Tag: childhood development

Oxytocin Shines a Light into Parental Attachment and Sex Differences

The developing brain of a two-week-old mouse pup under the microscope. The oxytocin system appears in green, the light-sensitive protein in red and cells that carry both show up in yellow. Cell nuclei are in blue. Credit: Weizmann Institute of Science

According to attachment theory, the attachment between an infant and a primary caregiver shapes the baby’s future social ties. Yet little is known about the biological mechanisms underlying childhood attachment, mainly because it is so difficult to study the young brain in natural conditions.

Now, scientists in Prof Ofer Yizhar’s laboratory at the Weizmann Institute of Science have developed a new, noninvasive research method that makes it possible to silence selected nerve cells deep within the brains of mouse pups without disrupting their natural behaviour. Using this method, the researchers investigated the role of oxytocin, a short protein released from nerve cells in the brain. While most oxytocin research has focused on adults, the new findings, published in Science, show that oxytocin also shapes the social behaviour of pups and may underlie emotional differences between males and females that emerge early in life.

Oxytocin, sometimes referred to as the “love hormone,” was once thought to simply promote sociability in adults. Over time, however, it became clear that its role is far more complex: In some circumstances, it intensifies behaviors and emotions far removed from love, such as anxiety or aggression. Recent research has also shown that young mammalian brains – including those of human children – are especially sensitive to oxytocin. In brain regions responsible for sensory processing, emotional regulation and social behavior, the number of oxytocin receptors peaks during early childhood: around ages two to three in humans, and two to three weeks in mice. Some studies have even linked oxytocin deficiency to childhood autism. Still, without sufficiently precise tools to examine neural activity deep within the developing brain, many aspects of the role of oxytocin in early life have remained a mystery.

“The findings may offer a clue as to why males and females diverge in their social behaviors and emotional worlds long before puberty”

To shed light on the subject, a team led by Dr Daniel Zelmanoff, a physician-scientist in Yizhar’s lab, developed a noninvasive technique to probe specific nerve cells in the young brain. The group, pioneers in the field of optogenetics – a technology that uses light to switch individual cells on or off – devised a method in which the targeted brain cells of mouse pups are infected with an engineered virus. This otherwise harmless virus introduces a foreign gene of mosquito origin that encodes a light-sensitive protein; when exposed to light, the protein “turns off” the nerve cell. In fact, the protein is so light-sensitive that the researchers could silence selected nerve cells deep inside the brain simply by shining red light on the pups’ heads.

“This new method allows us to peek inside the brain without disturbing the pups’ everyday lives, making it a powerful tool for studying nervous system development,” Yizhar explains. “It is especially useful for studying oxytocin because this hormone’s effects depend on social context – and our method lets us switch off the oxytocin system on demand, only during the exact situation we want to study.”

The researchers focused on oxytocin’s role during the temporary separation of a mouse pup from its mother and their reunion a few hours later – a situation familiar to every parent of a young child. The scientists observed increased oxytocin activity in the pup’s brain during separation, which returned to normal after reunion with the mother. Pups with an active oxytocin system during the separation gradually adapted to being alone in an unfamiliar environment, producing fewer ultrasonic vocalizations – the mouse equivalent of a baby’s cry. In contrast, pups whose oxytocin system was silenced did not adapt; they continued emitting distress calls at the same rate until reunited with their mothers. These findings show that the so-called “love hormone” also plays a critical role in coping with loneliness.

Attachment theory holds that children who are securely attached to their parents show distress when separated from them but are able to calm down over time, feeling free to explore their surroundings. “We discovered that mouse pups need an active oxytocin system in order to adapt to separation from their mothers,” says Yizhar. “This suggests that the oxytocin system plays a role not only in the brain of the parent, which was already known, but also in that of the infant. In addition, since oxytocin receptors are present in the sensory processing centers of the young brain, we hypothesize that this hormone also helps sharpen a pup’s senses when it is alone.”

