title: Towards an integrative picture of human sickness behavior.
abstract: Sickness behavior, a coordinated set of behavioral changes during infection and elicited by the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β), is well studied in non-human animals. Over the last two decades, several papers have expanded this research to include humans. However, these studies use a variety of research designs, and typically focus on a single cytokine and only a few of the many behavioral changes constituting sickness behavior. Therefore, our understanding of human sickness behavior remains equivocal. To generate a more holistic, integrative picture of this phenomenon, a meta-analysis of the human sickness behavior literature was conducted. Full model results show that both IL-6 and IL-1β have significant relationships with sickness behavior, and the strength of these relationships is affected by a number of study parameters, such as type of immune stimulus and inclusion of controls. In addition to research design heterogeneity, other issues to address in future studies include an unequal focus on different cytokines and different sickness behaviors.
authors.affiliation: Laboratory for Evolutionary Medicine, Department of Anthropology, University of Texas at San Antonio, San Antonio, TX, United States. Electronic address: eric.shattuck@utsa.edu.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Shattuck
authors.affiliation: Laboratory for Evolutionary Medicine, Department of Anthropology, University of Texas at San Antonio, San Antonio, TX, United States.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Muehlenbein
mesh_terms: D003863:Depression / Q000097:blood*; D006801:Humans; D055809:Illness Behavior; D053583:Interleukin-1beta / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*
chemical_list: C508585:IL1B protein, human; C508600:IL6 protein, human; D053583:Interleukin-1beta; D015850:Interleukin-6; C439524:TNF protein, human; D014409:Tumor Necrosis Factor-alpha
keywords: Cytokines; Depression; Meta-analysis; Psychoneuroimmunology; Sickness behavior