Cortisol and inflammatory biomarker levels in youths with attention deficit hyperactivity disorder (ADHD): evidence from a systematic review with meta-analysis

• Published in: Translational psychiatry Vol. 11; no. 1; pp. 430 - 10
• Main Authors: Chang, Jane Pei-Chen, Su, Kuan-Pin, Mondelli, Valeria, Pariante, Carmine M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.08.2021; Nature Publishing Group
• Subjects: 631/378; 631/443; Adolescent; Attention Deficit Disorder with Hyperactivity; Attention deficit hyperactivity disorder; Behavioral Sciences; Biological Psychology; Biomarkers; Case-Control Studies; Hormones; Humans; Hydrocortisone; Medicine; Medicine & Public Health; Meta-analysis; Neurosciences; Pharmacotherapy; Psychiatry; Review; Review Article; Saliva; Systematic review; Tumor necrosis factor-TNF
• ISSN: 2158-3188; 2158-3188
• DOI: 10.1038/s41398-021-01550-0

Several studies reported abnormal cortisol and inflammatory biomarker levels in youths with attention deficit hyperactivity disorder (ADHD), but the results have not been conclusive. We conducted a systematic review followed by a meta-analysis of case-control studies assessing blood or saliva cortisol levels and blood levels of inflammatory biomarkers in youth with ADHD. The effect sizes (ES) were synthesized by using a random-effects model. In the 19 studies on cortisol levels (totaling n  = 916 youth with ADHD and n  = 947 typically developing (TD), healthy youth), youth with ADHD have lower basal cortisol levels at any time-points during the day (effect size: .68; p  = 0.004) and lower cumulative levels of cortisol (ES: .39, p  = .008) throughout the day than TD youth. Moreover, morning cortisol levels were lower in ADHD youth when compared with TD youth (14 studies, n  = 1679, ES: .84, p  = 0.003), while there is no difference for the afternoon cortisol levels ( p  = 0.48). The meta-analysis on inflammation biomarker was conducted on 4 studies (totaling n  = 404 youth) showed that Tumour Necrosis Factor-alpha (TNF-α) was lower in ADHD when compared with TD (3 studies, n  = 257 youth, p  = 0.004), while no differences for Interleukin-1β(IL-1β) ( p  = 0.21), IL-6 ( p  = 0.09) and IL-10 ( p  = 0.77). The lower cortisol in the context of low TNF-α levels may indicate a specific pattern of biomarkers in ADHD, and further investigation is warranted.