Daily and dynamic fluctuations in PTSD symptoms, physical pain, and cannabis use among veterans

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PROJECT SUMMARY Posttraumatic stress disorder (PTSD) and physical pain are highly co-occurring among veterans. Nearly one- half of post-9/11 American veterans report physical pain, and nearly one-quarter report PTSD. Rates of PTSD are even higher among those with physical pain and vice versa. Veterans with co-occurring PTSD and physical pain may be at particular risk of problematic cannabis use, as both conditions are associated with self- medication and cannabis use disorder. Research is mixed on whether cannabis use improves PTSD symptoms and physical pain or makes them worse. Thus, understanding dynamic associations between co- occurring PTSD symptoms, physical pain, and cannabis use is vital. Several theoretical models have been developed to explain links between PTSD and physical pain and may carry implications for understanding problematic cannabis use. The mutual maintenance model posits a bidirectional relationship where PTSD symptoms make physical pain worse and vice versa. Thus, as PTSD symptoms and physical pain escalate, problematic cannabis use may increase as well. The shared vulnerability model implicates predisposing psychological factors such as anxiety sensitivity (i.e., a tendency to fear anxiety symptoms) in the development and maintenance of both PTSD and physical pain, and anxiety sensitivity may also increase risk of self- medication and cannabis problems. However, results of prior research on these associations are mixed and marred by methodological issues. Namely, most relevant studies have assessed symptoms measured at quarterly (i.e., 3-month) intervals, however PTSD symptoms, physical pain, and cannabis use are all known to fluctuate daily. Therefore, prior work may be subject to retrospective recall bias and may not accurately capture changes in co-occurring symptomology. Studies in which participants report symptoms daily (daily diary studies) may allow for a more precise assessment of the strength and direction of associations as well as the extent to which theoretical models, including mutual maintenance, shared vulnerability, and self-medication, describe these associations. The proposed dissertation study will leverage an existing daily diary study (1R21DA051802-01A1) of PTSD symptoms and problematic cannabis use among post-9/11 veterans (N=75). Analyses will utilize intensive longitudinal methods (i.e., dynamic structural equation models) to test the bidirectional associations between PTSD symptoms and physical pain, their dynamic associations with cannabis use, and the moderating role of anxiety sensitivity. Qualitative interviews will be used with a subsample of veterans (N=20) who screen for PTSD, report heightened physical pain, and have varying levels of problematic cannabis use. Interviews will explore veterans’ lived experience of co-occurring symptomology and problematic cannabis use and will employ narrative life history methods to understand how one’s key experiences as a service member and veteran relate to their symptomology and use.