Evolution-based investigations of beneficial fever and life history orientation effects on PTSD risk

Clint, Edward

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https://hdl.handle.net/2142/120195 Copy

Description

Title

Evolution-based investigations of beneficial fever and life history orientation effects on PTSD risk

Author(s)

Clint, Edward

Issue Date

2023-01-17

Director of Research (if dissertation) or Advisor (if thesis)

Rhodes, Justin

Doctoral Committee Chair(s)

Rhodes, Justin

Committee Member(s)

• Bell, Alison
• Dolcos, Florin
• Fessler, Daiel

Department of Study

Neuroscience Program

Discipline

Neuroscience

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• fever
• COVID-19
• PTSD
• life history theory

Abstract

Evolutionary frameworks provide unique and potent avenues of investigation for illness and mental illness. Ailments as commonly understood can be biological adaptations functioning properly (fever, nausea, inflammation), adaptive mechanisms in a state of dysfunction type 1 Diabetes), or adaptive mechanisms effecting malady due to evolutionary disequilibrium (metabolic syndrome caused by evolutionarily novel overabundance of dietary sugars). Understanding of the nature of adaptions of one of these varieties and the modern cultural setting in which they exist can inform risk factors and causes and may serve to aid efforts at prevention and treatment. This dissertation is an investigation of two such cases. First, the effects of pharmaceutical suppression of the adaptive fever response in the context of COVID-19 and second, the effects of early life adversity on vulnerability to adversity in adulthood in the context od PTSD. Fever, the rise in body set temperature in response to injury or infection, is an evolutionarily ancient defense against infectious disease documented in dozens of species. An increase in body temperature can impair and stress pathogenic microbes and infected body cells which can inhibit their replication directly and by making them more visible to immune system cells which hunt and destroy them. In humans, body temperature and fever are tightly regulated by the hypothalamus. Numerous animal model studies have documented an association between fever suppression and morbidity and mortality. A smaller number of human studies have more equivocal findings, complicated by modern medical care and ethical concerns. Nonetheless, there is significant empirical evidence suggesting that fever suppression can prolong illness and increase risk of adverse outcomes including mortality. Chapter two details a study of individuals afflicted with COVID-19 and use of antipyretic medications. The analysis found that use of antipyretic drugs was associate with worse illness outcomes controlling for several risk factors and measures of overall illness severity, which fever itself did not correlate with better or worse outcomes. Chapters three, four, and five concern an examination of post-traumatic stress disorder (PTSD) as dysregulation of evolved psychological mechanisms for coping with adverse and intensely stressful condition. The definitive symptoms of PTSD, such as hypervigilance and sleep disturbance and intrusive thoughts, are excessive degrees of otherwise healthy responses to threatening and intensely challenging situations: potential and actual threats should draw one’s focus and attention in order to be effectively coped with. The conventional view with strong empirical support in the published literature holds that early life adversity increases risk for PTSD in adulthood given exposure to trauma. However, psychological life history theory proposes that early life cues about ecological and social conditions provokes a shift in developmental trajectory that modifies the adult physical and psychological phenotype to better optimize it for those conditions. In this light, it seems reasonable that early adversity cues would shift development toward a phenotype that is better able to cope with future adversity rather than less able to cope. In chapter four, a large military data set is analyzed to detect the association between early adversity, adult life history orientation, and PTSD risk. Chapter five features a similar analysis on a large longitudinal civilian population. In both studies early life adversity is associated with a predicted corresponding life history orientation. However, in both cases the individuals who experienced more adversity were more vulnerable to PTSD as adults, controlling for several risk factors. Chapter six discusses the implications and possible interpretations of these findings.

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Edward Clint

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