Ilmari Määttänen

Testosterone and temperament traits in men: Longitudinal analysis

Testosterone is the main male hormone that has been associated with various behavioral traits in humans and other animals. We investigated whether levels of total testosterone, free testosterone, and sex hormone binding globulin were associated with temperament traits in a population-based sample of Finnish men at two measurement times taken 6 years apart (n=686 in year 2001, n=727 in year 2007). Temperament was assessed using the Temperament and Character Inventory that consists of four temperament traits: novelty seeking, harm avoidance, reward dependence, and persistence. Higher levels of total and free testosterone were associated with higher novelty seeking (standardized B=0.103, p<0.001). This association was also observed in a longitudinal within-person analysis (B=0.084, p=0.008), suggesting that the association is not confounded by stable between-individual differences in other characteristics. Within-individual variation in total testosterone was associated with higher reward dependence, and higher levels of free testosterone were marginally associated with higher reward dependence. Reward dependence reflects the importance of social rewards to an individual. These results provide additional evidence for the stable and time-varying associations between testosterone and temperament in humans.

Cloninger's temperament traits and inherited long QT syndrome

OBJECTIVE The long QT syndrome (LQTS) is an inherited cardiac disorder which predisposes the mutation carrier to ventricular arrhythmias that can lead to sudden death. The objective of the present study was to examine the association between the symptom status of congenital long QT syndrome mutation carriers and their temperament. METHODS The study subjects included 587 LQTS mutation carriers from the Finnish LQTS registry, and 2056 individuals from a database study, the Young Finns Study (YFS), representing general population and serving as control subjects. The LQTS subjects were divided into symptomatic (n=259) and asymptomatic (n=328) groups, according to their history of arrhythmic events. Temperament was assessed using the Cloningers Temperament and Character Inventory (TCI), assessing novelty seeking, harm avoidance and reward dependence. RESULTS Congenital long QT syndrome mutation carriers had a higher harm avoidance (HA) than those representing the general population (2.77 vs. 2.61, p<.001, η²=0.011). Symptomatic and asymptomatic LQTS mutation carriers did not differ from one another in any of the three Cloningers temperament traits. HA was significantly higher in women (2.72 vs. 2.54, p<0.001 η²=0.017). CONCLUSIONS LQTS mutation carriers may have higher stress proneness because of their high HA, which in turn may predispose them to the effects of environmental loading and thus increase the risk of arrhythmias.

Different social-learning strategies in wild and domesticated zebrafish, Danio rerio

Social learning probably functions as a mechanism to acquire public information about food, predators and conspecifics, without paying the costs required for individual learning. Social learning should be strategic rather than indiscriminate, and although it is often suggested that animals should show conformity (‘copy the majority strategy’), there are surprisingly few tests of this idea. Our goals were to test experimentally whether social learning plays a role in boldness behaviour of wild and domesticated zebrafish, and to investigate whether they utilize similar social-learning strategies and conformity in their boldness behaviour. We tested whether timid wild-derived zebrafish become bolder, and more likely to approach a moving stimulus, after interacting socially with bolder domesticated fish (and vice versa). We found that wild zebrafish exposed to domesticated fish were bolder than controls, whereas domesticated fish exposed to the more timid, wild zebrafish did not differ in their boldness score compared to controls. The changes in the behaviour of wild fish persisted after the nonfocal groups were removed; however, we found no evidence for conformity. Our findings indicate that zebrafish use social learning for assessing risk and adapt their social-learning strategies to the costs of a perceived risk. Future studies should be able to utilize this model species to incorporate genetic and genomic tools to study the development and evolution of social learning.

Social learning of an associative foraging task in zebrafish

The zebrafish (Danio rerio) is increasingly becoming an important model species for studies on the genetic and neural mechanisms controlling behaviour and cognition. Here, we utilized a conditioned place preference (CPP) paradigm to study social learning in zebrafish. We tested whether social interactions with conditioned demonstrators enhance the ability of focal naïve individuals to learn an associative foraging task. We found that the presence of conditioned demonstrators improved focal fish foraging behaviour through the process of social transmission, whereas the presence of inexperienced demonstrators interfered with the learning of the control focal fish. Our results indicate that zebrafish use social learning for finding food and that this CPP paradigm is an efficient assay to study social learning and memory in zebrafish.

