Executive Functions and ICF Core Sets in Cerebral Palsy: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis of 38 studies involving 1,633 individuals with cerebral palsy demonstrates that executive functions are meaningfully associated with all domains of functioning, particularly activity, supporting the integration of routine executive function assessment and intervention into clinical care.

The Gist

The Big Picture: The "Brain's CEO" and the "Body's Team"

Imagine a person with Cerebral Palsy (CP) as a high-tech construction crew.

• The Body (Motor Skills): This is the crew of workers. Sometimes, due to an injury to the brain's "blueprints" (the developing brain), some workers have trouble moving their arms, legs, or speaking clearly. This is the motor impairment most people know about CP.
• The Executive Functions (EF): This is the Site Manager or the CEO of the crew. The CEO doesn't do the heavy lifting, but they are responsible for planning the day, telling workers when to stop and start, remembering the instructions, and switching tasks when the plan changes.

The Problem: For a long time, doctors and researchers focused almost entirely on the workers (the body's movement). They asked, "How well can they walk? How well can they hold a cup?" But they often ignored the Site Manager (the brain's planning skills).

The Study's Goal: This paper wanted to find out: How much does the Site Manager (Executive Functions) affect the whole construction site (Daily Life), even if the workers (Body) are struggling?

---

What Did They Do? (The Detective Work)

The researchers acted like detectives. They didn't just look at one study; they gathered 38 different studies involving 1,633 people with CP. They used a special map called the ICF (International Classification of Functioning, Disability and Health).

Think of the ICF map as a four-story building that describes a person's life:

1. Basement (Body Functions): The hardware. (Brain structure, muscles, pain).
2. Ground Floor (Activity): Doing specific tasks. (Walking, writing, eating).
3. Second Floor (Participation): Joining the community. (Going to school, making friends, working).
4. Penthouse (Contextual Factors): The environment. (Family support, school rules, society).

The researchers asked: "If the Site Manager (EF) is having a bad day, does the whole building suffer?"

---

The Main Findings: The Connection is Real!

The answer was a resounding YES.

The study found a medium-to-strong connection between the Site Manager's skills and how well the whole building runs.

• The Strongest Link: The connection was strongest between the Site Manager and the Ground Floor (Activity).

  • Analogy: Imagine trying to walk down a hallway while carrying a tray of drinks. If your Site Manager is good at planning and focusing, you can walk even if your legs are a bit shaky. If the Site Manager is overwhelmed, you might drop the tray, even if your legs are strong.
  • Result: Good planning and focus skills helped people with CP do daily tasks (like schoolwork or moving around) much better.

• The Other Floors: The Site Manager also helped with the Basement (body functions) and the Second Floor (social life/participation), though the link was slightly less direct than with daily tasks.

Who Was Affected the Most? (The Moderators)

The study looked at who showed the strongest connections:

1. The "Mixed" Crew: People with Mixed Cerebral Palsy (a mix of different movement types) showed the strongest link between their brain skills and their daily life.
   • Why? It's like a construction site with a very diverse team. The Site Manager has to work extra hard to coordinate everyone, so their skills become the most critical factor for success.
2. The Younger Crew: The connection was stronger in younger children than in adults.
   • Why? Kids are still learning how to be independent. They rely heavily on their Site Manager to figure out how to do things. As adults, they often develop "routines" and habits (like a well-oiled machine running on autopilot), so they rely a little less on active, moment-to-moment planning.

What About the "Bad News"? (Limitations)

The researchers found a few bumps in the road:

• Missing Data: There weren't many studies on adults with CP. We know a lot about kids, but we don't know enough about how this works for grown-ups.
• The "Severe" Gap: Many studies focused on people who could walk or move their hands well. There were very few studies on people with severe disabilities who might need wheelchairs or communication devices.
  • The Issue: It's hard to test a Site Manager if the workers can't hold a pen to write down the answers. We need better ways to test the brain in people with severe physical limitations.
• The "Context" Gap: The Penthouse (Contextual Factors like family support or school rules) was rarely studied. The researchers think we need to look more at how the environment helps or hurts the Site Manager.

The Takeaway: What Should We Do?

This paper is a wake-up call for doctors, teachers, and parents.

