Jeffrey Gassen

• PhD Experimental Psychology
• PostDoc Position at University of California, Los Angeles

Objetivo: Aunque los hombres de minorías sexuales experimentan una discriminación sustancial, además de un mayor riesgo de varios problemas de salud mental y somáticos graves, los mecanismos biológicos subyacentes a estos efectos no están claros. Para abordar este tema, examinamos cómo las experiencias de seguridad social (es decir, conexión comuni...

Adverse Childhood Experiences (ACEs) are very common and presently implicated in 9 out of 10 leading causes of death in the United States. Despite this fact, our mechanistic understanding of how ACEs impact health is limited. Moreover, interventions for reducing stress presently use a one-size-fits-all approach that involves no treatment tailoring...

In the current research, we used data from a sample of 16,327 menstrual cycle tracking app users to examine the association between menstrual cycle characteristics and sexual motivation tracked over 10 months of app use. Guided by past work that finds links between menstrual cycle characteristics related to conception risk and sexual motivation, we...

Although seasonal changes in physiology are well documented, little is known about how human immune and metabolic markers vary across seasons, and no studies have examined how stress → health biomarker associations differ across the year. To investigate these issues, we analyzed data from 2118 participants of the Midlife in the United States (MIDUS...

Background: The foundation of precision psychiatry is to clearly link mechanisms to specific levels of psychopathology (e.g., syndromes vs. symptoms). A critical obstacle to this goal is that most biological psychiatry research has failed to consider that key mechanisms such as inflammation may be simultaneously and uniquely associated psychopathol...

Despite decades of stress research, there still exist substantial gaps in our understanding of how social, environmental, and biological factors interact and combine with developmental stressor exposures, cognitive appraisals of stressors, and psychosocial coping processes to shape individuals’ stress reactivity, health, and disease risk. Relativel...

Women using hormonal contraceptives (HCs) exhibit numerous signs of chronic inflammation, including elevated C-reactive protein levels and greater risk of developing mood and autoimmune disorders. However, users and non-users of HCs often have similar circulating proinflammatory cytokine levels, making the mechanism of association unclear. One poss...

Many species exhibit seasonal patterns of breeding. Although humans can shield themselves from many season-related stressors, they appear to exhibit seasonal patterns of investment in reproductive function nonetheless, with levels of sex steroid hormones being highest during the spring and summer months. The current research builds on this work, ex...

Objectives: Tattooing is not an evolved behavior, but it may be a phenotypic gambit to highlight immunological health. Phenotypic gambits are traits or behaviors that appear costly but occur at high rates as a honing process of natural selection not constrained by genetics. Tattooing is an ancient practice that is increasing in popularity worldwid...

Testosterone levels in men appear to be prognostic of a number of disease outcomes, including severe COVID-19 disease. Testosterone levels naturally decline with age and are lower in individuals with a number of comorbidities and chronic conditions. Low testosterone may therefore be both a cause and a consequence of illness, including COVID-19 dise...

Objective: Baylor University established a surveillance system to assess the needs of students and faculty in isolation from SARS-CoV-2 as well as any longer-term symptoms. Participants: Overall, there were 309 responses between March 20 and May 19, 2021. Methods: A survey covering experience in isolation, symptoms, vaccination, and demographic cha...

Background and Objectives Testosterone plays an important role in regulating male development, reproduction, and health. Declining levels across the lifespan may reflect, or even contribute to, chronic disease and mortality in men. Methodology Relationships between testosterone levels and male mortality were analyzed using data from multiple sampl...

Objectives: The selection pressures exerted by pathogens have played important roles in shaping the biology and behavior of animals, including humans. Immune systems recognize and respond to cues of infection or damage by coordinating cellular, humoral, and metabolic shifts that promote recovery. Moreover, animals also possess a repertoire of behav...

In early-2020, the epidemiology of the SARS-CoV-2 virus was still in discovery and initial reports about the role of asymptomatic individuals were developing. The Waco COVID Survey was implemented in mid-2020 with targeted serological surveillance to assess relationships among risk factors and asymptomatic transmission in McLennan County, Texas, US...

Background: Pandemic fatigue describes a phenomenon whereby individuals experience a decrease in COVID-19 concern over time, despite their risk for infection remaining stable, or even increasing. Individual differences in the experience of pandemic fatigue may have important implications for people’s adherence to public health recommendations. Des...

Objective Though it injures the body in many ways, tattooing may also prepare it for later dermal stress through psychoneuroimmunological means.Methods To test this, we examined salivary endocrine (cortisol), immune (secretory immunoglobulin A), and inflammatory (C-reactive protein) responses to receiving a new tattoo relative to previous tattoo ex...

Tattooing is a stressor similar to exercise, but researchers have only begun to characterize endocrine and immune responses to this particular cultural stressor. While previous research indicates an allostatic adjustment to lifetime tattoo experience of modern electric tattooing, it is unclear how the body reacts to intensive traditional hand-tap t...