Brief report: Emotional distress and recent stressful life events in long QT syndrome mutation carriers

To study emotional distress in symptomatic and asymptomatic long QT syndrome mutation carriers who had experienced a recent stressful life event. The participants were 209 symptomatic and 279 asymptomatic long QT syndrome mutation carriers. Emotional distress was assessed with the Cope questionnaire and stressful life events with the Social Readjustment Rating Scale. Symptomatic long QT syndrome mutation carriers with burdening recent stressful life events reported a higher emotional distress (β = 0.35, p < 0.001), while the asymptomatic did not show such difference (β = 0.13, p = 0.393). Symptomatic long QT syndrome mutation carriers who have experienced stressful life events recently report an increased emotional distress.

Stress proneness in molecularly defined long QT syndrome: a study using temperament assessment by behavioural inhibition system scale.

The long QT syndrome (LQTS) is an inherited cardiac disorder that predisposes the mutation carrier to ventricular arrhythmias that can lead to sudden death. The objective of the present study was to replicate the previous finding in terms of stress-related temperament trait, i.e. behavioural inhibition system (BIS). The study subjects included 583 LQTS mutation carriers (256 symptomatic and 327 asymptomatic) from the Finnish LQTS registry and 79 healthy subjects randomly derived from the population-based sample of the Young Finns Study. Symptomatic and asymptomatic LQTS mutation carriers did not differ from each other on BIS (3.27 versus 3.24, p > 0.05), whereas LQTS mutation carriers scored higher on BIS than the comparison group derived from the representative population-based sample (3.25 versus 2.99, p = 0.003, η² = 0.014). BIS was significantly higher in women than in men (3.32 versus 3.06, p < 0.001, η² = 0.017). The results confirm our previous finding of higher stress proneness of LQTS mutation carriers. Their innate stress proneness may have relevance because it increases our understanding on the role of stress in the manifestation of symptoms.

Work stress and the long QT syndrome: high job strain and effort-reward imbalance at work associated with arrhythmic risk in the long QT syndrome.

Objectives: To examine whether work stress is associated with a symptomatic status of the long QT syndrome (LQTS). Methods: The sample comprised 173 KCNQ1, KCNH2, or SCN5A gene mutation carriers (70 symptomatic) and control groups of 203 relatives without the family mutation, and of 1209 population-based young Finns control subjects. Work stress was assessed using the Job Content Questionnaire and Occupational Stress Questionnaire. Results: We found an association between the occurrence of symptoms in the LQTS and high work stress, higher job demands/effort, lower job control, and lower rewards compared with control subjects. We also found that symptomatic LQTS mutation carriers had higher work stress than asymptomatic LQTS mutation carriers. Conclusions: Higher work stress is related to arrhythmic risk in the LQTS. It may be useful to incorporate assessment of work conditions and stress interventions into management of high-risk patients.

Stressful life events and depressive symptoms among symptomatic long QT syndrome patients

We examined whether long QT syndrome status moderates the association between stressful life events and depressive symptoms. Participants were 562 (n = 246 symptomatic) long QT syndrome mutation carriers. Depressive symptoms were measured with a modified version of the Beck’s Depression Inventory. There was an interaction between long QT syndrome status and stressful life events on depressive symptoms. In the symptomatic long QT syndrome patients, stressful life events were associated with depressive symptoms (B = 0.24, p < 0.001). In the asymptomatic long QT syndrome mutation carriers, this association was 62.5 percent weaker (B = 0.09, p = 0.057). Compared to asymptomatic long QT syndrome mutation carriers, symptomatic long QT syndrome patients are more sensitive to the depressive effects of stressful life events.

Unobtrusive stress detection on the basis of smartphone usage data

Stress has become an important health problem, but existing stress detectors are inconvenient in long-term real-life use because users either have to wear dedicated devices or expend notable interaction efforts in system adaptation to specifics of each person. Adaptation is necessary because individuals significantly differ in their perception of stress and stress responses, but typical adaptation employs supervised learning methods and hence requires fairly large sets of labelled data (i.e. information on whether each reporting period was stressful or not) from every user. To address these problems, we propose a novel unsupervised stress detector, based on using a smartphone as the only device and using discrete hidden Markov models (HMM) with maximum posterior marginal (MPM) decisions for analysis of phone data. Our detector requires neither additional hardware nor data labelling and hence is truly unobtrusive and suitable for lifelong use. Its accuracy was evaluated using two real-life datasets: in the first case, adaptation was based on very short (a few days) phone interaction histories of each individual, and in the second case—on longer histories. In these tests, the proposed HMM-MPM achieved 59 and 70% accuracies, respectively, which is comparable with results of fully supervised methods, reported by other works.

Correction to: Unobtrusive stress detection on the basis of smartphone usage data

Due to miscommunication in the terms of using the first dataset a correction to the list of authors is required: Added authors, Ilmari Määttänen2 and Mikko Lindholm1.