Heatwaves and Mental Health

Trigger Warning: The following article has multiple references to suicide, mental health issues and correlational risk factors.

In acknowledgement of World Mental Health Day, Tuesday 10th October 2023, Shade the UK believe it important to raise awareness of the increasing evidence towards the impacts of anthropogenic climate change on mental health. As the world grapples with the consequences of extreme weather events, such as heatwaves, droughts, and flooding, we must recognise that mental health is an integral component of public health responses. The time has come to advocate for comprehensive strategies that consider both the physical and mental aspects of health, recognising their intricate connection with the health of the natural world.

The world is already experiencing the effects of anthropogenic climate change, through the increased frequency and intensity of extreme weather events. The speed at which this transition happens is often disproportionate to the speed at which human beings and nature can adapt; thus, increasing our vulnerability to effects of heatwaves.

The effects this has on human health globally is extensive and cascades to several aspects of health. However, while there has been substantial research into the physiological effects of increasing temperatures and heatwave occurrences, there has been comparatively little research into the psychological effects.

Heatwaves exacerbating existing conditions

Many studies have investigated the psychological vulnerabilities of society to heatwaves; amongst these studies, the strongest correlation between heat vulnerability and people was found to be among those who suffer from pre-existing mental health and behavioural disorders.

Extreme heatwaves can often interfere with the balance of biochemicals in the body. In turn, this imbalance can cause reactions that constitute compound stress built up over time. One study by the American Psychological Association found that psychiatric medication meant to deal with existing mental health conditions may interfere or inhibit with the body’s ability to thermoregulate, thereby exacerbating the heat stress experienced by a person.

Over the last few decades, there has been a growing interest in the effects of heatwaves on psychotic exacerbation all across the world. One study investigated the increased deaths of many psychiatric patients in the New York State psychiatric hospital due to heatwaves in the 1970s. The hospital took several preventive measures including air conditioning and regular monitoring of patients at close intervals. The study concluded that both the usage of antipsychotic medication and an existing psychiatric illness contributed to the increased risk of dying during heatwaves.

Furthermore, a study of the 2003 heatwave mortality in Paris which claimed more than 700 deaths found mental disorders to be a significant contributor. In Australia, a meta-analysis in 2007 deducted that pre-existing psychiatric illness tripled the mortality risk associated with death during heatwaves. Another Australian study conducted in 2008, found a 7% increase in hospital admissions from mental illnesses when ambient temperatures were greater than 26 degrees Celsius, including dementia, mood affective disorders, neurotic and stress related disorders, and disorders of psychological development, and senility.

Heatwaves creating mental health conditions

It is common for psycho-social aspects such as socialising, social networking, and livelihoods to be disrupted by heatwave events and this can seriously affect mental health. For example, those who work in agriculture are grossly affected by high temperatures and when crop yields are reduced, that directly affects the livelihoods. This can then lead to financial implications which often perpetrate ill mental health, and in extreme cases, can lead to suicide. For example, a study has shown that increased temperatures during India’s main agricultural season has a strong association with annual suicide rates.

Climate anxiety researchers are also talking about manifestations such as solastalgia, eco-anxiety, eco-depression, and eco-anger. Solastalgia is a term that refers to distress induced by unprecedented environmental change which is directly connected to people’s home and related environments. For example, a heatwave or draught event can induce a sense of powerlessness as they have little to no control over the change that is unfolding.

While solastalgia is related to current environmental change, eco-anxiety is to do with psychological distress induced by climate change and it’s future impacts. This phenomenon is mostly experienced amongst young people, for example, a recent survey determined that around 60% people aged 16-25 expressed that their anxieties about the climate crisis. Additionally, indigenous people tend to have heightened eco-anxiety as their traditions and livelihoods are deeply connected with nature. Eco-anxiety can also take the form of eco-depression, wherein people feel powerless in not being able to do anything about the environmental crisis. On the other hand, this feeling of powerlessness has been found to transform into eco-anger, which is often used as an adaptive emotional driver of engagement with the climate crisis.

Heatwaves and suicide

As of 2023, according to the World Health Organisation, over 700,000 people die by taking their own life annually. This  means that one person in crippling downcast attempts suicide every 40 seconds. The last 5 years have seen a noticeable rise in a variety of life-stressors, and understanding these new forms of life stressors can consequently inform suicide prevention strategies. One of the first steps towards this would be to understand the different aspects and factors that interact with suicidality and consequent suicidal behaviour. One such aspect, that is being increasingly researched into, is the role of heatwaves and increasing temperature on suicidality.

A systematic review investigated the relationship between high ambient temperatures, heatwaves, and mental health. Within the 35 studies analysed, more than 15 studies indicated an increase in suicide risk with rising temperatures. Another study, published by the French National Institute for Health and Medical Research, analysed the cause of deaths recorded between 1968 and 2016. From the 502,000 of 24.4 million people who were found to have died by suicide, the study suggests that when temperatures increase by 1 degree Celsius, suicides increase by 6%. Although a fraction of suicides is associated with high temperatures, the precise causal epidemiology is yet to be known.

Other studies necessitate further research to be conducted into the relationship between suicide and climate. A pilot study investigated whether there was a statistically significant correlation between heatwaves or relative humidity and suicide on a global scale, indicating that around half of the countries demonstrated a significant change in suicide rates with relative humidity. Contrary to previous studies indicating a positive correlation between heatwaves, humidity, and suicide, this study indicates that there are both increases and decreases in suicide with respect to increases in heatwave events.

Recommendations

To improve the well-being of individuals and communities in the face of climate change, it is clear that further research is needed. We should continue exploring the specific metrics of atmospheric conditions related to heatwaves, such as wet-bulb globe temperature, humidex, and more. This in-depth analysis will provide us with a nuanced understanding of the correlation between environmental factors and mental health. It is equally crucial that as we pursue adaptation and mitigation solutions, we consider not only the immediate physical impacts but also the potential social consequences that may affect mental health. For instance, strategies that involve blocking out direct sunlight and keeping people indoors may have unintended social and psychological ramifications. By embracing the interconnectedness of mental and physical health with the natural world, we can pave the way for comprehensive solutions that not only mitigate the adverse effects of climate change but also promote the mental well-being of people worldwide.

Mental and physical health is intricately intertwined with the health of the natural world and this must be seen in conjunction to improve well-being.

Written by Rashikkha Ra Iyer