Association between parental education level and intelligence quotient of children referred to the mental healthcare system: a cross-sectional study in Poland
It is well known that parental education is crucial in shaping children’s IQ1,2. Our research provides for the first-time strong evidence of a correlation between parental education and the IQ of children referred to the mental healthcare system. Furthermore, the general IQ of the children explained the largest percentage of variance among all intelligence areas and factors examined. Parental education exhibited a stronger predictive capacity for a child’s verbal intelligence than for nonverbal intelligence. A detailed analysis of the structure of intelligence also indicated that parental education predominantly explained the level of the Knowledge factor (KN IQ) and explained the Working Memory factor (WM IQ). These results are consistent with the assumptions of the Cattel-Horn-Carroll theory of intelligence, indicating that verbal IQ is more dependent on environmental factors, whereas nonverbal IQ is more dependent on biological factors19. Studies have consistently shown that while genetic factors are significant in explaining the IQ range in children, other environmental and developmental influences undoubtedly also contribute significantly to shaping IQ5,6,20. Previous research also shows that parents’ level of education influences the shaping of the home environment, which is significant not only in the context of normative development but also in providing children mental healthcare4. The KN IQ is highly sensitive to environmental stimulation, encouraged both within formal education and the home environment. Children who have extensive educational experience and are surrounded by a stimulating home environment often have a greater chance of developing knowledge and skills, which can translate into their performance in this factor19. On the other hand, working memory is a process with strong neurobiological connotations21, hence parental education may have less explanatory power regarding a child’s performance in WM IQ.
Moreover, the results revealed that maternal education level was more influential in predicting general IQ, as well as specific intelligence areas and factors, among children referred to the mental healthcare system. Despite the steadily increasing trend of involved and nurturing fatherhood, women are still predominantly responsible for caring for children22. This seems to be a likely reason why maternal education is a stronger predictor of children’s IQ. Although mothers’ education explained a larger percentage of the variance (18.23%), it is important to remember that the percentage explained by fathers’ education was also high (16.46%). Therefore, collecting data on the education of both parents is important, as the higher education of either parent can be significant in organizing mental health support, especially in the context of evolving childcare trends.
Additionally, the child’s sex proved to be an insignificant factor in the relationship between parental education and children’s general IQ. However, further analysis of specific IQ areas and factors suggests that the child’s sex serves as a moderator in the relationship between parents’ educational level and the child’s KN IQ, indicating a stronger significance among boys. Previous studies have shown that parental education plays a significant role in children’s educational achievements23. However, our results provide important findings regarding whether parental education also matters in the context of referring children to the mental healthcare system, particularly when they need specialized assistance. It appears that sex is not a significant factor in this regard.
However, the age of the child was found to be a significant factor in predicting the IQ of children referred to the mental healthcare system based on parental education level. Our findings indicate a negative correlation between the age of children whose parents had primary and lower secondary education and their general IQ when referred to the mental healthcare system. In contrast, children of parents with higher education showed a positive correlation with general IQ, which increased with age.
To delve deeper into the interaction of parental education with the child’s age in the impact on the IQ of children referred to the mental healthcare system, we employed regression broken-line models24 for each of the four parental education levels. These models capture the piecewise linear relationship between the child’s age and general IQ previously established as a primary outcome, with three straight lines connected at two breakpoints reflecting the expected turning points in the Polish educational system (first breakpoint: transition between stage 1 and stage 2; second breakpoint: end of primary school exam; see Appendix C). Table E8 and Figure E1 in Appendix E present the results of the analysis. During the preschool period, as children grow older, they are brought to the mental healthcare system with progressively lower average IQ levels. However, between the ages of six and eight, this relationship reverses—older children brought to the mental healthcare system tend to have higher IQs. For parents with primary and lower secondary or vocational education, this trend begins shortly after the child starts school, and ends soon after the child completes primary education. Children’s school readiness is assessed in the sixth year of life, which is mandatory in kindergartens and schools. Given that the mental health care system is free and widely accessible, it is possible that, as a result of the assessment outcomes, parents make decisions to further diagnose their children’s school readiness, even if the child does not exhibit significant difficulties in cognitive functioning. However, primary education concludes with an external exam, the results of which significantly affect the selection of children’s future educational pathways. It is important to note that parents with primary and lower secondary or vocational education generally bring children with significantly lower levels of intellectual functioning to the mental healthcare system. For parents with secondary or higher education, the reversal of the initial trend lasts for a shorter duration (between ages 7 and 10 years) but it is more pronounced.
