Effect of Pregnenolone vs Placebo on Self-reported Chronic Low Back Pain Among US Military Veterans: A Randomized Clinical Trial.

Importance: In response to the national opioid public health crisis, there is an urgent need to develop nonopioid solutions for effective pain management. Neurosteroids are endogenous molecules with pleotropic actions that show promise for safe and effective treatment of chronic low back pain. Objective: To determine whether adjunctive pregnenolone has therapeutic utility for the treatment of chronic low back pain in Iraq- and Afghanistan-era US military veterans. Design, Setting, and Participants: Randomized, double-blind, placebo-controlled clinical trial that enrolled for 42 months, from September 2013 to April 2017. Participants were Iraq- and Afghanistan-era veterans aged 18 to 65 years with chronic low back pain who received treatment in the Durham VA Health Care System in Durham, North Carolina, over 6 weeks. Data analysis began in 2018 and was finalized in March, 2019. Interventions: Following a 1-week placebo lead-in, participants were randomized to pregnenolone or placebo for 4 weeks. Pregnenolone and placebo were administered at fixed, escalating doses of 100 mg for 1 week, 300 mg for 1 week, and 500 mg for 2 weeks. Main Outcomes and Measures: The primary outcome measure was the change in mean pain intensity ratings from a daily pain diary (numerical rating scale, 0-10) between visit 3 (baseline) and visit 6. Secondary outcomes included pain interference scores (Brief Pain Inventory, Short Form). Preintervention and postintervention neurosteroid levels were quantified by gas chromatography with tandem mass spectrometry. Hypotheses tested were formulated prior to data collection. Results: A total of 94 participants (84 [89.4%] male; mean [SD] age, 37.5 [9.8] years; 53 [56.4%] of self-reported Caucasian race and 31 [33.0%] of self-reported African American race) were included. Forty-eight participants were randomized to pregnenolone and 52 to placebo, of whom 45 and 49, respectively, were included in baseline demographic characteristics secondary to noncompliance with medications as per protocol. Veterans randomized to pregnenolone reported significant reductions in low back pain relative to those randomized to placebo. Baseline unadjusted mean (SE) pain diary ratings were 4.83 (0.23) and 5.24 (0.22) for the placebo- and pregnenolone-treated groups, respectively (baseline unadjusted mean [SE] ratings for pain recall were 4.78 [0.24] and 5.15 [0.23], respectively). Unadjusted mean (SE) ratings following treatment (visit 6) were 4.74 (0.26) in the placebo group and 4.19 (0.30) in the pregnenolone-treated group. Unadjusted mean (SE) ratings for pain recall following treatment were 4.86 (0.27) for placebo and 4.18 (0.29) for pregnenolone. Least-square mean (LSM) analysis showed that pain scores significantly improved in the pregnenolone-treated group compared with placebo (LSM [SE] change in pain diary rating, -0.56 [0.25]; P = .02; LSM [SE] change in pain recall, -0.70 [0.27]; P = .01). Pain interference scores for work (LSM [SE] change, 0.71 [0.12]; P = .04) and activity (LSM [SE] change, 0.71 [0.11]; P = .03) were also improved in veterans randomized to pregnenolone compared with placebo. Pregnenolone was well tolerated. Conclusions and Relevance: Participants receiving pregnenolone reported a clinically meaningful reduction in low back pain and 2 pain interference domains compared with those receiving placebo. Pregnenolone may represent a novel, safe, and potentially efficacious treatment for the alleviation of chronic low back pain in Iraq- and Afghanistan-era veterans. Trial Registration: ClinicalTrials.gov Identifier: NCT01898013.

Widespread Cortical Thickness Is Associated With Neuroactive Steroid Levels.

BACKGROUND: Neuroactive steroids are endogenous molecules with regenerative and neuroprotective actions. Both cortical thickness and many neuroactive steroid levels decline with age and are decreased in several neuropsychiatric disorders. However, a systematic examination of the relationship between serum neuroactive steroid levels and in vivo measures of cortical thickness in humans is lacking. METHODS: Peripheral serum levels of seven neuroactive steroids were assayed in United States military veterans. All (n = 143) subsequently underwent high-resolution structural MRI, followed by parcellelation of the cortical surface into 148 anatomically defined regions. Regression modeling was applied to test the association between neuroactive steroid levels and hemispheric total gray matter volume as well as region-specific cortical thickness. False discovery rate (FDR) correction was used to control for Type 1 error from multiple testing. RESULTS: Neuroactive steroid levels of allopregnanolone and pregnenolone were positively correlated with gray matter thickness in multiple regions of cingulate, parietal, and occipital association cortices (r = 0.20-0.47; p < 0.05; FDR-corrected). CONCLUSION: Positive associations between serum neuroactive steroid levels and gray matter cortical thickness are found in multiple brain regions. If these results are confirmed, neuroactive steroid levels and cortical thickness may help in monitoring the clinical response in future intervention studies of neuroregenerative therapies.