A new study has found that the X chromosome passed down to the child from the mother might be responsible for accelerated brain ageing, potentially increasing the risk of conditions like Alzheimer’s disease. Only females have two X chromosomes (XX) while males have one X and one Y (XY). Given the natural order, the X chromosome carries a significant amount of genetic material, and any mutation or variation here can have profound effects, especially as one X chromosome in females is randomly inactivated in each cell.

Though women tend to live longer than men and have lower rates of dementia, one exception is Alzheimer’s disease which affects them at higher rates. Even then, some studies suggest that females survive longer with Alzheimer’s than males do. The researchers set out to find the reason and believed that the sex chromosomes, X and Y, could help explain the differences.

“Skewing of the X chromosome is common among humans, and there are certainly women who are walking around with much higher or lower levels of maternal X chromosomes than others, just by chance,” said Dena Dubal, senior author of the paper.

“There has been little research on the potential consequences of this,” she added.

Also Read | Anti-Ageing Influencer Bryan Johnson Ditches ‘Longevity’ Medicine Over Health Concerns

‘The experiment’

To further explore the idea, the researchers experimented with female lab mice of different ages. In some cases, the paternal X chromosomes were silenced, leaving only the mother’s X active. These mice were compared with others that had a mix of maternal and paternal X’s switched on.

As per the findings, the young “Mom-X” mice were cognitively similar to young mice but the older ones showed steep cognitive decline. In the brains of these mice, the maternal X chromosome sped up biological ageing in the hippocampus – a brain area crucial for learning and memory.

“These findings raise the possibility that some women who express more of their mom’s X chromosome just by pure chance may have more cognitive impairment with aging or an increased risk for diseases like Alzheimer’s,” said Ms Dubal.

“Ultimately, it could also help us find constructive strategies for slowing brain aging in both sexes.”

Though the research was conducted on mice, the findings, if they translate to humans, could point to drivers of cognitive decline related to a particular sex and, eventually, help us fund ways to prevent or treat them.

Wellington:

We hear a lot about women’s biological clock and how age affects the chance of pregnancy.

New research shows men’s fertility is also affected by age. When dads are over 50, the risk of pregnancy complications increases.

Data from more than 46 million births in the United States between 2011 and 2022 compared fathers in their 30s with fathers in their 50s.

While taking into account the age of the mother and other factors known to affect pregnancy outcomes, the researchers found every ten-year increase in paternal age was linked to more complications.

The researchers found that compared to couples where the father was aged 30–39, for couples where the dad was in his 50s, there was a:

• 16% increased risk of preterm birth
• 14% increased risk of low birth weight
• 13% increase in gestational diabetes.

The older fathers were also twice as likely to have used assisted reproductive technology, including IVF, to conceive than their younger counterparts.

Dads are getting older

In this US study, the mean age of all fathers increased from 30.8 years in 2011 to 32.1 years in 2022.

In that same period, the proportion of men aged 50 years or older fathering a child increased from 1.1% to 1.3%.

We don’t know the proportion of men over 50 years who father children in Australia, but data shows the average age of fathers has increased.

In 1975 the median age of Australian dads was 28.6 years. This jumped to 33.7 years in 2022.

How male age affects getting pregnant

As we know from media reports of celebrity dads, men produce sperm from puberty throughout life and can father children well into old age.

However, there is a noticeable decline in sperm quality from about age 40.

Female partners of older men take longer to achieve pregnancy than those with younger partners.

A study of the effect of male age on time to pregnancy showed women with male partners aged 45 or older were almost five times more likely to take more than a year to conceive compared to those with partners aged 25 or under. More than three quarters (76.8%) of men under the age of 25 years impregnated their female partners within six months, compared with just over half (52.9%) of men over the age of 45.

Pooled data from ten studies showed that partners of older men are also more likely to experience miscarriage. Compared to couples where the male was aged 25 to 29 years, paternal age over 45 years increased the risk of miscarriage by 43%.

Older men are more likely to need IVF

Outcomes of assisted reproductive technology, such as IVF, are also influenced by the age of the male partner.

A review of studies in couples using assisted reproductive technologies found paternal age under 40 years reduced the risk of miscarriage by about 25% compared to couples with men aged over 40.

Having a male under 40 years also almost doubled the chance of a live birth per treatment cycle. With a man over 40, 17.6% of treatment rounds resulted in a live birth, compared to 28.4% when the male was under 40.

How does male age affect the health outcomes of children?

As a result of age-related changes in sperm DNA, the children of older fathers have increased risk of a number of conditions. Autism, schizophrenia, bipolar disorders and leukaemia have been linked to the father’s advanced years.

