Sleeping in prone position was identified as the major risk factor for sudden infant death syndrome (SIDS) in the early 1990s.  Royalty-free image – Association Naître et Vivre and ANCReMIN

In several European countries where the incidence rates of sudden infant death syndrome (SIDS) are high, a high frequency of unsafe parental sleep practices has also been observed. In addition, it is known that pictures conveying implicit or explicit health messages can lead to the modification of health practices. Researchers from Inserm, Université Paris Cité and HEC Paris, in collaboration with the Greater Paris University Hospitals (AP-HP), Nantes University Hospital and other European research structures, studied images shown on baby diaper packaging in 11 European countries, including France. The team showed that a very high proportion of pictures were inconsistent with safe infant sleep recommendations – with many images depicting babies sleeping on their stomach (prone position) or on their side, on loose bedding or surrounded by objects, or sharing a sleep surface with another person. These findings highlight the discrepancy between the pictures used on diaper packaging and safe infant sleep recommendations. They should encourage manufacturers and the legislator to take steps to ensure that these products – and more generally all commercial and official photographs – are consistent with the recommendations for the prevention of SIDS. The study has been published in The Journal of Pediatrics.

Sudden infant death syndrome (SIDS) is the unexpected death of a baby under the age of one year old[1], which remains unexplained after a full investigation, including a review of the medical history, investigation of the scene of death, and an autopsy. Putting a baby to sleep in the prone position was identified as the major risk factor for SIDS in the early 1990s. Other risk factors related to the sleep environment were then identified, particularly loose bedding or soft objects (pillows, pillow-like toys, stuffed toys, quilts, comforters, sheepskins, blankets, non-fitted sheet, or bumper pads) and sharing the sleep surface with another person (parent, brother, sister, etc.).

This epidemiological work led to the development and dissemination of international safe infant sleep recommendations. The implementation of these recommendations from the 1990s has helped reduce the incidence of SIDS in France by 80%, which currently stands at between 250 and 350 deaths per year. However, in several European countries, including France, the incidence rates of SIDS are no longer decreasing (or only very slowly), and a high frequency of unsafe parenting practices has been noted.

According to the scientific literature, we know that images can convey implicit or explicit health messages, which has been effective in modifying many health practices (alcohol consumption during pregnancy, breast-feeding, etc.). We also know that while advertising images have historically been important tools for persuasion, they have also always been a source of information for consumers.

Studies have analyzed pictures of sleeping babies in parenting magazines, newspapers, brochures, commercial photo bank websites and on Instagram^® and have reported alarming rates of inconsistency with safe infant sleep recommendations ranging from 35% to 93% depending on the medium.

In this context, researchers from Inserm, Université Paris Cité, HEC Paris, Greater Paris University Hospitals (AP-HP), Nantes University Hospital in collaboration with other European research structures, decided to study pictures on diaper packaging in Europe – a product which young parents frequently use.

The scientists systematically searched the internet for the packaging of diapers sold in 11 European countries for babies weighing less than 5 kg, as they are the most at risk of SIDS.

For each packaging identified, they extracted the following data: was there a picture depicting a baby, was the baby sleeping and, if so, was the baby sleeping in accordance with 3 of the 7[1] recommendations for the prevention of SIDS that can be easily evaluated on the images? Statistical analyses (known as “meta-analyses”) were then carried out using the data obtained in each country to evaluate whether there was any inconsistency with sleeping recommendations.

The research team identified 631 diaper packaging for babies weighing less than 5 kg. On 49 % of them, there was a picture with a sleeping baby. The analyses indicated that 79% of packages depicting a sleeping baby, i.e. 34% of all of the packages, were inconsistent with at least one recommendation for the prevention of SIDS.

For example, a baby was depicted in prone position or on the side on 45% of these packs, with soft objects or loose bedding (pillows, pillow-like toys, stuffed toys, quilts, comforters, sheepskins, blankets, non-fitted sheet, or bumper pads) on 51% of them, or sharing the sleep surface with another person on 10% of them.