Children do not quickly forget the experience of being separated from their parents, and this separation shapes how they behave when reunited. For example, a securely attached child separated from a parent for a few hours will seek contact upon reunion, and is quickly calmed. The researchers found that activation of the oxytocin system in mouse pups during separation not only strengthened them in the moment but also determined how they behaved when their mothers returned. These pups emitted more ultrasonic calls than usual, and the frequency of the calls grew as they got closer to their mothers. Using artificial intelligence, the team identified a distinct vocal pattern: Before attaching to the mother’s nipple, the pups made high-pitched, frequent calls; afterwards, their calls dropped in pitch and slowed in tempo.

“Activating the oxytocin system during separation increases the pup’s motivation to regain closeness to the mother when reunited,” Yizhar explains. “This is reflected in the heightened rate and unique pattern of their calls. We now understand that these ultrasonic vocalizations are much more than just crying: The high-pitched, rapid calls appear to signal a request for closeness, while the lower-pitched, slower-paced calls likely express a quick return to calm and a wish to remain attached. Of course, more research is needed to pin down the exact meaning of each vocalization type.”

In the next stage, the researchers explored whether oxytocin’s role in pups differs between the sexes, as it does in older animals. They found that female pups with an active oxytocin system emitted many more ultrasonic calls when reunited with their mothers than females with silenced oxytocin systems, whereas the calls of male pups were unaffected by the status of their oxytocin systems. “This is the first sex difference observed in oxytocin system activity at such an early stage of development,” Yizhar notes. “It may offer a clue as to why males and females diverge in their social behaviours and emotional worlds long before puberty.”

“Most known functions of oxytocin are shared by all mammals,” Yizhar concludes. “Still, future studies must check whether the hormone affects the development of social behaviour, emotional maturity and maternal attachment in the brains of children. If so, this could help us better understand what can go wrong in emotional and social development – as in autism spectrum disorder, for example – and how to intervene at an early stage.”

Source: Weizmann Institute of Science

ADHD Drugs Are Being Prescribed Too Quickly to Preschool Children

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A Stanford University-led study has found that young children with attention deficit/hyperactivity disorder (ADHD) often receive medication just after being diagnosed, which contravenes treatment guidelines endorsed by the American Academy of Pediatrics.

The findings, from published JAMA Network Open, highlight a gap in medical care for 4- and 5-year-olds with ADHD. Treatment guidelines recommend that these young children and their families try six months of behaviour therapy before starting ADHD medication.

But paediatricians often prescribe medication immediately upon diagnosis, according to an analysis of medical records from nearly 10 000 young children with ADHD who received care in eight paediatric health networks in the United States.

“We found that many young children are being prescribed medications very soon after their diagnosis of ADHD is documented,” said the study’s lead author, Yair Bannett, MD, assistant professor of paediatrics. “That’s concerning, because we know starting ADHD treatment with a behavioural approach is beneficial; it has a big positive effect on the child as well as on the family.”

Medications not appropriate to under-6s

In addition, stimulant medications prescribed for the condition cause more side effects in young patients than they do in older children, Bannett said. Before age 6, children’s bodies don’t fully metabolise the drugs.

“We don’t have concerns about the toxicity of the medications for 4- and 5-year-olds, but we do know that there is a high likelihood of treatment failure, because many families decide the side effects outweigh the benefits,” he said. Stimulant medication can make young children more irritable, emotional, and aggressive.

ADHD is a developmental disorder characterised by hyperactivity, difficulty paying attention, and impulsive behaviour.

“It’s important to catch it early because we know these kids are at higher risk for having academic problems and not completing school,” Bannett said. Early identification and effective treatment for ADHD improve children’s academic performance. Research has shown that good treatment also helps prepare individuals with ADHD for many aspects of adulthood, such as maintaining employment, having successful relationships, and avoiding trouble with the law.

Complementary treatments

Behavioral therapy and medication, the two mainstays of ADHD treatment, have different purposes.

“Behavioral treatment works on the child’s surroundings: the parents’ actions and the routine the child has,” Bannett said. The therapy helps parents and kids build skills and establish habits compatible with how the child’s brain works.

