Climate Change and Brain Health: How Rising Temperatures Impact the Brain

The first thing that comes to mind when we think of climate change is significant changes in weather patterns. However, did you know that climate change also affects the brain?

Climate change can significantly affect every area of our lives, from altered climates that affect drought and flooding to changes in air, water, and soil quality and pollution, as well as changes in ecology and food production. These combined will have a detrimental effect on our health, including our brain health. 

The effects of global warming on our physical health—from an increase in heart and lung diseases to a rise in allergies and waterborne infections—have received a lot of attention. However, the impact of climate change on mental health has received less attention.

Indeed, as temperatures and other climate-related impacts continue to rise, more people will experience psychological distress; an increasing amount of research highlights the connection between climate change and mood swings, aggression, a decline in learning and productivity, mental illness, and infectious diseases. There is even a link between climate and neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and Amyotrophic Lateral Sclerosis [1]. 

Let’s look into the details on how climate change impacts brain health.

How Does Climate Change Impact the Brain?

Studies have connected the deterioration of symptoms of several brain disorders to climate change [2]. Stroke, migraines, meningitis, epilepsy, multiple sclerosis, schizophrenia, Alzheimer’s disease, and Parkinson’s disease are among the conditions that might get worse as temperatures and humidity rise.

Our brains control how we react to environmental stressors, particularly high temperatures and humidity. For instance, they can trigger perspiration and tell us to move into the shade to avoid the sun. 

Our brain’s neurons work best at a particular temperature range. Humans have evolved to tolerate temperatures between 68 and 78.8 degrees Fahrenheit (20 and 26 degrees Celsius) and humidity levels between 20% and 80% [3].

Our brains are already functioning near the upper end of those ranges. When climate change raises temperature and humidity levels, our brains may struggle to regulate our bodies’ temperatures and even malfunction. Indeed, a typical definition of heat stroke is a core body temperature of more than 104 degrees Fahrenheit (40 degrees Celsius) coupled with cognitive impairment, such as confusion or difficulty thinking [4]. 

Weather events, including heat waves, floods, and storms, as well as extreme temperatures and significant temperature swings, can exacerbate neurological disorders. Rising temperatures are associated with increased rates of dementia hospitalization, worsening multiple sclerosis symptoms, a greater incidence of stroke and stroke-related mortality, and worsened seizure control in individuals with epilepsy [5]. 

Heat and Mental Health

There is increasing evidence that high temperatures might cause cognitive issues. 

• Heat Stroke Affects the Brain

Heat exhaustion results from the body losing too much water and salt through perspiration; symptoms include lightheadedness, clammy skin, and a rapid pulse. Heat exhaustion can quickly develop into heat stroke if left untreated. Heat stroke occurs when the body’s cooling system malfunctions, causing the internal temperature to increase catastrophically. The brain suffers significantly from this hyperthermia: a 2022 analysis found that between 10% and 28% of heat stroke survivors have persistent brain damage [6]. 

• Psychotropic Drugs May Exacerbate the Heat Stroke Risk

Some medicines used to treat neurological and psychiatric disorders exacerbate the issue by impairing the body’s reaction, such as decreasing perspiration or interfering with the brain’s temperature-regulating systems [7]. Every psychotropic drug, except for benzodiazepines, can affect the body’s capacity to withstand heat, increasing the risk of heat exhaustion and heat stroke. 

• Heatwaves Aggravate Disorders Like Epilepsy

Heatwaves cause sleep disturbances, which exacerbate disorders like epilepsy [8]. People with multiple sclerosis may experience worsening symptoms in hot weather because heat waves can aggravate malfunctioning brain wiring [9]. Additionally, dehydration can cause the blood to thicken and become more likely to clot, resulting in strokes. Heat stroke is deadly and can kill nearly two-thirds of those who suffer from it during heat waves [6]. 

• Heat Worsens Symptoms of Several Mental Disorders

Heat appears to make mental health symptoms worse for a variety of diseases [10]. The hottest summer days resulted in an 8% increase in mental health visits compared to the coolest days, according to a U.S. study on mental health-related ED visits. The rise varied by disorder, ranging from 5% to 11% [11]. Substance use disorders, mood disorders, anxiety and stress-associated disorders, schizophrenia and related disorders, self-harm, and childhood behavioral disorders were among the specific mental health conditions that heat aggravated.

