In this study, we replicated a rigorous test of the proposed mechanisms of change associated with Mothering from the Inside out (MIO), an evidence-based parenting therapy that aims to enhance maternal reflective functioning and mental representations of caregiving in mothers enrolled in addiction treatment and caring for young children. First, using data from 84 mothers who enrolled in our second randomized controlled trial, we examined whether therapist fidelity to core MIO treatment components predicted improvement in maternal reflective functioning and mental representations of caregiving, even after taking fidelity to non-MIO components into account. Next, we examined whether improvement in directly targeted outcomes (e.g., maternal mentalizing and mental representations of caregiving) led to improvements in the indirectly targeted outcome of maternal caregiving sensitivity, even after controlling for other plausible competing mechanisms (e.g., improvement in maternal psychiatric distress and substance use). Third, we examined whether improvement in targeted parenting outcomes (e.g., maternal mentalizing, mental representations of caregiving and caregiving sensitivity) was associated in improvement in child attachment status, even after controlling for competing mechanisms (e.g., improvement in maternal psychiatric distress and substance use). Finally, we examined whether improvement in maternal mentalizing and caregiving representations was associated with a reduction in relapse to substance use. Support was found for the first three tests of mechanisms but not the fourth. Implications for future research and intervention development are discussed.

Mothers with histories of alcohol and drug addiction have shown greater difficulty parenting young children than mothers with no history of substance misuse. This study was the second randomized clinical trial testing the efficacy of Mothering From the Inside Out (MIO), a 12-week mentalization-based individual therapy designed to address psychological deficits commonly associated with chronic substance use that also interfere with the capacity to parent young children. Eighty-seven mothers caring for a child between 11 and 60 months of age were randomly assigned to receive 12 sessions of MIO versus 12 sessions of parent education (PE), a psychoeducation active control comparison. Maternal reflective functioning, representations of caregiving, mother-child interaction quality, and child attachment were evaluated at baseline and posttreatment and 3-month follow-up. Mother-child interaction quality was assessed again at 12-month follow-up. In comparison with PE mothers, MIO mothers demonstrated a higher capacity for reflective functioning and representational coherence at posttreatment and 3-month follow-up. At 12-month follow-up, compared to PE cohorts, MIO mothers demonstrated greater sensitivity, their children showed greater involvement, and MIO dyads showed greater reciprocity. As addiction severity increased, MIO also appeared to serve as a protective factor for maternal reflective functioning, quality of mother-child interactions, and child attachment status. Results demonstrate the promise of mentalization-based interventions provided concomitant with addiction treatment for mothers and their young children.