Academic journal article Environmental Health Perspectives

Relation of Cumulative Low-Level Lead Exposure to Depressive and Phobic Anxiety Symptom Scores in Middle-Age and Elderly Women

Academic journal article Environmental Health Perspectives

Relation of Cumulative Low-Level Lead Exposure to Depressive and Phobic Anxiety Symptom Scores in Middle-Age and Elderly Women

Article excerpt

BACKGROUND: Different lines of evidence suggest that low-level lead exposure could be a modifiable risk factor for adverse psychological symptoms, but little work has explored this relation.

OBJECTIVE: We assessed whether bone lead--a biomarker of cumulative lead exposure--is associated with depression and anxiety symptoms among middle-age and elderly women.

METHODS: Participants were 617 Nurses' Health Study participants with K-shell X-ray fluorescence bone lead measures and who had completed at last one Mental Health Index 5-item scale (MHI-5) and the phobic anxiety scale of the Crown-Crisp Index (CCI) assessment at mean [+ or -] SD age of 59 [+ or -] 9 years (range, 41-83 years). With exposure expressed as tertiles of bone lead, we analyzed MHI-5 scores as a continuous variable using linear regression and estimated the odds ratio (OR) of a CCI score [greater than or equal to] 4 using generalized estimating equations.

RESULTS: There were no significant associations between lead and either outcome in the full sample, but associations were found among premenopausal women and women who consistently took hormone replacement therapy (HRT) between menopause and bone lead measurement (n = 142). Compared with women in the lowest tertile of tibia lead, those in the highest scored 7.78 points worse [95% confidence interval (CI): -11.73, -3.83] on the MHI-5 = 0.0001). The corresponding OR for CCI [greater than or equal to] 4 was 2.79 (95% CI: 1.02, 7.59; p-trend = 0.05). No consistent associations were found with patella lead.

CONCLUSIONS: These results provide support for an association of low-level cumulative lead exposure with increased depressive and phobic anxiety symptoms among older women who are premenopausal or who consistently take postmenopausal HRT.

KEY WORDS: anxiety, depression, environmental exposure, epidemiology, lead, longitudinal study. Environ Health Perspect 120:817-823 (2012). http://dx.doi.org/10.1289/ehp.1104395 [Online 29 February 2012]

The public health burden of psychiatric disorders such as depression and anxiety is tremendous--an estimated 450 million people worldwide suffer from psychiatric disorders [World Health Organization (WHO) 2001]. In the United States, the lifetime prevalence of major depressive disorder [using survey ascertainment of symptoms consistent with Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnostic criteria (American Psychiatric Association 1987, 1994)] is approximately 10% for men and 20% for women (Kessler et al. 1994; Steffens a al. 2000). Furthermore, very high percentages of older people suffer from depressive (10-30%) or anxiety (-20%) symptoms that do not meet full diagnostic criteria (Beekman et al. 1999; Himmelfarb and Murrell 1984) but are associated with excess morbidity and functional impairment (Beekman a al. 1999; de Beurs a al. 1999; Himmelfarb and Murrell 1984; Lyness et al. 2007), greater risk of subsequent clinical diagnoses of depression and anxiety (Horwath et al. 1992; van't Veer-Tazelaar et al. 2009), and greater health care service use and costs (de Beurs a al. 1999; Simon a al. 1995). Improved understanding of risk factors for anxiety and depressive symptoms could help address the public health burden of these disorders.

Few studies have considered the possible link between environmental toxicant exposures at low levels found in the community and mental health outcomes, despite the evidence from occupational studies that aspects of mood may be particularly sensitive to such exposures (Johnson et al. 1987). Given that many toxicant exposures are potentially modifiable, this group of potential risk factors for mental health outcomes should be of interest. Lead exposure is of particular interest because it is an established neurotoxicant (Bressler et al. 1999) with known effects on several brain systems implicated in depression and anxiety, including monoaminergic signaling (Kala and Jadhav 1995; Lasley et al. …

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