Inflammation in children and adolescents with neuropsychiatric disorders: a systematic review

Objective: There has been rapid growth in research regarding inflammation in neuropsychiatric disorders as it relates to youth. We therefore set out to systematically review the literature on inflammation and neuropsychiatric disorders in children and adolescents.

Method: A systematic review of the literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Studies were included if proinflammatory markers (PIMs) in children and/or adolescents with neuropsychiatric disorders were measured.

Results: Sixty-seven studies were included, involving 3,952 youth. Evidence for a proinflammatory state is strongest for autism spectrum disorders (ASD). PIMs are elevated in children and adolescents with major depressive disorder (MDD), bipolar disorder (BD), post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), Tourette's disorder (TD), attention-deficit/hyperactivity disorder (ADHD), and schizophrenia (SZ). However, the data are inconsistent. Evidence for specific PIMs is equivocal at this stage, although the findings in youth with MDD, BD, and PTSD converge with the extant adult literature in these areas. Definitive conclusions are limited by methodologic factors including cross-sectional and retrospective study design, between-study differences in specific markers and methods of analysis, small sample size, and other sources of heterogeneity.

Conclusion: The literature regarding inflammation among children and adolescents with neuropsychiatric disorders represents nearly 4,000 youth. There is preliminary evidence for elevated markers of inflammation in this population. Larger, prospective studies are needed to realize the goal of inflammatory markers informing clinical practice. In the interim, present findings suggest that further examination of this topic is warranted.