The consequences for children born with birth defects and developmental disabilities encompassed by foetal alcohol spectrum disorder (FASD) are profound, affecting all areas of social, behavioural and cognitive functioning. Given the strong evidence for a core deficit in executive functioning, underpinned by impaired self-regulation skills, there has been a growing focus on the development of interventions that enhance or support the development of executive functions (EFs).
The primary objective of this review is to synthesise the evidence for structured psychological interventions that explicitly aim to improve EF in children. The review also sought to ascertain if the effectiveness of interventions were influenced by characteristics of the intervention, participants or type of EF targeted by the intervention.
Sixteen databases, 18 grey literature search locations and 9 trial registries were systematically searched to locate eligible studies (up to December 2020). These searches were supplemented with reference harvesting, forward citation searching, hand searches of topic-relevant journals and contact with experts.
Studies were included in the review if they reported on an impact evaluation of a psychological intervention aiming to improve EF in children 3–16 years who either had confirmed prenatal alcohol exposure or a formal diagnosis falling under the umbrella term of FASDs. Eligible study designs included randomised controlled trials (RCTs) and quasi-experimental designs with either no treatment, wait list control or an alternative treatment as a comparison condition. Single-group pre-post designs were also included.
Data Collection and Analysis:
Standard methodological procedures expected by the Campbell Collaboration were used at all stages of this review. Standardised mean differences (SMDs) were used to estimate intervention effects, which were combined with random effects meta-analysis (data permitting). Risk of bias was assessed using the Cochrane Risk of Bias Tool (RoB2) and Cochrane Risk of Bias in Non-Randomised Studies-Interventions tool (ROBINS-I).
The systematic search identified 3820 unique records. After title/abstract and full-text screening, 11 eligible studies (reported in 21 eligible documents) were deemed eligible, with a combined 253 participants. Of the 11 studies, 6 were RCTs, 1 was a quasi-experiment and 4 were single-group pre-post intervention designs. All studies were rated as having an overall high or serious risk of bias, with some variation across domains for RCTs. For RCT and quasi-experimental studies, the overall effect of EF interventions on direct and indirect measures of EF generally favoured the experimental condition, but was not statistically significant. There was no difference between intervention and comparison groups on direct measures of auditory attention (k = 3; SMD = 0.06, 95% confidence interval [CI] = −1.06, 1.18), visual attention (k = 2; SMD = 0.90, 95% CI = −1.41, 3.21), cognitive flexibility (k = 2; SMD = 0.23, 95% CI = −0.40, 0.86), attentional inhibition (k = 2; SMD = 0.04, 95% CI = −0.58, 0.65), response inhibition (k = 3; SMD = 0.47, 95% CI = −0.04, 0.99), or verbal working memory (k = 1; d = 0.6827; 95% CI = −0.0196, 1.385). Significant heterogeneity was found across studies on measures of auditory attention and visual attention, but not for measures of cognitive flexibility, attentional inhibition or response inhibition. Available data prohibited further exploration of heterogeneity. There was no statistical difference between intervention and comparison groups on indirect measures of global executive functioning (k = 2; SMD = 0.21, 95% CI = −0.40, 0.82), behavioural regulation (k = 2; SMD = 0.18, 95% CI = −0.43, 0.79), or emotional control (k = 3; SMD = 0.01, 95% CI = −0.33, 0.36). Effect sizes were positive and not significant for meta-cognition (k = 1; SMD = 0.23, 95% CI = −0.72, 1.19), shifting (k = 2; SMD = 0.04, 95% CI = −0.35, 0.43), initiation (k = 1; SMD = 0.04, 95% CI = −0.40, 0.49), monitoring (k = 1; SMD = 0.25, 95% CI = −0.20, 0.70) and organisation of materials (k = 1; SMD = 0.25, 95% CI = −0.19, 0.70). Effect sizes were negative and not statistically different for effortful control (k = 1; SMD = −0.53, 95% CI = −1.50, 0.45), inhibition (k = 2; SMD = −0.08, 95% CI = −0.47, 0.31), working memory (k = 1; SMD = 0.00, 95% CI = −0.45, 0.44), and planning and organisation (k = 1; SMD = −0.10, 95% CI = −0.55, 0.34). No statistically significant heterogeneity was found for any of the syntheses of indirect measures of EF. Based on pre-post single-group designs, there was evidence for small to medium sized improvements in EF based on direct measures (cognitive flexibility, verbal working memory and visual working memory) and indirect measures (behavioural regulation, shifting, inhibition and meta-cognition). However, these results must be interpreted with caution due to high risk of bias.
This review found limited and uncertain evidence for the effectiveness of interventions for improving executive functioning in children with FASD across 8 direct and 13 indirect measures of EF. The findings are limited by the small number of high-quality studies that could be synthesised by meta-analysis and the very small sample sizes for the included studies.