Food and Behaviour Research

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Nutrition, immunological mechanisms and dietary immunomodulation in ADHD

Verlaet AA1, Noriega DB, Hermans N, Savelkoul HF (2014) Eur Child Adolesc Psychiatry. 2014 Feb 4. [Epub ahead of print]   

Web URL: View this and related abstracts via PubMed here

Abstract:

Attention-deficit hyperactivity disorder (ADHD) etiology is not completely understood, but common comorbid dysfunction of the gastrointestinal and immune system suggests that these systems may be affected by a common genetic background and molecular mechanisms. For example, increased levels of specific cytokines were observed in ADHD. Moreover, ADHD has a high comorbidity with both Th1- and Th2-mediated disorders like ear infections, eczema and asthma.

A common pathophysiological mechanism was suggested to underlie both asthma and ADHD, while several genes that are linked to ADHD have immune functions. Furthermore, immunological recognition of food provoking ADHD-like behavior was suggested. An immune imbalance, probably requiring a predisposing genetic background, is therefore suggested to contribute to ADHD etiology, with immune dysregulation being more likely than a single subcellular defect. However, next to allergic mechanisms, also pharmacological mechanisms (especially in case of food additives) might be involved.

In addition, though cellular (cytokine-related) rather than antibody-mediated immune mechanisms seem involved, specific immune-inflammatory markers other than antibodies have not been systematically studied in ADHD. Substantial alterations implicated in ADHD apparently occur in the immune system and epigenetic regulation of gene expression. As a result, chronic inflammation and oxidative stress could develop, which can lead to ADHD symptoms, for example by chronic T-cell-mediated neuroinflammation.

If immune pathways contribute to ADHD, both its diagnosis and treatment should be reconsidered. Modulation of immune system activity might have potential in ADHD treatment, for example by nutritional approaches providing safe and low-cost ADHD therapy, but further research in these fields is implicated.

FAB RESEARCH COMMENT:

This new review explores the associations between ADHD and a wide range of disorders or imbalances of immune system functioning, including proneness to infection, atopic disorders such as asthma and eczema, and food allergies.  The prevalence of these conditions in children and adults with ADHD and related conditions is familiar to clinicians, but has been relatively neglected in research. 

Given the evidence for abnormalities of cell-mediated (i.e. non-acquired) immunity in ADHD the authors propose that targeted research in this area - including the evaluation of dietary strategies to reduce inflammation - could lead to new strategies for both the diagnosis and management of ADHD.

Anti-inflammatory actions are just one of the properties of the omega-3 long-chain polyunsaturated fatty acids, EPA and DHA. These nutrients have shown promise not only in the management of ADHD symptoms, but also in clinical depression - which is often associated with immune system dysfunction.