The evidence-based behavioral treatment recommended by the American Academy of Pediatrics is called parent training in behavior management. The training helps parents build strong, positive relationships with their children; offers guidance in rewarding a child’s good behaviors and ignoring negative behaviors; and recommends tools that help kids with ADHD, such as making visual schedules to help them stay organized.

In contrast, medication relieves ADHD symptoms such as hyperactivity and inattentiveness, with effects that wear off as the body breaks down each dose of the drug.

Both approaches are needed for most kids with ADHD to do well. But previous studies of preschoolers diagnosed at age 4 or 5 show that it’s best to start with six months of behavioural treatment before prescribing any medication.

Rapid prescriptions

The researchers analysed data from electronic health records for children seen at primary care practices affiliated with eight US academic medical centres. They began with 712 478 records from children aged 3, 4, or 5 years old and were seen by their primary care physician at least twice, over a period of at least six months, between 2016 and 2023.

From these records, the scientists identified 9708 children who received an ADHD diagnosis, representing 1.4% of the children in the initial sample. They found that 42.2% were prescribed medication within a month of their ADHD diagnosis. Only 14.1% of children with ADHD first received medication more than six months after diagnosis. The researchers did not have access to data on referrals to behavioural therapy, but since young children are supposed to try the therapy alone for six months before receiving medication, any who were prescribed medication sooner were likely not being treated according to academy guidelines. A smaller study of recommendations for behaviour therapy, published in 2021, found only 11% of families got the therapy in line with guidelines.

Children who were initially given a formal diagnosis of ADHD were more likely to get medication within the first 30 days than those whose medical charts initially noted some ADHD symptoms, with a diagnosis at a later time. But even among preschoolers who did not initially meet full criteria for the condition, 22.9% received medication within 30 days.

Barriers to behavioural treatment?

Because the study was based on an analysis of electronic medical records, the researchers could not ask why physicians made the treatment decisions they did. But in informal conversations with physicians, outside the scope of the study, the researchers asked why they prescribed medication.

“One important point that always comes up is access to behavioural treatment,” Bannett said. Some locales have few or no therapists who offer the treatment, or patients’ insurance may not cover it. “Doctors tell us, ‘We don’t have anywhere to send these families for behavioural management training, so, weighing the benefits and risks, we think it’s better to give medication than not to offer any treatment at all.’”

Bannett said he hopes to educate primary care paediatricians on how to bridge this gap. For example, free or low-cost online resources are available for parents who want to learn principles of the behavioural approach.

And while the study focused on the youngest ADHD patients, behavioural management therapy also helps older children with the diagnosis.

“For kids six and above, the recommendation is both treatments, because behavioural therapy teaches the child and family long-term skills that will help them in life,” Bannett said. “Medication will not do that, so we never think of medication as the only solution for ADHD.”

Source: Stanford University

Beyond Hormones: Researchers Define X and Y Chromosome Contributions to Height

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A Geisinger study provides new insight into height differences between adult men and women, demonstrating that Y chromosome genes contribute more to height than their X chromosome counterparts, independent of male sex determination. The results were published this week in the Proceedings of the National Academy of Sciences.

Typical females have two X chromosomes, while typical males have one X and one Y chromosome. The differences between the X and Y chromosomes cause hormonal differences between males and females, but these differences have been insufficient to explain the average 13cm height difference between the sexes.

“Because height shows a large and reproducible difference between sexes and is widely measured, it serves as a valuable model for investigating the genomic factors underlying sex differences,” said Matthew Oetjens, Ph.D., assistant professor in Geisinger’s Department of Developmental Medicine and one of the study leads.

The Geisinger research team sought to determine the effects of sex-related factors on human height by examining height in people with an abnormal number of X or Y chromosomes, a genetic condition known as sex chromosome aneuploidy.

