Teens who hit puberty later could face bone health issues later in life, studies suggest


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Ahmed Elhakeem, University of Bristol

Puberty is a time of dramatic development for both boys and girls. Not only are those hormones raging, but there’s all the bodily changes to contend with.

Puberty is driven by the activity of sex hormones and its onset is announced by the appearance of pubic hair, beards and breasts. Along with the dramatic hormone-driven changes to a child’s body, another defining features of puberty is the adolescent growth spurt – children become taller and eventually physically mature into adults.

For boys and girls this growth spurt generally happens at different ages. And there can be big differences as to when the growth spurt happens. For girls, rapid growth generally occurs around age eleven and a half years but can begin as early as eight or as late as 14 while for boys it generally happens a year or two later than girls. Children continue to get taller during their growth spurt until the ends of their long bones fuse and stop increasing in length, which happens around the end of puberty.

Children’s bones develop rapidly during puberty. And our new findings published in JAMA Network Open suggest that teens who have their pubertal growth spurt later could have more problems with their bone health in the future. In essence our research shows that the timing of puberty might influence or at least signal a child’s bone strength throughout adolescence and into early adulthood.

Weak bones

Our study is not the first to report a link between the timing of puberty and bone strength. A 2016 study of British people born in 1946 showed that children who had their growth spurt at an older age had lower bone density near the end of their forearm bone when measured decades later in old age, making them more likely to get a broken wrist.

More recently, a study of adolescents and young adults from Philadelphia showed that people who were genetically predisposed to later puberty had lower bone density at the spine and hips sites which are known to be susceptible to osteoporosis in later life. This is an ageing-related condition where bones lose their strength and become more likely to break.

Our study tracked the development of bone strength in a group of British children through to adulthood and found that teens who hit puberty at an older age tend to have lower bone mineral density which is a strong indicator of having weaker bones. We found that this continued to be the case for up to several years of their adult life.

Measuring puberty

We analysed data from more than 6000 children from the Children of the 90s study. This is a multi-generational study that has tracked the lives of a large group of people born in the early 90s around Bristol in the south west of England.

Children whose genetic makeup triggers a later-than-average start to puberty are at increased risk of having weaker bones as adults.
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We made use of multiple bone density scans taken from each child to assess their bone strength across a 15-year period between the ages of ten and 25 years.

To calculate the age when the children went through puberty, we tracked each child’s height and used this information to estimate the age when each child went through the adolescent growth spurt. We then assumed that children that had their growth spurt at an older age must have started puberty later. As a check, we repeated our analysis in girls using the age they reported getting their first period as a different indicator of when they hit puberty and we came to the same conclusions.

Rebuilding bone density

Our research adds to the growing evidence that children who mature later may be at increased risk of breaking a bone as they grow and mature. And that they may also have an increased risk of getting osteoporosis later in life.

Of course, there are things people can do to strengthen their bones. But given our findings, it is clear there is now a need for bigger and more detailed studies into the very complex relationships between puberty, growth and bone development. Continuing to track the lives of the people in our study will be crucial if we are to discover how puberty might impact people’s bones as they go through adult life and eventually move into old age. This will help to further understand the causes of osteoporosis and ultimately help people to maintain healthy bones throughout their lives.The Conversation

Ahmed Elhakeem, Epidemiologist, University of Bristol

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

Depression: where we’re at and where we’re going

To mark Mental Health Awareness Week, IEU PhD researcher Alex Kwong takes us on a tour of the research on depression in young people.

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What is depression and why should we care?

Depression is one of the biggest public health challenges we’re currently facing and is expected to be the highest global burden of disease by 2030. The world health organisation (WHO) estimates that around 300 million people worldwide currently experience depression and that at least one in five people will experience depression at some stage of their life. Treatment is not always successful with only around 40-60% of individuals responding positively to antidepressant medication, and other forms of treatment such as cognitive behavioural therapy (CBT) or other talking based therapies requiring long waiting times of up to two years. It’s no surprise to see that depression and other mental health treatments are considered to be in a ‘crisis’ as we continually look for new and effective ways to combat this disease.

Research suggests that depression may first begin to manifest early in adolescence and young adulthood. This may have serious downstream consequences as depression during adolescence is related to both concurrent and later self-harm and suicide, corresponding mental health problems (like anxiety, addiction and psychosis) and impaired social functioning (reduced cognitive functioning and reclusiveness), to name a few. It also appears that depression during adolescence and young adulthood may actually be getting worse. Now whether or not this is because young people are talking more about their mental health than before remains to be seen, but that has not stopped researchers identifying potential causes for depression in adolescence in the hope of developing new and effective treatments and interventions. The message seems to be clear: by stopping/reducing depression in young people, we can potentially improve the quality of life later on.

What is responsible for depression in young people?

The lived experience of depression between young people differs from one person to the next, meaning there is no ‘one-size-fits-all’ approach. But with the help of research, we have begun to identify things that individuals experiencing depression have in common, that could be useful for treating and even preventing depression in young people. What follows is a whistle stop tour of some of the findings of potential causes of depression in young people.

