Speech and language therapy for preschool children: what the evidence shows

Speech and language therapy can help children who have difficulties with communication. For parents, understanding the evidence behind these therapies can help inform decisions. This article looks at research on speech and language therapy for preschool children with primary speech and language delay or disorder. This means the findings apply to children whose language difficulties are not primarily due to other diagnosed conditions, such as hearing loss, autism spectrum disorder, or a learning disability, nor to language differences that arise from bilingualism.

About 6% of children experience speech and language difficulties [1]. While many of these difficulties may resolve on their own, those that continue into primary school can sometimes lead to long-term challenges [1]. These challenges can affect a child's literacy, how they socialize, their behaviour, and their school performance [1].

Understanding primary speech and language delay or disorder

When researchers study speech and language therapy, they often focus on specific groups of children. The studies discussed in this article looked at children diagnosed with a "primary speech and language delay or disorder" [1, 3]. This term describes children whose main developmental challenge is related to their speech or language [1].

It is important to understand what this definition includes and excludes. "Primary" is the key word: the Cochrane review describes this group as children whose speech and language difficulties are their main difficulty, the majority of whom do not have other significant developmental difficulties [1]. So these findings are not about language difficulties that form part of another diagnosed condition. They are also not a statement about children who are learning more than one language — growing up bilingual is a language difference rather than a disorder, and whether a particular child's development is on track is a question for a registered speech-language pathologist who can assess them in all the languages they use. The research focuses specifically on children whose speech or language delay is considered their primary area of difficulty.

Evidence from a Cochrane Review

A comprehensive review published in 2003 by Law and colleagues examined the effectiveness of speech and language interventions [1]. This review, part of the Cochrane Database of Systematic Reviews, combined the results of 25 randomized controlled trials (RCTs) [1]. A Cochrane review is a type of systematic review that follows strict guidelines to identify, evaluate, and summarize evidence from research studies. This approach aims to provide reliable information about healthcare interventions [1].

The studies included in this review focused on children and adolescents with primary speech and language delay or disorder [1]. The researchers looked at how interventions affected different areas of language: expressive and receptive phonology, syntax, and vocabulary [1].

Different results for different language areas

The Cochrane review found different levels of evidence for the effectiveness of speech and language therapy depending on the specific language area targeted [1]. This is an important distinction, as a child's communication challenges can vary widely.

• Expressive phonology and vocabulary: The review found that speech and language therapy was effective for children who had difficulties with expressive phonology or expressive vocabulary [1].

  • Expressive phonology refers to a child's ability to produce speech sounds correctly and clearly so others can understand them. For example, a child might have difficulty saying "cat" instead of "tat."
  • Expressive vocabulary relates to the words a child uses to communicate their thoughts and needs. This could involve a child having a smaller range of words than expected for their age.
  • For these two areas, the combined results from the studies showed a positive effect [1].

• Expressive syntax: The findings were more mixed when it came to the effectiveness of interventions for children with difficulties in expressive syntax [1].

  • Expressive syntax involves a child's ability to combine words into grammatically correct sentences. For example, a child might say "Me go park" instead of "I want to go to the park."
  • The review included data from 233 children for this outcome, and the results showed a wide range of possible effects, indicating less certainty about the overall effectiveness [1].

• Receptive language: For children with receptive language difficulties, there was less evidence that interventions were effective [1].

  • Receptive language refers to a child's ability to understand spoken language. This could involve difficulties following instructions, understanding questions, or comprehending stories.
  • The review found no significant positive effect for interventions targeting receptive language, and highlighted a need for further research in this area [1].

Delivery methods and group settings

The Cochrane review also explored different ways speech and language therapy can be delivered [1]. The findings suggest flexibility in how therapy can be provided:

• Clinician-administered versus parent-implemented: The review found no significant difference in effectiveness between interventions delivered directly by a clinician and those implemented by trained parents [1]. This suggests that parents, with appropriate training, can play a valuable role in delivering therapy.
• Group versus individual therapy: The studies did not show a difference in the effects of group interventions compared to individual interventions [1]. This indicates that both settings can be effective.
• Including peers: Interestingly, the use of peers who have typical language development in therapy was shown to have a positive effect on the outcome of the therapy [1].