The study results highlight that ensuring equality in access to the mental healthcare system requires more than the provision of an open, universally accessible system. It is also crucial to identify at-risk groups using readily available data. Our results indicate that parental education level may be one such important indicator of risk.
Therefore, it seems beneficial to consider introducing educational programs for parents on normative child development and early signs of potential developmental difficulties. Although all parents should be included in these initiatives, caregivers with lower levels of education appear to require particular support. It is essential that these programs are grounded in evidence-based practices and consider socially sensitive factors such as low socioeconomic status, ethnicity, and disability25. We are aware of the significant financial and human resources required for widespread implementation of such programs. However, in the long run, it could enable faster identification of difficulties and reduce the costs associated with later assistance and treatment. A less direct solution could be expanding the scope of periodic medical screening programs to encompass more complex issues related to mental health and psychological aspects of child and adolescent development.
Our observations on the relationship between the education system and referrals to the mental healthcare system warrant further investigation. However, it seems essential to strengthen cooperation between the education sector and the healthcare system, as pivotal points in the education system, such as external examinations, may have a significant impact on the timing of seeking help for developmental challenges.
To the best of our knowledge, this is the first study to investigate the association between parental education level and IQ of children referred to the mental healthcare system. It is particularly noteworthy that data on the education levels of both parents from a large sample were analyzed. Additionally, data on the child’s IQ level were analyzed using SB5, a method that allows for the broadest assessment of intelligence structure26. In the present study, we analyzed free and widely accessible data from the mental health care system. This allowed for the inclusion of individuals with a lower education or SES. Therefore, the results can be generalized to a wider population of children referred to mental healthcare system.
The present study has certain limitations. A significant limitation was the necessity to limit the analysis to 80,303 of 419,135 participants. For clarification, we conducted an additional comparison of the demographic composition of the study sample with the original sample minus the study sample (see Appendix F, Table F1). As shown, both samples (the study sample with available parental education data and the sample with missing data) do not differ significantly in terms of gender, age group, place of residence, and, most importantly, level of intelligence. Additionally, we replicated the model fit for the regression analysis testing the relationship between mother’s education and children’s intelligence levels referred to the mental healthcare system using the expanded sample, independent of father’s education information availability (see Appendix F, Table F2). As can be seen, the results of this analysis are stable and comparable to the previous ones, even when applied to a sample more than twice the size (N = 203,690). Regardless of the results of the comparisons outlined above, the missing data reported should still be considered a limitation in generalizing the results to the population of children referred to the mental healthcare system.
Secondly, for formal reasons, we lacked knowledge of the specific diagnoses provided to each participant. The data collection system is restricted by data protection regulations, which prevent the identification of individual participants for medical history analysis. Additionally, this study only examined a very narrow part of the diagnostic process, specifically IQ measurement. It is not known what other diagnostic procedures were performed or what their results were. Future research should broaden the scope of this study to include other psychological variables and aspects of mental health. However, our research emphasizes the importance of identifying demographic factors that are relatively easy to obtain, do not incur additional storage and acquisition costs, and can serve as indicators for identifying risk groups for exclusion, even in open and widely accessible assistance systems. In the context of mental health in children and adolescents, a deeper focus on factors that may influence the formation of the family environment is warranted so that potential difficulties can be identified at very early stages of a child’s life.
In summary, our study revealed a correlation between parental education and the IQ of children referred to the mental healthcare system. General IQ explained the largest variance among the examined intelligence areas, with parental education being more predictive of verbal intelligence than of nonverbal intelligence. Maternal education level had a stronger impact on children’s IQ, possibly because of mothers’ predominant role in childcare. However, it is crucial to collect data on the educational levels of both parents because of the potential protective effects of having at least one parent with a higher level of education.
The Polish mental health care system is open, free, and widely accessible. However, our research indicates that parents with lower educational levels are more likely to refer children with lower IQ scores to this system. This suggests that universal access to the mental healthcare system does not guarantee equal care access. Social factors, such as the caregiver’s educational level, may allow access to this system. Therefore, regardless of the type of mental healthcare system, increasing efforts and funding for caregiver education concerning children’s and adolescents’ developmental trajectories as well as mental health are essential.
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