Examples of diaper packaging for babies in France and Europe with an image that is inconsistent with the recommendations for the prevention of SIDS: baby not sleeping on their back (A, C); baby sleeping with loose bedding or a soft object (pillow, blanket, toy) (A, B, C, D); baby sharing the sleep surface with another person (D)

The researchers also conducted a search, this time non-systematic, on the websites of health agencies or scientific societies and once again found images inconsistent with the prevention of SIDS.

“Our findings highlight a discrepancy between the messages conveyed on these everyday products or on institutional sites, to which many parents are highly exposed, and the recommendations for the prevention of SIDS. These findings suggest the need for action with manufacturers and legislators addressing this issue. We need to reduce exposure to commercial or official images that are inconsistent with the recommendations for the prevention of SIDS in order to prevent unsafe sleep practices. In doing so, manufacturers and legislators would fully contribute to accurate health information,” concludes Martin Chalumeau, last author of the study, epidemiologist at Inserm, professor at Université Paris Cité and pediatrician at AP-HP.

[1] S de Visme et al., J Pediatr 2020 Nov; 226:179-185.e4. doi : 10.1016/j.jpeds.2020.06.052

[2] The 7 recommendations of the American Academy of Pediatrics: (1) back to sleep for every sleep, (2) on a firm sleep surface in (3) a safety crib (crib, bassinet, portable crib, play yard), (4) in the parents’ room, (5) without any soft objects or loose bedding on, under, beside (pillows, pillow-like toys, stuffed toys, quilts, comforters, sheepskins, blankets, non-fitted sheet, or bumper pads), (6) without sharing the sleep surface with another person, and (7) offering a pacifier.

Scientists have studied the risk of incident cardiovascular disease in relation to five sleep dimensions. © Adobe Stock

The association between sleep disorders and cardiovascular risk is already well documented. Apnea, sleep deficit, and insomnia are linked to an increased risk of cardiovascular diseases and stroke. A new study published in European Heart Journal has now explored this association in much greater depth. Led by Inserm research director Jean-Philippe Empana and his team at the Paris Cardiovascular Research Center (Inserm/Université Paris Cité) in collaboration with the Centre hospitalier universitaire vaudois (CHUV, Lausanne), the study shows that five aspects of sleep  are almost each equally important to explain the association between sleep and the risk of coronary events and stroke.Improving one of these aspects over time can bring significant benefit. These five aspects are nighttime sleep duration, chronotype (being a morning or evening person), frequency of insomnia, excessive daytime sleepiness, and sleep apnea.

Sleep is essential to health and well-being, and several physiological mechanisms explain this. Poor sleep quality or quantity is therefore associated with a deterioration in health: mood problems, depression, weight gain, infections, diabetes, hypertension, etc. A link has also been established with cardiovascular risk – an issue which Jean-Philippe Empana’s Inserm team at the Paris Cardiovascular Research Center decided to explore further.

To do this, the team studied the risk of cardiovascular accidents (acute coronary syndrome or stroke) in relation to five aspects of sleep: nighttime sleep duration, chronotype (being a morning or evening person), frequency of insomnia, excessive daytime sleepiness, and sleep apnea.

“Usually, studies focus on a single sleep dimension, mainly sleep duration or the presence of sleep apnea, but good or healthy sleep encompasses several dimensions,” clarifies Aboubakari Nambiema, first author of this publication and postdoctoral researcher at Inserm.

The researchers incorporated these five patterns of sleep into a single score in order to account for the multifactorial nature of sleep. Each of these patterns was evaluated using a specific questionnaire validated by the scientific community and appropriate for large studies (Pittsburgh sleep quality index-PSQI, Berlin questionnaire or Epworth Sleepiness Scale) and counts for 1 point when it is optimal and 0 points when it is not. The overall score therefore varies from 0 (worst score) to 5 (optimal score corresponding to: 7 to 8 hours of sleep per night, being a morning person, not having insomnia, apnea, or excessive daytime sleepiness).

Monitoring over time

This score was used in two population surveys that study the determinants of cardiovascular health.

