In a recently published study BMC MedicineResearchers estimate how exposure to various trace elements in drinking water may increase the risk of depression and anxiety.
study: Associations between drinking water quality and psychological well-being and the effects of dietary change: a prospective cohort study. Image source: New Africa/Shutterstock.com
Mental health disorders, particularly depression and anxiety, remain a leading cause of disability and premature death worldwide. The global prevalence of anxiety and depression has increased by approximately 25% following the coronavirus disease 2019 (COVID-19) pandemic, illustrating the widespread prevalence of these mental illnesses.
Several factors may increase an individual’s risk for depression or anxiety, including genetics, social environment, and physical environment. In the physical environment, exposure to heavy metals such as cadmium has been shown to increase the risk of depression and anxiety, while other elements such as manganese, copper and selenium can fight oxidative stress and potentially reduce the risk of depression.
To date, most studies investigating the impact of environmental risk factors on the incidence of depression and anxiety have been cross-sectional. In China, few longitudinal studies have examined how exposure to metallic and non-metallic elements in drinking water affects the risk of depression and anxiety.
About the study
In this study, researchers identified people diagnosed with depression and anxiety disorders in the Yinzhou area using International Classification of Diseases codes F32 and F41, respectively, based on data retrieved from the Yinzhou Health Information System (YHIS). Atomic absorption spectrophotometry (AAS) was used to determine the contents of manganese, zinc, copper, iron, aluminum, cadmium, selenium and fluorine in tap water samples from 37 points in Yinzhou District.
Water samples are collected four times per year and at least once per season. Exposure levels were assigned to participants based on their residential address and the location of the tap water collection point. Daily exposure to all trace elements in drinking water was calculated and adjusted based on participants’ daily drinking water intake and their age and sex.
A baseline survey was conducted to collect data on the frequency of participants’ consumption of leafy vegetables, meat, fruit, and fish, and to categorize intake of these dietary components as low, moderate, or high. Data on sociodemographic status, lifestyle, and medical history were also obtained.
The final analysis included 24,285 people between 2016 and 2021 without a history of depression or anxiety. During a median follow-up of 4.72 and 4.68 years, these individuals reported 765 and 1,316 cases of depression and anxiety disorders, respectively.
Women and those who have never smoked or drank alcohol are more likely to develop depression, in addition to being at greater risk of hypertension, dyslipidemia, cancer, and stroke. In contrast, women, people with less education, older adults, people who never drink alcohol, non-smokers, and people with lower incomes, in addition to lower levels of seafood and meat consumption, are more likely to suffer from the disease. There’s anxiety, diabetes, dyslipidemia, cancer and stroke. .
Exposure to aluminum in drinking water was more common among individuals diagnosed with depression, while patients with anxiety disorders had higher exposure to manganese, iron, and aluminum in drinking water. People with anxiety disorders were also exposed to lower levels of zinc than healthy participants.
Long-term exposure to zinc, iron, aluminum, selenium and fluoride does not affect the risk of depression. Likewise, long-term exposure to zinc, copper, aluminum, cadmium, and fluoride does not increase the risk of anxiety.
There was no significant effect of diet on the relationship between depression risk and exposure to manganese, copper, and cadmium in drinking water. However, the risk of anxiety was greater for people who ate less fruit, more seafood and meat, and were exposed to manganese and iron in their drinking water. Long-term exposure to copper, selenium and fluoride also increases the risk of anxiety in people who consume fewer leafy vegetables and fruits.
Lower socioeconomic level is associated with increased exposure to heavy metals, especially copper, in drinking water. Additionally, older adults, those with lower incomes, and those with less education who are exposed to cadmium in drinking water are also at greater risk for depression.
Higher educational levels were more common among anxious individuals exposed to manganese and selenium in drinking water. In contrast, iron exposure in drinking water was also more common among older adults with anxiety disorders and those with less education.
The current findings highlight the need to improve drinking water quality and adopt healthy dietary habits to reduce the burden of depression and anxiety, as these measures may contribute to the pathophysiology of depression and anxiety. Public health policy should also address the inequitable impact of various trace elements in drinking water on increased risk of mental illness among people from lower socioeconomic classes.
- Zhou S., Su M., Shen P. et al. (2024). Associations between drinking water quality and psychological well-being and the effects of dietary change: a prospective cohort study. BMC Medicine twenty two(53). Number: 10.1186/s12916-024-03269-3