New research published in JAMA Network Open links higher childhood blood lead concentrations with increased depressive symptoms in adolescence. The investigators report that each doubling of mean childhood blood lead concentrations was associated with higher risk of elevated child-reported depressive symptoms, and that even low childhood lead levels were related to self-reported depressive symptoms later in childhood. The rise in risk was especially pronounced when exposures occurred in late childhood and early adolescence, with results indicating that exposure around age 8 was particularly consequential for onset and severity.
The team examined data from 218 caregiver–child pairs in the Health Outcomes and Measures of Environment Study, which followed families from the second trimester of pregnancy to age 12. Blood lead concentrations were measured at ages 1, 2, 3, 4, 5, 8, and 12, and anxiety and depression were assessed around age 12.
The authors discussed biological processes that might explain the link, including altered neurotransmitter function, reduced neurogenesis and disrupted synaptic plasticity in mood-related brain regions, oxidative stress and inflammation, and genetic modifications that could affect symptom onset or persistence. Joseph Braun and other researchers emphasized the need for continued prevention and efforts to reduce lead exposure in older children. The work received funding from the National Institutes of Environmental Health Sciences.
- Altered neurotransmitter function and reduced neurogenesis
- Oxidative stress and inflammation
- Genetic modifications affecting symptom onset or persistence
Difficult words
- concentration — amount of a substance measured in bloodconcentrations
- depressive — relating to feelings of deep sadness
- adolescence — period between childhood and early adulthood
- exposure — contact with a harmful substance or agentexposures
- neurogenesis — formation of new neurons in the brain
- synaptic plasticity — ability of brain connections to change
- oxidative stress — cell damage caused by reactive oxygen molecules
- onset — start or beginning of symptoms or disease
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Discussion questions
- What public health actions could help reduce lead exposure in older children, based on the study's findings?
- Why might exposure around age 8 be particularly consequential for the onset and severity of depressive symptoms later?
- How could families and schools respond to the finding that even low childhood lead levels relate to later self-reported depressive symptoms?
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