Cognition and well-being are inextricably intertwined during development and may be malleable to social and biological factors

Well-Being and Cognition Are Coupled During Development: A Preregistered Longitudinal Study of 1,136 Children and Adolescents. Delia Fuhrmann, Anne-Laura van Harmelen, Rogier A. Kievit. Clinical Psychological Science, August 31, 2021. https://doi.org/10.1177/21677026211030211

Abstract: Well-being and cognition are linked in adulthood, but how the two domains interact during development is currently unclear. Using a complex systems approach, we preregistered and modeled the relationship between well-being and cognition in a prospective cohort of 1,136 children between the ages of 6 to 7 years and 15 years. We found bidirectional interactions between well-being and cognition that unfold dynamically over time. Higher externalizing symptoms in childhood predicted fewer gains in planning over time (standardized estimate [β] = −0.14, p = .019), whereas higher childhood vocabulary predicted smaller increases in loneliness over time (β = −0.34, p ≤ .001). These interactions were characterized by modifiable risk and resilience factors: Relationships to parents, friendship quality, socioeconomic status, and puberty onset were all linked to both cognitive and well-being outcomes. Thus, cognition and well-being are inextricably intertwined during development and may be malleable to social and biological factors.

Keywords: adolescent peer relations, complex systems, loneliness, Study of Early Child Care and Youth Development (SECCYD), vocabulary, preregistered

Discussion

We investigated the interactions between cognition and well-being in a large longitudinal cohort of 1,136 children and adolescents. Replicating previous, and largely cross-sectional, work (Irie et al., 2019; Rock et al., 2014), we showed pervasive cross-sectional links between cognition and well-being that indicated that cognition and well-being were already linked at 6 to 7 years of age. After we modeled longitudinal changes over time, however, a more subtle pattern emerged. Longitudinal links existed only for very specific domains and showed evidence of dynamic coupling.

Lower externalizing symptoms in childhood predicted more favorable planning trajectories. Externalizing symptoms include overactivity, poor impulse control, noncompliance, and aggression. Externalizing symptoms are linked to deficits in planning and similar executive function tasks in children with ADHD (Kuja-Halkola et al., 2015). We here show that ADHD in our study, too, predicts externalizing trajectories. Our findings extend this literature by showing similar associations in the general population. Our findings further indicate that behavioral symptoms may precede cognitive problems. Speculatively, behavioral problems may lead to social issues in school (Timmons & Margolin, 2015), which, in turn, may hamper academic attainment and cognitive development (Okano et al., 2020).

The opposite directionality emerged for the link between vocabulary and loneliness: Higher vocabulary in childhood predicted less loneliness in adolescence. The link is intuitive: Better verbal skills may allow children to relate better to others and protect against loneliness (Fritz et al., 2018). However, there is currently surprisingly little research investigating longitudinal links between vocabulary and loneliness, let alone longitudinal links in the general population (but see Forrest et al., 2018). We know that loneliness is linked to physical and mental health (Eccles et al., 2020; Matthews et al., 2016). Self-reported loneliness has been shown to be predictive of sleep (Eccles et al., 2020) and depression (Matthews et al., 2016)—and more so than more objective measures of social isolation (Matthews et al., 2016).

The complexity of our models required several statistical decisions that were not anticipated at the time of preregistration. For instance, we preregistered using linear latent growth curve models but found universally poor fit for these models. We therefore used a latent basis function approach that allowed us to freely estimate growth shapes and significantly improved model fit. Some statistical issues persisted even after attempts to improve model fit. The models to assess interactions between math and well-being showed poor model fit, for instance. These models, therefore, need to be interpreted with caution. For transparency, we clearly highlight deviations from our preregistration throughout the article.

Our findings suggest that interventions aimed at addressing behavioral problems and fostering verbal skills could be promising for improving cognition and well-being outcomes. Past research has shown that behavioral problems can be targeted by interventions, including measures such as parent training, family support, and school-based programs. However, long-term effectiveness has been studied little so far (Smedler et al., 2015), and little is known about possible effects on cognitive development. There is comparatively good evidence that loneliness is malleable to interventions. Most loneliness interventions have targeted older adults (Cattan et al., 2005) and used strategies such as improving social skills, enhancing social support, increasing opportunities for social contact, and addressing maladaptive social cognition (Masi et al., 2011). A meta-analysis showed that these are generally effective for reducing loneliness, particularly when targeting social cognition (Masi et al., 2011). Fewer interventions exist for young people, and of those available, most target loneliness as a side effect of physical health conditions. Because of the potential ramifications of loneliness for physical and mental health, we recommend replicating and extending our findings in future research to better understand how vocabulary relates to loneliness and test whether interventions improving vocabulary have positive effects on loneliness.

