Every year, millions of children are diagnosed with neurodevelopmental disabilities. This term covers a wide range of conditions, from genetic syndromes to brain injuries such as cerebral palsy. Children with neurodevelopmental disabilities often struggle in multiple areas, including language development. While standard speech therapy mainly focuses on understanding and producing words, these children may also have difficulties with the social and communicative skills needed for language. The parent-child relationship is especially important for helping kids develop in their early years.

This clinical trial aims to find out if an intervention focused on early social and communication skills, and involving parents, can help children with neurodevelopmental disabilities. The study includes children aged 6 months to 5 years. It seeks to answer two key questions:

• Does this intervention improve social and communication skills better than standard speech therapy?
• Does this intervention affect how parents interact with their child?

To find the answers, the study will compare two groups: one group will get the parent-involved intervention that focuses on early communication skills, while the other group will get standard speech therapy.

In the first intervention, therapists will guide parents in observing and supporting their child's social and communication behaviors during various activities like playtime and snack time. In contrast, the standard speech therapy will focus on traditional goals, such as improving the child's ability to vocalize, understand, and use words, without involving parents.

Both interventions will follow the same schedule-eight weekly sessions, each lasting 45 minutes, over two months.

Before and after the interventions, the children and parents will:

• Have an assessment of the child's language, social, and communication development.
• Participate in a 10-minute video recording of parent-child playtime, which will be used to study parenting behavior.

Background: Every year millions of children receive a diagnosis of neurodevelopmental disability (NDD), with a systematic report documenting a prevalence rate estimated in 13.3% of children younger than 5 years in 195 countries. The term neurodevelopmental disability includes diverse clinical conditions ranging from congenital disorders, such as genetic syndromes, to acquired brain damage, such as cerebral palsy. From birth, children with NDD often show difficulties in different developmental domains. For instance, these children may exhibit atypical interactive and attentional skills, they may use less vocal and affective signals and also display difficulties in emotional-behavioral regulation. Such altered interactional and behavioral patterns affect the development of primary intersubjectivity, which refers to the attentional and emotional coordination between parent and child during face-to-face exchanges. Additionally, these challenges can hinder the development of secondary intersubjectivity, where both the parent and child focus their attention on a shared object in the environment. These forms of intersubjectivity are crucial for the emergence of verbal communication. Nonetheless, these abilities are not easily measured by conventional assessments during early childhood, which may result in delayed identification and promotion of early intervention. Assessing and addressing these early socio-communicative difficulties through targeted interventions is thus crucial to promote better communication and relational outcomes for children with NDD.

The parent-child relationship serves as the primary context in which the child develops cognitive, linguistic, and social-emotional skills through contingent and synchronous interactions with the parent. However, contingent interactions between parents and children can be challenging when the child has a NDD, as their communicative behaviors may be unclear or difficult to interpret. Reduced or partial signals, such as facial expressions, gestures like pointing, reaching, or showing objects, can hinder the parents' ability to accurately interpret the child's cues and intentions, complicating the interaction and making it more difficult for parents to respond appropriately. Indeed, Indeed, alterations in early preverbal intersubjective and socio-communicative skills-such as vocalizations, eye contact, smiling, and shared attention-can disrupt the quality of daily parent-child interactions. These disruptions may negatively impact on parenting behavior, potentially leading to long-term adverse effects on the child's cognitive and language development. Involving parents in early interventions may help them perceive and understand early communicative signals of their children, enabling an appropriate response and providing suitable and contingent stimulations.

Primary aim of the study: The main aim is to compare the feasibility and efficacy of an intervention focused on socio-communicative intersubjective skills, actively involving one of the parents (SPEAK intervention), with those of standard speech therapy. The goal is to determine whether the intervention tailored to these specific skills and involving parents provides greater benefits in supporting early communication and social development.

Secondary aims of the study: A secondary aim is to evaluate whether the SPEAK intervention actively involving parents will lead to improvements in how parents interact with their children.

Exploratory aims: Additional exploratory aims of this study include: (a) verifying whether the SPEAK intervention may also result in improvements in children's socio-cognitive skills and socio-emotional development; (b) investigating associations between parenting behaviour and other outcome measures at T0 across groups; (c) assessing the psychometric properties of the recently developed tool "Observation of Prelinguistic Intersubjective and Socio-Communicative Skills" (OPISCoS; Strazzer et al., 2023), through comparisons with standardized tests that evaluate communication and social development.

