score.
Second, we asked whether this unique constellation of personality markers would be useful in detecting risky excitement-seekers in a normal population as well. To investigate this, we re-examined Skydiving Personality Markers in the Estonian Biobank dataset of 3,558 adults who had beforehand provided personality ratings and answered different questions about their health-related behaviours. Our findings suggest that individuals in the large population-based sample who scored higher on Skydiving Personality Markers tended to be more physically active and both physically and mentally healthier compared to low-scorers. However, those same individuals had a greater probability of having experienced traumatic injuries and had started drinking alcohol at a younger age. Thus, in a normal population, a higher score of the Skydiving Personality Markers seems to refer to a risk-taker who is generally well and healthy, implying there is a functional side of risky excitement-seeking.
Compared to the excitement-seeking facet scale, the Skydiving Personality Markers score was in the larger sample less associated with the reports of having smoked or used drugs, but it was far more effective in predicting mental health and traumatic injury rates. The strong link between higher scores on the Skydiving Personality Markers score and better mental health can probably be explained by the items in the poly-item personality score that refer to low Neuroticism (for instance, ‘not feeling helpless and needing a lot of help’). There is ample evidence that Neuroticism is a robust correlate of mood and anxiety disorders. Similarly, the item referring to low impulsivity (‘being able to resist cravings’) is partly responsible for the relatively weaker association of the Skydiving Personality Markers score with substance use. The significant association between the Skydiving Personality Markers score and injuries is also interesting because there are numerous ways people can get hurt. Even an individual who almost never leaves home can still slip and fall on a wet bathroom floor and get seriously injured. However, we speculate that in addition to such unforeseeable events, people whose personality profiles are similar to skydivers might be more prone to engage in a variety of daring activities that could result in different accidents.
In sum, this data-driven personality score helped us to differentiate skydivers from each other in terms of who behave more and less risky and to identify risky excitement-seekers in a large non-skydiving sample too. A high Skydiving Personality Markers score seems to suggest that an individual likely is physically active and mentally healthy. At the same time, it also suggests that individual has a slightly higher probability of experiencing traumatic injuries.
Genetic associations of risky excitement-seeking
Having examined personality characteristics of skydivers and risky excitement-seekers, we took a closer look at the possible genetic underpinnings of this phenotype. Behavioural genetic studies have shown that risk-taking and excitement-seeking have a substantial biological basis. Aydogan and colleagues (2021) recently demonstrated that engaging in real-world risky behaviours is “visible” in different brain regions and that these neuroanatomical features are heritable. However, there is still a lot of unclarity about specific genes and the pathways through which they exert their effects.
We approached examining genetic associations in two separate steps. First, we re-examined several previously proposed candidate genes of excitement-seeking. Most of the genetic variants studied in relation to seeking excitement are linked to the function of dopamine and serotonin. Both of these neurotransmitters influence a variety of physical and psychological functions in humans and other animals. However, many findings concerning candidate genes, such as the dopamine D4 receptor (DRD4) gene have not been replicated. That said, a hypothesis-driven selection of polymorphisms can still be a meaningful approach, especially when studying unique or extreme populations.
We selected 19 candidate gene polymorphisms from the previous literature and examined their contribution to skydiving behaviour. For this analysis, we used the same sample of 298 skydivers and matching controls as described above. We found that the selected set of genetic polymorphisms indeed enabled us to classify individuals into two groups — skydivers and controls — with some accuracy. Across the 19 selected variants, two polymorphisms in the serotonin transporter gene (SERT, also called SLC6A4) were the strongest predictors of skydiving. Nevertheless, the evidence in our data was not strong enough for drawing any profound conclusions.
Complex behavioural phenotypes are most probably influenced by tiny effects of a vast number of gene variants and gene-environment interactions. Thus, in the second step, we decided to take advantage of the results of previous genome-wide association (GWA) studies and examine risky excitement-seeking in association with polygenic scores. In short, a polygenic score is calculated by the sum of many (hundreds, thousands or even several hundreds of thousands) trait-associated single nucleotide polymorphisms (SNPs), which are generated from GWA studies. In these polygenic scores, the SNPs are weighted by their effect sizes.
We then calculated risk-taking polygenic scores for the 3,558 individuals in the Estonian Biobank sample on basis of the results reported by Karlsson Linnér and colleagues (2019). The resulting polygenic scores summarized individuals’ genetic liability towards general risk tolerance, adventurousness, and risk-related behaviours — drinking alcohol, having smoked, number of sexual partners, and automobile speeding propensity. We were interested to see whether these risk-related polygenic scores are linked to individuals’ Skydiving Personality Markers score, which, as shown earlier, can be considered an indicator of risky excitement-seeking.
We found that the Skydiving Personality Markers score was indeed linked to several polygenic scores of risk-taking — for instance to the polygenic scores of risk tolerance, adventurousness, and speeding propensity. Interestingly, these three polygenic scores have one important aspect in common. Namely, in all these scores the SNPs with the largest weight belong to the cell adhesion molecule 2 (CADM2) gene. This gene is mainly expressed in the brain and is involved in synaptic organization and signalling. The association of CADM2 gene with risk-taking behaviour was already detected by Strawbridge et al. (2018). However, this gene seems to play an important role not only in risky behaviours but in brain functioning more generally. In fact, a recent study found significant associations of different variants within the CADM2 gene with altogether 51 psycho-behavioural traits. The strongest associations were found for cognitive ability, risk-taking, diet, body mass index, physical activity, neuroticism-like traits, sexual behaviour, and substance use.
However, the detected effect sizes in our study were exceedingly small. For instance, the polygenic score of adventurousness, which consisted of altogether 126 genetic variants, explained only about 0.2% of the variance in the Skydiving Personality Markers score. Nevertheless, it appears that the risk tolerance and adventurousness of individuals whose personality has some specific features that are common to skydivers can be weakly detected in their genetic makeup.
Implications and conclusions
This research highlights the need for a detailed psychometric assessment of the excitement-seeking phenotype and other psychological phenotypes. Our data showed that engaging in the seemingly simple activity of skydiving has complex personality associations: skydivers are not just prone to risk-taking but also emotionally stable, open-minded, and active. Supplementing personality questionnaires with data about actual behaviour has several advantages. For instance, it enables comparisons across studies that have otherwise used different psychometric assessment tools. Conversely, a detailed investigation of personality seems to be especially useful when exploring real-world outcomes.
In a nutshell, the results of our study demonstrated that a small set of answers within a personality questionnaire can be quite powerful in predicting a specific real-world outcome – that is, whether a person would jump out of an airplane with a parachute to feel excitement or not. Risk-taking and excitement-seeking can be expressed in a variety of behaviours. Our findings support the idea that skydiving is a specific, perhaps more functional, form of excitement-seeking, but the adventurous lifestyle is risky and may be accompanied by traumatic injuries. Our results also provide some novel insight into the genetics of risky excitement-seeking, but as with most complex traits, more studies with larger samples and multiple methods are necessary to reach more conclusive outcomes.