A review of studies assessing the impact of advanced paternal age reported that children of older fathers have increased rates of psychiatric disease and behavioural impairments.

But while the increased risk of adverse health outcomes linked to older paternal age is real, the magnitude of the effect is modest. It’s important to remember that an increase in a very small risk is still a small risk and most children of older fathers are born healthy and develop well.

Improving your health can improve your fertility

In addition to the effects of older age, some chronic conditions that affect fertility and reproductive outcomes become more common as men get older. They include obesity and diabetes which affect sperm quality by lowering testosterone levels.

While we can’t change our age, some lifestyle factors that increase the risk of pregnancy complications and reduce fertility, can be tackled. They include:

Get the facts about the male biological clock

Research shows men want children as much as women do. And most men want at least two children.

Yet most men lack knowledge about the limitations of female and male fertility and overestimate the chance of getting pregnant, with and without assisted reproductive technologies.

We need better public education, starting at school, to improve awareness of the impact of male and female age on reproductive outcomes and help people have healthy babies.

For men wanting to improve their chance of conceiving, the government-funded sites Healthy Male and Your Fertility are a good place to start. These offer evidence-based and accessible information about reproductive health, and tips to improve your reproductive health and give your children the best start in life.

(Author:Karin Hammarberg, Senior Research Fellow, Global and Women’s Health, School of Public Health & Preventive Medicine, Monash University)

(Disclosure Statement:Karin Hammarberg works for the Victorian Assisted Reproductive Treatment Authority which manages the Your Fertility program)

This article is republished from The Conversation under a Creative Commons license. Read the original article.
 

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

On a summer morning at Ritan Park in the heart of Beijing, an 80-year-old man, who has lost most of his front teeth, is pushing his own wheelchair and going from one equipment to another at the open gym, stretching himself and doing light exercises.

Another group of elderly people is playing with a diabolo, half of the ping-pong tables are taken over by grey-haired men and women, and multiple groups of people – mostly elderly women – are dancing in different parts of the park.

At one of the groups near the main gate, as the song changes to an upbeat one, a spectacled woman wearing a loose brown top and her grey hair tied into a bun, steps in and starts dancing with a man, who was till now dancing with someone else.

“I come here every day to dance, be it Saturday or Sunday. If I don’t come here, I will sleep at my house and I don’t feel good. Most of these people are like me,” said 73-year-old Hu Yulin, as she hummed and moved to the music, while watching her friends continued to dance.

Ms. Hu’s husband passed away three years ago and she lives alone, as her only daughter lives in the U.S. She wakes up at 6 a.m. every day and after having a breakfast, mostly of eggs and milk, she reaches the park by 9 a.m. and dances till 11 a.m. with her friends – she has been doing this for about 12 years now.

Across parks of Beijing, groups of elderly people can be seen ‘square dancing’, exercising, or playing different types of games. These groups need not only a space for physical activity, but also much-needed social interaction.

“Leisurely Physical Activity (LPA) such as dancing or exercising of elderly is going up across China. On the other hand, Work Related Physical activity (WPA) is going down,” said Lili Xie, a Professor at Center for Population and Development Studies in the Chinese government-run Renmin University.

Ms. Xie’s observations are based on data from China Longitudinal Ageing Social Survey (CLASS), a survey done by the Renmin University, in which over 13,000 people from 23 provinces took part in 2020.

By the end of 2023, the population of people above 65 years of age in China was 15.4% of the total population and China is projected to be “super-aged” (population of people above 65 years would move up more than 20% of population) by 2050, she said. According to the UN, the number of people above 65 years of age in China by 2050 will be close to 400 million – more than the current entire population of the U.S.

Physical inactivity among adults is increasing globally and in 2022, 31% of adults worldwide – about 1.8 billion people – did not meet the recommended levels of physical activity, according to a study published last month by researchers from the World Health Organisation (WHO) and others. If the trend continues, levels of inactivity are projected to further rise to 35% by 2030.

Dr. Regina Guthold, a scientist working with the WHO and one of the authors of study, told The Hindu, “Elderly people in China are more physically active than their counterparts in most parts of the world, except for countries in Oceania and Sub-Saharan Africa, as per the study. But there is no separate ranking of countries based on physical activity of people above 60 years of age.”

Over the years, the overall physical activity has fallen in China and it is expected to fall further by 2030, if the trend continues, according to the study. But the overall physical activity in China is better than many countries such as the U.S. and Canada, but worse than others, including Finland, Denmark, the U.K., and several African countries.

The WHO’s definition of “physical activity” is inclusive and considers leisurely, work-related and other forms of physical activity. “In most countries, men are more active than women, but interestingly in China, women are more physically active,” Ms. Guthold said.

