Reexamination of diathesis stress and neurotoxic stress theories: A qualitative review of pre‐trauma neurobiology in relation to posttraumatic stress symptoms

OBJECTIVE: Associations of neurobiological differences with posttraumatic stress disorder (PTSD) have generated interest in their temporal relation. Support has been voiced for the neurotoxic stress theory (NST) in which neurobiological differences develop following exposure and PTSD development. In contrast, the diathesis stress theory (DST) posits that neurobiological differences existed prior to exposure and may be vulnerability factors for PTSD. Studies in the first wave of neurobiological PTSD research were all cross sectional, but a second wave of research followed which used prospective repeated‐measures designs that measured neurobiology prior to trauma exposure experiences, allowing greater causal inference. METHODS: This study reviewed the second‐wave studies in hopes of developing a preliminary consensus to support either the NST or the DST based on this more powerful prospective, repeated‐measures study design. RESULTS: Twenty‐five second‐wave studies were located that measured neurobiology prior to traumatic experiences. Nineteen studies supported the DST. Of 10 studies that were capable of testing the NST, only 3 were supportive. CONCLUSION: The implications of the NST versus the DST have profound implications for understanding the fragility of the human brain and possible paths forward for future research on assessment, treatment, and social policy.