It has long been hypothesized that attractiveness provides a cue to a target's health and immunocompetence. However, much of the research testing this hypothesis has relied on a small number of indirect proxies of immune function, and the results of this research have been mixed. Here, we build on this past research, examining the relationship betw...

Much research indicates that exposure to early life adversity (ELA) predicts chronic inflammatory activity, increasing one’s risk of developing diseases of aging later in life. Despite its costs, researchers have proposed that chronic inflammation may be favored in this context because it would help promote immunological vigilance in environments w...

Disgust is reasoned to operate in conjunction with the immune system to help protect the body from illness. However, less is known about the factors that impact the degree to which individuals invest in pathogen avoidance (disgust) versus pathogen management (prophylactic immunological activity). Here, we examine the role that one’s control over pa...

Decades of research finds associations between personality traits and health. In recent years, it has become clear that the activities of the immune system play a key role in linking these variables. In the current work, we add to this research by exploring the relationship between Big Five personality traits and (Study 1) polymorphisms known to im...

Thermoregulation is a complex, dynamic process involving coordination between multiple autonomic, endocrine, and behavioral mechanisms. In the context of infection, this intricate machinery generates fever, a process believed to serve vital functions in the body's defense against pathogens. In addition to increasing core temperature, infection can...

Despite concern about environmental protection, travelers often underestimate the contribution they may have to disease transmission to other species, as well as the risk of becoming infected themselves. Tourists in general tend to accept more physical risks when traveling than when at home, and much of this can be blamed on the temporary loss of s...

Risk perception and consequently engagement in behaviors to avoid illness often do not match actual risk of infection, morbidity, and mortality. Unrealistic optimism occurs when individuals falsely believe that their personal outcomes will be more favorable than others' in the same risk category. Natural selection could favor overconfidence if its...

Early life stress increases one’s risk for health problems later in life, and many studies find that these effects are sex-differentiated. Here, we examined relationships between multiple sources of early life stress and adult immune function in humans across several functional assays. Adult participants provided retrospective information about the...

It is currently unclear whether early life stress (ELS) affects males and females differently. However, a growing body of work has shown that sex moderates responses to stress and injury, with important insights into sex-specific mechanisms provided by work in rodents. Unfortunately, most of the ELS studies in rodents were conducted only in males,...

We examined relationships between multiple sources of early life stress and adult immune function in humans. Adult participants provided retrospective information about their childhood a) socioeconomic status, b) household unpredictability, and c) exposure to adverse experiences. Participants’ peripheral blood mononuclear cells were then isolated f...

Although the criminal justice system is designed around the idea that individuals are invariant in their responses to punishment, research indicates that individuals exhibit a tremendous amount of variability in their punishment sensitivity. This raises the question of why; what are the individual- and situation-level variables that impact a person...

A growing body of research indicates that one's early life experiences may play an important role in regulating patterns of energy intake in adulthood. In particular, adults who grew up under conditions characterized by low socioeconomic status (SES) tend to eat in the absence of hunger (EAH), a pattern that is not generally observed among higher-S...

Objective Here, we provide an experimental test of the relationship between levels of proinflammatory cytokines and present-focused decision-making. Methods We examined whether increases in salivary levels of proinflammatory cytokines (interleukin-1β and interleukin-6) engendered by visually priming immunologically-relevant threats (pathogen threa...

A growing body of research finds that the activities of the immune system—in addition to protecting the body from infection and injury—also influence how we think, feel, and behave. Although research on the relationship between the immune system and psychological and behavioral outcomes has most commonly focused on the experiences of those who are...

Winter is characterized by stressful conditions which compromise health and render animals more vulnerable to infection and illness than during other times of the year. Organisms are hypothesized to adapt to these seasonal stressors by increasing investment in immune function in response to diminished photoperiod duration. Here, we examined this hy...

Here, we propose a novel theoretical model linking present-focused decision-making to the activities of the immune system. We tested our model by examining the relationship between inflammatory activity – in vivo and in vitro – and decision-making characterized by impulsivity, present focus, and an inability to delay gratification. Results support...

Abstract: Although frequently characterized as undesirable, risk-taking is an integral part of human social life. Research into the factors that influence risk-taking therefore represents an important area of study in the evolutionary sciences. The current research draws from research on humans’ pathogen avoidance psychology, life history theory, a...

The human menstrual cycle is characterized by substantial variability both within and between women. Here, we sought to account for such variability by examining whether human menstrual cycle frequency varies as a function of the projected fitness payoffs associated with investment in mating effort. We used structural equation modeling to test the...

Here, we present a mechanistically grounded theory detailing a novel function of the behavioral immune system (BIS), the psychological system that prompts pathogen avoidance behaviors. We propose that BIS activity allows the body to downregulate basal inflammation, preventing resultant oxidative damage to DNA and promoting longevity. Study 1 invest...

Pepper & Nettle's theory of the behavioral constellation of deprivation (BCD) would benefit from teasing apart the conceptually distinct – although related – constructs of predictability and control. Our commentary draws from prior research conducted in the learning domain to demonstrate that predictability moderates the effects of control and inde...