Childhood neurodevelopmental difficulties and risk of adolescent depression: the role of irritability

Background
Children with neurodevelopmental disorders are at increased risk of developing depression. Irritability predicts depression in the general population and is common in children with neurodevelopmental disorders. Thus, it is possible that irritability in children with neurodevelopmental disorders contributes to the link with later depression. This study aimed to (a) examine the association between childhood neurodevelopmental difficulties and adolescent depression and (b) test whether irritability explains this association.


Methods

Children with any neurodevelopmental difficulty at the age of 7–9 (
n
 = 1,697) and a selected, comparison group without any neurodevelopmental difficulty (
n
 = 3,177) were identified from a prospective,
UK
population‐based cohort, the Avon Longitudinal Study of Parents and Children. Neurodevelopmental difficulties were defined as a score in the bottom 5% of the sample on at least one measure of cognitive ability, communication, autism spectrum symptoms, attention‐deficit/hyperactivity symptoms, reading or motor coordination. The Development and Well‐Being Assessment measured parent‐reported child irritability at the age of 7, parent‐reported adolescent depression at the age of 10 and 13, and self‐reported depression at the age of 15. Depression measures were combined, deriving an outcome of major depressive disorder (
MDD
) in adolescence. Logistic regression examined the association between childhood neurodevelopmental difficulties and adolescent
MDD
, controlling for gender. Path analysis estimated the proportion of this association explained by irritability. Analyses were repeated for individual neurodevelopmental problems.



Results

Childhood neurodevelopmental difficulties were associated with adolescent
MDD
(
OR
 = 2.11, 95%
CI
 = 1.24, 3.60,
p
 = .006). Childhood irritability statistically accounted for 42% of this association. On examining each neurodevelopmental difficulty separately, autistic, communication and
ADHD
problems were each associated with depression, with irritability explaining 29%–51% of these links.



Conclusions

Childhood irritability appears to be a key contributor to the link between childhood neurodevelopmental difficulties and adolescent
MDD
. High rates of irritability in children with autistic and
ADHD
difficulties may explain elevated rates of depression in the neurodevelopmental group.