Study results published in the Journal of the American Academy of Child & Adolescent Psychiatry identified neighborhood crime rate, poverty level, and lead exposure as risk factors for psychotic-like experiences (PLEs) in children aged 9 to 11 years. In this nationwide cohort study, certain environmental exposures emerged as correlates of childhood PLEs, even when including internalizing and externalizing symptoms.
Investigators extracted cross-sectional data from the Adolescent Brain Cognitive DevelopmentSM (ABCD) study, a large-scale study conducted at 21 research sites across the United States. During the baseline ABCD visit, children completed the Prodromal Questionnaire-Brief Child Version, which captured PLEs. Internalized and externalized symptoms were assessed by parental report. Children also underwent magnetic resonance imaging (MRI) of the brain. Environmental risk factors were determined based on the child’s primary address. Risk factors of interest included neighborhood safety and crime rates, likelihood of environmental toxins in the home, and socioeconomic status disadvantage as measured by the Area Deprivation Index. Hierarchical linear models were used to assess the relationship between environmental risk factors and the likelihood of PLEs. Mediation models were used to examine the impact of structural MRI abnormalities on the relationship between environmental risk factors and PLEs.
The study cohort comprised 10,328 children aged 9 to 11 years. PLEs were found to be significantly associated with measures of urbanicity, safety, and crime. Specifically, greater total drug offense exposure (R2 =.022) and lower perception of neighborhood safety (R2 =.019) were positively associated PLEs. Greater overall neighborhood deprivation (R2=.034), greater neighborhood poverty rates (R2=.024), and fewer years of neighborhood residence (R2 =.021) were also associated with higher rates of PLEs. Although a variety of environmental toxins were assessed, only increased lead exposure emerged as a correlate of PLEs (R2 =.019), and although internalizing and externalizing symptoms showed similar associations with these environmental risk factors, the relationship was more pronounced with PLEs. Compared with internalizing and externalizing symptoms, PLEs showed significantly stronger associations with total drug offense exposure, greater deprivation, as well as rate of poverty (all P <.001). In mediation models, cortical volume appeared to partially mediate the association between neighborhood poverty levels and PLEs. Specifically, reduced cortical volume was significantly associated with increased PLEs and increased environmental risk factors. Cortical volume also partially mediated the impact of neighborhood safety and lead exposure risk on PLEs.
The current study has a number of limitations. The fact that all measures were collected at the ABCD study baseline assessment limits the conclusions that can be drawn from this study. In addition, information about the degree of each individual’s exposure to environmental risk factors limits the conclusions that can be drawn from these analyses and requires future research to examine dose-response associations. Self-reporting of PLEs was also not followed up with a clinical interview. Associations with other self-reports were in the small to moderate range (βs≤.23), and a number of participants (n=1546) had missing data and therefore were not included in analyses. Also, the researchers did not include race/ethnicity as a covariate due to the all too frequent confounding of minority status with other relevant factors involved in the current study.
Results from this study suggest that myriad environmental exposures may precipitate PLEs in childhood. Certain structural MRI measures also appeared to mediate the relationship between certain environmental exposures and PLEs. Further research is necessary to assess the neurologic underpinnings of these associations. “Future clinical interventions and public health policies to reduce exposure to deprivation, correlates of urbanicity… and environmental toxins will be important for reducing negative effects of exposure on psychosis risk,” the investigators wrote.
Karcher NR, Shiffman JE, Barch DM. Environmental risk factors and psychotic-like symptoms in children aged 9-11. J Am Acad Child Adolesc Psychiatry. Published online July 16, 2020. doi:10.1016/j.jaac.2020.07.003