Procedure: Sixty children with NDD, aged between 6 months and 5 years, will be recruited from rehabilitation centers affiliated with Associazione La Nostra Famiglia. All centers treat similar clinical populations and utilize a consistent rehabilitative approach. Eligible participants will be referred by the attending physician to the research team. Parents will be informed about the study's procedures and asked to provide informed consent.

Participants will be randomly assigned to either the experimental group, which will receive an intervention focused on socio-communicative and intersubjective skills (SPEAK intervention), or the control group, which will receive standard speech therapy (care as usual). Stratified randomization with permuted blocks will be used to ensure balanced group assignment based on age and developmental quotient. Age will be split as follows: 6 - 35 months, 36 - 59 months. The cut-off for developmental quotient will distinguish participants with moderate/severe psychomotor delay (< 55 or non-assessable) and with mild psychomotor delay/borderline functioning (≥ 55). This way, participants will be assigned to the two arms according to the permuted sequences within the four stratification blocks (16 patients per block).

Participants assigned to the experimental arm will receive eight sessions of an intervention focused on early socio-communicative and intersubjective skills, which will actively involve one of the parents. Participants assigned to the control group will receive standard speech therapy. Both interventions will be carried out by previously formed speech therapists, and will have the same duration - 8 45-minute weekly sessions, over two months.

Before starting any intervention sessions, participants will be administered with standardized tests to assess primary and secondary outcomes. Information regarding previous or concurrent rehabilitative treatments (e.g., psychomotricity), as well as other pertinent clinical and socio-demographic data (e.g., socio-economic status), will be collected from medical records or through specific questionnaires.

Adherence to the study Given the rehabilitative nature of the interventions and the fact that parents request access to rehabilitation centers for speech therapy, significant adherence challenges are not anticipated. In line with previous early intervention studies, a drop-out rate of 10-15% is expected among recruited patients. At the time of recruitment, it will be required that at least one parent attends all sessions to minimize differences in drop-out rates between the experimental and control groups, since only the experimental intervention involves active parental participation. Adherence will be monitored by recording the number of participants who discontinue treatment, documenting reasons for withdrawal where possible, and tracking the number of sessions completed by each participant.

Evaluation of the potential benefit/risk ratio for the population. No risks are anticipated for the study population. The assessments and procedures to be implemented are consistent with the activities already conducted in the clinical practice at the recruiting rehabilitation centers. The assessments conducted both at the beginning and end of intervention directly benefit participants by providing a comprehensive evaluation of their progress. Indirectly, the study will encourage a more focused approach to socio-communicative and intersubjective skills in speech therapy with children with NDD. Additionally, the study will promote the specialized training of the speech therapists involved, further enhancing care quality.

Inclusion criteria:

For children:

• Age between 6 months (corrected age in cases of prematurity) and 5 years.
• Documented developmental delay and/or socio-communicative difficulties, based on clinical signs or standardized developmental scales (e.g., Griffiths Scales).
• Mental age of at least 6 months.
• Diagnosis of neurodevelopmental disability, including cerebral palsy, genetic syndromes, rare diseases with non-progressive neurological impairments, or congenital disorders of undetermined nature.

For parents:

• Adult age (≥ 18 yo)
• Good knowledge and fluency in Italian.
• No manifest psychiatric conditions.
• No documented intellectual disability.

Exclusion criteria:

For children:

• Age greater than 5 years at the time of recruitment.
• Mental age below 6 months.
• Absence of developmental delay (developmental quotient > 85) and socio-communicative difficulties.
• Diagnosis of neurodevelopmental disability resulting from neurodegenerative diseases or brain tumor outcomes.
• Severe sensory impairments (profound deafness and/or blindness).

For Parents:

• Inability to speak Italian.
• Documented psychiatric conditions or intellectual disability.

Anonymized raw data will be made available through public repositories, such as ZENODO.

Psychologists administering the Bayley-III Socio-Emotional Questionnaire and ESB Battery, as well as evaluating parenting behavior using the PICCOLO, will be blinded to each participant's group assignment. However, due to the nature of the assessments and treatment, the therapists conducting OPISCoS cannot be blinded.