One was conducted in Paris and included 10 157 adults aged 50 to 75 years (Paris Prospective Study III, PPS3) and the other in Lausanne, Switzerland, brought together 6 733 participants aged over 35 years (CoLaus|PsyCoLaus study).

The score was calculated at the point of inclusion and then two to five years later. The occurrence of cardiovascular events was then monitored for approximately eight to 10 years.

“Although the use of a composite score to study sleep habits had already been tested in the past, this is the first time to our knowledge that a study has investigated its evolution over time and its potential association with cardiovascular diseases,” explains Jean-Philippe Empana.

By combining the data from the two surveys, an initial analysis confirms that the higher the initial (baseline) score, the lower the risk of incident cardiovascular disease. Compared to the participants with a score of 0-1 (10% of the participants), the risk of cardiovascular disease is reduced by 10% for those with a score of 2 (21% of the participants), by 19% for those with a score of 3 (32% or the majority of the participants), by 38% for a score of 4 (27% of the participants) and by 63% for those with the best score of 5 (10% of the participants).

“In other words, almost 60% of incident cardiovascular disease could potentially be avoided if all individuals had an optimal sleep score (score of 5), thus highlighting the potential public health implications of the results,” clarifies Jean-Philippe Empana.

A second analysis that took an unprecedented look at the change in sleep score over time showed that sleep improved in 8% of the participants, deteriorated in 11% and remained stable in the majority of the participants (2/3 of them remained with a score equal to or greater than 3). Importantly, these changes are associated with the occurrence of cardiovascular disease. In particular, this risk decreased by 16% per one point increase in the score over time, regardless of which dimension of the score was improved. “They each seem to be of equal importance,” specifies Nambiema.

The researchers now hope that healthcare professionals and the general population will take advantage of this tool: “the ease and speed of use of the questionnaires as well as the simplicity of calculating the sleep score should encourage their understanding and good adherence,” they predict.

To what extent does early or excessive screen exposure affect children’s cognitive development? © AdobeStock

To what extent does early or excessive screen exposure affect children’s cognitive development? This is a question that is currently dividing scientists. A team led by Inserm researcher Jonathan Bernard at the Center for Research in Epidemiology and Statistics (Inserm/INRAE/Université Paris Cité/Université Sorbonne Paris Nord) studied the data of nearly 14,000 children from the French Elfe cohort[1] for each child from the age of 2 to 5.5 years. While this is not the first study to show a negative relationship between exposure time and development, it also highlights that this relationship is not true for all domains of cognition and is much weaker when the family context is properly taken into account. Its findings also confirm[2] a non-negligible negative relationship between exposure to television during family meals and early language development. This research, published in The Journal of Child Psychology and Psychiatry, suggests that while screen time is important, the context of exposure also matters.

In the face of rapid changes in the use of screens and their growing place in everyday life, one question continues to divide scientists: to what extent does too early and/or excessive exposure to screens influence child development? With the majority of studies having focused on language development, less attention has been paid to other cognitive domains. The same applies to the potential influence of the family environment, as well as the child’s daily activities.

The team led by Inserm researcher Jonathan Bernard at the Center for Research in Epidemiology and Statistics (Inserm/INRAE/Université Paris Cité/Université Sorbonne Paris Nord) sought to evaluate the associations between screen use and cognitive development in early childhood, taking into account factors related to social, perinatal, family, and lifestyle conditions. To do this, it looked at data from nearly 14,000 children from the French cohort Elfe, collected for each child from the age of 2 to 5.5 years, between 2013 and 2017.

The parents reported their children’s daily screen time at ages 2, 3.5 and 5.5 years. They were also asked to report whether they had the television on during family meals in their children’s second year. Many factors related to the children’s lifestyle and daily activities also had to be specified. Finally, various cognitive domains were evaluated: language development at age 2, non-verbal reasoning at age 3.5 and overall cognitive development at ages 3.5 and 5.5.

The research team observed that at ages 3.5 and 5.5, screen exposure was associated with lower overall cognitive development scores, particularly in the areas of fine motor, language and autonomy. However, when lifestyle factors likely to influence cognitive development were taken into account in the statistical models, the negative relationship decreased and became of small magnitude.