• Heat-Related Mental Health Problems May Affect Older Adults More

According to a recent systematic review and meta-analysis headed by Jingwen Liu of the University of Adelaide School of Public Health, older persons appear to be particularly vulnerable to heat-related mental health problems, just as heat waves pose a physical threat to them [12]. According to that review, for every 1.8°F increase in ambient temperature, there is a 2.2% increase in mental health-related mortality and a 0.9% increase in mental health morbidity. Those with substance use disorders had the highest overall death rate. A disproportionate number of those over 65 and those residing in tropical and subtropical regions were also impacted. 

• Brain Diseases Like Alzheimer’s and Parkinson’s can Become Frequent

Heat can intensify the effects of chronic air pollution, which can enter the brain through the mouth and nose and produce low-grade inflammation in brain tissue. Long-term inflammation can lead to problems like Parkinson’s disease and dementia. Researchers who recently studied the brains of more than 200 deceased residents of the Atlanta area discovered that the brain plaques linked to Alzheimer’s disease were most prevalent in the areas with the highest levels of traffic-related pollution [13]. 

• Heat Stress is also Linked to Cognitive Issues

Heat stress has also been associated with cognitive issues. One study in Shanghai involved 36 healthy participants who were placed at workstations and subjected to temperatures between 75.2°F and 82.4°F. Researchers routinely monitored their physiological reactions as participants completed a series of routine office tasks, such as typing and doing basic arithmetic. As workers experienced hotter temperatures, their cognitive performance decreased on nearly all tasks; at the hottest temperatures, cognitive performance could drop by as much as 10% compared to the coolest [14].

•  Heat May Impair Decision-Making and Provoke Irritability

Heat has the potential to impair judgment and elicit irritability by interfering with sleep, producing discomfort, or just making it harder for the brain to function under less than ideal conditions. According to a recent economic decision-making experiment conducted in Nairobi and California, the practical effects could be nuanced and intricate. Researchers in that study discovered that under hot temperatures, players were more likely to choose to destroy other players’ assets in a game, even when doing so would not benefit them [15].

Proposed Mechanisms Underlying Heat and Brain Pathophysiology 

Potential explanations for heat and brain pathology include several abnormal cellular processes occurring in the brain.

Prolonged exposure to heat has also been associated with increased oxidative stress indicators and inflammation. Heat exposure can cause Tau pathology, the hallmark of dementia neurodegeneration, and oxidative stress in mice. When toxic free radicals are in excess and antioxidants are not enough to counteract them, oxidative stress results. Cognitive decline is known to be influenced by these mechanisms. Higher temperatures cause neuronal cells to express less superoxide dismutase (SOD), an enzyme that displays antioxidant activity, which results in cell death [16].

Increased temperatures can also cause seizures, leading to heatstroke and hyperthermia. TRPV4 channel and NMDAR signaling activation brought on by heat may be one of the mechanisms behind seizures..

TRPV4 is similar to a temperature sensor. It is located in the hippocampus and other bodily tissues and gets activated at room temperature. It helps the body sense pain and heat and stay hydrated. Prolonged exposure to high temperatures may alter TRPV4 activity, potentially reducing hippocampal function and negatively impacting cognitive abilities such as memory and learning [17].

N-methyl-D-aspartate (NMDA) receptor signaling is critical in the body’s reaction to heat stress, and its activation contributes to both heat-induced seizures and heat stroke. Research has indicated that elevated NMDAR signaling plays a role in the onset of heat-induced seizures and heat stroke. It implies that activation of NMDA receptors may worsen neuronal injury during hyperthermia [18]. 

Changes in behavior, diet/water intake, and other lifestyle changes may also negatively impact our brain health. 

Alzheimer’s Research Association is a non-profit organization dedicated to helping caregivers of Alzheimer’s disease and dementia. We provide the latest information and news about the illness and helpful tips to help caregivers cope with their daily caregiving challenges. We realize the most important thing that a caregiver needs is financial assistance. Therefore, we provide grants to caregivers to ease their financial burden. Caregivers can apply for grants here: Alzheimer’s Grant Application. 

You can also help caregivers in their endeavor by donating as much as possible: Donation To Alzheimer’s Research Associations.

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