Understanding the Role of Adolescent Dysmenorrhoea as a risk factor for the transition to chronic Pain (RoAdPain)

Chronic pain is defined as pain that lasts for more than 3 months. It is really common, affecting up to 30% of people worldwide with impacts on all areas of life. Chronic pain is difficult to treat once it has developed. Therefore, understanding which people might be at risk of developing chronic pain and protecting them from it starting, would be a really positive step forward.

We know that women are more likely to develop almost all types of chronic pain than men. We start to see a sex difference in chronic pain after puberty, suggesting that changes happening at this time may be contributing to this increased risk. One important change that happens at this time is periods starting. Despite periods often being very painful, period pain has traditionally been dismissed as "normal" and something girls must learn to live with. However, in adult women with period pain we see many differences across a range of body systems when compared to women without period pain. These include increased sensitivity to pain; increased sensitivity of the bladder, bowel and womb; altered brain structure and function; and altered stress responses. Similar changes to those seen with period pain can be seen with other chronic pain. We don't know whether these changes are caused by repeated or continuous pain or if they are part of the reason why chronic pain develops, or a combination of both.

Our project has 3 aims:
1. To understand whether period pain during adolescence increases the risk of developing chronic pain as a young woman.
2. To see whether the differences in other body systems described above in adult women with period pain are also seen in girls in the first few years of having periods.
3. To find out whether there are any factors present in childhood that increase the risk of period pain developing in the first few years of having periods.

We will use two different approaches to answer these questions. For questions 1 and 3, we will use data collected in the Avon Longitudinal Study of Parents and Children (ALSPAC). ALSPAC is a large research resource which has been collecting data from children born in the early 1990s and their parents for almost 30 years. This dataset includes:
- detailed assessments of chronic pain at the ages of 17 and 26 years
- questions about periods every year between the ages of 8 and 17 years
- a wide variety of childhood assessments
- information about the mothers health and wellbeing
- genetic information.
For objective 2 we will recruit a group of adolescent girls, including those with and without period pain, 1, 3 and 5 years after starting their periods. With their agreement, we will undertake tests to understand more about their body systems and pain. All the tests we will use have been previously used in children and adolescents and do not involve significant pain.

We hope this work will reduce the risk of both adolescent girls and adult women suffering with period pain and other chronic pain conditions. We will use what we learn about the long term risks of period pain, including how long it takes for experiencing period pain to increase your risk of chronic pain, to make sure period pain is taken seriously and to produce advice and guidance for those with period pain, health professionals, policy makers and educators. A better understanding of the risk factors for developing period pain when periods start will let us identify girls at risk of early-onset period pain, ensuring they are educated and empowered to seek treatment early. Our findings on how period pain leads to chronic pain will be developed into novel strategies to prevent chronic pain, including future work with other researchers and drug companies.

The research team come from a wide variety of backgrounds and have strong links with key stakeholders and industry partners. We will use these existing networks to ensure our findings are widely publicised (including to the public) and developed to maximise benefits.

Chronic pain affects up to 30% of people worldwide with significantly reduced quality of life and associated socioeconomic cost. Once established it is difficult to treat and therefore preventative strategies are urgently required. Being a woman is a risk factor for chronic pain and this sex difference emerges after puberty. Periods, which start during puberty, are themselves painful for many women. Alterations in a variety of pain-relevant body systems have been demonstrated in adults with dysmenorrhoea, including sensitivity to noxious stimuli, visceral sensitivity, brain structure and function and activity of both the hypothalamic-pituitary-adrenal axis and the autonomic nervous system. We hypothesise that the experience of dysmenorrhoea during adolescence is a risk factor for the development of chronic pain, with the potential to act through a variety of pathways. We will address this in two ways. Epidemiological analyses will use the ALSPAC data, a resource that has been collecting prospective data from children born in the early 1990s and their parents for almost 30 years, to determine whether adolescent dysmenorrhoea is an independent risk factor for chronic pain in young women. We will additionally explore whether factors present in childhood increase the risk of dysmenorrhoea early in menstrual life. Alongside this work, an experimental study using psychophysical and neuroimaging assessments will determine whether dysfunction in pain-relevant systems can be demonstrated in adolescent girls in the early years of menstruation. We anticipate results with clear and direct implications for adolescent menstrual health and for drug target discovery of relevance to chronic pain in women. We will use findings from this project to highlight the importance of dysmenorrhoea and optimise its timely management. Ultimately we hope that this work will reduce the risk of both adolescent girls and adult women suffering with dysmenorrhoea and other chronic pain conditions.