TABLE 4.

Causal mediation model results.

Hypothesized functional connectivity mediator	Behavioral measure	Coefficient (β) for controlled direct effect estimate (CDE) (Bootstrap 95% confidence intervals)	p-Value direct for effect (path A)	Mediation: coefficient (β) for natural indirect effect estimate (NIE) (Bootstrap 95% confidence intervals)	p-Value for mediation (paths B, C)	Covariates (control factors)
rSMG-aCC	Depression (NeuroQOL)	0.986 (0.89, 1.082)	<0.0001	−0.231 (−0.372, −0.091)	0.0012	Age, BMI, pain severity, and baseline social role score
rlPL-aCC	Depression (NeuroQOL)	0.721 (0.657, 0.786)	<0.0001	0.033 (−0.81, 0.148)	0.5686	Age, BMI, pain severity, and baseline social role score
MTG-aCC	Social role (NeuroQOL)	1.645 (2.150, 1.049)	<0.0001	−1.733 (−2.428, −1.038)	<0.0001	Age, BMI, pain severity, and baseline depression score
PFC-aCC	Social role (NeuroQOL)	0.292 (−0.011, 0.595)	0.0591	0.154 (−0.459, 0.815)	0.6063	Age, BMI, pain severity, and baseline depression score
MTG-aCC	Acceptance and action (AAQ-II)	1.395 (1.195, 1.50)	<0.0001	−0.062 (−0.197, 0.072)	0.3620	Age, BMI, baseline depression score, and pain severity
rSMG-aCC	Chronic pain acceptance (CPAQ total)	−1.088 (−1.144, −1.031)	<0.0001	1.060 (0.813, 1,306)	<0.0001	Age, BMI, pain severity, baseline depression score, and baseline social role score
MTG-aCC	Chronic pain acceptance (CPAQ total)	−0.452 (−0.675, −0.228)	<0.0001	0.424 (0.153, 0.695)	0.0022	Age, BMI, pain severity, baseline depression score, and baseline social role score
rlPL-aCC	CPAQ – pain willingness	−0.020 (0.029, −0.009)	0.0001	0.002 (−0.029, −0.010)	0.6091	Age, BMI, pain severity, baseline depression score, and baseline social role score
rlPL-aCC	Pain interference (PROMIS)	1.970 (1.057, 2.882)	<0.0001	−0.1679 (−2.870, −0.529)	0.0044	Age, BMI, baseline depression score, and baseline social role score
rSMG-aCC	Pain severity	0.810 (0.474, 1.146)	<0.0001	−0.507 (−0.950, −0.065)	0.0247	Age, BMI, baseline depression score, and baseline social role score
rlPL-aCC	Pain severity	1.2756 (1.225, 1.326)	<0.0001	−0.9725 (−1.426, −0.519)	<0.0001	Age, BMI, baseline depression score, and baseline social role score

Relationships between hypothesized functional connectivity mediators and behavioral outcome scores (post- minus pre-ACT). Functional connectivity mediator is measured as the change (post- minus pre-ACT) in the NBS. Independent variable, Pre-ACT Behavioral Score; Dependent variable, Post-ACT Behavioral Score. Controlled direct effect (CDE) simulate an RCT by hypothetically assigning the same value of the mediator to the individuals in the sample (Naimi et al., 2014).