The goal of this mechanistic clinical trial is to examine whether parent-coaching aimed at increasing child positive affect will increase child neural response to reward. The main questions it aims to answer are:

Aim 1. Characterize child neural reward response and its relation to maternal socialization of positive emotions at baseline in healthy young children.

Aim 2. Evaluate how coaching-related changes in maternal socialization of positive emotion expression contribute to increases in child neural reward response over time.

Aim 3. Examine how maternal socialization of positive emotion expression contributes to increases in child neural reward response in the moment.

Participating mother-child dyads will be randomized to either 3 sessions of parent coaching of child positive affect or 3 sessions of a general parenting support intervention and neural response to reward and affective behavior will be examined pre and post intervention.

Reward-related brain function is consistently linked to greater motivation, pleasure, and goal-directed behavior and lower risk for depression across the lifespan. Healthy neural reward response supports socioemotional development, particularly during early childhood as self-regulatory skills and child reward-related brain function are rapidly developing in the context of the caregiving environment. Maternal socialization of positive emotion is one important influence on early reward circuitry development. Mothers with depression are more likely to discourage (and less likely to encourage) child positive emotions compared to healthy mothers, which may contribute to early neural reward alterations in their children. Characterizing mechanisms of influence of maternal socialization on child neural reward response and positive emotion during early childhood is a critical window of opportunity when parents have a large influence on child socioemotional development. Importantly, maternal behavior is amenable to change by training parents on emotion coaching, and these maternal behavior changes may result in direct and immediate changes in child neural reward function. Thus, the overarching aim of this proposal is to use a mechanistic trial design to experimentally test the hypothesis that maternal encouragement of child positive emotion will lead to in-vivo increases in child neural reward response. Event-related potentials (ERPs) are uniquely suited to non-invasively assess in-vivo, fast-occurring changes in child reward response during parent-child interactions, including reward positivity (RewP), and the late positive potential (LPP) amplitudes. Toward this aim, the investigators will randomize 180 mothers with clinically significant depression symptoms and their 4- to 6-year-old children (50% female) to receive either 3 control sessions or 3 positive emotion coaching modules from the Parent-Child Interaction Therapy-Emotion Development (PCIT-ED, which trains mothers on how to encourage positive emotion in their young children. Children will complete reward tasks at pre- and post-coaching, while neural reward response is assessed via ERP (RewP and LPP) with their mothers present allowing for in-vivo assessment of maternal behavior. At both timepoints, the investigators will assess child neural reward response and mothers' self-reported maternal socialization behaviors. Understanding how disrupted neural reward responding develops in early childhood is critical for the promotion of child emotional wellness and can be directly used to develop preventive interventions tailored to young children at familial risk for depression.

Inclusion Criteria for Mothers:

• Birth mother (biologically female, any gender)
• Providing regular care for participating child (i.e., at least 50% of time)
• Elevated, clinically significant levels of depression (16 or higher on CES-D)
• Aged 18+

Exclusion Criteria for Mothers:

• Lifetime history of a bipolar disorder
• Lifetime history of a psychotic disorder

Inclusion Criteria for Participating Child:

-Aged 4-6 years

Exclusion Criteria for Participating Child:

• T-score greater than 63 on the internalizing or externalizing composites of the CBCL
• Lifetime history of a psychiatric illness
• Lifetime history of neurodevelopmental disorder
• Lifetime history of neurological disorder

Data will be shared with the NIH NDA per NIH requirements, which include all primary study measures and demographic information. Participant identifying information is used to create an anonymized GUID to identify participants in the NDA but no identifiable information will be shared publicly.

We will begin to upload data to the NIH NDA beginning in July 2025 per NIMH requirements, which would then be made publicly available by November 2025. Data in the NDA will be made available indefinitely as long as the NDA exists as a resource.

Informed consent documents, protocol information, and statistical analysis plan information will all be uploaded to clinicaltrials.gov. Access to participant level data will be managed by the NIH National Data Archive where all the individual participant data and supporting information will be uploaded. Additional data regarding statistical analyses and corresponding code will be provided as supplemental material to publications that use this data. Since this is a mechanistic clinical trial and not an RCT, a CSR is not applicable.