The team analysed genetic and clinical data on nearly one million participants enrolled in Geisinger’s MyCode Community Health Initiative, the National Institutes of Health’s All of Us cohort and the UK Biobank. Of these participants, 1225 had a sex chromosome aneuploidy. By incorporating people with more or fewer than two sex chromosomes into a model of height, they found that exchanging an X for a Y chromosome increased height by 3.1cm, independent of other sex-related factors, including hormonal differences. This result suggests that an estimated 23% of the average difference in height between men and women is explained by increased expression of shared genes on the Y chromosome relative to the X chromosome.

“Beyond its implications for understanding human height, this study provides broader insights into how sex chromosome aneuploidy research can uncover the mechanisms behind observed sex differences in various medical conditions,” said Alexander Berry, PhD, bioinformatics scientist and study co-lead.

SHOX, a gene found on both the X and Y chromosomes, is a known contributor to human height, but because two copies are found in both men and women, it has not been considered a likely contributor to the sex difference in height. However, recent studies have shown that SHOX is partially silenced on the second X chromosome in individuals with two or more X chromosomes. The Geisinger study’s results are consistent with the hypothesis that reduced SHOX expression in females results in a net difference in height between the sexes.

Source: Geisinger Health System

Why Are Urban Children More Prone to Allergies?

Study finds unique immune cell linked to risk

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A previously uncharacterised subset of immune cells may play a critical role in the development of allergic diseases and explain differences between urban and rural populations. The finding, published in the journal Allergy, provides new insight into how the immune system is shaped in early life – and why urban children are more prone to allergies than children from rural areas.

Led by researchers from the University of Rochester Medical Center (URMC) Department of Pediatrics, including MD/PhD student Catherine Pizzarello and senior author Kirsi Järvinen-Seppo, MD, PhD, the study uncovered a unique subpopulation of T cells known as helper 2 (Th2) cells with distinct molecular characteristics.

T-cells are the foundational immune cells that fight off infections, but there is evidence that this specific subtype is recognizing certain foods as allergenic and attacking them, according to Jarvinen-Seppo.

“These pro-allergic T cells are more inflammatory than anything previously described in this context,” said Järvinen-Seppo, chief of Pediatric Allergy and Immunology at UR Medicine Golisano Children’s Hospital. “They were found more frequently in urban infants who later developed allergies, suggesting they may be a predictive biomarker or even a mechanistic driver of allergic disease.”

The study compared blood samples from urban infants with those from infants in a farming community, specifically the Old Order Mennonites (OOM) of New York’s Finger Lakes region – known for their low rates of allergies. Researchers found that while urban infants had higher levels of the aggressive Th2 cells, OOM infants had more regulatory T cells that help keep the immune system in balance and reduce the likelihood of allergic responses.

While additional research is needed to identify a possible cause, Jarvinen-Seppo speculates that differences in the development of the gut microbiome between the two populations, and more exposure to “healthy” bacteria in rural children, may be a factor.

“The farming environment, which is rich in microbial exposure, appears to support the development of a more tolerant immune system. Meanwhile, the urban environment may promote the emergence of immune cells that are primed for allergic inflammation,” said Jarvinen-Seppo.

The work is part of a broader, NIH-funded investigation into how early-life exposures influence long-term immune outcomes. In 2023, Järvinen-Seppo’s team received a $7 million grant from the National Institute of Allergy and Infectious Diseases (NIAID) to study environmental, microbiome, and immune differences between OOM and urban infants. The goal is to continue this foundational work to uncover protective factors that could be translated into preventive therapies, including probiotics or microbiome-supporting interventions.

“If we can identify the conditions for this disparity between the different T cell subpopulations, we can potentially find solutions in allergic disease development,” Järvinen-Seppo said.

Source: University of Rochester Medical Center

Scientists Discover the Genes that Influence When Babies Start Walking

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In the first study of its kind, scientists analysed the genetic information of more than 70 000 infants. They identified 11 genetic markers influencing when babies start walking, thus offering multiple targets for future in-depth biological investigation. 

In a paper published in Nature Human Behaviour, the study found that genetics accounts for about a quarter of the differences in when children take their first steps.

For years, researchers knew that environmental factors could influence when babies begin to walk, but this new finding shows that genetics also has a major impact. It suggests that, just like with other traits such as height, some children may naturally start walking earlier or later because of their genetic propensity. 