Limitations of the Cochrane Review

The reviewers noted that there was a "large degree of heterogeneity" in the results of the studies they analyzed [1]. This means there was significant variation among the study findings, and the sources of this variation would need further investigation [1]. It is also worth noting that this review was published in 2003, and research in the field continues to evolve.

Parent-implemented language interventions

Many Canadian public programs for early language intervention use a model where parents are coached to deliver therapy strategies at home. A meta-analysis published in 2011 by Roberts and colleagues specifically evaluated the effectiveness of these parent-implemented language interventions [2]. A meta-analysis combines the results of multiple independent studies to provide a more comprehensive understanding of an intervention's effect.

This meta-analysis included 18 studies and focused on children between 18 and 60 months of age [2]. The population included children with primary and secondary language impairments, meaning it covered children with language difficulties both with and without intellectual disabilities [2].

Positive impact on language skills

The results of this meta-analysis indicated that parent-implemented language interventions have a significant and positive impact on the receptive and expressive language skills of young children [2]. This positive effect was observed in children both with and without intellectual disabilities [2].

The effect sizes for child measures, which indicate the strength of the intervention's impact, ranged from -0.15 to 0.82 [2]. These findings support the use of parent-implemented approaches in early language intervention [2].

Implications for practice

The conclusion of the Roberts et al. review was that parent-implemented language interventions are an effective approach for young children with language impairments [2]. This is relevant for programs that aim to empower parents to support their child's language development in natural, everyday settings.

Real-world effectiveness of therapy

Beyond systematic reviews and meta-analyses, individual studies can also provide valuable insights into the effectiveness of speech and language therapy. A randomized controlled trial (RCT) conducted by Broomfield and colleagues, published in 2011, looked at the real-world impact of therapy [3]. An RCT is a study design where participants are randomly assigned to either receive an intervention or a control condition (like no intervention), which helps to minimize bias and strengthen the evidence for cause and effect.

Study design and participants

This RCT involved 730 children who were referred to a Paediatric Speech and Language Therapy Service [3]. The children, up to 16 years old, were diagnosed with primary speech and/or language impairment, meaning they did not have other learning, physical, or sensory difficulties [3].

The study compared outcomes for children who received treatment versus those who did not [3]. The treatment involved clinic-based interventions, which were provided according to local guidelines [3]. On average, children in the treatment group received about 5.5 hours of contact over a 6-month period, though the amount varied from 0 to 24 hours [3]. Assessments were completed within eight weeks of referral, and intervention began immediately after [3].

Treatment versus no treatment

The study found that treatment was significantly more effective than no treatment over the 6-month period [3]. This positive effect was observed overall and for each of the three diagnostic categories: comprehension (receptive language), expression (expressive language), and speech (articulation/phonology) [3].

The researchers concluded that an average of 6 hours of speech and language therapy over a 6-month period can lead to significant improvement in performance [3]. They found it to be more effective than receiving no treatment for children with primary speech and/or language impairment [3].

What this means for you

The research suggests that speech and language therapy can be an effective support for preschool children with primary speech and language delays or disorders. The evidence is strongest for difficulties with expressive phonology (making speech sounds) and expressive vocabulary (using words) [1, 3]. For challenges with expressive syntax (forming sentences), the findings are more mixed [1]. More research is needed to understand the effectiveness of interventions for receptive language difficulties (understanding language) [1].

It is also encouraging that therapy can be delivered in various ways, including by trained parents, and can be effective in both individual and group settings [1, 2].

If you have concerns about your child's speech or language development, it is helpful to consult with a regulated professional. A licensed speech-language pathologist can assess your child's specific needs and determine if therapy is suitable. They can also help create a personalized intervention plan that considers your child's unique situation. You can learn more about when to seek a speech-language assessment for your child.

Regulation of speech-language pathology is province-dependent, so the right check depends on where you live. In the provinces that regulate the profession, a provincial college registers practitioners and publishes their standards — in Alberta, that is the Alberta College of Speech-Language Pathologists and Audiologists (ACSLPA), and that is where a registration check belongs [4]. Speech-Language and Audiology Canada is a national professional association that offers its own certification; it does not hold registration, so it cannot confirm that someone is registered to practise in your province [5].

To find a speech-language pathologist, you might search directories for clinics in your area, such as speech therapy clinics in Calgary or speech therapy clinics in Edmonton.