PSYCH 021: Pharmacogenetics

PSYCH 021: Pharmacogenetics

Why does one patient respond well to a medication while another experiences no benefit - or significant side effects? Pharmacogenetics seeks to answer this question by examining how genetic variation influences drug metabolism, efficacy, and tolerability. In this episode, we explore how differences in genes encoding drug-metabolising enzymes, receptors, and transporters can alter how medications are processed and how they act within the brain. Variations in systems such as cytochrome P450 enzymes can determine whether a drug is broken down too quickly, too slowly, or unpredictably. We examine how these differences translate into clinical outcomes - affecting dosing, response rates, and risk of adverse effects. This introduces the possibility of more personalised prescribing, moving away from trial-and-error approaches. However, pharmacogenetics also comes with limitations. Genetic factors are only one part of the picture; environment, comorbidity, and psychological context also shape treatment response. The promise of precision must therefore be balanced with clinical judgement. This chapter reframes prescribing as an interpretive process - where biology informs decisions, but does not dictate them. It offers a glimpse of a more tailored future, while reminding us of the complexity inherent in treating the human mind. Key Takeaways * Pharmacogenetics studies how genetic variation affects drug response. * Genes influence drug metabolism, receptor sensitivity, and transport mechanisms. * Variations in enzymes (e.g. cytochrome P450) can alter drug levels and effects. * Genetic differences contribute to variability in efficacy and side effects. * Pharmacogenetics supports more personalised approaches to prescribing. * Clinical decisions must still integrate non-genetic factors. * Precision medicine enhances, but does not replace, clinical judgement. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]

PSYCH 020: Epigenetics in Psychiatry: The Promise for New Biomarkers and Treatments

If the genome provides the script, epigenetics determines how it is read. This chapter explores how environmental influences - from early life experiences to chronic stress - can modify gene expression without altering the underlying DNA sequence. In this episode, we examine mechanisms such as DNA methylation and histone modification, which regulate whether genes are activated or silenced. These processes act as molecular switches, shaping how genetic potential is realised across development and throughout life. Crucially, epigenetics provides a bridge between biology and experience. It offers a framework for understanding how adversity, trauma, and environment can become biologically embedded - influencing vulnerability to psychiatric disorders. We also explore the emerging potential of epigenetic markers as biomarkers for diagnosis and prognosis, as well as targets for novel treatments. However, this promise is accompanied by complexity - epigenetic changes are dynamic, context-dependent, and not easily reduced to simple clinical tools. This chapter reframes nature versus nurture as a false dichotomy. Instead, it presents a dynamic interaction where experience continuously shapes biology - and biology, in turn, shapes experience. Key Takeaways * Epigenetics involves changes in gene expression without altering DNA sequence. * Mechanisms include DNA methylation and histone modification. * Environmental factors can influence gene expression across the lifespan. * Epigenetics provides a biological link between experience and psychiatric vulnerability. * Adversity and stress can become biologically embedded through these mechanisms. * Epigenetic markers hold potential as biomarkers and treatment targets. * Gene–environment interaction is central to understanding psychiatric disorders. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]

PSYCH 019: Gene Mapping Investigations of Psychiatric Disorders

If multi-omics reveals layers of biological complexity, gene mapping attempts to locate patterns within that complexity. This chapter explores how researchers identify genetic contributions to psychiatric disorders - not through single genes, but through probabilistic associations across the genome. In this episode, we examine approaches such as linkage studies, candidate gene studies, and genome-wide association studies (GWAS). These methods do not identify deterministic causes, but patterns of increased risk distributed across many genetic loci. We explore the concept of polygenicity - the idea that psychiatric disorders arise from the cumulative effect of many small genetic variations rather than a single mutation. This reframes conditions such as schizophrenia, depression, and bipolar disorder as complex traits rather than discrete genetic diseases. We also examine the challenges: small effect sizes, overlapping genetic risk across disorders, and the difficulty of translating statistical associations into biological mechanisms or clinical practice. Gene mapping does not provide simple answers. Instead, it offers a map of probabilities - a way of understanding vulnerability as distributed, shared, and context-dependent. This chapter invites a shift from certainty to pattern recognition - where risk is not located in a single place, but emerges from the architecture of the genome as a whole. Key Takeaways * Gene mapping identifies associations between genetic variants and psychiatric disorders. * Methods include linkage studies, candidate gene approaches, and GWAS. * Psychiatric disorders are highly polygenic, involving many variants with small effects. * Genetic risk is probabilistic, not deterministic. * There is significant overlap in genetic risk across different psychiatric conditions. * Translating genetic findings into clinical practice remains challenging. * Understanding risk requires thinking in patterns rather than single causes. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]