According to a 2023 study done by Ms. Xie and others at Renmin University, physical activities, social interactions and cognitive activities can help older adults to maintain cognitive health. The study with a sample size around 9,800 elderly, also found that while light and moderate physical activities were beneficial, vigorous physical activity negatively impacted cognition.

Not just dancing

At Ritan Park, a big speaker on a tricycle continued to play slow music and about 20 couples, including Ms. Hu, moved to a song, with some holding their partner’s hands and others with hands around their waists.

“I have known many of them for years and we talk about our families, sons, daughters, cheap vegetables and other things,” she laughed, deepening the wrinkles on her face.

The feeling of friendship was evident in other groups too.

A little away from Ms. Hu’s group, Zhu Guo Quiang takes off his t-shirt. Wearing a pair of black shorts and sunglasses, he effortlessly does multiple 360 degree spins on a pull up bar – Mr. Zhu is 70 years old.

He and four of his friends – all of them shirtless – chit chats and laughs as they continue with their exercise. Two people sitting on a bench watching them are in their 80s and one of them can also do about five pull ups on the bar.

“I have been doing this for over 10 years. I enjoy coming here and we talk about fitness, medical things, current affairs and even about international issues such as Russia-Ukraine and Israel-Palestine,” Mr. Zhu said. “My wife sometimes comes here to dance. But I’m not much of a dancer.”

Another group of around five elderly is playing ‘Dou Kong Zhu’ (diabolo), a game in which an hourglass-shaped top is balanced and spun on a string stretched between the tips of two sticks.

Li Guo Qiang, 73, throws the top about 20 feet up in the air and catches it on the thread. At times, he throws the top and then skips using the string before it comes down and catches the top with the same thread.

“I have been doing this for more than 10 years, but I have been coming here for over 15 years and playing other games. I like coming here. All of them are my friends,” he said.

Why more?

Explaining the reason behind more elderly people taking up leisurely physical activities, Ms. Xie said: “The current cohort of people who are entering the old age are born in the 1950s and 60s are different from the previous cohorts. Their lifestyle and needs are different as they have more money and free time and they want to do more compared to earlier cohorts of elderly people, who were more focused on family and looking after grandchildren.”

Ms. Xie said that compared to 15 years back, she sees more people dancing or exercising in public spaces in Beijing or her hometown in Chengdu.

About ‘square dancing’, she said it started getting popular around 2015 and earlier, elderly used to dance in closed spaces such as community halls or at a festival, but these were not a regular activities. “But ‘square dancing’ is a form of exercise and it happens almost every day,” she added.

But the overall social network of elderly people in China is showing a declining trend, as per CLASS data, Ms. Xie said. “Number of elderly people living alone and ‘empty nest’ older adults are increasing,” she added. “But there is a difference between urban and rural areas. While social networks in cities are shrinking, it is going up in rural areas as per CLASS surveys.”

Urban v. rural divide

The divide doesn’t stop here. Square dancing and idle activities such as watching TV or reading books are also more popular in urban areas.

Similarly, leisurely physical activity is more in urban areas and work-related physical activity is more in rural areas. “For non-agricultural activities, there is a strict retirement age. But there is no retirement age for farmers. Many people in rural areas are working even after turning 60. They do not want to work, but they have no choice,” she said.

Ms. Xie said physical activity for older people is part of different national policies, especially after 2019. “It will be good not only to the individuals, but also to the society as it will reduce the government’s spending on healthcare for the elderly.”

She said China needs more public spaces for older people to exercise and more programmes and volunteering opportunities for them. “Though the government is increasing facilities for physical activities, it not enough as shown by the CLASS data. Also, more awareness and education is needed on why and how to exercise.”

The professor said China is learning many things from Japan, as they have already super-aged. “We are looking at their old age care systems, long-term care systems etc..”

Ms. Guthold said physical activity will help in the long run to reduce non communicable diseases and even if you start physical activity in old age, you still get benefits. With China ageing fast, this has become a necessity, so that the elderly stay healthy as exercising can lead to better cognition and mental health and social interactions can lead to more live satisfaction also reduce risk of depression, Ms. Xie said.

“For a country like China it is a necessity, because if they don’t try to have active, social connected, and happy old people, they are in trouble as the number of elderly people in China is set to be very high,” Ms. Guthold said.

Meanwhile, at Ritan Park, an elderly man and woman got up from their wheelchairs and tried to move their bodies slowly with a group that was dancing.

As Ms. Hu was about to leave, a friend walked up to her and chatted with her in Mandarin. “She said she hasn’t seen me in two days and she missed me. I also miss dancing when I go to visit my daughter in the U.S. These are all my friends,” she said.

(The correspondent was in China at the invitation of the China Public Diplomacy Association)