Childhood ADHD diagnosis increases risk for subsequent psychotic disorder

Childhood ADHD appeared linked to increased risk for a subsequent psychotic disorder, according to results of a systematic review and meta-analysis published in JAMA Psychiatry.

“Epidemiologic evidence examining the association between ADHD and [psychotic disorder] remains largely inconsistent,” Mikaïl Nourredine, MD, MSc, of the University Hospital Service of Pharmaco Toxicology at the University Hospital of Lyon in France, and colleagues wrote. “Because [psychotic disorders] cause a high degree of disability, it is important to evaluate potential risk factors. The aim of this study was to synthesize the current evidence regarding the association between ADHD during childhood and the subsequent risk [for] developing any [psychotic disorder] in a systematic review and meta-analysis.”

The investigators searched four databases from inception to July 7, 2020, and included cohort and case-control studies that examined the relative risk for developing a psychotic disorder among individuals diagnosed with ADHD at younger than 18 years vs. control individuals without ADHD. An association between ADHD and psychotic disorder according to international classification served as the main outcomes and measures. They included 15 studies in the review and pooled 12 in the meta-analysis, representing 1.85 million individuals.

Results showed a significant increase in the risk for subsequent psychotic disorder associated with ADHD diagnosis in childhood, with a pooled relative effect of 4.74 (95% CI, 4.11-5.46). Nourredine and colleagues observed no significant between-group differences for subgroup analyses according to psychotic disorder (OR = 5.04; 95% CI, 4.36-5.83) or schizophrenia (OR = 4.59; 95% CI, 3.83-5.5) outcomes, cohort (OR = 4.64; 95% CI, 4.04-5.34) or case-control (OR = 6.81; 95% CI, 4.21-11.03) study design and adjusted (OR = 4.72; 95% CI, 4.11-5.46) or unadjusted (OR = 3.81; 95% CI, 1.39-10.49) estimates. Upon using sex and bias score as covariates, the researchers found meta-regressions were not significant. They also reported no evidence of publication bias.

“To improve our knowledge, further cohort studies should be conducted,” Nourredine and colleagues wrote. “Ideally, these studies would ensure a sufficiently long follow-up to account for the mean age at which [psychotic disorders] develop. Such studies should consider the use of psychostimulants and the role of [substance use disorder] in the causal path between ADHD and [psychotic disorder].”