The results of the study also show that, regardless of exposure time, having the television on during family meals at age 2 (which concerned 41% of children) was associated with lower language development scores at the same age. These children also had poorer overall cognitive development at age 3.5.

“This could be explained by the fact that television, by capturing the attention of family members, interferes with the quality and quantity of interactions between parents and child. Yet such interaction is crucial at this age for the acquisition of language,” explains Shuai Yang, PhD student and first author of the study. He continues: In addition, television adds background noise to family discussions that makes it difficult for the child to decipher sounds and limits verbal understanding and expression. “

These findings suggest that screen time is not the only factor to consider: the context in which screen use takes place could also be an important factor. It is also suggested that not all areas of cognition would be affected in a similar way.

“The first years of life are decisive, not just for cognitive development but also for the establishment of lifestyle habits, adds Bernard. When a child uses a screen excessively, they do so at the expense of other social activities or interactions that are essential for their development. “

The robustness of this study is due to the large number of participants, but also the consideration of factors related to the social profile of the families and the activities of the children.

“While our findings suggest that the harmful effects of screen use in early childhood have a low impact on cognitive development at the individual level and can be compensated for in the years that follow, they do however justify remaining vigilant at population level. When it comes to public health, these little things all add up,” explains Bernard. He added that more long-term studies are needed to evaluate the cumulative impact of these effects from early childhood to adolescence.

The research by his team is continuing through the follow-up of the children in the Elfe cohort in order to answer these questions.

[1]Elfe is France’s first national, longitudinal study dedicated to the follow-up of children from birth to adulthood. More than 18,000 children born in metropolitan France in 2011 were enrolled in it (i.e. one in every 50 children born in 2011). Since the first contact with the families during the maternity stay, the participating parents are regularly interviewed in order to better understand how the environment, family setting and living conditions influence the development, health and socialization of the children. The ELFE study mobilizes around 150 researchers from a variety of scientific disciplines.

[2]See our press release from June 8, 2021: Television During Meals Linked to Poorer Language Development in Young Children

The scientists used the data reported by 95,442 French adults participating in the NutriNet-Santé study. © Mathilde Touvier/Inserm

Emulsifiers are among the additives most widely used by the food industry, helping to improve the texture of food and extend its shelf life. Researchers from Inserm, INRAE, Université Sorbonne Paris Nord, Université Paris Cité and Cnam, as part of the Nutritional epidemiology research team (EREN-CRESS), studied the impacts on cardiovascular health of the consumption of emulsifiers. They analyzed the health data of 95,442 adults participating in the French NutriNet-Santé cohort study in terms of their overall consumption of this type of food additive. The results suggest an association between the dietary intake of emulsifiers and an increased risk of cardiovascular disease. They have been published in the British Medical Journal.

In Europe and North America, 30 to 60% of dietary energy intake in adults is provided by ultra-processed foods. Recent epidemiological studies have linked high intakes of ultra-processed foods with higher risks of obesity, mortality and chronic diseases (cardiovascular disease, type 2 diabetes, cancer, etc.). Emulsifiers are among the most commonly used additives in industrial foods. They are often added to processed and packaged foods such as certain industrial cakes, cookies and desserts, as well as ice creams, candy bars, breads, margarines and ready meals, in order to improve their appearance, taste and texture and lengthen shelf life. These include celluloses, mono- and diglycerides of fatty acids, modified starches, lecithins, carrageenans, phosphates, gums and pectins.

As with all food additives, the safety of emulsifiers is regularly evaluated on the basis of the scientific evidence available at a given time. However, some recent studies suggest that emulsifiers can disrupt the gut microbiota and increase the risk of inflammation, leading to potentially increased susceptibility to cardiovascular problems.

In order to explore this question in greater depth, French researchers undertook to evaluate the links between exposure to emulsifiers and the risk of cardiovascular disease, including coronary heart- and cerebrovascular disease, i.e. conditions that affect blood circulation and blood vessels in the heart and brain.

