Mental Disorders Up in Youth With Prenatal Cannabis Exposure

Michael Vlessides

September 14, 2022

Exposure to cannabis in the womb may leave children at risk for psychiatric disorders and problematic substance abuse, particularly as they enter peak periods of vulnerability in late adolescence, new research shows.

In a study published September 12 in JAMA Pediatrics, the investigators say the results should prompt further caution against the use of cannabis during pregnancy.

A 2019 study found that 7% of women reported using cannabis during pregnancy in 2016–2017, up from about 3.4% in 2002–2003.

The findings come from an analysis of data from the Adolescent Brain Cognitive Development (ABCD) Study, the largest long-term investigation of brain development and health in children and teens in the United States. As part of the study, researchers regularly measure participants' brain structure and activity and collect psychological, environmental, and cognitive information, according to David A. A. Baranger, PhD, a postdoctoral research associate at Washington University in St. Louis.

The results are potentially concerning, because adolescence is a period marked by significant change, neurally, socially, emotionally, and cognitively. Dr David Baranger

"The results are potentially concerning, because adolescence is a period marked by significant change, neurally, socially, emotionally, and cognitively," Baranger said. "What's more, it's period when mental health disorders tend to have their initial onset."

In 2020, the group first reported that such children appeared to be at increased risk for psychopathology in middle childhood.

"In the current study, we're following up on that original observation," Baranger said. "It's been a few more years, and we want to know what's changed for these children."

In the current investigation, Baranger and his colleagues categorized maternal cannabis use in one of three ways: only before knowing of pregnancy (n = 391); before and after knowing of pregnancy (n = 208); and no exposure (n = 10,032).

Prenatal exposure to the drug was associated with persisting vulnerability to psychopathology, as measured with the Child Behavior Checklist (CBCL) and the Prodromal Questionnaire–Brief Child Version (PQ-BC), according to the researchers.

Among children who had been exposed to cannabis both before and after their mothers knew of their pregnancy, the mean Total Problems score on the CBCL was 31.47 ± 23.41, which was significantly greater than the 23.78 ± 19.66 among those whose mothers consumed cannabis prior to knowing of their pregnancy only (P < .001), and the 16.70 ± 15.55 for those who were not exposed to cannabis at all (P < .001). Similar relationships were found in the various subscales of the CBCL.

On the PQ-BC, among the children exposed to cannabis both before and after their mothers knew they were pregnant, the mean score was 3.14 ± 3.32 for psychotic-like experiences, compared with 2.95 ± 2.97 (P = .26) among those exposed to the drug only before their mothers learned of the pregnancy and 2.01 ± 2.54 (P = .03) for those not exposed at all. Significant findings were primarily driven by exposure following maternal knowledge of pregnancy, Baranger said.

"So things have actually stayed the same; the elevated mental health burden we observed at ages 9 and 10 have persisted through ages 11 and 12," Baranger told Medscape Medical News.

The findings help demonstrate that exposure to cannabis in the womb is associated with persistent vulnerability to broad-spectrum psychopathology as children progress through early adolescence.

Yet, Baranger added, the effects shown by the study are relatively small and need to be taken in context.

"While I think there's cause for a bit of concern and caution, I want to make sure the results are not overblown," he said.

Nora D. Volkow, MD, director of the National Institute on Drug Abuse, said the findings are particularly relevant given marijuana's increasing popularity.

"We need to understand that as more people are choosing to use marijuana, there may be potential negative effects of that consumption," Volkow told Medscape Medical News. "And we have been particularly concerned about the use of marijuana during pregnancy, because already the data show that mothers who use marijuana tend to have smaller children and to deliver newborns prematurely."

The ABCD Study data used in the research can be found here. Baranger and Volkow have disclosed no relevant financial relationships.

JAMA Pediatr. Published online September 12, 20212. Abstract

Michael Vlessides is a best-selling author and medical journalist in Canmore, Canada.

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