Professor Angelica Ronald, Professor of Psychology and Genetics, said: “Most babies take their first step sometime between ages 8 months and 24 months, so it is a wide window in which this exciting milestone happens. It is a big moment for both parents and baby; it symbolises a new phase in a child’s life.”

Dr Anna Gui, an author of the study and a researcher at the University of Rome Tor Vergata and Birkbeck, University of London said: “Until now, we didn’t understand what causes the wide differences between children in when they take their first step. Parents might often worry that walking early or late is a bad sign or that they have done something wrong. We see that genetics play a considerable role in influencing the timing of this milestone.

Walking isn’t just a key milestone in the development of a child, but it is connected in terms of genetic influences with many other important aspects of human development. The study found that the genetic factors influencing when children take their first step are partly the same genetic factors that influence brain development including the amount of folding and ridges in the outer surface of the brain (the “cortex”). Moreover, walking later within the typical range was linked genetically with less chance of developing ADHD. Finally, the study showed that relatively later onset of walking was influenced by some of the same genes involved in higher educational attainment.  

Prof Ronald added: “It is exciting to be able to discover the genes that influence when children learn to walk. Starting to walk independently is a major milestone for young children. We hope these new genetic findings can advance fundamental understanding about the causes of walking and be used to better support children with motor disorders and learning disabilities.”

She added that parents should still see a GP if there was concern, there is a lot of variety in when children take their first unaided step,

Led by scientists in the UK, the study was made possible through a large collaboration with scientists in the UK, Netherlands and Norway, and through UK and international funding including from the Simons Foundation for Autism Research Initiative.  

Divorce during Childhood Increases Odds of Stroke in Later Life

Data on 13 205 adults suggests an increased risk of later life stroke among people who had experienced parental divorce in childhood

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People whose parents divorced during their childhood may be at a greater risk of stroke later in life, according to a new study published January 22, 2025 in the open-access journal PLOS One by Esme Fuller-Thomson of University of Toronto, Canada, and colleagues. 

Each year, approximately 795 000 individuals in the U.S. have a stroke. Previous work has established many sociodemographic risk factors for stroke, as well as connections between adverse childhood events and stroke. In the new study, researchers looked specifically at the impact of childhood parental divorce among adults with no history of childhood abuse. They used data on 13 205 adults aged 65 and over from the 2022 Behavioral Risk Factor Surveillance System.

The study found that people who had experienced parental divorce before they were 18 years old had 1.61 times higher odds of having a stroke when compared to respondents who did not experience parental divorce (AOR=1.61, 95% CI=1.15-2.24). The association did not vary by sex, and remained even after controlling for known risk factors such as diabetes, depression, and small social support networks.

The current study was not designed to analyse the potential mechanism of this association, nor to prove causation. The conclusions may not be generalisable to younger generations, who have experienced overall higher rates of parental divorce. In addition, several potential confounding factors – including blood pressure, cholesterol, contraceptive use, age at parents’ divorce, and types of strokes – were not available in the data.

However, the authors say that their data supports an association between parental divorce during childhood and increased stroke risk, even in the absence of childhood abuse and other trauma. 

Senior author Esme Fuller-Thomson adds: “It is extremely concerning that older adults who grew up in divorced families had 60% higher odds of stroke, even after excluding those who had been physically or sexually abused as children. The magnitude of the association between parental divorce and stroke was comparable to well-established risk factors for stroke such as male gender and having diabetes.”

Provided by PLOS

Heart Rate Activity Influences When Infants Speak

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The soft, gentle murmurs of a baby’s first expressions, like little whispers of joy and wonder to doting parents, are actually signs that the baby’s heart is working rhythmically in concert with developing speech.

Jeremy I. Borjon, University of Houston assistant professor of psychology, reports in Proceedings of the National Academy of Sciences that a baby’s first sweet sounds and early attempts at forming words are directly linked to the baby’s heart rate. The findings have implications for understanding language development and potential early indicators of speech and communication disorders.