1. Test the Manager, Not Just the Workers: When assessing a child with CP, don't just check if they can walk. Check if they can plan, focus, and switch tasks. If the Site Manager is struggling, the whole crew will struggle, even if the workers are strong.
2. Train the Manager: Interventions shouldn't just be about physical therapy. We need to train the Executive Functions (planning, organizing, self-control).
3. Connect to Real Life: The best way to train the Site Manager is to practice in real-life situations (like getting ready for school or cooking a meal), not just in a quiet room with a computer game.
4. Help the Younger Ones: Since the link is strongest in kids, early intervention is crucial. Help them build good habits while they are young.

In a Nutshell

Think of Cerebral Palsy not just as a "movement problem," but as a team coordination challenge. This study proves that the brain's planning skills (Executive Functions) are the glue that holds the daily life of a person with CP together. If you help the "Site Manager" get better at their job, the whole "construction crew" (the person's daily life, school, and social life) works much better.

Technical Summary

1. Problem Statement

Cerebral Palsy (CP) is a heterogeneous group of disorders characterized by movement and posture abnormalities, often accompanied by non-motor impairments, including deficits in Executive Functions (EF). EF are advanced cognitive processes (e.g., inhibitory control, working memory, cognitive flexibility) essential for goal-directed behavior and daily functioning.

While previous research has established that individuals with CP experience EF impairments, there is a lack of synthesized evidence quantifying the magnitude of the relationship between EF and broader domains of functioning. Specifically, no study has systematically mapped these associations across the full spectrum of the International Classification of Functioning, Disability and Health (ICF) framework (Body Functions & Structures, Activity, Participation, and Contextual Factors) using CP-specific Core Sets. This gap hinders the ability to determine how EF deficits translate into functional limitations and to what extent they should be targeted in clinical interventions.

2. Methodology

Study Design and Protocol

• Type: Systematic Review and Meta-Analysis.
• Registration: PROSPERO (CRD42024614057).
• Guidelines: PRISMA 2020.
• Search Strategy: Comprehensive search across eight electronic databases (PubMed, EMBASE, MEDLINE, Cochrane, CINAHL, Web of Science, ERIC, APA PsycArticles) up to July 14, 2025.
• Eligibility Criteria:
  • Participants: Individuals with a diagnosis of CP (mixed populations allowed if ≥80% CP).
  • Exposure: Assessment of at least one EF domain (based on Miyake/Diamond or Anderson models: inhibitory control, working memory, cognitive flexibility, higher-order EF, or composite scores).
  • Outcome: Association with at least one ICF domain mapped to the CP-specific ICF Core Sets.
  • Study Type: Peer-reviewed primary studies.

Data Extraction and Quality Assessment

• Extraction: Two reviewers independently extracted data on demographics, CP subtypes, functional classifications (GMFCS, MACS, CFCS, VSS), EF assessment tools, and correlation coefficients ($r$).
• Mapping: EF outcomes were standardized into five categories. ICF outcomes were mapped to four domains: Body Functions & Structures, Activity, Participation, and Contextual Factors.
• Quality Control: Risk of Bias (RoB) was assessed using the Quality in Prognosis Studies (QUIPS) tool across six domains (Study participation, attrition, prognostic factor measurement, outcome measurement, confounding, statistical analysis).

Statistical Analysis

• Model: Three-level random-effects meta-analytic models were employed to account for the dependency of multiple effect sizes within the same study.
  • Level 1: Sampling variance.
  • Level 2: Within-study variance.
  • Level 3: Between-study variance.
• Effect Size: Correlation coefficients ($r$) were transformed to Fisher's $z$ for analysis and back-transformed for interpretation. Benchmarks: Small (0.10–0.25), Medium-to-Large (0.25–0.40), Large (>0.40).
• Heterogeneity & Moderators: $I^2$ statistics quantified heterogeneity. Moderator analyses (using mixed-effects models) examined the influence of CP subtype, EF domain, assessment tool type (performance-based vs. questionnaire), and mean age.
• Bias & Sensitivity: Publication bias was assessed via Egger's test and funnel plots, with trim-and-fill adjustments. Sensitivity analyses excluded high RoB studies.

