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Mental disorders are a big part of the global disease burden. They are also well-known for their strong association with environmental-related disasters. What’s more, ongoing climate change is expected to increase the frequency and magnitude of cyclical environmental events, such as El Niño.

Between 2015 and 2017, the northern coast of Peru endured repeated periods of intense precipitation, flooding and landslides related to El Niño. Many residents of the area live below the poverty line and have limited access to mental and physical health services.

Given the global impact and ongoing nature of El Niño, I believe that we need to improve our understanding of its possible adverse effects on the mental health of communities at risk.

What is an El Niño event?

By way of background, El Niño refers to a cyclical environmental phenomenon that leads to periodic extreme weather irregularities. It occurs when there is an abnormal warming of at least 0.5°C on the mean sea surface temperature (SST) in the equatorial Pacific Ocean. This is defined over a five-month period. Its related effects cause disasters such as floods and landslides. In addition, El Niño causes intense precipitations in the surrounding coastal areas. Understandably these effect wreak a significant psychological and health toll on those affected.

Environmental disasters and mental health

Environmental disasters contribute to the development and worsening of common mental disorders. Such disasters can affect a community’s wellbeing through primary and secondary stressors. Primary stressors directly relate to the impact of the disaster itself. These include the levels of exposure, losses or the threat or harm. Moreover secondary stressors will indirectly contribute to the negative impact of the disaster. They could include potential economic and work losses, health-related repercussions among others. Combined with a specific person’s vulnerabilities, these stressors will affect the mental well-being of those exposed to the disaster, before and after it takes place.

Vulnerabilities and risk to environmental disasters

There is evidence that climate change will increase both the frequency and the magnitude of cyclical environmental events such as El Niño. What’s more, they will have a greater impact in  developing countries, where large groups of vulnerable people reside.

Risks and exposure will also be different among vulnerable groups. Furthermore some groups could be likely to experience even worse disaster’ effects. For example, these could include residents of high-risk areas for flooding or landslides. Other particularly vulnerable groups include residents of informal settlements and the elderly. They could also include people with a chronic health condition, disability or those with fewer economic resources or support networks.

Despite this, there has been little research on El Niño’s influence on the mental health of vulnerable communities. This is especially lacking in historically affected areas such as coastal Peru in South America.

The study: Linking Ecological and Individual data from 2014 to 2017 in the North Peruvian coast

We performed a secondary data analysis, using ecologic-level data provided by Peruvian national agencies. These included environment, disasters and civil defence & agriculture, and the individual assessments of depression. They came from a trial conducted in six villages of the northern coast of Peru with over 2300 participants. We aimed to explore if there were any changes in the participant’s depression scores, the most frequent mental disorder in the general population. These were measured every five months over the three years the study took place. Furthermore this overlapped over the periods when El Niño of 2015-2016 and El Niño costero -in early 2017- events occurred. We evaluated if the depression scores changed by its exposure to flooding, damages and landslides, per village and its association by a specific group of risk factors. These included age group, sex, income, access to health services, chronic diseases, disability and lifestyle factors settings among others.

Findings and Interpretation

In our study, we did not find evidence that the environmental and disaster impact variables collected of 2015-2017 El Niño events affected depression cases among individual residents.

We also found that the depression cases steadily decreased across time, among both males and females. This was irrespective of El Niño events. We found an association with the risk of developing depression and lacking access to health services. This also included having a chronic health condition, initial depression diagnosis, and being low-resourced.

These findings do not have a clear explanation. However, we can presume the existence of local factors that promote resilience related to the disaster occurrence, which we did not measure. Additionally, the study participants received additional benefits during the time the trial was implemented. These included attendance to health-promoting educative campaigns, health assessments by trained workers and opportunity to talk about their concerns periodically. We believe that somehow this may have influenced these results. Moreover most of the depression cases  found among the participants had mild symptoms. These symptoms may have remitted spontaneously, without medication or therapy over time.

Potential ways forward

We believe that these results should prompt more questions and decisive actions for future research and policy.

First of all, how we can ensure the protection of the mental well-being of vulnerable groups in high-risk areas for environmental disasters? How can we identify, explore and enhance resilience-promoting factors among these groups? And, what would be the best way to work towards these prevention goals, along with securing infrastructural prevention and recovery measures upon disasters? Finally, what actions can we take to ease the unequal risks to groups of people among communities living in flood-prone areas?

There is an impending risk of future El Niño events, fuelled by climate change effects. As such, we strongly believe that disciplinary research teams and policymakers should urgently consider these questions and actions.

Elaine C. Flores is a Peruvian physician and PhD candidate at the Centre for Global Mental Health at LSHTM, in the Epidemiology and Population Health faculty. Her main areas of interest include the impact of natural and man-made disasters, including climate change and environmental factors, on mental health.