Low-grade inflammation decreases emotion recognition – Evidence from the vaccination model of inflammation

Abstract

The ability to adequately interpret the mental state of another person is key to complex human social interaction. Recent evidence suggests that this ability, considered a hallmark of 'theory of mind' (ToM), becomes impaired by inflammation. However, extant supportive empirical evidence is based on experiments that induce not only inflammation but also induce discomfort and sickness, factors that could also account for temporary social impairment. Hence, an experimental inflammation manipulation was applied that avoided this confound, isolating effects of inflammation and social interaction. Forty healthy male participants (mean age = 25, SD = 5 years) participated in this double-blind placebo-controlled crossover trial. Inflammation was induced using Salmonella Typhi vaccination (0.025 mg; Typhim Vi, Sanofi Pasteur, UK); saline-injection was used as a control. About 6 h 30 m after injection in each condition, participants completed the Reading the Mind in the Eyes Test (RMET), a validated test for assessing how well the mental states of others can be inferred through observation of the eyes region of the face. Vaccination induced systemic inflammation, elevating IL-6 by +419% (p < .001), without fever, sickness symptoms (e.g., nausea, light-headedness), or mood changes (all p's > .21). Importantly, compared to placebo, vaccination significantly reduced RMET accuracy (p < .05). RMET stimuli selected on valence (positive, negative, neutral) provided no evidence of a selective impact of treatment. By utilizing an inflammation-induction procedure that avoided concurrent sicknesses or symptoms in a double-blinded design, the present study provides further support for the hypothesis that immune activation impairs ToM. Such impairment may provide a mechanistic link explaining social-cognitive deficits in psychopathologies that exhibit low-grade inflammation, such as major depression.

Loneliness in healthy young adults predicts inflammatory responsiveness to a mild immune challenge in vivo

“…Loneliness scores ranged between 22-64 (M = 39, SD = 10) and typhoid vaccination increases in IL-6 ranged from 1.1-8.8 pg/mL (M = 3.8, SD = 1.6) (see also Balter et al, 2018). At baseline, IL-6 was not significantly correlated with loneliness scores (r(36) = -.123, p = .487).…”

“…The current analysis is based on the same sample as in Balter et al, (2018) and stem from secondary analysis of a larger study.…”

“…The study involved a within-subjects double blind placebo-controlled design, presented in detail elsewhere (Balter et al, 2018). Forty healthy young male students from the University of Birmingham were enrolled (M age = 24.7, SD = 5.2 years).…”

Selective effects of acute low-grade inflammation on human visual attention

“…Other cognitive tests, not reported here, included measures of emotion recognition, memory, learning, and response inhibition. For a detailed description of the complete study procedures, see Balter et al (2018). The final blood sample was taken about 8 hours post-injection.…”

Sickness and sleep health predict frustration and affective responses to a frustrating trigger

“…While one or two nights of total sleep loss may be rare outside the sleep laboratory, mild reductions in sleep duration and quality, and the presence of other stressors, such as symptoms of infection like a cough or a stuffy nose, or sickness-related depressed mood, occur on a day-to-day basis in many individuals. Even though small variations in sickness, inflammation, and sleep have each been shown to change social behaviour, impair emotional regulation and cognitive functioning, intensify stress, anxiety, and anger, and reduce overall wellbeing [3][4][5][25][26][27][28][29] -all of which can have direct implications for how we respond to our environment-we know very little of whether these common life stressors are associated with feeling frustrated and the sensitivity to becoming frustrated.…”