Effects of horticultural therapy versus handiwork on anterior cingulate cortex activity in people with chronic low back pain: A randomized, controlled, cross-over, pilot study

To assess the efficacy of horticultural therapy (HT) on anterior cingulate cortex (ACC) activity and the changes in rumination and catastrophizing scores in individuals with chronic low back pain (LBP). We conducted a randomized, controlled, cross-over, 3-week pilot study (ClinicalTrials.gov Identifier: NCT04656158). The departments of physical medicine and rehabilitation (hospital grounds and occupational therapy room) and imaging research were involved. The participants were adults with non-specific chronic LBP. All participants underwent two 90-min HT sessions and two 90-min handiwork sessions per week. The activity sequence order was randomized, and the activities were separated by a wash-out period of 1 week. Each participant underwent 3 brain MRIs: before, after the first, and after the second activity. The primary outcome was the change in ACC perfusion in ml/100g/min using arterial spin labeling MRI. The secondary outcomes were the changes in self-reported rumination and catastrophizing scores after each activity compared to baseline. Sixteen participants were included: 14 women (87.5%), LBP intensity (numeric rating scale) mean (SD) 45.1 (27.2)/100, specific activity limitation (Roland Morris disability questionnaire) 9.3 (4.1)/24. Change in ACC perfusion from baseline was -0.1 (10.7), 95% CI [-5.6, 5.8] ml (blood)/100g (tissue)/min after handiwork and -0.1 (8.7), [-4.7, 4.6] after HT and did not differ between the 2 activities (p = 0.91). Change in rumination [-0.5 (4.4) after handiwork and -0.3 (2.8) after HT] and catastrophizing scores [-2 (2.8) after handiwork and -1.4 (2.3) after HT] did not differ between activities (p = 0.99 and 0.22, respectively). Limited exposure to the interventions and the sample profile (moderate levels of pain) may explain our results. Our results highlight the need for future studies using the most appropriate outcomes to determine the exact effects of nature experiences in people with chronic musculoskeletal disease.