Enzyme immunoassay may be inadequate for measuring salivary testosterone in older men

No evidence for relationship between paternal post-partum depressive symptoms and testosterone or cortisol in first-time fathers

Male life history strategies are regulated by the neuroendocrine system. Testosterone (T) and cortisol regulate male behaviors including parenting and facilitate managing tradeoffs at key transitions in development such as first-time fatherhood. Both hormones demonstrate marked fluctuations in the postnatal period, and this presents an opportunity to investigate the role of T and cortisol in postpartum depressive symptoms-comparably less studied in fathers than in mothers in the evolutionary literature. Prior work on depressive symptoms has yet to integrate insights from the "dual hormone hypothesis (DHH)" which has focused on how T and cortisol interact to jointly regulate traits associated with dominance and status-seeking (i.e., mating effort) but has yet to be included in models of parenting effort. In this research, we use secondary data to investigate the relationship between DHH and traits ostensibly opposed to status seeking (i.e., depressive symptoms). First-time fathers (n = 193) provided morning saliva samples 10 months following parturition and reported on the presence of depressive symptoms (BDI-II). Responses were decomposed into three factors: cognitive, affective, and somatic. Using hybrid latent variable structural equation modeling, we did not find evidence that T predicted variability in cognitive, affective, or somatic depressive symptom factors. We found a null effect for cortisol as well. Finally, we could not find evidence that the DHH variable (T × cortisol interaction) predicted any variability in cognitive, affective, or somatic depressive symptoms. While we did not find evidence to support our hypotheses using a secondary data set, this study contributes to research on the neuroendocrinology of depression in fathers. Discussion focuses on the limitations of sample demographics, timing of saliva and self-report collection, and the lack of extant theory specific to paternal postpartum depression.

The postnatal testosterone rebound in first-time fathers and the quality and quantity of paternal care

In human males, testosterone (T) decreases in the period following the birth of offspring. This decline has been widely interpreted as a facultative neuroendocrine response that facilitates parenting effort. Conversely, research on if (or when) this decline in T would be followed by an eventual recovery and subsequent shift away from parenting effort is lacking. In a U.S. community sample of 225 males transitioning to first-time fatherhood, we measured T at three occasions: third trimester, infant 3 months postnatal, and infant 9-10 months postnatal. Using a piecewise latent growth curve model (GCM), we detected a T rebound from when infants were 3 months old to when infants were 9-10 months old. The slope of this rebound was able to predict paternal care using two distinct measures: (a) an experience sampling method (ESM) that gathered data on paternal time allocation over the course of the study period and (b) independent coders rating fathers for the quality of paternal care during a structured task designed to elicit an infant fear response. As predicted, the more accelerated one's T rebound (slope), the less time fathers invested in their infants across the study period. However, we found a positive relationship between T rebound and quality of paternal care during a challenging activity. Discussion will focus on nuanced reasons that contribute to these findings as well as speculate on the ultimate function of a human paternal T rebound.

Unstable correspondence between salivary testosterone measured with enzyme immunoassays and tandem mass spectrometry

Although some studies reveal that saliva handling and storage practices may influence salivary testosterone concentrations measured with immunoassays, the effect of these method factors on the validity of testosterone immunoassays remains unknown. The validity of immunoassays can be assessed by comparing hormone concentrations measured with immunoassays to a standard reference method: liquid chromatography tandem mass spectrometry (MS). We previously reported the correspondence between salivary testosterone measured with enzyme immunoassays (EIAs) and with MS when there was less variance in (or more control over) method factors related to saliva handling and storage across measurement methods (Welker et al., 2016). In the present study, we expanded the original dataset and compared the correspondence between Salimetrics EIAs and MS when there was greater variance in (or less control over) method factors across EIAs and MS (high method variance), to when there was less variance in these factors (low method variance). If variance in these method factors impacts the validity of testosterone measurement, then the EIA-MS correspondence should be stronger when method variance is low compared to when it is high. Our results contradicted this hypothesis: Salimetrics EIA-MS correspondence was stronger when variance in method factors was high compared to when it was low. The composite average correlation across both method variance comparisons provides an updated estimate of Salimetrics EIA-MS correspondence, but the instability in this correspondence may pose challenges to the reproducibility of psychoneuroendocrinology research. We discuss possible explanations for the surprising pattern of results and provide recommendations for future research.

Mothers' and fathers' joint profiles for testosterone and oxytocin in a small-scale fishing-farming community: Variation based on marital conflict and paternal contributions

INTRODUCTION

Testosterone and oxytocin are psychobiological mechanisms that interrelate with relationship quality between parents and the quantity and quality of parenting behaviors, thereby affecting child outcomes. Their joint production based on family dynamics has rarely been tested, particularly cross-culturally.

METHODS

We explored family function and salivary testosterone and oxytocin in mothers and fathers in a small-scale, fishing-farming society in Republic of the Congo. Fathers ranked one another in three domains of family life pertaining to the local cultural model of fatherhood.

RESULTS

Fathers who were viewed as better providers had relatively lower oxytocin and higher testosterone than men seen as poorer providers, who had lower testosterone and higher oxytocin. Fathers also had higher testosterone and lower oxytocin in marriages with more conflict, while those who had less marital conflict had reduced testosterone and higher oxytocin. In contrast, mothers in conflicted marriages showed the opposite profiles of relatively lower testosterone and higher oxytocin. Mothers had higher oxytocin and lower testosterone if fathers were uninvolved as direct caregivers, while mothers showed an opposing pattern for the two hormones if fathers were seen as involved with direct care.

CONCLUSIONS

These results shed new light on parents' dual oxytocin and testosterone profiles in a small-scale society setting and highlight the flexibility of human parental psychobiology when fathers' roles and functions within families differ across cultures.

Testosterone, cortisol, and status-striving personality features: A review and empirical evaluation of the Dual Hormone hypothesis

Decades of research in behavioral endocrinology has implicated the gonadal hormone testosterone in the regulation of mating effort, often expressed in primates in the form of aggressive and/or status-striving behavior. Based on the idea that neuroendocrine axes influence each other, recent work among humans has proposed that links between testosterone and indices of status-striving are rendered conditional by the effects of glucocorticoids. The Dual Hormone hypothesis is one particular instance of this argument, predicting that cortisol blocks the effects of testosterone on dominance, aggression, and risk-taking in humans. Support for the Dual Hormone hypothesis is wide-ranging, but considerations of theoretical ambiguity, null findings, and low statistical power pose problems for interpreting the published literature. Here, we contribute to the development of the Dual Hormone hypothesis by (1) critically reviewing the extant literature-including p-curve analyses of published findings; and, (2) "opening the file drawer" and examining relationships between testosterone, cortisol, and status-striving personality features in seven previously published studies from our laboratories (total N = 718; median N per feature = 318) that examined unrelated predictions. Results from p-curve suggest that published studies have only 16% power to detect effects, while our own data show no robust interactions between testosterone and cortisol in predicting status-striving personality features. We discuss the implications of these results for the Dual Hormone hypothesis, limitations of our analyses, and the development of future research.