BACKGROUND: Animal studies have reported an association between phthalates and depression, although there is limited evidence from epidemiological studies. We investigated the association between phthalate exposure and symptoms of depression in an elderly population.

METHODS: Repeated measures surveys up to three times were conducted during the study period (2012-2014) in the 535 elderly subjects. We measured the following urinary phthalate metabolite levels: mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-n-butyl phthalate (MnBP), and mono-benzyl phthalate (MBzP). MEHHP, MEOHP, and MECPP are metabolites of diethylhexyl phthalates (DEHP). MnBP and MBzP are metabolites of dibutyl phthalate and butyl benzyl phthalate, respectively. The phthalate metabolite concentrations were evaluated to identify associations with the symptoms of depression using the Korean version of the Geriatric Depression Scale-Short Form (SGDS-K). After factor analysis of the components of SGDS-K, we evaluated the association between phthalate exposure and SGDS-K subgroups to determine which symptoms of depression were affected by phthalate exposure.

RESULTS: Concentrations of DEHP metabolites were positively associated with the risk of depressive symptoms in the elderly population (Odds ratio (95% confidence interval); 1.92 (1.17-3.13) for sum of three DEHP metabolites), while we found no significant association between depressive symptoms and either MnBP or MBzP. When we evaluated the associations between phthalate metabolite concentrations and the SDGS-K subgroup, we found that affective and spiritual symptoms were significantly associated with DEHP metabolite concentrations.

CONCLUSIONS: Our study suggests that DEHP exposure is associated with depressive symptoms, particularly, the affective and spiritual symptoms, among the elderly population.