PSYCH 018: Genome, Transcriptome, and Proteome: The Molecular Genetics, Biochemistry, and Multi-Omics Underlying the Neurobiology of Mental Disorders

If genes are the script, they are only the beginning of the story. This chapter expands the lens to multiple layers of biological information - genome, transcriptome, and proteome - revealing how psychiatric disorders emerge not from single mutations, but from complex systems of regulation and interaction. In this episode, we explore how the genome provides the foundational code, while the transcriptome reflects which genes are actively expressed, and the proteome represents the functional molecules that carry out biological processes. Together, these layers form a dynamic, multi-level system - often referred to as “multi-omics”. We examine how these systems interact across time and context, influenced by development, environment, and experience. The same genetic code can lead to different outcomes depending on how it is expressed and regulated. This framework moves psychiatry beyond simple genetic determinism. Mental disorders are not the result of isolated gene defects, but of complex networks involving gene expression, protein function, and environmental interaction. The chapter also introduces the potential of multi-omics approaches in advancing diagnosis, prediction, and personalised treatment - while highlighting the current limitations and complexity of translating these findings into clinical practice. Ultimately, this is a chapter about depth - revealing that beneath observable symptoms lies a layered biological system, intricate and still only partially understood. Key Takeaways * The genome provides genetic code, but expression occurs through transcriptome and proteome layers. * Multi-omics integrates these levels to understand biological function. * Gene expression is dynamic and influenced by environment and development. * Psychiatric disorders arise from complex interactions, not single gene defects. * Biological processes operate across multiple interconnected layers. * Multi-omics offers potential for personalised psychiatry but remains complex. * Understanding these systems shifts thinking from static genetics to dynamic regulation. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]

PSYCH 017: Basic Science of Appetite

Appetite is often mistaken for a simple biological drive, but it is in fact a finely regulated system integrating energy balance, reward, emotion, and cognition. This chapter explores how the brain determines when to eat, what to eat, and when to stop. In this episode, we examine the interplay between homeostatic systems - which monitor energy needs - and hedonic systems, which assign pleasure and reward to food. The hypothalamus plays a central role in maintaining balance, responding to hormonal signals such as leptin and ghrelin. At the same time, reward circuits involving dopamine shape motivation and craving. We explore how appetite is influenced by context, emotion, and environment. Eating is not simply about energy - it is embedded in social, psychological, and cultural frameworks. Dysregulation in these systems can lead to a range of psychiatric and behavioural conditions, from eating disorders to obesity and addiction-like patterns of consumption. These are not failures of willpower, but alterations in the systems that regulate need and reward. This chapter reframes appetite as a negotiation - between biological necessity and experiential desire - revealing how the brain balances survival with meaning. Key Takeaways * Appetite is regulated by both homeostatic and hedonic systems. * The hypothalamus monitors energy balance and responds to hormonal signals. * Hormones such as leptin and ghrelin influence hunger and satiety. * Reward systems, particularly dopamine pathways, shape food-related motivation. * Appetite is influenced by emotional, social, and environmental factors. * Dysregulation can contribute to eating disorders, obesity, and addictive behaviours. * Eating reflects both biological need and psychological meaning. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe [https://drmanaankarray.substack.com/subscribe?utm_medium=podcast&utm_campaign=CTA_2]