HQ Team
November 15, 2024:Allergies are a source of great social and physical impairment for people suffering from them. Treatments are long-drawn, expensive and often reoccur once medicines are stopped. Moreover, allergic diseases can impact the mental health of a sufferer due to an interaction of psychological and somatic conditions.
Allergic conditions are caused by genetic, environmental, immunity and sometimes even mental stress.
Many studies have been carried out to unravel the complex mechanism that triggers allergies and an interesting factor found is that people suffering from severe allergic diseases are more likely to experience adverse mental health conditions too.
But these studies are observational and a true association between allergic diseases and mental health conditions has yet to be published.
A recent review of 21 existing studies and articles on correlations between allergic diseases such as dermatitis, food allergies and asthma found that they are associated with increased risk of a range of mental health conditions, with the strongest association between asthma and attention-deficit/hyperactivity disorder (ADHD).
Significant overlap
The investigators in their reviews found significant overlapping associations between allergic diseases and mental health conditions. They identified 15 overlapping associations, with varying degrees of correlation. This analysis highlights the complexity of these relationships and underscores the need for further research to establish causality.
Using the corrected covered area (CCA) methodology to measure the degree of overlap between allergic diseases and mental health conditions, the reviewers identified 10 associations exhibiting high overlap (CCA between 10.71% and 47.37%). One association demonstrated a moderate overlap, and 4 associations were categorized as having slight overlap.
Notably, the association between asthma and ADHD was graded as “convincing evidence,” with an odds ratio (OR) of 1.34 (95% CI, 1.24-1.44) indicating a robust link between these two conditions
Other associations, such as allergic rhinitis with tic disorders and atopic dermatitis with anxiety, were classified as “highly suggestive evidence”
The methodological quality of the included studies was assessed using the AMSTAR 2 tool. Of the 21 articles included, 8 (38%) were graded as high-quality, 5 (24%) were graded as moderate quality, 3 (14%) were graded as low quality, and 5 (24%) were graded as critically low quality. Some articles were graded low quality due to assessment bias and adequate research.
Limitations of causation
The investigators noted “that although we tentatively identified associations between allergic diseases and mental health conditions, these associations do not necessarily imply causality,” due to the basis of the review being observational studies. Critically, they write that “the scientific basis for some of these speculations and assumptions remains as yet insufficient.”
Furthermore, the study authors could not completely rule out the influence of potential confounders on the results, which they discuss “is important in interpretation and requires caution.” The added that there was also large heterogeneity among these studies, with more “high-quality preliminary studies” necessary to identify causality.
Additional Insights
Further research corroborates these findings. A meta-analysis indicated a strong association between asthma and ADHD, reporting an adjusted or of 1.5 after controlling for confounding factors in over 300,000 participants.
This suggested that shared risk factors may exist between these disorders, potentially linked to common inflammatory processes. Additionally, studies have shown that individuals with asthma are at increased risk for anxiety and depression. For instance, one review found that approximately 36% of patients with persistent asthma exhibit symptoms of anxiety and depression. the presence of comorbidities significantly complicates asthma management and is associated with worse health outcomes
While current evidence suggests significant links—particularly between asthma and ADHD—establishing causality remains a challenge due to methodological limitations in existing studies. Future research should focus on high-quality longitudinal studies to explore these relationships more deeply and identify underlying mechanisms that may be contributing to both allergic and mental health disorders.
The review is published in the Journal of Allergy and Clinical immunology.
