We would like to congratulate Maggie Westwater on completing her PhD! Maggie completed her PhD thesis titled “Neurobiological and metabolic mechanisms of binge-eating in anorexia and bulimia nervosa” under the supervision of Prof Paul Fletcher and Dr. Hisham Ziauddeen. Here, Maggie gives us a quick summary of her work and findings.
Can you give us a short background into what your PhD/MPhil was about?
My PhD was focused on understanding the physiological and neurocognitive correlates of a transdiagnostic eating disorder symptom, binge-eating. ‘Binge-eating’ is characterised by the consumption of an objectively large amount of food within a relatively short period of time, and whilst it is commonly associated with obesity, individuals who fall along the full weight spectrum suffer from this syndrome. However, at the start of my PhD, there was limited knowledge on whether the mechanisms underlying binge-eating are conserved across disorders and weight classes.
To address this gap in the literature, I carried out an experimental medicine study that examined perturbations across multiple ‘levels’ (metabolic, neurobiological, cognitive and behavioural) in women who suffered with the binge-eating/purging diagnostic subtype of anorexia nervosa, bulimia nervosa and those with no personal history of mental illness under neutral and stressful conditions. My work was guided by the understanding that (ab)normal eating reflects dynamic interactions between the gut, the brain and one’s environment, which must be considered together when attempting to characterise the aetiology of disordered eating.
· How would you sum up your main findings?
My findings revealed unique metabolic and neurocognitive correlates across two psychiatric conditions with strikingly similar symptom profiles. One key finding indicated that patients with anorexia nervosa and bulimia nervosa have unique hormonal responses to acute psychological stress, and this work was recently published in Psychological Medicine. Specifically, stress increased levels of both ‘hunger’ and ‘satiety’ gut hormones in patients with anorexia nervosa, yet this was not observed in bulimia nervosa. We think that the hormonal responses to stress in anorexia nervosa may, in part, contribute to difficulties in sensing hunger that may leave patients vulnerable to engaging in disorder eating behaviour following a stressful event.
Another key finding emerged from the neuroimaging arm of the study, where I tested a popular theory, which suggests that stress can cause loss-of-control eating by reducing our capacity for impulse control. My results showed that stress uniquely altered functional activity of the prefrontal cortex in patients with anorexia and bulimia nervosa as they performed an inhibitory control task; however, patients did not show any stress-induced performance deficits. As such, we did not find evidence to support stress-induced impairments in impulse control as a comprehensive explanation for binge-eating in these illnesses.
Taken together, my findings highlight the need for integrative models of mental illness that consider how dysfunction across multiple, interacting levels can lead to, or maintain, the disorder. These models will be particularly important for our understanding of the common and unique aetiology of disorders that share cardinal symptoms.
What made you want to do a PhD?
I became interested in medicine at a young age, and as an undergraduate, I became particularly curious about the neural underpinnings of cognition and behaviour. This led me to pursue volunteer research opportunities related to functional neuroimaging, and I happened to volunteer on an fMRI study of bulimia nervosa. I quickly became involved in the clinical screening aspects of the study, and it was through speaking with women who suffered with eating disorders that I learned how devastating these illnesses can be to the sufferer. Eating disorders are notoriously difficult illnesses to treat, and by pursuing a PhD in the neuroscience of eating disorders, I felt I could advance our understanding of how these illnesses come about, which would, in turn, pave the way for novel clinical interventions.
What was your best day during your PhD?
The best day was probably the day that I finished data collection for my study after an intense fourteen months! It was a very challenging protocol to run, and after my last testing session, I felt truly proud of what I was able to accomplish with the help of all of the women who graciously took part, our tireless nursing staff and the fantastic WBIC radiographers.
What was your worst day during your PhD?
I’m not sure if there was a ‘worst day’ – PhDs have their peaks and valleys throughout! However, I was rather stressed for a few days when organising my plasma hormone samples prior to delivering them to the Core Biochemical Analysis Laboratory at Addenbrooke’s. Sorting over one thousand aliquots whilst ensuring that neither they nor the freezer became too warm was a challenge to say the least. My advice for future students: Check how your samples are to be organised before starting your study.
Do you have any words of advice to future PhD/MPhil students in Psychiatry?
My advice to future students would be to take advantage of the incredible resources at Cambridge, whether that is attending talks, workshops or courses, or forming collaborations with students and researchers from across the university. I was fortunate to work closely with clinicians and scientists from the Institute of Metabolic Science and the Department of Engineering, and this made a real difference in how I conceptualised my own research questions. In addition, I think all students should try to attend the Conversations with Experts by Experience sessions that are led by Dr Hisham Ziauddeen; they are a fantastic way to learn more about the lived experience of various mental health conditions.
What do you hope to do next?
My hope is to continue studying the multi-faceted drivers of disordered eating as a postdoctoral researcher, so I may ultimately lead my own program of research in this area as a Principal Investigator.
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