Reflections on my PhD and life afterwards

Niamh MacSweeney started her PhD in 2019 at Edinburgh University as a Mental Health UK Scholar. Her research title was: The adolescent brain and depression: A neuroimaging approach to understanding biological and psychosocial risk factors. She completed her PhD this year and has obtained a prestigious postdoctoral fellowship at the University of Oslo. In this blog she shares her experience of her PhD and her plans to build on that work as a postdoctoral researcher. Congratulations to Niamh.

If someone had told me at the start of my PhD in January 2019, that over four years later I would have navigated a global pandemic (see my previous blog post on this here), passed my PhD viva, and would be working as a postdoctoral researcher in Oslo with my dream research group, I wouldn’t have believed them! But here I am, writing this blogpost from my office with views of the Oslo fjord and thinking, that hard work can pay off and life does provide!

Of course, the final few months of my PhD were dominated by long library days as I wrote my thesis, an effort that was fuelled by the company of friends who were also in the final stretch of their PhDs, and lots of coffee! I submitted my PhD thesis in December 2022 and enjoyed a restful Christmas break to recharge my rather depleted batteries.

My PhD thesis, entitled: “The adolescent brain and depression: A neuroimaging approach to understanding biological and psychosocial risk factors” examined how structural and functional features of the adolescent brain relate to depression risk, and how this is associated with puberty and irritability. The first two studies of my PhD used brain imaging (MRI) data from volunteers in a large population study of adolescents, The Adolescent Brain Cognitive Development (ABCD) Study, which is based in the United States. My first study examined how brain structure is associated with depression in early adolescence. I found that differences in brain structure, especially in brain regions involved in emotion regulation and decision making, were associated with higher levels of depressive symptoms in youth aged 9-11 years. Overall, the differences in brain structure that were related to adolescent depression were like those observed in adults with depression. However, there were also some differences in brain structure specific to adolescent depression. This suggests that brain structural alterations may be present early in the disease course of depression and that some of these differences may be specific to adolescent-onset depression. This study was published in eClinicalMedicine in December 2021.

My second PhD project tested whether earlier pubertal timing is associated with an increased risk for depression in adolescence, and how brain structure might affect this relationship. Pubertal timing refers to an individual’s pubertal development relative to their same-age, same-sex peers. Previous research has found that earlier pubertal timing is associated with an increased risk for depression in both males and females but the role of brain structure in this association remained unclear. I replicated previous research using a large, demographically diverse sample and found that individuals, aged 10-11 years, who began puberty before their peers were more likely to report higher levels of depression two years later, when they were aged 12-13 years. I also explored whether specific aspects of brain structure played a role in this association, but I did not find that this was the case. This highlights the need to explore the role that other biological (e.g., genetics, brain function), psychological (e.g., self-esteem), and social factors (e.g., peer and family relations) may play in the association between earlier pubertal timing and increased depression risk in adolescence. This study was published as a Registered Report, an Open Science publishing format, in Developmental Cognitive Neuroscience in April 2023.

In my final PhD project, I used data that I collected myself after the Covid-19 restrictions had been eased. The aim of this study was to explore how brain function is associated with irritability in adolescence, and how this relates to depressive symptoms. Irritability is a core symptom of adolescent depression and an early indicator of emotion regulation difficulties. However, existing research on irritability typically overlooks the social nature of adolescence. Therefore, I worked with young people to design an irritability task that aimed to reflect the experience of irritability as a young person today. Our reflections on the value of co-producing research with young people and the development of this new irritability task were recently published as a review paper in Frontiers in Behavioural Neuroscience, which included two youth researchers as co-authors. In this study, I first investigated whether patterns of brain activity differed between the irritability task and a scan when the brain is at rest (i.e., the participant looks at a cross on a screen for the duration of the scan). I found that the patterns of brain activity differed between the two conditions, and a brain network involved in decision making and goal-oriented behaviour was more likely to be occupied during the irritability task. This suggests that our novel task may induce a state of mind related to emotion regulation. I also found that certain patterns of brain activity were associated with depressive symptoms, which may provide insight into how differences in brain activity contribute to the emergence of depression in adolescence. I am currently preparing this fourth paper of my PhD for publication.

I am very thankful to Mental Health Research UK, their trustees and supporters, for funding my PhD research. This work has advanced our understanding of the features of brain structure and function that are associated with depression in adolescence, and how other aspects of social behaviour, such as irritability, relate to mental health difficulties. I enjoyed an exciting and engaging discussion of my work at my PhD viva in January 2023, and was delighted to pass bringing this formative chapter of my life to a close. I recently returned to Edinburgh for my official PhD graduation ceremony on July 7th 2023, which was a lovely opportunity to reflect on the lessons I have learned during my PhD and the many friends I made on this journey!

In May 2023, I started a postdoctoral research fellowship with Prof. Christian Tamnes at Diakonhjemmet Hospital and the PROMENTA Research Centre at the University of Oslo, which is funded by Helse Sør-Øst. My postdoc research will extend my PhD work by using newly available data that has been collected over multiple years to explore the factors contributing to individual differences in adolescent brain maturation and pubertal development, and how they relate to mental health risk over time. The overall aim of my research is to identify factors that predict both positive and negative developmental trajectories so that we can create an environment that gives young people every opportunity to flourish in their development.

Niamh MacSweeney

Niamh upon passing her PhD viva

on January 18th, 2023.

Niamh at her PhD graduation ceremony, University of Edinburgh, July 7th, 2023