(999 words, 5-minute read)

Think about your interactions with neurodiverse friends. Do you treat them differently compared to others? Are you more sensitive to their unique needs? Well, we would expect mental health services to meet these needs, but worryingly it’s not the case! Why should they bother? How can they better address specific needs of neurodiverse children?

The last 3 years saw a 50% increase in mental health issues, and 1 in 6 children have a psychiatric diagnosis. Worryingly, these issues often precede poor outcomes in adulthood (e.g., unemployment, criminal behaviour), emphasising the importance of prevention among children.

It’s not all bleak though – research has found that previous externalising mental health issues (behaviour related; e.g., conduct-related and substance misuse disorders) often predict internalising mental health issues 1-2 years later (psychological/emotional; e.g., mood and anxiety disorders). Specifically, issues in early primary-to-secondary school seem important, representing a “sensitive period” for potential treatments. For example, clinicians could aim to boost a child’s self-esteem and socialisation experiences implicated in this externalising-to-internalising directional relationship.

Why the worry for neurodiverse individuals? Well, autism spectrum disorder, also known as autism, is a neurodevelopmental disorder characterised by socialisation difficulties and repeated restrictive behaviours. Importantly, autistic individuals face increased mental health issues due to their difficulties and deserve additional efforts to prevent poor long-term outcomes. However, preventative treatments are less straightforward here.

Developmental delays that autistic individuals face could represent different “sensitive periods”. Additionally, socialisation difficulties could represent different, or stronger, directional relationships between internalising and externalising issues. It is unclear if known directional relationships and their “sensitive periods” apply to autistic individuals, which questions: are directional relationships between internalising and externalising issues similar between autistic and non-autistic individuals?

What did we do?

Here, at the CORE Data Lab, we took longitudinal data from the Millennium Cohort Study (MCS), which follows the lives of children born from 2000-2002 onwards. 6 MCS waves (MCS2-MCS7) collected parent-reported scores on the Strength and Difficulties Questionnaire (SDQ), where parents numerically quantify children’s behavioural problems on five subscales. On this questionnaire, emotional and peer subscales relate to internalising issues, while hyperactivity and conduct subscales relate to externalising issues.

The 6 waves related to children when they were 3-, 5-, 7-, 11-, 14- and 17-years-old. This provided data from 15,701 non-autistic and 571 autistic children, on which we employed a special technique called ‘random Intercept Cross-Lagged Panel Modelling’ (RI-CLPM). This sounds complicated but essentially the technique gives values for cross-lagged paths, which represents directional internalising-to-externalising and externalising-to-internalising relationships (what we are really only interested in). To test whether directional relationships between internalising and externalising issues are similar between autistic and non-autistic individuals, we:

1. Estimated RI-CLPM for everyone, which would provide values for cross-lagged paths representing direction and size of relationships between internalising and externalising issues (across autistic and non-autistic individuals).
2. Told the model that cross-lagged paths need to be the same values across autistic and non-autistic individuals (group constraints), and checked if this affected model fit and cross-lagged path values. Poor fit or mismatching cross-lagged path values between autistic and non-autistic individuals represented autism-specific relationships.
3. Estimated RI-CLPM for autistic and non-autistic individuals separately and checked for other autism-specific relationships, just to be extra sure!

What did we find?

Autistic individuals have more specific “sensitive periods”!

Externalising-to-internalising cross-lagged paths were significantly positive from ages 5-14, while internalising-to-externalising paths were significantly negative from ages 3-17. This provides additional support for how previous externalising issues drive increase in future internalising issues from early primary to early secondary school (positive relationship). However, negative internalising-to-externalising paths additionally mean that previous internalising issues drive a decrease in (or “protect against”) future externalising issues from preschool to late secondary school (negative relationship), which is a new finding.