Bullying

It may seem obvious, but childhood and adolescent bullying is one of the strongest predictors of current and later depression. One recent study found that individuals who had been bullied during adolescence were almost 3 times more likely to be depressed at age of 18. Bullying is particular prevalent during school years but can also occur well into the workplace or later education, which can have lasting effects on an individual’s mental health. Stopping bullying from occurring will be difficult, but that does not mean we cannot support individuals who have been bullied in order to help prevent depression from occurring or getting more severe.

Parental Depression

A lot of research has focused on the role of parental mood and later depression in young people. The role of parenting cannot be understated as numerous studies have shown that children of depressed parents are more likely to go on to have depression themselves, see research by Pearson et al, Stein et al and Gutierrez-Galve et al. However, it’s not clear if this is passed on genetically from the parent to child, or if there is something in the “environment” that transmits depression from parent to child. Whilst we don’t know for sure, the answer looks like it could be a bit of both. Parents may pass on depression genetically to their children, but depressed parents may also create an environment that makes the child more liable to depression. It is even possible that the parent passes on their genetics and the child then creates an environment for themselves that makes them more liable to depression. This is a form of gene-environment correlation that I won’t discuss in detail, but research is beginning to tease this apart with regard to parent and childhood depression.

Genetics

Interest in the genetics of depression has been heightened in the last few years. We always knew from twin studies that depression was likely to be heritable (i.e., that depression can be passed on from generation to generation), but convincing some that depression could have a strong genetic basis was tough (for a really good debate on this involving Professor Marcus Munafò, you can listen to this episode of BBC Start the Week). Most recently it has been shown that common genetic variants associated with depression in adulthood seem to predict greater levels of depression in children and adolescents, as well as varying patterns of depressive mood across adolescence. Importantly, it’s clear that there is no ‘one gene’ for depression. Instead, there are multiple genes which can be referred to as ‘polygenicity’ or ‘polygenic risk scores’; “poly” meaning multiple and “risk” indicating that individuals carrying multiple risk genes are more liable or ‘at risk’ to depression. By using polygenic risk scores we can begin to identify individuals experiencing depression early by using knowledge of their genetic make-up. However, it is really important to state here that genetic liability to depression does not equal genetic determinism. Just because someone is more genetically liable to depression, does not mean they will get depressed. There are multiple other factors at play, and we do not know how genetic liability to depression impacts on other pathways (i.e., does having genetic liability make you more likely to seek out an environment that could leave you more depressed?); but many researchers are beginning to ask these questions.

Taken together, these findings highlight how diverse depression is and how many factors could underlie depression in adolescence. There are a ton of other factors that have been related to adolescent depression that I have not had time/space to talk about. That is not to say they are not important, because most likely some are. As research develops and we are able to utilise different methods, we will get a better picture of what underpins depression in adolescence and what can be done to prevent and treat it.

What can we do?

Well for one, we have to keep up the research. We don’t know nearly enough about the underlying mechanisms and pathways that truly underlie adolescent depression. Researchers are beginning to examine this further with novel and promising techniques, but we also have to streamline the time it takes for research to be put into practise. The prolific mental health blog “The Mental Elf” states that it takes 17 years for research to reach clinical practise. That’s a long time and means a lot of people could miss out on the treatment they deserve.

Secondly, we have to be more forthright in how we talk about depression. You may have heard the expression ‘it is ok to be not be ok”. Avoiding telling people to “man-up” when they’re feeling depressed, speaking out and campaigns will only drive this forward. We have to normalise the fact that depression is a disease and like any other disease, it is good to talk about it. Only by talking about depression can we really move forward to end the stigma that being depressed is some kind of weakness. In fact one of my favourite instances of this recently was well explained by the England international Danny Rose.

Where do we go from here?

We appear to be reaching a turning point where more and more people are discussing mental health issues. This may be celebrities, royals or just your average Jo from down the street. But what is important is that we recognise the problem. That depression is a global burden that may be getting worse and requires our utmost attention and action. We are beginning to understand the causes of depression and how we might tackle it through research and reducing the social stigma that surrounds depression. However, the question is whether or not we can take advantage of these changes to really make a difference. Can we build on the progress we have made to finally one day beat depression? Yes. I really believe we can.

Resources for if you’re feeling down

If you’re ever feeling low, then I cannot speak highly enough for these guys: https://www.samaritans.org/

There are a lot of charities who specialise in mental health and depression who provide some excellent resources and information:
https://www.mqmentalhealth.org/
https://www.mind.org.uk/

There are some awesome twitter feeds out there who I have always found to be really helpful and supportive of mental health issues. These people really get depression and are leading the charge in one way or another so do please give them a follow:

MENtalHealth
Paul McGregor
Gareth Griffith
Miguel Cordero Vega
Louise Arseneault
Dr Erin C Dunn