For infants, producing recognisable speech is more than a cognitive process. It is a motor skill that requires them to learn to coordinate multiple muscles of varying function across their body. This coordination is directly linked to ongoing fluctuations in heart rate.

Borjon investigated whether these fluctuations in heart rate coincide with vocal production and word production in 24-month-old babies. He found that heart rate fluctuations align with the timing of vocalizations and are associated with their duration and the likelihood of producing recognisable speech.

“Heart rate naturally fluctuates in all mammals, steadily increasing then decreasing in a rhythmic pattern. It turns out infants were most likely to make a vocalisation when their heart rate fluctuation had reached a local peak (maximum) or local trough (minimum),” reports Borjon.

“Vocalisations produced at the peak were longer than expected by chance. Vocalisations produced just before the trough, while heart rate is decelerating, were more likely to be recognised as a word by naïve listener,” he said.

Borjon and team measured a total of 2708 vocalisations emitted by 34 infants between 18 and 27 months of age while the babies played with a caregiver. Infants in this age group typically don’t speak whole words yet, and only a small subset of the vocalisations could be reliably identified as words by naïve listeners (10.3%). For the study, the team considered the heart rate dynamics of all sounds made by the baby’s mouth, be it a laugh, a babble or a coo.

“Every sound an infant makes helps their brain and body learn how to coordinate with each other, eventually leading to speech,” Borjon said.

As infants grow, their autonomic nervous system grows and develops. The first few years of life are marked by significant changes in how the heart and lungs function, and these changes continue throughout a person’s life.

The relationship between recognisable vocalisations and decelerating heart rate may imply that the successful development of speech partially depends on infants experiencing predictable ranges of autonomic activity through development.

“Understanding how the autonomic nervous system relates to infant vocalisations over development is a critical avenue of future research for understanding how language emerges, as well as risk factors for atypical language development,” said Borjon

Source: University of Houston

Raising Happy Eaters: Unlocking the Secrets of Childhood Appetite

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The foundation for healthy eating behaviour starts in infancy. Young children learn to regulate their appetite through a combination of biological, psychological, and sociological factors. In a new paper published in Social Science & Medicine, researchers at the University of Illinois Urbana-Champaign propose a model that explores these factors and their interactions, providing guidelines for better understanding childhood appetite self-regulation.

“When we talk about obesity, the common advice is often to just eat less and exercise more. That’s a simplistic recommendation, which almost makes it seem like an individual’s willpower solely determines their approach to food,” said lead author Sehyun Ju, a doctoral student in the Department of Human Development and Family Studies, part of the College of Agricultural, Consumer and Environmental Sciences at Illinois. 

Appetite self-regulation is related to general self-regulation, but it specifically concerns an individual’s ability to regulate food intake, which affects healthy development and obesity risk. Children are born with a capacity to regulate appetite based on hunger and satiety signals, but with increased exposure to environmental factors, their eating is increasingly guided by psychological reasoning and motivations. Therefore, it is important to take a developmental perspective to trace changes in eating behaviours over time, Ju stated.

Ju and her colleagues provide a comprehensive framework based on the biopsychosocial pathways model, which outlines three interacting categories: Biological factors, including sensory experience, physiological hunger and satiety signals, brain-gut interaction, and the influence of the gut microbiome; psychological factors, including emotional self-regulation, cognitive control, stress regulation, and reward processing; and social factors, such as parental behaviour and feeding practices, culture, geographic location, and food insecurity.

The researchers combine this framework with temperamental theory to explore how the pathways are modified by individual temperament.

Children react differently to stimuli based on their psychological and emotional make up, Ju explained. For example, openness to novelty and positive anticipation can affect whether a child is willing to try new foods. If a parent pressures their child to eat, it could be counter-productive for a child with heightened sensitivity to negative affect, causing the child to consume less.

The model also takes children’s developmental stages into account. Infants have basic appetite regulation based on physiological cues. They gradually become more susceptible to external influences and by age 3-5, children begin to exhibit greater self-control and emotional regulation.