On a theoretical level, our findings of bidirectional relations between specific domains of cognition and well-being in childhood and adolescence provide evidence for mutualistic relationships between cognition and well-being that unfold dynamically over development. Small individual differences in externalizing in childhood may set children on different planning trajectories. Small differences in vocabulary may predict different trajectories of loneliness. This supports the complex systems account of mental health problems and cognitive development (Borsboom, 2017; Burger et al., 2020; Fritz et al., 2018; Kievit et al., 2017; Lunansky et al., 2020; McElroy et al., 2018; Van Der Maas et al., 2006). Our study shows that not only are cognition and well-being complex systems in and of themselves, but they also interact with one another during development, generating yet further dynamic processes.

Risk and resilience factors explain heterogeneity in trajectories

Relationships between well-being and cognition were highly heterogeneous, particularly for loneliness and its relationship with cognition. Lower vocabulary was associated with a spike in loneliness around 8 to 9 years for 12% of the sample. Around ages 10 to 11, adolescents in the United States transition from elementary to middle school. However, there are no obvious school transitions around ages 8 to 9 in the United States, which makes it more likely that spikes in loneliness around this age reflect a more intrinsic developmental pattern. Previous work suggests that the period between late childhood and early adolescence represents a time of biological and social change (Andersen & Teicher, 2008; Blakemore & Mills, 2014; Fuhrmann et al., 2019). This may lead to increases in loneliness and reduced well-being for a subset of young people.

In our sample, a subset of young people was characterized by risk factors including earlier puberty, lower socioeconomic status, lower friendship quality, and poorer relationships with parents. This is in line with previous work highlighting the links between early physical maturation and mental health (Lewis et al., 2018; Sequeira et al., 2017). Early puberty onset has also been associated with lower performance, particularly on self-control and risk-taking tasks (Laube et al., 2020), and lower academic attainment (Cavanagh et al., 2007). Developmental theories suggest that early puberty may accentuate preexisting differences in childhood (Caspi & Moffitt, 1991) or impair plasticity and learning (Schulz et al., 2009). Note, however, that several empirical (Chaku & Hoyt, 2019; Koerselman & Pekkarinen, 2017) and theoretical studies (Belsky et al., 2007; Laube & Fuhrmann, 2020) now suggest that in supportive environments, early puberty can be linked to more positive cognitive outcomes, too. Chaku and Hoyt (2019) showed that early maturation may be associated with lower self-control but also better attention. The social context also shapes outcomes after early puberty (Belsky et al., 2007). Preliminary evidence suggests that supportive contexts may allow early maturers to benefit from new learning opportunities in adolescence (Klopack et al., 2020).

Overall, these findings underline that biological factors intersect with social risk and resilience factors such as socioeconomic status, parental closeness, and friendship quality. All three were here found to be independently linked to poorer cognitive and well-being outcomes (after controlling for the other two social risk factors). This finding is in line with an emerging body of literature highlighting that socioeconomic status (Hackman et al., 2015), friendship quality (van Harmelen et al., 2016, 2017; Ybarra et al., 2010), and relationships to parents (Laursen & Collins, 2009) are linked to cognitive, well-being, and mental health outcomes. This underscores the importance of social support in schools to improve well-being.

These findings highlight several promising avenues for future research. For this study, we used a rich longitudinal data set with high-quality measures of cognition and well-being that covered major aspects of each domain. Future studies could explore other interesting aspects of cognition (e.g., working memory) and well-being (e.g., life satisfaction and depression). Although SECCYD allowed us to assess developmental sequences and identify potential risk and resilience factors in a large and diverse cohort, the observational nature of the sample precludes any assessments of causality. Future experimental and intervention research will therefore need to establish cause and effect in the development of cognition and well-being. The heterogeneity in loneliness trajectories observed here using exploratory methods also invites further study. Future studies of heterogeneity are needed to confirm which young people are most at risk of loneliness and at what point in their life. We will need to test candidate mechanisms (e.g., pubertal changes) and later life outcomes (e.g., mental health). Loneliness itself is a heterogeneous experience: It may be experienced as neutral or even positive depending on the individual and circumstances. Better understanding and more specific measurement of negative and positive experiences of loneliness in adolescence, as well as the relationship between loneliness, social dissatisfaction, and social isolation, will allow us to better tease apart the underlying mechanisms. Finally, alternative analytic approaches may yield complementary insights into developmental processes. Cross-lagged panel models, for instance, could isolate effects from one wave to the next, which could be particularly interesting for the study of developmental transitions.