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Childhood lead exposure may have lifelong mental health consequences
Higher blood lead levels in childhood were linked to greater psychopathology throughout life and with difficult personality traits in adulthood, according to results from a longitudinal cohort study of participants followed up for more than 30 years.
Prior research has failed to fully characterize the long-term mental and behavioral health consequences of early-life lead exposure, researchers wrote in JAMA Psychiatry.
“We have long known that lead disrupts child brain development. Children exposed to lead display lower IQ and greater problem behaviors than their peers,” Aaron Reuben, MEM, from the department of psychology and neuroscience, Duke University, told Healio Psychiatry. “We wanted to know whether behavioral problems might extend into adulthood, and additionally, whether the generation of lead exposed children (those born in the ‘60s, ‘70s, and ‘80s) might have experienced greater rates of mental health problems throughout adulthood.”
The researchers conducted the longest and largest psychiatric follow-up to date in a cohort of adults exposed to lead in childhood — ascertained as blood lead levels measured at age 11 years — to evaluate whether childhood lead exposure was tied to greater lifelong psychopathology and personality issues in adulthood.
Using data from a population-representative birth cohort of people born in New Zealand followed up to age 38 years, the investigators examined adult mental health disorder symptoms via clinical interview at ages 18, 21, 26, 32 and 38 years and adult personality via the Big Five Personality Inventory at ages 26, 32 and 38 years.
Overall, 579 study participants were tested for lead exposure at age 11 years (53.7% male) and the mean child blood lead level was 11.08 g/dL.
Reuben told Healio Psychiatry that study participants with greater lead exposure in childhood tended to exhibit more psychiatric symptoms in adulthood between the ages of 18 and 38 years. Specifically, they reported more internalizing symptoms (eg, depression and anxiety) and thought disorder symptoms (eg, obsessive-compulsive disorder and schizophrenia).
Analysis showed that each 5-g per dL rise in childhood blood lead level was linked to a 1.34-point rise (95% CI, 0.11-2.57) in general psychopathology. This relationship was largely driven by associations between increased childhood blood lead levels and increased internalizing (b = 1.41; 95% CI, 0.19-2.62) and thought disorder (b = 1.3; 95% CI, 0.06-2.54) symptoms.
“Compared to other findings from this sample, the associations reported in this article are similar to those reported for lead and IQ and are stronger than those reported for lead and criminal offending,” Reuben said.
In addition, each 5-g per dL increase in childhood blood lead level was tied to an increase in neuroticism, as well as decreases in agreeableness and conscientiousness by age 38 years as measured via the Big Five Personality Inventory.
“These personality traits have been previously linked to a number of poor life outcomes, including greater psychopathology, worse physical health, less job satisfaction and troubled interpersonal relationships,” Reuben said.
“For the larger health system, follow-up in children exposed to lead should include mental health services and, furthermore, should focus on potential long-term persistence of changes to behavior, emotion and interpersonal relations,” he told Healio Psychiatry. “For clinicians, adult patients with a history of childhood lead exposure may benefit from mental health screening and services.”
According to Reuben, these findings add to the list of reasons why removing lead from the environment is an important public health goal. The consequences of childhood lead exposure are “greater than we used to believe and appear to persist, at least to midlife,” he said. – by Savannah Demko
Disclosure: The authors report no relevant financial disclosures.