Effects of Chronic Pain Diagnoses on the Antidepressant Efficacy of Transcranial Magnetic Stimulation

BackgroundMajor depressive disorder (MDD) and chronic pain are highly comorbid and bidirectionally related, such that MDD typically interferes with chronic pain treatment and vice versa. Repetitive transcranial magnetic stimulation (rTMS) over the dorsolateral prefrontal cortex (DLPFC) is effective in treating MDD, but additional research is needed to determine if chronic pain interferes with rTMS for MDD. MethodParticipants were 124 veterans (Mage=49.1, SD=13.8) scheduled for 30 sessions of rTMS across six weeks at the Veterans Affairs San Diego Healthcare System. Depression severity was monitored weekly using the Patient Health Questionnaire-9. Having any pain diagnosis, low back pain, or migraine/headache were assessed by chart review. Latent basis models were used to estimate change and change-by-pain diagnosis in depression scores during rTMS treatment. ResultsA total of 92 participants (74%) had a documented pain diagnosis, 58 (47%) had low back pain, and 32 (26%) had migraine/headache. Depression scores initially decreased (linear slope estimate=-2.04, SE=0.26, p<.0001), but the rate of decrease slowed over time (quadratic slope estimate=0.18, SE=0.04, p<.001). Having any pain diagnosis, low back pain, or migraine/headache did not significantly differentiate overall amount of change. However, individuals with headache/migraine showed greater initial improvement but then an even faster slowing in rate of decrease than those without headache/migraine. ConclusionsHaving any pain diagnosis, low back pain, or headache/migraine did not significantly interfere with improvement in depression; however, headache/migraine affected the timing of change. These data contribute to the ongoing support of rTMS as a viable treatment option for comorbid populations.