A: The increase in core temperature observed during illness is commonly called fever and occurs in response to infection by a pathogen or certain types of physical injury. When a person becomes infected with bacteria, the white blood cells of the immune system recognise the incoming pathogen as foreign and initiate the first stages of the immune response: the acute phase.

In this reaction, white blood cells called monocytes release a variety of proteins called cytokines. They are central to the immune response. In particular, there is a predominance of two types of cytokine called interleukin-1 and tumour necrosis factor-alpha. These cytokines cause an increase in body temperature.

It is not clear how but it is known that they also cause the production of other chemicals in the brain. The main group of chemicals here are the postaglandins. They react very strongly with the hypothalamus area of the brain, which then sends a signal to the body to increase the temperature.

The mechanisms that the brain employs to effect this are not certain but are known to include increasing the metabolic rate and shivering. These two processes burn metabolic fuel faster than normal, and body heat is given off.

Experimental work shows that elevated temperatures can enhance certain aspects of the immune response. The growth rates of various types of bacteria are slowed at temperatures above normal body temperature.

– Nigel Eastmond, University of Liverpool

Migraine and depression often co-exist, and traditional antidepressants are not consistently effective for treating migraine. Fremanezumab may reduce the cumulative burden on patients with both conditions, potentially marking a breakthrough in integrated treatment | Image used for representational purpose only
| Photo Credit: Getty Images

A migraine drug has shown to significantly reduce symptoms of depression in patients — the first trial to show improvements in both the conditions using a single drug, researchers said.

Dual benefit of fremanezumab

In the study involving 540 patients, ‘fremanezumab’ was found to reduce days of migraine in a month and symptoms of depression, compared to a placebo (inactive substance producing no effects). The drug, administered as an injection beneath the skin (subcutaneous), is available in India.

Published in The Journal of the American Medical Association (JAMA) Neurology, the study is the first to demonstrate significant improvements in migraine and depressive symptoms — often seen to co-exist in patients — with a single drug, the researchers, including those from Albert Einstein College of Medicine, US, said.

Migraine and depression

Patients of migraine — a common neurological condition marked by recurring headaches — have been studied to be two to four times more likely to develop depression. The two conditions are suggested to have common genetic basis and biological processes that control levels of brain chemicals, such as serotonin and glutamine.

The researchers said that patients having migraine and depression are treated with antidepressants — which work by improving serotonin levels. Serotonin helps regulate mood, and low levels can cause sadness, anxiety and irritability.

However, antidepressants are not uniformly effective for migraine. Further, data is limited on the efficacy of migraine therapy in people also experiencing psychiatric conditions.

Trial across 12 countries

The trial was conducted over a 28-week period at 61 centres across 12 countries, including the US, UK, France, and Germany, between July, 2020, and August, 2022.

The participants were randomly assigned to receive a monthly dose of fremanezumab (225 milligrams) or a placebo at the study’s start and at the end of week four and week eight. “Although treatment with fremanezumab and placebo both resulted in clinically meaningful reductions in depressive symptoms, fremanezumab achieved statistical significance vs placebo at week 8,” the authors wrote.

They suggested that the reduced depressive symptoms could be an indirect effect of the drug actively treating migraine, although further analyses are required to understand this.

The results “suggest that fremanezumab was effective in a difficult-to-treat clinical population with migraine and comorbid major depressive disorders and may also be effective in alleviating psychiatric comorbidities, therefore reducing the cumulative burden on patients.”

The lack of widespread, equitable preparedness and awareness increases the risk, especially for daily wage workers, outdoor laborers, and communities with limited access to healthcare or shelter |Image used for representational purpose only
| Photo Credit: Getty Images

At least 35,000 lives were lost in India due to exposure to extreme hot and cold temperatures between 2001 and 2019, a new study has found.

Climate extremes and health impacts

In 2015 alone, it estimated 1,907 deaths due to a heatstroke and 1,147 because of cold exposure. Data for analysis was taken from the India Meteorological Department and National Crime Records Bureau, among other datasets. Findings, published in the journal Temperature, show an upward-moving, increasing trend in deaths due to a heatstroke and exposure to cold temperatures.

Lead author Pradeep Guin from O P Jindal Global University, Haryana, said that deaths due to exposure to extreme temperatures are avoidable and that measures to mitigate health impacts need to be put in place.

“With an intense heatwave forecast to hit most of the country this summer and extreme weather events becoming more frequent around the globe as the world warms, there is no time to be lost in raising awareness about the dangers of extreme temperatures and putting in place measures to reduce their impact,” Guin said.

He added, “Support systems exist, but more needs to be done.” Deaths due to extreme temperatures were found to be more common among men of working age.

During the study period of 2001-2019, deaths due to extreme heat were three to five times higher among men, while those due to extreme cold were four to seven times higher, compared to women, the researchers said.

Extreme weather risks and response plans

State-wise, Andhra Pradesh, Uttar Pradesh, and Punjab were found to record the most deaths due to a heatstroke, whereas the most deaths due to exposure to extreme cold came from Uttar Pradesh, Punjab, and Bihar.

The authors wrote, “Between 2001 and 2019, India reported 19,693 and 15,197 deaths due to heatstroke and cold exposure, respectively.” Guin said, “Deaths due to heatstroke is more significant, compared to deaths due to cold exposure, albeit recording an upward trend.” Co-author Nandita Bhan from the school of public health and human development at O P Jindal Global University, said the results highlight the urgent need of heat and cold action plans for vulnerable states.

“Several states in India are developing heat action plans that can provide relief through innovative built environment initiatives, and these need study as well as scale-up, including expanding cold action plans across more vulnerable states,” Bhan said.

Previous studies have largely looked at health impacts of extreme temperatures in developed countries and one-off events, such as a heatwave, rather than looking at low- and middle-income countries, the researchers said.

They added that with India experiencing temperature extremes each year, it is important to know places most at risk, which can help in designing measures to keep population safe.

Rapid weather fluctuations

A recently published study in the journal Nature Communications showed that ‘rapid flips’ in temperatures — a switch between hot and cold extremes in a relatively short time — have increased in 60 per cent of the world’s areas over the past 60 years.

It said that because of the limited time available to adapt to temperature changes, these flips could magnify the negative effects of hot and cold extremes on societies and nature, impacting humans and animals, infrastructure and agriculture.