The unseen effects of climate change on mental health

Research has found people with schizophrenia may be at greater risk of succumbing to heat-related deaths than those with kidney or heart disease

Updated - May 09, 2024 03:26 pm IST

Published - May 08, 2024 05:30 am IST

A man uses a cardboard box to shield himself from the Sun in Kochi, May 3, 2024.

A man uses a cardboard box to shield himself from the Sun in Kochi, May 3, 2024. | Photo Credit: Thulasi Kakkat/The Hindu

The mercury is soaring across India, with many places reporting unusually high temperature readings. It may not be possible to link each heat event to climate change, but we know climate change is bringing such anomalies to more areas, and with greater intensity.

We also know climate change is disproportionately affecting society’s most vulnerable members, including those with physical ailments, the elderly, the poor, and the socially and economically marginalised. And we also know climate change has become the basis of a slew of psychological afflictions of its own, including eco-anxiety, eco-paralysis, and solastalgia (a form of emotional or existential distress rendered by environmental changes), together with seeding general concerns in communities worldwide about their livelihoods, future, the future of their children, and their culture.

But let’s not forget that climate change’s multi-dimensional assault on reality as we know it also potentially includes being able to worsen existing mental health conditions.

A dubious distinction

A study published in 2023 in the journal GeoHealth reported that an extreme heat event in the Canadian province of British Columbia in 2021 affected people with schizophrenia more than those with kidney and heart disease. The study’s authors, of the British Columbia Centres for Disease Control and Health Canada, also wrote that people with mental health conditions seem to be at a greater risk of succumbing to heat-related deaths. The stakes were found to be even higher for people diagnosed with schizophrenia, anxiety or bipolar disorder.

During the eight-day extreme heat event in 2021, the province of British Columbia experienced temperatures as high as 40 degrees C when the average temperatures have been around 20 degrees C. The region recorded around 740 excess deaths during this heat wave.

To understand who was affected the most during this event, the researchers compared 1,614 deaths recorded over a month in 2021 with 6,524 deaths recorded in the same time period nine years ago. They analysed the data based on 26 medical conditions, including heart disease, schizophrenia, chronic kidney disease, dementia, depression, Parkinson’s disease, and osteoporosis.

The scientists wrote that they expected to find people with kidney and heart diseases to be most at risk, but were surprised to find that that dubious distinction belonged to people with schizophrenia. In particularly, they reported that 8% of the people surveyed in 2021 were previously diagnosed with schizophrenia as opposed to 2.7% of the people surveyed nine years ago. This was a 200% increase from a summer in which heat waves weren’t recorded.

To be sure, while people with schizophrenia were found to be at greater risk of heat-related distress than those with kidney and heart diseases, the latter weren’t immune: they were at risk as well, just less so.

Dysfunction of the hypothalamus

A closer look at the data revealed that of the 280 people whose deaths were confirmed to be related to heat, 37 people had schizophrenia. “These results show that people with schizophrenia need extra protection, extra support and extra care,” Sarah Henderson, one of the epidemiologists who led the study and the scientific director of Environmental Health Services at the British Columbia Centre for Disease Control, told Science.

The researchers believe one of the main reasons people with schizophrenia were more vulnerable to heat stress could be as a result of the dysfunction of the hypothalamus, a structure embedded deep in the human brain. Its main function is to maintain the homeostasis of the body, i.e. to keep the body in a stable condition that ensures it can carry out its normal function. This means it controls of the body’s temperature, heart rate, hunger, thirst, mood, libido, sleep, and the regulation of hormones.

Certain antipsychotic medications prescribed to people with schizophrenia have also been found to interfere with the hypothalamus’s workings. One side-effects of such drugs has been a tendency to raise the body’s temperature, which when coupled with anomalously high ambient temperatures can rapidly prove fatal. This side-effect is not only limited to people with schizophrenia but also people with anxiety, depression and bipolar disorder who are treated with antipsychotic medication.

People with schizophrenia also often have psychotic symptoms such as hallucinations, delusions, disorganised thinking, and memory loss. They may also suffer from anosognosia: a condition in which they’re unable to sense that they’re ill. All this together with comorbidities like diabetes and hypertension can make life very difficult for people with schizophrenia, including potentially interfere with their ability to seek help.

As it happens, marginalisation, lower economic status, and a propensity for loneliness are risk factors for people with schizophrenia, and the same factors can heighten an individual’s vulnerability to heat-related illnesses, as the infamous 1995 Chicago heat event demonstrated.

Yet another tentacle

But for some antipsychotic medicines’ potential to interfere with people’s experience of anomalous ambient heat, scientists have cautioned that they shouldn’t be discontinued or tampered with because these are ‘lifesaving therapies’. They have suggested that the risk factors associated with schizophrenia, including social isolation, should be tackled instead with interventions like counselling and checking in on them regularly.

In a statement issued by the British Columbia Centres for Disease Control, Faydra Aldridge, CEO of the British Columbia Schizophrenia Society, said, “As demonstrated by the recent research, because individuals living with schizophrenia are more susceptible to heat-related illness, it is essential that families and caregivers are aware of the increased risk, identify potential risk factors and take prompt action to help their loved one during a heat wave.”

She added that “educating ourselves to recognise symptoms of heat-related illness and take emergency cooling measures will help ensure everyone’s safety during heat waves.”

One of the defining characteristics of climate change is the nonlinear nature of its effects, i.e. their ability to compound rapidly, affecting several walks of human life both directly and indirectly. The GeoHealth study elucidated one more example of this ability, adding to previous work that has examined its influence on everything from domestic violence to child-trafficking.

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