Brain functional basis of the association between positive expectation and acupuncture efficacy in knee osteoarthritis.

Expectation is an important psychological factor affecting clinical treatment outcomes in chronic diseases; however, its underlying neural basis remains unclear. The aim of this study is to explore the neurofunctional mechanisms of expectation and investigate how expectations influence acupuncture treatment efficacy in the brains of patients with knee osteoarthritis (KOA). A total of 90 patients diagnosed with KOA were enrolled in this study. The acupuncture group (AG, age 45-65) and sham acupuncture group (SG, age 48-65) received either 12 sessions of 30-min acupuncture treatment or sham acupuncture treatment, whereas the waiting-list group (WG, age 45-65) did not receive any interventions. Patients' baseline positive expectations were assessed. Neuroimaging, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and other clinical data were collected at baseline and after treatment (week 4). Correlation analyses between the brain imaging and clinical data were performed. Baseline expectations and improvements in WOMAC function were associated with fractional amplitude of low-frequency fluctuation (fALFF) changes in the posterior cingulate cortex (PCC)/precuneus and increased PCC/precuneus-medial prefrontal cortex (mPFC) connectivity in the AG, but not in the SG or WG. Both altered fALFF in the PCC/precuneus and enhanced PCC/precuneus-mPFC connectivity were neural correlates of the association between positive expectations and the therapeutic efficacy of acupuncture.