During heat waves, hospital admissions for mental health conditions increase. The last ten years have been the hottest on record. It’s important to take steps to improve our preparedness for excessive temperatures.

Extreme heat poses well-known risks such as heat stress, heat exhaustion, and heat stroke. However, excessive heat can have a negative impact on mental health as well as physical health. Many people may relate to the sleepless nights of the hot summer months, as well as anecdotal reports of irritability and violence when thermally uncomfortable.

However, for persons suffering from mental problems, the dangers of high heat outweigh temperamental reactions to daily disturbances. The heat is worsening existing mental diseases in persons with schizophrenia, increasing the likelihood of hospitalization and even mortality under warmer temperatures (1).

Researchers are increasingly identifying environmental and health connections as public health concerns, as air and water quality issues, as well as heat-related deaths, make headlines. According to research, lower socioeconomic groups, colored persons, and the unhoused are more likely to be exposed to hotter circumstances, whilst older folks are more sensitive.

Link Between Heat and Mental Illnesses

The association between mental disease and temperature has only lately been quantified, as medical records and understanding of mental illnesses have advanced. Urbanization and heat affect human health. Researchers investigated the various unanticipated effects of heat on humans. They specifically looked at those who have been diagnosed with schizophrenia.

Schizophrenia is a mental condition that impairs the flow of information to the brain (2). The area of the brain most affected also contains our thermoregulatory processes. It is the component that warns us when we are too hot and should sweat, or when we are too cold and should shiver in order to stay warm.

As a result, persons with schizophrenia are unable to respond to excessive heat in the same way that the normal population does; their bodies are not signaling them to take measures. Furthermore, drugs used to treat schizophrenia boost core body temperature. This suggests that when taking the medicine, people with schizophrenia are closer to the heat stress and stroke risk thresholds than the general population.

Between 2006 and 2014, researchers studied hospitalizations for schizophrenia in Phoenix (where summertime overnight low temperatures average 30 degrees Celsius). They discovered that the minimum air temperature (the overnight low temperature) had a significant relationship with the number of hospitalizations for schizophrenia on that day and the next day. The nightly low-temperature accounts for around 3% of all schizophrenia admissions during that period.

The risk is greatest in both severely cold (below 3 C) and highly hot situations (over 30 C). These hospitalizations cost the Phoenix healthcare system more than $2 million (in 2024 USD). Certainly, Canadians experience much colder temperatures than 3 C at night, but rarely overnight lows above 30 C; however, the 2021 heat dome resulted in over 600 deaths in British Columbia, and researchers discovered that schizophrenia was the chronic condition most associated with the risk of death during the extreme heat.

Extreme heat may have a terrible effect on people with mental illnesses, our healthcare system, and communities.

Schizophrenia is not the most prevalent mental illness in Canada. However, it can be used to demonstrate how environmental factors might influence mental disease. Every year, one out of every five Canadians develops a mental disease. More than 250,000 Canadian youth suffer from serious depression, which is compounded by discrepancies in mental health treatment and care.

While numerous factors might contribute to mental illness, heat plays a significant impact in a variety of mental health conditions. Making whatever efforts we can to alleviate the strain on persons living with mental illnesses may have a knock-on effect on the rest of society, such as reduced use of hospital emergency departments during heat waves.

Coping with Climate Change

So, if climate change continues to cause hotter summers, what can be done to reduce hospitalizations and deaths? Some methods have broader implications beyond enhancing mental health outcomes during excessive heat.

The usual first step is to ensure that all Canadians have access to air conditioning. Statistics Canada emphasized the necessity of air conditioning for vulnerable populations. Warming circumstances have caused portions of Canada that did not require air conditioning 30 years ago to become oppressively hot inside buildings without sufficient cooling.

Nonetheless, air conditioning relies on the electrical grid and continues to emit waste heat and greenhouse gases. There is a better way: make our cities greener. There are numerous previously established benefits of greening cities, including reduced urban heat islands, improved air quality, and, in some situations, increased property values (both good and negative results).

However, there are some mental health benefits. I contributed to a review of urban greenery mitigation research and emphasized the mental health advantages, such as decreased depression, irritability, and aggression.

Urban green space has been demonstrated to increase mood, self-esteem, and even hasten the recovery from disease. So, as the temperature rises and you turn on the air conditioning and grab for the cold drinks, remember that there are consequences for all of us that go beyond our physical health, and take note of how the heat affects your mood.

Extreme heat will continue to affect Canada (and worsen as the climate changes). However, the detrimental effects on the most vulnerable, particularly those suffering from mental illness, can be mitigated to some extent by taking steps to ensure that our cities benefit everyone.

References:

1. High temperatures on mental health: Recognizing the association and the need for proactive strategies-A perspective
   
   Rony MKK, Alamgir HM. High temperatures on mental health: Recognizing the association and the need for proactive strategies-A perspective. Health Sci Rep. 2023 Dec 4;6(12):e1729. doi: 10.1002/hsr2.1729. PMID: 38059052; PMCID: PMC10696165.




2. Schizophrenia
   
   Kahn RS, Sommer IE, Murray RM, Meyer-Lindenberg A, Weinberger DR, Cannon TD, O’Donovan M, Correll CU, Kane JM, van Os J, Insel TR. Schizophrenia. Nat Rev Dis Primers. 2015 Nov 12;1:15067. doi: 10.1038/nrdp.2015.67. PMID: 27189524.

Source-Medindia