3. Key Contributions

1. First Comprehensive Mapping: This is the first study to synthesize evidence linking EF to all ICF domains (including Contextual Factors) specifically within the CP population using CP-specific Core Sets.
2. Quantitative Synthesis: Provides the first meta-analytic estimates of the strength of the relationship between EF and functional outcomes in CP.
3. Identification of Moderators: Clarifies how specific factors (e.g., CP subtype, age, assessment method) influence the strength of the EF-functioning association.
4. Methodological Critique: Highlights significant gaps in current literature, including the underrepresentation of adults, severe motor impairments (GMFCS IV-V), and contextual factors, as well as the lack of standardized EF assessment protocols for CP.

4. Results

Study Characteristics

• Sample: 38 studies included, comprising 1,633 participants with CP.
• Demographics: Mean age ranged from 3 to 62 years (heavily skewed toward children 7–12 years). Spastic CP was the most common subtype (74% of reported motor types).
• Quality: 53% of studies had moderate RoB; 29% had high RoB, primarily due to study confounding and participation issues.

Meta-Analytic Findings (Pooled Effect Sizes)
A medium-to-large positive association was found between EF and functioning across all ICF domains combined ($r = 0.26, p < 0.001$). Domain-specific breakdowns:

• ICF Activity: Strongest association ($r = 0.38, p < 0.001$). This includes tasks like learning, applying knowledge, and mobility (walking, hand use).
• ICF Participation: Medium-to-large association ($r = 0.26, p < 0.01$). Includes social interactions, school, and community life.
• ICF Body Functions & Structures: Medium association ($r = 0.21, p < 0.01$). Includes mental functions (intellect, language) and brain structures.
• ICF Contextual Factors: Underrepresented (only 3 studies); excluded from quantitative meta-analysis due to low sample size.

Moderator Analyses

• CP Subtype: Significantly moderated the relationship ($p = 0.023$). Mixed CP samples showed the strongest association ($r = 0.47$), while Spastic ($r = 0.14$) and Dyskinetic ($r = -0.16$) subtypes showed weaker, non-significant effects.
• Age: Mean age significantly moderated the relationship ($p = 0.013$). Younger age was associated with stronger EF-functioning correlations; associations weakened in older samples.
• Assessment Tool: Performance-based tests showed a significant medium-to-large association ($r = 0.33$), whereas questionnaires showed a smaller, non-significant association ($r = 0.13$).
• EF Domain: While not statistically significant as a moderator overall, Working Memory showed the largest descriptive effect size ($r = 0.39$).

Bias and Sensitivity

• Publication bias was detected in three of four models. Trim-and-fill adjustments reduced effect sizes (e.g., overall $r$ dropped to 0.12), but associations remained statistically significant and robust.
• Sensitivity analyses excluding high RoB studies confirmed the stability of the findings, particularly for the Activity domain.

5. Significance and Implications

Clinical Implications

• Routine Assessment: The findings support the integration of routine EF assessments into standard clinical care for individuals with CP, as EF are meaningful correlates of daily functioning.
• Intervention Targets: EF should be viewed not just as a cognitive deficit but as a critical intervention target to improve functional outcomes (Activity and Participation).
• Age-Specific Strategies: Interventions for younger children should focus on enhancing EF capacities, while interventions for older individuals may benefit more from optimizing routines and environmental supports to compensate for age-related declines in the EF-functioning link.

Research Implications

• Standardization: There is an urgent need for standardized, accessible EF assessment protocols specifically validated for the CP population, particularly for those with severe motor and speech impairments.
• Diverse Sampling: Future research must include more adults with CP and individuals with severe motor disabilities (GMFCS IV-V) to ensure findings are generalizable across the lifespan and severity spectrum.
• Contextual Factors: Research must expand to include ICF Contextual Factors (environmental and personal), which are currently underexplored despite their theoretical importance in the ICF model.

Conclusion
Executive functions are significantly and meaningfully associated with multiple domains of functioning in individuals with CP. The strongest link is with Activity, suggesting that EF are crucial for task execution and daily performance. These findings validate the inclusion of EF assessment and intervention in holistic CP management strategies.