Children with ADHD are more likely to develop psychosis later in life, according to a new study, but little is understood why.
That’s the conclusion of a meta-analysis published today in Journal of the American Medical Association.
“These findings suggest that childhood ADHD is associated with an increased risk of a subsequent psychotic disorder,” the authors reported. “Further studies are required to determine the mechanisms linking these common conditions and whether early intervention for ADHD might reduce the risk of subsequent psychotic disorder.
ADHD affects about 5 percent of children and 2.5 percent of adults worldwide. It can be associated with other disorders including borderline personality disorder and psychotic disorder.
Genetic, environmental factors play into psychosis risk
Research already has hinted at shared genetic traits between psychotic disorder and ADHD. “From a genetic standpoint, shared genetic susceptibility for large, rare chromosomal deletions and duplications as well as for common genetic variants have been described, and the risk of developing schizophrenia among first-degree relatives of people with ADHD is approximately twice as high as that of in healthy control individuals,” the authors explained.
Shared environmental risks also are factors in both diseases. “Similar early environmental risk factors have also been observed in schizophrenia and ADHD, including obstetric complications, preterm birth, and low birth weight,” the authors said. “From a physio pathological standpoint, ADHD and schizophrenia can be associated with deficits in shared overlapping brain circuits, such as the mesolimbic and mesocortical dopaminergic systems.”
The authors of the meta-analysis reviewed 15 studies including almost 2 million people. “These findings suggest that childhood ADHD is associated with an increased risk of a subsequent psychotic disorder,” they concluded. “Further studies are required to determine the mechanisms linking these common conditions and whether early intervention for ADHD might reduce the risk of subsequent psychotic disorder.”
Several mechanisms of action could be at play between ADHD and psychotic disorder. “Many potential mechanisms could underlie the association between ADHD and subsequent psychosis,” the authors said. “This association could be explained by a common developmental path with shared genetic susceptibility or social environmental factors. Prenatal factors, such as diabetes during pregnancy or neonatal complications, are also frequently reported as risk factors for both disorders.”
Does cannabis use cause psychosis in those with ADHD?
People with ADHD are at increased risk for substance abuse, especially a propensity toward cannabis. Some have speculated that could be the cause of ADHD-related psychosis.
“Causality interpretation of the cannabis-schizophrenia association, whether it is entirely causal, entirely noncausal, or partly causal and partly confounded by social/genetic effects and/or reverse causation, is still undergoing debate,” the authors admit. “Future longitudinal studies assessing the risk of subsequent psychotic disorder in children with ADHD should retrieve specific information on substance abuse disorder (e.g., start of the substance use, amount and type of substance use, and time of diagnosis) to bring insight on the causal path from ADHD to psychotic disorder.”
The authors also discovered a link between psychostimulant medications given children with ADHD and psychosis.
“A review of 49 randomized clinical trials by the U.S. Food and Drug Administration found significantly more psychotic- or manic-type effects during the follow-up of children taking psychostimulants compared with those taking a placebo,” according to the study. “In 92 percent of these cases, stopping stimulant therapy was associated with a remission of the psychotic symptoms without use of an antipsychotic.”
Sometimes doctors can see the psychosis coming. “Patients with psychotic disorder often show neuropsychological deficits and the deterioration of academic functioning before the onset of full-blown psychosis, such as attention disorders, heightened levels of impulsivity, and deficits in executive function,” the authors reported.
“Misclassification bias could occur if substance abuse disorder and psychostimulant use increase psychotic symptoms and substance-induced psychosis, which could be misdiagnosed as schizophrenia.”