Degree Type


Date of Award


Degree Name

Doctor of Philosophy





First Advisor

Jacob Meyer


Depression is a prevalent and costly condition. Identifying effective means to manage depressive symptoms for adults with clinical and subclinical symptoms is an area in need of further research. Increasing physical activity (PA) and reducing sedentary time (ST) are behavior changes that show promise for reducing depressive symptom severity. The purposes of this dissertation were 1) to examine depressive symptoms of depression prior to and following an 8-week intervention to decrease ST and break up ST greater than 1 hour, 2) to examine associations of ST and PA with inflammation and glucocorticoid resistance (GCR) for adults with major depressive disorder (MDD), as well as compare GCR between adults with and without MDD, and 3) to examine associations of PA and ST with suicidal ideation (SI) severity in adults with MDD. Results for the first study showed that symptoms of depression decreased following the intervention to reduce ST, compared to a wait-list control group for adults with chronic low back pain (CLBP) and elevated symptoms of depression. This occurred along with changes in self-reported leisure time passive sitting between groups, but without decreases in objectively-measured ST. The second study found the majority of the inflammatory markers and measures of GCR examined were not associated with PA or ST, suggesting our participants' lifestyle PA and ST had a negligible influence on immune function. The third study did not find associations for ST or PA with SI severity. However, when examining only participants that were experiencing a current major depressive episode, those who reported SI of any severity accumulated significantly fewer steps per day those who did not report SI.

This dissertation adds to the current research by examining how PA and ST are associated with depression severity in adults with and without MDD with the use of objective measures of PA and ST. The findings of the current research can help better target interventions to reduce symptoms of depression for adults with CLBP, provides insight on how PA and ST relate to immune function to adults with MDD, and may be useful for future suicide prevention efforts in adults with MDD.


Copyright Owner

Maria Perez



File Format


File Size

141 pages