Heatwave raises death risk for schizophrenic people by 200%: research

Schizophrenia is considered to be one of the most debilitating mental illnesses to exist. The illness is characterised by incoherent or illogical thoughts, bizarre behaviour and speech, and delusions or hallucinations, such as hearing voices. As per WHO, the illness affects approximately 1 in 300 people worldwide. Previous research has established a relationship between extreme heat and the worsening of mental health.  But, a recent study published in GeoHealth brings to light just how grave the relationship between heat and schizophrenia can be.

Michael Lee, an epidemiologist at the British Columbia Centre for Disease Control and his team analyzed the record-breaking heat wave that occurred in British Columbia, Canada in 2021. This infamous period witnessed an unprecedented increase in population mortality and has been called the deadliest weather event in Canada to date. The analysis compared the prevalence of 26 chronic conditions among people who died during the eight-day period of the 2021 heatwave, with people who died on the same dates in the nine previous years. The study found that while mental illnesses were among the conditions that left people most susceptible to death. Further, those with schizophrenia were at the highest risk.

The research found that a staggering 8 per cent of those who died due to heat had been diagnosed with schizophrenia and that schizophrenic people were 200 per cent more likely to die during heat waves than in normal conditions. 

How do our bodies react to prolonged exposure to extreme heat?

Several processes are involved when our body tries to wade off heat. Sweat glands spring to action. The body pushes sweat out onto the surface of our skin. As the air absorbs it (evaporation), it draws heat away thereby cooling it down. At the same time, our blood vessels dilate as a response to brain signals. This pushes blood away from the hot center of the body and toward the skin to cool off. These two systems work together to keep the body around 37 °C.

However, prolonged exposure to extreme heat severally tests the body. When the body senses it is too hot, the medulla oblongata – the part of the brain that controls vital processes including heartbeat, breathing and blood pressure – tells the heart to increase the amount of blood pumped for every beat. But with blood pressure lowered, the heart has to work harder to push the blood around the body. Hence, the heart rate increases. At extreme temperatures, the quantity of blood circulated increases dramatically. The heart becomes exhausted and blood flow can suddenly plummet.

As a result, the brain and vital organs are deprived of oxygen. The person can become dizzy or disoriented. The person’s thinking slows. Intestines and kidneys undergo severe dysfunction. 

Why are heat waves especially dangerous for people with schizophrenia?

Researchers acknowledge that the reasons for the above-mentioned are not clearly known. But they say, several factors confound and add to the vulnerability.

• Scientists speculate that schizophrenia can affect the brain’s hypothalamus. The hypothalamus is considered to be the brain’s inner thermostat- which helps regulate temperature through sweating and shivering. A recent Washington Post article recounts an experiment from the 1930s. In the experiment, the two doctors in Massachusetts placed people with and without schizophrenia in a small, windowless room with eight electric heaters. The researchers observed that schizophrenic patients witnessed body temperatures which rose farther and faster than the control group. 

• Schizophrenia has also been linked to problems regulating dopamine, the chemical that makes the body feel good. Studies show that altered levels of dopamine can also prevent the body from effectively cooling itself off. 

• As per the American Psychological Association (APA), some psychiatric medications, including some antidepressants and antipsychotics, can affect the way the body regulates temperature. Drugs prescribed for schizophrenia and other serious mental illnesses are known to dehydrate patients. Therefore, make it harder for their bodies to manage high temperatures. Some have a side effect of suppressing sweating. Hence, prevents the body’s natural air-conditioning system from functioning normally.  Furthermore, medications with lithium, often prescribed to patients with bipolar disorder or schizoaffective disorder, is known to become toxic and deadly if the user is dehydrated. Dehydration is a likely scenario during a heatwave.

• Psychosis, said to occur when a person has lost touch with reality, is one of several symptoms of schizophrenia. Patients may experience delusions or hallucinations, forget where they are, or believe that others are attempting to harm them. The problem exacerbates when people with schizophrenia do not know or believe that they are sick. This condition known as “anosognosia.” During a psychotic episode, people with schizophrenia may wander off into the streets which in itself is dangerous, but deadly when extended for hours during a heatwave.

• Finally, given the debilitating nature of schizophrenia and its impact on a person’s socio-economic well-being, the illness is associated with isolation. People with schizophrenia are more likely to be economically unstable as well, rendering them prone to homelessness and without support during a heat wave

India, heatwave, and Schizophrenia

Very recently, an analysis by The Washington Post and CarbonPlan —showed that by 2030, 500 million people around the world, particularly in places such as South Asia and the Middle East, would be exposed to extreme heat for at least a month. Out of these, the largest population to be affected — 270 million — would be from India.

Furthermore, the study speculates that by 2050, the number of people suffering from a month of inescapable heat could further grow to an astounding 1.3 billion, exposing them to dangerous extreme humid heat. Specific research studying a correlation between schizophrenia and heat-related deaths in India could not be found. Despite that, it would be safe to say factors such as widespread homelessness, poverty, lack of awareness related to mental health and poor state of Heat Action Plans in our country make people with serious mental illnesses even more vulnerable. Immediate attention in terms of filling the research gap and taking note of different vulnerabilities in the heat action plans is imperative to understand and mitigate the problem.

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