Food Allergy in the Brain

Preventing food allergic reactions predominantly relies on allergen avoidance and managing this daily causes high anxiety in some patients, while having an allergic reaction can cause a post-traumatic stress disorder-like syndrome in children. The underlying mechanisms of these psychological changes are poorly understood, but one potential mechanism may be post-natal hippocampal neurogenesis (HN). HN is the production of new neurons from stem cells in the hippocampus which is one of the brain centres for memory and mood regulation. HN has been associated with cognitive function and some psychiatric disorders. Importantly, it can be influenced by both internal (bloodstream) and external (exercise, diet, etc.) factors. This study will explore the link between food allergy and children's mental health and cognition, and to determine whether this is linked to changes in HN.

Preventing food allergic reactions predominantly relies on allergen avoidance and managing this daily causes high anxiety in some patients, while having an allergic reaction can cause a post-traumatic stress disorder-like syndrome in children. The underlying mechanisms of these psychological changes are poorly understood, but one potential mechanism may be post-natal hippocampal neurogenesis (HN). HN is the production of new neurons from stem cells in the hippocampus which is one of the brain centres for memory and mood regulation. HN has been associated with cognitive function and some psychiatric disorders. Importantly, it can be influenced by both internal (bloodstream) and external (exercise, diet, etc.) factors. This study will explore the link between food allergy and children's mental health and cognition, and to determine whether this is linked to changes in HN.

This study will recruit child patients (aged 8-15 years), and their legal parent/guardian, that are attending a routine clinic appointment at the Paediatric Allergy Unit at St Thomas' Hospital. Parent/guardians and the child will be approached by the patient's direct clinical team, who will explain the study procedures involved in participation. Consented adult (parent/guardian) participants will be asked to complete three anxiety questionnaires, to assess the influence of parental anxiety on that of the child. Consented child participants will be asked to complete two anxiety questionnaires and a memory task. Blood samples from the patient will also be collected in addition to those taken as part of their routine clinic appointment. Specifically, blood will be collected in the following tubes: gold top Vacutainer tube containing clot activator and gel for serum separation (4ml 8-15yrs), green top Vacutainer tube containing lithium heparin for whole blood (4ml 8-15yrs), and blue top Vacutainer tube containing citrate for peripheral blood mononuclear cell (PBMC) and plasma separation and storage (30ml 8-12yrs; 50ml 13-15yrs).

The plasma and serum from this collection will be used on two stem cell models that mimic food allergic reactions and HN, respectively. Any differences in these processes will be analysed alongside the questionnaire and memory task data and, if a link is successfully demonstrated, further work will aim to identify blood-borne factors responsible for these changes. This study will shed light on the impact of food allergy on children's mental health as well as the biological processes behind it.

Eligibility Criteria:
Inclusion Criteria:

* • Children ≥ 8 years old and \<16 years

  * Suspected food allergy (non-defined allergen)
  * Undergoing blood collection for IgE testing at their clinic appointment
  * Fluent / age-appropriate level of English (verbal and written) of both the child and legal parent / guardian

Exclusion Criteria:

* Diagnosed neurological disorders and learning disabilities, including autism spectrum disorder, attention deficit hyperactivity disorder, Down's Syndrome.

  * Undergoing any allergen-specific immunotherapy or other immunomodulatory treatments such as biologics and immunosuppressants