Their conclusions are based on the analysis of data from 95,442 French adults (average age 43 years; 79% women) with no history of cardiovascular disease who voluntarily participated in the NutriNet-Santé cohort study (see box below) between 2009 and 2021.

During the first two years of follow-up, the participants completed at least three (and up to 21) days of online dietary records. Each food or drink consumed was then matched against databases to identify the presence and level of food additives, including emulsifiers. Laboratory assays were also performed in order to provide quantitative data.

The participants were asked to declare any major cardiovascular events, such as heart attack or stroke, which were validated by an expert committee following examination of their medical records. Deaths related to cardiovascular disease were also recorded using the French national registry of deaths.

Several well-known risk factors for heart disease, including age, sex, weight (BMI), educational level, family history, smoking and levels of physical activity, as well as overall quality of the diet (e.g. consumption of sugar, salt, energy and alcohol) were taken into account.

After an average follow-up of seven years, the scientists found that the higher intakes of total celluloses (food additive codes E460[1] to E468) were associated with higher risks of cardiovascular disease. In particular, this combination was specifically observed for intakes of E460 (microcrystalline cellulose, powdered cellulose) and E466 (carboxymethylcellulose).

On the other hand, higher intakes of mono- and diglycerides of fatty acids (E471 and E472) were associated with higher risks for all the diseases studied. Among these emulsifiers, lactic ester of mono- and diglycerides of fatty acids (E472b) was associated with a higher risk of cardiovascular and cerebrovascular disease, and citric acid ester of mono- and diglycerides of fatty acids (E472c) was associated with a higher risk of cardiovascular- and coronary heart disease.

High intake of trisodium phosphate (E339) was also associated with an increased risk of coronary heart disease.

No association was detected in this study between the other emulsifiers and the development of cardiovascular diseases.

Given its observational nature, the study cannot therefore establish causality on its own, and the scientists acknowledge it to have certain limitations. For example, the high proportion of women, the higher educational background and overall more health-conscious behaviors among the NutriNet-Santé study participants compared with the general French population, which may limit the generalizability of the results.

That being said, the study sample was large and the authors were able to consider a wide range of potentially confounding factors, while using detailed and unique data on food additives, down to the brand of the products consumed. In addition, the results remained unchanged after multiple sensitivity analyses, thereby strengthening their robustness.

“While these findings need to be replicated in other studies worldwide, they bring new key knowledge to the debate on re-evaluating the regulations around the use of additives in the food industry, in order to better protect consumers,” explains Mathilde Touvier, Research Director at Inserm, and Bernard Srour, Junior Professor at INRAE, principal authors of the study.

[1] Food additives are identified in the list of ingredients by a European code consisting of the letter “E”, followed by a number making it possible to easily identify the category. For example, E100 for colorants, E200 for preservatives, E400 for emulsifiers and texture agents.

© Freepik

Numerous studies are now reporting the harmful effects of air pollution on the central nervous system (neurodegenerative diseases in adults, neurodevelopmental disorders in children). Glaucoma, the second leading cause of blindness worldwide, is a neurodegenerative disease of the optic nerve whose principal characteristic is thinning of the retinal nerve fiber layer. In a study of a cohort of 683 elderly Bordeaux residents followed up over 10 years, researchers from Inserm and Université de Bordeaux at the Bordeaux Population Health research center showed accelerated thinning of the retinal nerve fiber layer in the participants more exposed to air pollution, especially those who had a greater exposure to PM_2.5 (fine particulate matter of a diameter of 2.5 microns or less). This study therefore suggests a possible increased glaucoma risk for the inhabitants of areas with fine particulate pollution, even at levels below the current European Union regulatory thresholds (25 micrograms/cubic meter). The results have been published in Environmental Research.

Air pollution is a global public health issue. The harmful effects of air pollutants on respiratory and cardiovascular functions have been widely documented in the scientific literature. It is also increasingly evident that chronic exposure to air pollution has adverse effects on the central nervous system, with an increased risk of neurodegenerative diseases in adults and neurodevelopmental disorders in children.