“By analysing the pathways outlined in our model, we can better understand the combined influences of multiple factors on children’s appetite self-regulation and their motivations to approach food,” Ju said. “For example, the presence of palatable food may not generate similar responses in everyone. Children could approach food as a reward, for pleasure-seeking, or to regulate emotions. The underlying motivations can be diverse, and they are influenced by external factors as well as temperamental characteristics.”

Socio-environmental influences include parent-child interactions around food, as well as non-food-related caregiver practices that can impact the child’s emotional regulation. The household food environment, cultural value of food intake, and food availability are also important factors, the researchers stated.

“If we understand the differential susceptibility to various factors, we can identify and modify the environmental influences that are particularly obesogenic based on children’s temperamental characteristics. Then we will be able to provide more refined approaches to support children’s healthy eating behaviour,” Ju explained.

Source: University of Illinois College of Agricultural, Consumer and Environmental Sciences

First Menstrual Periods are Arriving Earlier for Younger Generations

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The average age at menarche, the first menstrual period, has been decreasing among younger generations in the US, especially those belonging to racial minorities and lower socioeconomic statuses, according to a new study led by researchers at Harvard T.H. Chan School of Public Health. It also found that the average time it takes for the menstrual cycle to become regular is increasing.

The study, published in JAMA Network Open, is the latest publication from the Apple Women’s Health Study, a longitudinal study of menstrual cycles, gynaecological conditions, and overall women’s health conducted by Harvard Chan School, the National Institute of Environmental Health Sciences, and Apple.

“Our findings can lead to a better understanding of menstrual health across the lifespan and how our lived environment impacts this critical vital sign,” said co-principal investigator Shruthi Mahalingaiah, assistant professor of environmental, reproductive, and women’s health at Harvard Chan School.

While previous studies have shown trends towards earlier menarche over the past five decades, data has been limited on how these trends present within different racial groups and socioeconomic statuses. Additionally, few studies have had sufficient data to identify any trends regarding time to menstrual cycle regularity.

The researchers used the Apple Women’s Health Study’s large, diverse dataset to fill this research gap. The 71 341 participants who enrolled between November 2018 and March 2023 self-reported the age at which they first began menstruating and their race and socioeconomic status. The researchers divided the participants into five age brackets: born between 1950–1969, 1970–1979, 1980–1989, 1990–1999, and 2000-2005. Ages of menarche were defined as early (younger than 11 years old), very early (younger than 9), and late (ages 16 and above). A subset of participants (61 932) self-reported the time it took for their menstrual cycle to become regular and were divided into five categories: up to two years, between three and four years, longer than five years, hasn’t become regular, or became regular with use of hormones. Another subset (9865) provided their body mass index (BMI) at their age of menarche.

The study found that as birth year increased (meaning younger participants), average age at menarche decreased and time from menarche to menstrual cycle regularity increased. Among participants born from 1950–1969, the average age at menarche was 12.5 years, and the rates of early and very early menarche were 8.6% and 0.6%, respectively. Among participants born from 2000–2005, the average age of menarche was 11.9 years, and the rates of early and very early menarche were 15.5% and 1.4%, respectively. Across the two groups, the percentage of participants who reached menstrual cycle regularity within two years of menarche decreased from 76% to 56%. The researchers observed that these trends were present among all sociodemographic groups but were most pronounced among the participants who identified as Black, Hispanic, Asian, or mixed race, and who rated themselves as belonging to a low socioeconomic status.

The findings showed that BMI at age of menarche could explain part of the trend toward periods starting earlier. Other possible factors that might explain the trend include dietary patterns, psychological stress and adverse childhood experiences, and environmental factors such as endocrine-disrupting chemicals and air pollution.

“Continuing to investigate early menarche and its drivers is critical,” said corresponding author Zifan Wang, postdoctoral research fellow in Harvard Chan School’s Department of Environmental Health. “Early menarche is associated with higher risk of adverse health outcomes, such as cardiovascular disease and cancer. To address these health concerns – which our findings suggest may begin to impact more people, with disproportionate impact on already disadvantaged populations – we need much more investment in menstrual health research.”

