Air Pollution and Symptoms of Depression in Elderly Adults
Lim, Youn-Hee, Kim, Ho, Kim, Jin Hee, Bae, Sanghyuk, Park, Hye Yin, Hong, Yun-Chul, Environmental Health Perspectives
BACKGROUND: Although the effect of air pollution on various diseases has been extensively investigated, few studies have examined its effect on depression.
OBJECTIVES: We investigated the effect of air pollution on symptoms of depression in an elderly population.
METHODS: We enrolled 537 participants in the study who regularly visited a community center for the elderly located in Seoul, Korea. The Korean version of the Geriatric Depression Scale-Short Form (SGDS-K) was used to evaluate depressive symptomatology during a 3-year follow-up study. We associated ambient air pollutants with SGDS-K results using generalized estimating equations (GEE) We also conducted a factor analysis with items on the SGDS-K to determine which symptoms were associated with air pollution.
RESULTS: SGDS-K scores were positively associated with interquartile range (IQR) increases in the 3-day moving average concentration of particulate matter with an aerodynamic diameter [less than or equal to] 10 [micro]M.sub.10]) [17.0% increase in SGDS-K score, 95% confidence interval (CI): 4.9%, 30.5%], the 0-7 day moving average of nitrogen dioxide [[NO.sub.2]; 32.8% (95% CI: 12.6%, 56.6%)], and the 3-day moving average of ozone [[0.sub.3]; 43.7% (95% CI: 11.5%, 85.2%)]. For these three pollutants, factor analysis showed that air pollution was more strongly associated with emotional symptoms such as feeling happy and satisfied than with somatic or affective symptoms.
CONCLUSIONS: Our study suggests that increases in [PM.sub.10], [NO.sub.2], and [0.sub.3] may increase depressive symptoms among the elderly. Of the symptoms evaluated, ambient air pollution was most strongly associated with emotional symptoms.
KEY WORDS: air pollution, depressive symptoms, elderly, factor analysis, panel study. Environ Health Perspect 120:1023-1028 (2012). http://dx.doi.org/10.1289/ehp.1104100 [Online 18 April 2012]
Depression is one of the common mental health problems experienced by the elderly and has been found to lead to increased mortality and suicide in this age group (Blazer et al. 2001; Waern et al. 2003). Known risk factors for depression among the elderly are alcohol and substance abuse, sleep disturbance, bereavement, medical conditions, family history, and being female (Cole and Dendukuri 2003; Mulsant and Ganguli 1999). Hypotension and a low lipid level also have been found to be associated with depressive symptoms among the elderly and women, respectively (Horsten et al. 1997; Kim et al, 2010).
Plausible biological mechanisms of depression include reactivity to exogenous stressors; alterations of neurohumoral, immune, and autonomic regulation; dysfunction of neurotransmitter systems; and oxidative stress (Grippo 2009; Ng et at 2008). Because depletion of dopamine in the central nervous system (CNS) is known to be an underlying pathophysiological mechanism of depression (Hasler 2010), air pollution could affect depressive moods by inducing dopaminergic neurotoxicity, possibly due to oxidative stress (Block et al. 2004). Research with cell cultures and experimental animals has provided evidence of neuropathological effects of exposure to particles (Block et al. 2004; Campbell et al. 2005; Veronesi et al. 2005). However, only a few studies have evaluated the association between air pollution and depressive symptoms in humans. In Canada, researchers reported short-term effects of air pollution on emergency department visits because of depression and suicide attempts (Szyszkowicz 2007a; Szyszkowicz et al. 2009b, 2010). Their time-series analyses focused on the diagnosis of depression resulting from severe pathophysiological alterations in the CNS, and their results suggest that air pollution may have aggravated symptoms of depression among a pool of patients in the community who were suffering from depression. However, Bullinger (1989) has proposed that short-term exposure to air pollution more likely affects daily mood rather than causes major depressive illnesses Although studies have found that major (Valvanne et al. …