Childhood asthma is associated with cognitive disorders, particularly episodic memory disorders, a memory that develops during childhood. This is what emerges from an American longitudinal study, without being able to separate the part of the pathology and its possible inflammatory component on the central nervous system (CNS) from that of the treatments, in particular corticosteroids, those -these are not documented in this work (1). This association mainly affects children who have developed early-onset asthma. In the future, we should also explore whether the damage is more linked to the precocity of the onset of asthma or to its duration, observe the authors.
A longitudinal cohort study of nearly 500 children
This study is part of the American observational cohort on the cognitive development of adolescents, initiated in 2015. This cohort brings together more than 11,000 children, aged 9 to 10 years at inclusion, and followed/reassessed at one and two years. . Among them, the authors included nearly 500 children, 135 of whom were already asthmatic at inclusion, i.e. early development; they were 9.9 years old on average, and 56% were boys.
In the cohort of 500 children, 102 developed asthma later (onset during the two years of follow-up); they were aged on average 9.9 years at inclusion, with 53% boys. There remained 237 control children, free of asthma, aged on average 9.9 years at inclusion, with 51% boys.
Less good acquisition of episodic memory during follow-up
Comparison of the scores of children in the longitudinal cohort highlights a delay in the progression of episodic memory in children who developed early-onset asthma. As a reminder, this is the memory allowing us to remember past events in detail, a memorization capacity linked to the hippocampus, which develops during childhood.
In the non-asthmatic control group, this memory capacity increased during follow-up (+0.28; p p = 0.01). On the other hand, no significant difference was found between the control group and the so-called “late-onset asthma” group, children in whom asthma developed during follow-up.
Reduced memory, speed of execution and inhibition/attention
To complete the panorama, the authors carried out a cross-sectional study on this same cohort, using 1,031 asthmatic children matched with 1,031 non-asthmatic children, with an average age of 12 years.
However, among these asthmatics we observe overall poorer episodic memory (-0.09: p = 0.04), reduced execution speed (-0.13; p = 0.01) and worse inhibition/attention scores (-0.11; p = 0.02). And these results are not modified by the covariates.
A pathophysiology possibly linked to inflammation of the CNS
Asthma, whose pathophysiology remains incompletely understood, is dominated by an inflammatory process which is not limited to the lungs and could extend to neuroinflammation of the CNS. This is in any case what recent work carried out in rodents suggests, in which asthma is associated with neuronal damage in the hippocampus, a brain structure particularly vulnerable to inflammation. It is also possible that breathing difficulties themselves lead to epidoses of cerebral hypoxia which can cause damage to the hippocampus. “And asthma appearing early, at a young age, could disrupt the neurodevelopment of the CNS, particularly in regions with significant plasticity at this age, such as the hippocampus”suggest the authors.
(1) N J Christopher-Hayes et al. Asthma and Memory Function in Children. JAMA Network Open. 2024;7(11):e2442803
