Meta-Analysis: Significant Association Between ADHD and Asthma
Researchers found a strong association between ADHD and asthma after studying the combined results from a meta-analysis and population-based study. Though it’s unclear whether the association is causal or due to shared factors, acknowledgement of the relationship could improve diagnostic delays for both conditions.
August 15, 2018
Results from two studies — a meta-analysis and a Swedish population-based study — show a significant association between attention deficit disorder (ADHD or ADD) and asthma, according to a study recently published in The Lancet Psychiatry.1
Awareness of this strong association may have a significant clinical and public health impact as ADHD specialists can refer patients with early forms of asthma, and asthma specialists can refer patients with early ADHD symptoms, “thus helping to reduce the diagnostic delay that is concern for both ADHD and asthma,” noted the researchers.
The meta-analysis included published and unpublished data from 49 datasets including 210,363 participants with ADHD and 3,115,168 without ADHD. This is “a substantial increase from the 5 or 6 datasets included in previous meta-analyses,” noted Jessica Agnew-Blais, Ph.D., from the genetic and developmental psychiatry center at King’s College in London, United Kingdom, in accompanying editorial.2
Since the studies included in the meta-analysis used different potential confounders to calculate the odds ratios (ORs) for the association between ADHD and asthma, researchers also conducted a population-based cohort study controlling for a wide range of shared risk factors including sex, year of birth, maternal age at birth, birthweight, gestational age, parental education, and family income. The Swedish population-based study included 1,575,377 individuals, 57,957 of whom had ADHD and 259,253 of whom had asthma.
In the meta-analysis, data indicated a significant relationship between ADHD and asthma: pooled unadjusted OR 1.66 (95% CI, 1.22-2.26) vs adjusted OR 1.53 (95% CI, 1.41-1.65). In the population-based study, the association remained significant after adjusting for sex and year of birth (OR 1.60, 95% CI, 1.57-1.63), and more so after adjusting for all confounders (OR 1.45; 95% CI, 1.41-1.48).
“Cortese and colleagues have provided robust evidence of a cross-sectional association between asthma and ADHD,” noted Dr. Agnew-Blais. The authors stressed that longitudinal studies are needed to determine whether this association is causal or due to shared factors. Dr. Agnew-Blais echoed this statement saying, “Clarification of the nature of this association is needed from future studies to identify potential pathways for prevention and treatment.”
Disclosure: This study was in part funded by Shire International GmbH. Henrik Larsson, Ph.D., has served as a speaker for Eli Lilly and Shire and has received research grants from Shire.
1Cortese S, Sun S, Zhang J, et al. Association between attention deficit hyperactivity disorder and asthma: a systematic review and meta-analysis and a Swedish population-based study. Lancet Psychiatry. 2018 Jul 24. doi: 10.1016/S2215-0366(18)30224-4
2Agnew-Blais J. Intriguing findings regarding the association between asthma and ADHD. Lancet Psychiatry. 2018 Jul 24. doi: 10.1016/S2215-0366(18)30258-X