The retinal nerve fiber layer (RNFL) is part of the central nervous system, and its thinning represents the main characteristic of glaucoma[1], an eye disease associated with the progressive destruction of the optic nerve, most often caused by excessive pressure inside the eye. This disease is the second leading cause of blindness in the developed countries.

Researchers from Inserm and Université de Bordeaux studied the effect of exposure to higher concentrations of air pollutants (fine particulate matter[2] and nitrogen dioxide) on the ocular neurodegenerative processes. To do that, they followed up for a 10-year period a population of 683 people aged 75 years or over who were resident in Bordeaux at the time of their inclusion in the Aliénor[3] cohort. This is the first prospective study on this subject.

As part of this study, the volunteers underwent eye exams every two years between 2009 and 2020 in order to measure changes in RNFL thickness.

In addition, their exposure to air pollution over the previous 10 years was determined using their home address, with the help of annual exposure maps for each pollutant. These detailed maps, with a resolution of 100 meters, were produced using air quality control station measurements and meteorological and geographical characteristics (proximity of a road, population density, distance from the sea, altitude, etc.)[4].

According to the results of this study, people having been exposed to higher concentrations of fine particulate matter had more rapid thinning of the retinal nerve layer over time.

These results are represented in the figure above which shows that the participants exposed to a 25 µg/m³ concentration of PM_2.5 had a faster reduction in the thickness of this layer compared to those exposed to a 20 µg/m³ concentration.

These findings suggest that exposure to a high concentration of pollutants over time could increase the risk of glaucoma.

As regards PM_2.5, the 10-year average exposure estimates were below the annual regulatory threshold of the European Union (established at a maximum of 25 μg/m³) for all participants, but above the limit values recommended by the WHO in 2005 (10 μg/m³) and further reduced in 2021 (5 μg/m³).

“The results of this study confirm the previous observations on the effects of air pollution on neurodegenerative processes – at ocular level in our case. They constitute an additional argument in favor of lowering the European regulatory thresholds[1], as recommended by the WHO, as well as lowering the effective exposure of the French population, which continues to exceed current regulatory thresholds in some places,” explains Laure Gayraud, PhD student in epidemiology and first author of the study.

“More generally, our study documents the effects of air pollutants on neurological aging. Taking the example of ocular aging, it suggests that exposure to high concentrations of pollutants over time could lead to an acceleration of neurological ageing, as was observed in studies on brain aging,” explains Cécile Delcourt, Inserm research director and last author of this research.

The aim is now for the scientists to expand the field of study to national level, using data from other French cohorts in order to learn more about the effects of pollutants on eye aging.

Diagram of the eye and retina

© Adobe stock

[1]To learn more, consult our in-depth article on glaucoma (only available in French).

[2]PM_2.5 corresponds to fine particulate matter of a diameter of 2.5 microns or less.

[3]Alienor is an epidemiological study in the general elderly population that explores the relationships between age-related eye diseases and other major determinants of these diseases (genetic, nutritional, environmental, or vascular factors).

[4]These maps were previously produced by the team of Kees de Hoogh and Danielle Vienneau from the Swiss Tropical and Public Health Institute (co-authors of the publication).

[5]The Members of the European Parliament’s Environment Committee recently voted in favor of lowering the thresholds for several pollutants by 2030, including fine particulate matter.

Europe is the continent experiencing the greatest warming, up to 1°C above the global average. © Adobe Stock

The summer of 2022 was the hottest ever recorded in Europe, characterized by an intense series of heatwaves that beat records of temperature, drought, and forest fires. Although Eurostat had already reported unusually high excess mortality for these dates, the fraction of mortality that could be attributed to the heat had not until now been quantified. And this is precisely what a study by scientists from Inserm and the Barcelona Institute for Global Health (ISGlobal) set out to do. Their analysis estimates that between May 30 and September 4, 2022 there had been 61,672 heat-related deaths in Europe. These findings suggest that our current strategies for adapting to heatwaves may still be insufficient. The full study has been published in Nature Medicine.

