The RAINBOW study is a fully remote study focused on understanding and treating behavior problems in young children with tuberous sclerosis complex (TSC). The first goal is to enroll a group of 100 children with TSC between the ages of 3 and 6 years old, with and without problem behaviors, to learn about how best to measure behavioral challenges in TSC and how common these behaviors are during this age period. All families will get feedback from the clinical assessments collected. Eligible children who are experiencing behavior problems will be invited to enroll in a pilot clinical trial of internet-based Parent-Child Interaction Therapy (or PCIT), which is meant to help parents better manage their children's challenging behaviors. Adaptations to PCIT are incorporated to suit the needs of TSC children and families. Some participants will be randomly selected to receive the intervention immediately and others after a 6-month delay, but all families will receive the same intervention. Intervention sessions occur on a weekly basis for up to 20 weeks. Follow-up assessments, which include play interactions, parent interviews, and questionnaires occur about 3 and 6 months after the first visit. The delayed treatment group has an extra brief assessment about 12 months from the initial visit. This study will increase what is known about the types of behavior problems that come up during preschool age in TSC and how best to help children and families with TSC who are experiencing these problems.

The proposed study uses a telehealth approach to remotely assess and treat behavior problems in preschool-aged children with TSC. This study aims to 1) measure the prevalence and quality of externalizing behavior problems and their relation to family functioning in preschool-aged children with TSC; 2) examine the feasibility and acceptability of internet-based PCIT (I-PCIT) in children with TSC; 3) investigate the effects of I-PCIT on child and parent behavior in preschool-aged children with TSC and behavior problems; and 4) examine predictors of treatment response.

For Aim 1, 100 children with TSC ages 3-6 years old will be enrolled. Developmental abilities and behavior problems will be assessed using norm-referenced parent report measures and video recordings of parent-child interactions. The prevalence of behavior problems in young children with TSC and relation to family functioning will be assessed. A subset of the children from Aim 1 who exhibit elevated externalizing behavior will be recruited for the pilot intervention, with a target sample size of 32. Children will be randomized to an immediate treatment or waitlist control group. Assessments will be performed at baseline (using Aim 1 data), mid-point (3 months later), and post-treatment (6 months later). Families randomized to the waitlist group will have a brief, additional post-treatment assessment 12 months post-baseline). Sessions occur on a weekly basis for up to 20 weeks. Preliminary efficacy will be examined by comparing trajectories from baseline to post-treatment between the immediate treatment and waitlist control groups. Data on feasibility, acceptability, and predictors of treatment response will be studied across all intervention participants.

Inclusion Criteria:

For assessment visit:

• Clinical diagnosis of TSC
• Chronological age of 3 years, 0 months to 6 years, 11 months old at enrollment.
• English or Spanish as primary language in the home.

For intervention study only:

• Elevated behavior problems
• Parent/caregiver available to participate in PCIT

Exclusion Criteria:

For assessment visit:

• None

For intervention study:

• Plan for epilepsy surgery during study period

Outcome assessments will be performed by assessors who are blind to group status. Investigators will be kept blind to study outcomes until data collection for the primary outcome is complete.