Exposure to deprivation in early life was significantly associated with impaired executive functioning in children and adolescents, based on data from a systematic review and meta-analysis of 91 studies.
Previous research has shown connections between early-life adversity (ELA) and changes in psychological, cognitive, and neurobiological development, including increased risk of anxiety, depression, attention-deficit/hyperactivity disorder, conduct disorder, suicidality, and substance use disorder; however, research focusing on the associations between different types of ELA and specific processes is limited, wrote Dylan Johnson, MSc, of the University of Toronto and colleagues.
“We directly addressed this gap in the literature by examining the association between the type of ELA and executive functioning in children and youth,” they said.
In a study published in JAMA Pediatrics, the researchers identified 91 articles including 82 unique cohorts and 31,188 unique individuals aged 1-18 years.
The articles were selected from Embase, ERIC, MEDLINE, and PsycInfo databases and published up to Dec. 31, 2020. The primary outcomes were measures of the three domains of executive functioning: cognitive flexibility, inhibitory control, and working memory. To correct for small sample sizes in some studies, the researchers standardized their measures of association into Hedges g effect sizes.
Overall, the pooled estimates of the association of any childhood adversity with the three domains of executive functioning showed significant heterogeneity, with Hedges g effects of –0.49 for cognitive flexibility, –0.39 for inhibitory control, and –0.47 for working memory.
The researchers also examined a subsample of ELA–executive functioning associations in categories of early-life exposure to threat, compared with early-life deprivation, including 56 of the original 91 articles. In this analysis, significantly lower inhibitory control was associated with deprivation compared to threat (Hedges g –0.43 vs. –0.27). Similarly, significantly lower working memory was associated with deprivation, compared with threat (Hedges g –0.54 vs. Hedges g –0.28). For both inhibitory control and working memory, the association of adversity was not moderated by the age or sex of the study participants, study design, outcome quality, or selection quality, the researchers noted.
No significant difference in affect of exposure threat vs. deprivation was noted for the association with cognitive flexibility. The reason for this discrepancy remains unclear, the researchers said. “Some evidence suggests that individuals who grow up in unpredictable environments may have reduced inhibitory control but enhanced cognitive flexibility,” they noted.
However, the overall results suggest that exposure to deprivation may be associated with neurodevelopmental changes that support the development of executive functioning, they said.
The study findings were limited by several factors, including the substantial heterogeneity in the pooled estimates and the need to consider variation in study design, the researchers noted. In addition, the cross-sectional design of many studies prevented conclusions about causality between ELA and executive functioning, they said.
“Future research should explore the differences between threat and deprivation when emotionally salient executive functioning measures are used,” the researchers emphasized. “Threat experiences are often associated with alterations in emotional processing, and different findings may be observed when investigating emotionally salient executive functioning outcomes,” they concluded.