In 2003, Europe experienced one of the most intense heatwaves in its history, causing over 70,000 deaths. Since then, adaptation strategies have been developed in an attempt to respond quickly to intense heat and protect the most vulnerable populations. Given the continuous increase in heatwave episodes in recent years and the estimations that they could double in number by 2050, it is crucial to better characterize the mortality associated with them and evaluate the efficacy of the strategies put in place.

With the summer of 2022 being the hottest ever recorded in Europe, scientists from Inserm at the France Cohorts JSU[1] and the Barcelona Institute for Global Health looked at the number of heat-related deaths for this period.

The research team obtained temperature and mortality data for the 2015-2022 period in 823 regions of 35 European countries, representing a total population of over 543 million people. These data were used to estimate epidemiological models to predict heat-related mortality for each region and week of the summer period.

The records first revealed that the temperatures were above average throughout all the weeks of the summer period. The largest heat-related abnormality was recorded between July 11 and August 14, during which, according to the researchers, 38,881 deaths were caused by the heat. In this period, there was a particularly intense pan-European heatwave between July 18 and 24, for which a total of 11,637 deaths were attributed to the excess heat. All in all, the analysis reveals that between May 30 and September 4, 2022 there would have been 61,672 heat-related deaths in Europe.

France is the country that recorded the greatest increase in temperature compared with the seasonal averages, with +2.43ºC above the average values for 1991-2020, followed by Switzerland (+2.30ºC), Italy (+2.28°C), Hungary (+2.13ºC) and Spain (+2.11ºC).

Analyses by Country, Age and Sex

Based on the epidemiological models they built, incorporating data on temperature and number of deaths[2], the scientists were also able to propose a country-specific analysis. They showed in absolute terms that the country with the largest number of heat-related deaths throughout the summer of 2022 was Italy, with a total of 18,010 deaths, followed by Spain (11,324), and Germany (8,173). France comes in 4th place with 4,807 heat-related deaths[3].

Beyond the estimated number of heat-related deaths, the study also included an analysis based on age and sex. At European level, the results highlight a very marked increase in mortality in the upper age groups, with the vast majority of deaths concentrated in the age range of 80 and over.

For the sex-based analysis, the data show that heat-related premature mortality was 63% higher in women than in men. This increased vulnerability of women to heat is observed in the general population and above all among the over-80s, where the mortality rate is 27% higher than that of men. In contrast, the male mortality rate is 41% higher among those under 65 and 13% higher between the ages of 65 and 79.

For the research team, these findings should encourage us to take action to implement more robust preventive and protective measures. Indeed, the fact that many countries already had active prevention plans, unlike in 2003, suggests that the adaptation strategies available to us today may still be insufficient.

“The acceleration of warming observed over the past ten years underlines the urgency of in-depth re-evaluation and reinforcement of prevention plans, paying particular attention to the differences between European countries and regions, as well as between age and sex, which currently mark the differences in vulnerability to heat,” explains Hicham Achebak, Inserm researcher and last author of the study.

Europe is the continent with the highest level of warming, up to 1°C more than the world average. In this context, the team’s estimates also suggest that in the absence of an effective adaptive response, the continent will face an average of over 68,000 excess deaths each summer by 2030 and over 94,000 by 2040.

[1] The France Cohorts Joint Service Unit (JSU) brings together several academic supervisory bodies, including Inserm, Ined, Université Paris-Saclay, Université Paris Cité, and Sorbonne Université. Its long-term objective is to offer a range of services for epidemiological cohorts.

[2] The mortality data were obtained via Eurostat and the temperature data via ERA5-land reanalysis.

[3] This study focuses on heat-related mortality during the summer of 2022 using weekly data and estimated nearly 5,000 deaths in France. On the other hand, Santé Publique France has recently used daily data for the same period and estimated nearly 7,000 deaths. This difference is due to the fact that the weekly data generally underestimate the impact of heat on mortality.

