Submitted by acs95 on Wed, 05/03/2025 - 15:37
Name: Samantha N. Sallie
Research group: Interventional Neuropsychiatry Group
Supervisor: Professor Valerie Voon
Advisor: Professor Jeffrey Dalley
Title of your PhD: The Neurocognitive Dynamics Underlying Loss of Control in Alcohol Misuse and Addiction
Can you give us a short background into what your PhD was about?
My thesis delved into the neurocognitive processes that drive the “loss of control” observed in alcohol misuse and addiction, particularly examining the transition from impulsivity to compulsivity as the condition worsens and becomes increasingly resistant to treatment. The investigation focused on how these behavioural changes affect domains central to addiction, including incentive salience, negative emotionality, and executive functioning. Drawing from seminal research in rodents, the research scope broadened to consider the influence of both psychological factors, such as affective states, and external stressors, notably the societal repercussions of the COVID-19 pandemic, on alcohol consumption patterns.
To advance this inquiry, I adopted a threefold methodological framework: Firstly, I developed cognitive tasks to assess distinct subtypes of impulsivity and compulsivity, particularly in relation to addiction psychopathology, including cue and emotional reactivity. Secondly, I applied neuromodulation techniques, such as repetitive transcranial magnetic stimulation (rTMS), emphasising accelerated and paired pulse variants, to identify biomarkers relevant for treatment in both general and addicted populations. Lastly, I utilised epidemiological approaches, deploying large-scale surveys to examine alcohol use behaviours and their determinants at a population level.
How would you sum up your main findings?
This research highlighted the dynamic pathways through which impulsivity can confer risk to the development of compulsive alcohol use behaviours. It demonstrated a strong association between the co-occurrence of traits sensation-seeking (pursuit of novel and intense experiences) and waiting impulsivity (inability to delay gratification for anticipated rewards) with increased severity of alcohol use, marked by symptoms of physical dependence and adverse alcohol-related outcomes, in otherwise healthy individuals. Further examination of habitual control, considered a precursor to more entrenched and problematic drinking patterns, revealed distinct behavioural responses linked to these impulsivity subtypes in the context of alcohol use. While sensation-seeking was associated with outcome-insensitive behaviours toward threat, paired with a deficit in learning from negative outcomes, waiting impulsivity was implicated in the establishment of reward-driven habits which alcohol use intensified. The research also identified urgency (the tendency toward rash action in response to strong emotions) as a key contributor to escalated drinking severity during the initial phase of pandemic-induced isolation.
Additionally, the research emphasised the involvement of interconnected fronto-striatal networks implicated in impulsivity and compulsivity. We identified the left inferior frontal gyrus (L-IFG) as key in inhibiting impulsive action towards rewards, offering a potential therapeutic target for addiction disorders. Moreover, we detected compromised plasticity of the response inhibition network among individuals with a history of alcohol addiction. This finding illuminates potential mechanisms contributing to cognitive control deficits in this demographic, suggesting new directions for improving neuromodulation interventions.
Finally, the thesis underscored the multifaceted nature of alcohol misuse and addiction, framing them as biopsychosocial phenomena. It detailed how various lifestyle elements, including occupations in health care, parental responsibilities, and geographical variables such as living in the United Kingdom, played a role in shaping alcohol use behaviours during the pandemic period. These findings stress the need for intervention strategies that are responsive and tailored to addressing these varied determinants in the face of global challenges.
What made you want to do a PhD?
My decision to pursue a PhD stemmed from a deep interest in optimising mental health and unravelling the complexities of neuropsychiatric disorders, with a particular focus on addiction. Recognising the pressing need for novel approaches within this challenging field, I viewed a PhD, guided by expert mentorship, as an avenue to make significant societal contributions by conducting meaningful research and applying its findings to tackle addiction issues effectively.
What was your best day during your PhD?
A memorable day was when I resolved a longstanding issue with fine-tuning a cognitive task designed to assess habitual control among various patient groups, a challenge that had been obstructing the advancement of my project for some time.
What was your worst day during your PhD?
The day we learned that in-person testing was no longer feasible due to COVID-19 lockdowns marked a significant challenge in my PhD journey. It was a pivotal moment that necessitated a shift from traditional research methods to more novel remote alternatives. This experience underscored the importance of flexibility and adaptability in research.
Do you have any words of advice to future PhD students in Psychiatry?
Approach your PhD as an adventure, equipping yourself with curiosity, resilience, and humour. Every research obstacle presents an opportunity for growth, offering invaluable insights. Remember to appreciate the journey, embracing both unexpected discoveries and collaboration with peers, which together make the experience profoundly rewarding.
What do you hope to do next?
I plan to undertake postdoctoral research within the Interventional Neuropsychiatry Group, concentrating on the efficacy of neuromodulatory techniques—encompassing both invasive and non-invasive modalities—to enhance therapeutic efficacy in the management of addiction disorders.