Resting-state Connectivity and Individual Differences in Affective Placebo Responsiveness

Condition(s) studied

Investigational drug(s) / intervention(s)

No intervention: No intervention

Study summary

Expectation effects on affective states are central to mechanisms relevant for mood disorders and their treatment. This study will test whether inter-individual differences in resting-state functional connectivity (rsFC) within emotion regulation networks is associated with affective placebo responsiveness in healthy volunteers. Approximately 50 healthy participants will be pooled from two cross-over placebo studies in which participants receive intranasal saline either labeled as "oxytocin" in the placebo condition or as saline in the control condition.

Primary indices of placebo responsiveness are placebo-control difference scores of mood state, emotional paradigm responses, as well as expectation and experience ratings.

rsFC will be estimated using the CONN toolbox. Confirmatory analyses will use an a priori seed-based approach, with prefrontal seeds derived from previous task-based fMRI findings on affective placebo effects. These analyses will be complemented by secondary summaries of within- and between-network connectivity across the saliency network, the fronto-parietal control network, and the default mode network.

We hypothesize that interindividual differences in target rsFC networks will be associated with affective placebo effects, indicating general, trait-like mechanisms of placebo responsiveness.

Eligibility

Primary outcome measure(s)

• Resting-state functional connectivity measures in prefrontal-emotion-related circuitry — During one separate post-paradigm MRI session lasting approximately 45 minutes, after completion of the preceding placebo study protocol.
  Resting-state fMRI will be used to estimate Fisher r-to-z transformed functional connectivity using seed-based and ROI-to-ROI analyses within prefrontal-emotion-related circuitry. These rsFC measures will be tested for associations with participant-level placebo-response indices derived from prior placebo/control sessions.

Trial sites (1)