The authors noted some limitations to the study, including that it relies heavily on retrospective self-reporting.

Source: Harvard T.H. Chan School of Public Health

New Research Affirms Five Factors to Ensure an Infant Thrives

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The “Thrive 5” are five conditions to ensure an infant in the first year of life has what they need for healthy development. Those conditions include environmental stimulation, nutrition, neighbourhood safety, positive caregiving and regular circadian rhythms and sleep. Simple, and yet, it has not yet been prioritised for many reasons including the fact that researchers had not provided empirical data to support making the Thrive 5 a public health priority.

Researchers at Washington University in St. Louis think it’s time to change that. In new research published in JAMA Pediatrics, Deanna Barch and Joan Luby make the case that “Thrive Factor” is a key element of healthy human brain, behavioural and cognitive development.

“When they have access to these basic supports, even in the face of adverse environments, it enhances their brain development, cognition (measures of IQ) and social-emotional development,” said Luby, MD, the university’s Samuel and Mae S. Ludwig Professor of Child Psychiatry at the School of Medicine.

There have been plenty of studies touting the benefits of individual thrive factors, such as encouraging breast-feeding to facilitate growth in general, but this new study looks at several key factors known to influence brain development and shows their relationship to outcomes at age 3.

“The novelty here is putting them all together and thinking of them as a constellation of things that are necessary and important for a child to be able to thrive,” said Barch, PhD, vice dean of research, a professor of psychological & brain sciences in Arts & Sciences and the Gregory B. Couch Professor of Psychiatry at the School of Medicine.

The study is part of a change in thinking in the child development field as scientists have learned that much of our health is not just genetically predetermined but is powerfully influenced by the psychosocial environment. The human brain is still undergoing rapid development at birth, and researchers are trying to understand the environmental factors that shape this development.

The study of 232 infants and their mothers looked at positive factors in the environment in the foetal period and first year of life that enhance brain development, minimise negative behaviours and increase cognitive outcomes. Participants were evaluated on social disadvantage indexes beginning in utero and early life T-Factor scores were also calculated. As infants approached age 3, they were re-evaluated for social, emotional and cognitive development along with using MRIs to scan brain structure.

The results were clear that T-Factor is powerful: Even infants coming from adverse conditions and under-resourced backgrounds can have healthy development if they get their Thrive 5.

The researchers note that policymakers and paediatric primary care providers should be informed about the importance of focusing on elements of the T-Factor and how they can lead to many downstream advantages for both the child and society.

It may seem obvious to anyone that a baby needs care, sleep, food, stimulation and safety but “nobody has particularly focused on or prioritised the importance of this during foetal development and in the first year of life to enhance critical developmental outcomes,” Luby said.

“The Thrive Factor provides a solid foundation for healthy development. It has been underappreciated in primary care just how malleable the brain is to experience,” Luby added.

Barch said the next step will be setting up interventions to test in randomised controlled trials. Another advantage to T-Factor is it is highly feasible to share and promote in broad populations.

Interventions would likely take the form of multiple Zoom sessions with parents to educate and coach them on how to best provide each thrive factor. But that would just be the start, since parents need resources to help them provide thrive factors.

Though T-Factor can help kids overcome adverse conditions, Barch emphasised the need for understanding just how tough those adverse conditions can be on a new parent.

“If you’ve never suffered from financial adversity, you don’t understand how hard that makes life,” she said.

Parents can struggle to provide conditions to thrive because they may have to support many people in their household, may not have adequate number of rooms to ensure easier child sleep training, must work multiple jobs and can’t get away to breast feed, and live in unsafe neighbourhoods that keep them in a constant state of vigilance.

Though education can help caregivers, it will take public policy interventions to ensure parents can access all the Thrive Factors, especially when it comes to access to safe housing and adequate income to support even these basic needs of developing infants.

“We need to make it so families can have the resources necessary to provide these core things to kids because it’s going to have such a big impact on kids’ development across the course of their lifespan,” she said.

Source: Washington University in St. Louis