Lead levels in blood linked to depression, panic disorder

Young adults with elevated levels of lead in their blood are at higher risk of developing major depression and panic disorders, even if lead concentration levels are considered low, according to a new study published in the Archives of General Psychiatry.

"Lead is omnipresent in air, soil, dust and water," says Dr Maryse F. Bouchard, a researcher at the Université de Montreal Department of Environmental and Occupational Health in Canada and the Harvard School of Public Health in the United States. "While the elimination of lead from gasoline has dramatically decreased average lead levels, populations remain exposed though several sources including dust from old paints, select cooking pottery and water that is contaminated through old piping and industrial processes."

Dr Bouchard and her team analysed data from 1,987 young American adults representative of the general population, aged 20 to 39 years, who took part in the National Health and Nutrition Examination Survey. Participants provided blood samples and completed a diagnostic interview to identify any mental disorder. Some 6.7 percent of paticipants had a major depressive disorder, 2.2 percent had panic disorder and 2.4 percent had generalised anxiety disorder.

Average blood lead levels were 1.61 micrograms per decilitre. One-fifth of participants had led levels of 2.11 micrograms per decilitre, which made them 2.3 times more likely to develop major depressive disorder and 4.9 times more likely to develop panic disorder compared to other participants.

Even low lead exposure can disrupt brain processes – the neurotransmitters, catecholamine and serotonin associated with depression and panic disorders. In individuals predisposed to mental disorders, lead exposure could trigger outbreaks, increase severity and reduce treatment response. "Combined with recent reports of adverse behavioural outcomes in children with similarly low blood lead levels as participants of our study, our findings accentuate the need to further reduce sources of environmental lead exposures," stresses Dr Bouchard.

(Source: Université de Montreal: Archives of General Psychiatry: December 2009)