Model fit was not significantly affected when implementing group constraints across autistic and non-autistic individuals, which shows that relationships between internalising and externalising problems are generally similar between autistic and non-autistic children. However, among specifically autistic individuals, positive externalising-to-internalising relationships were stronger from 11-14-years, while negative internalising-to-externalising relationships were stronger from 5-7-years and 11-14-years. This means that autistic children develop more severe internalising issues from existing externalising issues at early secondary school, and greater reductions in externalising issues from existing internalising issues at early primary school and early secondary school.

The figure below neatly summarises these, where coloured arrows represent cross-lagged paths (directional internalising-to-externalising or externalising-to-internalising relationships) relevant to our study aims. Green arrows represent positive relationships and red arrows represent negative relationships. Larger arrows represent paths where relationships are stronger (the specific “sensitive periods”) for autistic individuals.

What should we do about this?

Quite a few things actually!

1. Positive externalising-to-internalising relationships mean that children internalise their outward behavioural problems and develop subsequent mood problems. Clinicians could prevent this through cognitive restructuring (type of therapy).
2. Negative internalising-to-externalising relationships mean that internalising issues may persist through self-blame and self-deprecating thoughts instead of being expressed as externalising issues. Clinicians could encourage self-compassion and reduction in dwelling on negative feelings.
3. Autism-specific vulnerabilities hint at specific “sensitive periods” at early primary (5-7-years-old) and early secondary school (11-14-years-old). Parents, teachers and clinicians should pay special attention at these crucial ages where autistic children need additional support (understandably so as these ages represent new environments with increased obstacles).

Nonetheless, limited autistic individuals in the models means that replication is needed. Additionally, autism diagnosis and SDQ scores were parent-reported, meaning any measures were based only on home behaviour and parental-memory. Therefore, further studies recruiting more autistic individuals and using other valid assessments could boost these findings.

Key Takeaways

• In addition to how previous behavioural (externalising) problems drive increases in subsequent mood (internalising) problems, previous mood (internalising) problems also drive decreases in subsequent behavioural (externalising) problems.
• Autistic individuals require more support at early primary school and early secondary school in dealing with behavioural and mood problems.

Yes, autistic individuals have unique personal experiences and we need to better meet specific needs of our neurodiverse friends; and that is all of us – you, me and the healthcare system!

References

1. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596
2. Goodman, A., Lamping, D. L., & Ploubidis, G. B. (2010). When to use broader internalising and externalising subscales instead of the hypothesised five subscales on the Strengths and Difficulties Questionnaire (SDQ): data from British parents, teachers and children. Journal of abnormal child psychology, 38, 1179-1191. https://doi.org/10.1007/s10802-010-9434-x
3. Hammerton, G., Murray, J., Maughan, B., Barros, F. C., Gonçalves, H., Menezes, A. M. B., … & Heron, J. (2019). Childhood behavioural problems and adverse outcomes in early adulthood: A comparison of Brazilian and British birth cohorts. Journal of developmental and life-course criminology, 5, 517-535. https://doi.org/10.1007/s40865-019-00126-3
4. Oland, A. A., & Shaw, D. S. (2005). Pure versus co-occurring externalizing and internalizing symptoms in children: The potential role of socio-developmental milestones. Clinical Child and Family Psychology Review, 8, 247-270. https://doi.org/10.1007/s10567-005-8808-z
5. Mulder, J. D., & Hamaker, E. L. (2021). Three extensions of the random intercept cross-lagged panel model. Structural Equation Modeling: A Multidisciplinary Journal, 28(4), 638-648. https://doi.org/10.1080/10705511.2020.1784738
6. Murray, A. L., Eisner, M., & Ribeaud, D. (2020). Within‐person analysis of developmental cascades between externalising and internalising problems. Journal of Child Psychology and Psychiatry, 61(6), 681-688. https://doi.org/10.1111/jcpp.13150

Credits

1. Cover Picture from https://blog.mighty-well.com/2020/09/what-is-neurodiversity/