© AdobeStock

Although physical activity is regularly discussed as being one of the avenues for preventing Parkinson’s disease (PD), studies so far had been unable to eliminate certain biases or had not focused on its specific role in women. Researchers from Inserm, Université Paris-Saclay and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ) with the Gustave Roussy Institute studied the impact of physical activity on the development of PD in nearly 100,000 women from the French cohort E3N followed up over 29 years. They observed that the more the participants had been active in their lives, the lower was their risk of developing the disease – with such a benefit already present more than 20 years before diagnosis. The researchers have also shown that in women with PD there had been a significant decrease in physical activity in the 10 years prior to diagnosis, probably due to bothersome precursor symptoms. These findings, to be published in Neurology, call for consideration to be given to the rollout of preventive physical activity-based programs in people at risk of PD.

Parkinson’s disease (PD) is a progressive neurodegenerative disease characterized by the destruction of certain neurons in the brain and the accumulation of proteins toxic to them. It is the second most common neurodegenerative disease in France and there is still no cure; therefore it is essential to identify avenues for prevention.

Previous studies had shown a reduced risk of developing PD in people with who engage in high levels of physical activity. However, the limited number of such studies involving women did not make it possible to confirm this association in that population. In addition, these studies generally had a relatively short participant follow-up period with only one evaluation of physical activity, which did not make it possible to eliminate certain biases – particularly that of reverse causation.

Reverse causation is expressed as follows: precursor symptoms of PD (constipation, sleep disorders, smell disorders, subtle motor signs, etc.) may be present several years before the disease is diagnosed. Their effects could lead people to modify their behavior (such as how much physical activity they do) prior to diagnosis, which is liable to distort the statistical analyses that study the relationship between these behaviors and the risk of developing the disease.

A team led by Alexis Elbaz, Inserm researcher at the Epidemiology and Population Health Research Center (Inserm/Université Paris-Saclay/UVSQ), studied the impact of physical activity on the onset of PD in women from the E3N cohort over a follow-up period of 29 years. E3N is a French cohort of nearly 100,000 women who have been followed-up since 1990. With nearly 1,200 women with PD identified in 2018[1], it is currently the world’s largest female prospective cohort for this disease.

The changes in the physical activity[2] of each participant throughout the 29 years of follow-up were estimated based on the information collected via six individual questionnaires completed at different stages of the follow-up. The data obtained compared the practice of physical activity prior to diagnosis in the participants with PD with those of the participants of the same age without PD.

In order to reduce the risk of a reverse causation bias resulting from the potential influence of the precursor symptoms on physical activity in the years prior to diagnosis, the scientists examined the impact of physical activity evaluated more than 5, 10, 15 and 20 years prior to diagnosis on the risk of developing PD.

What they observed was that the more physically active the participants, the less likely they were to develop PD, even when the physical activity had been evaluated more than 20 years before diagnosis. The most active women therefore had a 25% less risk of developing the disease compared with the least active.

Overall, the participants with PD had been less active than the others throughout the follow-up period, including more than 20 years before diagnosis. This gap between women with and without PD increased further in the 10 years before diagnosis, suggesting that the precursor symptoms occurring in this interval could indeed be responsible for a decrease in physical activity in the women who will go on to develop the disease but who have not yet been diagnosed.

“These findings support the protective effect in women of physical activity against the risk of developing Parkinson’s disease, even over the very long term, specifies Berta Portugal, PhD student and first author of this research. They support the utility of implementing physical activity programs to prevent Parkinson’s disease in people at risk and call for conducting other studies in order to understand what activity type and level of intensity are the most beneficial,” she adds.

“This study demonstrates the importance of studies with a lengthy follow-up within large-scale cohorts to better account for the precursor symptoms and the statistical bias they cause in evaluating the benefit of physical activity on the development of Parkinson’s disease,” concludes Elbaz.

[1]The percentage of women with PD in the cohort is similar to that of the general population in Europe over the same period of time.

[2]The concept of “physical activity” goes beyond sport alone. In this study, it is quantified by the distance walked daily, the number of flights of stairs climbed, journeys taken by bicycle, time spent doing light and heavy household activities, time spent doing recreational activities, whether light (gardening, sports of moderate intensity) or vigorous (intensive sports).