Dr. Cohen’s laboratory has pioneered the application of induced pluripotent stem cell (iPSC) technology to generate patient-specific brain cells in vitro, allowing detailed exploration of molecular and metabolic anomalies otherwise inaccessible in living individuals. “We now have tools giving us leads we lacked forty years ago,” he explains, highlighting how these experimental models reveal consistent abnormalities in mitochondrial energy metabolism that impair neuronal signaling and resilience. These findings suggest that impaired cellular bioenergetics are not secondary effects but fundamental contributors to neuropsychiatric illness pathophysiology. By identifying precise metabolic targets, Dr. Cohen’s approach paves the way for developing innovative therapeutics aimed at restoring cellular energy balance, potentially altering the disease course rather than merely alleviating symptoms.

The implications of these discoveries are profound, marking a paradigm shift in psychiatric science. Traditionally, research emphasis has rested on the neurotransmitter imbalances presumed to cause mental disorders; however, Dr. Cohen’s metabolic perspective reframes psychiatric conditions as systemic disorders rooted in cellular dysfunction. His lab has demonstrated that neurons derived from patients with schizophrenia, bipolar disorder, and Alzheimer’s disease exhibit intrinsic metabolic deficits detectable before clinical symptom onset, underscoring opportunities for early intervention. This places bioenergetic dysfunction at the forefront of potential preventive therapies, a notion that could revolutionize clinical practices worldwide by enabling interventions before irreversible brain damage and functional decline.

Equally transformative is Dr. Cohen’s critique of conventional diagnostic frameworks in psychiatry, which rely heavily on categorical labels like “schizophrenia” and “bipolar disorder.” He advocates for a dimensional approach that replaces rigid categories with symptom-based spectra reflecting biological and clinical heterogeneity. This approach not only reduces stigma but aligns psychiatric nosology with emerging biological data, enhancing diagnostic precision and personalizing treatment strategies. The dimensional model accounts for variability in symptom expression across individuals and cultures, offering a universal language better suited for global application. Such a system would facilitate the formation of more homogeneous research cohorts, accelerating discovery while improving clinical outcomes through targeted therapies attuned to distinct symptom profiles.

Dr. Cohen’s multidisciplinary methodology exemplifies cutting-edge science by integrating genomics, neuroimaging, and cellular models, producing a richly detailed picture of neuropsychiatric disorder mechanisms. Genomic analyses identify risk variants; brain imaging delineates structural and functional abnormalities; and iPSC-derived neuronal cultures enable experimental manipulation and therapeutic screening. This synergy lends unparalleled power to uncover disease-relevant pathways and potential pharmacological targets, setting a new standard for international psychiatric research. As Dr. Cohen explains, “Understanding the biological complexity requires tools from multiple disciplines, combining molecular data with clinical observations to unravel these enigmatic disorders.”

Beyond the laboratory, Dr. Cohen’s tenure as President and Psychiatrist-in-Chief at McLean Hospital illustrates the real-world impact of his vision. From 1997 to 2005, he led significant institutional reforms that reversed financial decline and fostered a culture of innovation and compassionate care. His leadership emphasized empowering frontline clinicians and minimizing bureaucracy, strategies that resulted in expanded clinical programs, increased research funding, and enhanced educational opportunities. Under his stewardship, McLean pioneered community-focused initiatives including Waverley Place, a peer-run support center designed to integrate mental health care with societal reintegration, demonstrating how psychiatric institutions can balance mission-driven service provision with financial sustainability.

Dr. Cohen’s personal journey deeply informs his scientific philosophy. His early fascination with physics and mathematics instilled a rigorous analytic mindset that propelled his psychiatric research. The turning point came during medical training when witnessing a young patient’s remarkable recovery on psychotropic medication solidified his commitment to psychiatry’s transformative potential. Despite personal challenges, including social anxieties, he underscores perseverance and intellectual curiosity as drivers of scientific success. His enduring family support, notably from his prominent internist father and long-standing marriage, provides a grounding that sustains his demanding career. This human dimension enriches the narrative, illustrating how personal and professional experiences intertwine to propel scientific advancement.

Looking ahead, Dr. Cohen expresses guarded optimism about the trajectory of psychiatric research. He highlights the emergence of targetable mechanisms shaping illness risk and underscores the feasibility of preventive interventions, especially as psychotic disorders and dementias typically emerge after adolescence and late adulthood respectively. Advances in cellular reprogramming and high-throughput genomic technologies democratize access to cutting-edge tools, enabling a global scientific community to accelerate discovery. Dr. Cohen calls for broader support of unconventional ideas and early-career investigators, cautioning against funding biases favoring incremental “next step” research within established paradigms. His inclusive vision aligns with open-access models championed by organizations like Genomic Press, ensuring that breakthroughs transcend institutional and geographical barriers.

This richly detailed interview embodies the essence of innovation in psychiatric research — merging molecular biology, clinical insight, and compassionate leadership to unravel one of medicine’s most challenging frontiers. Dr. Bruce M. Cohen’s multidisciplinary approach not only elucidates complex determinants of psychiatric disorders but offers a blueprint for global scientific collaboration and clinical transformation. His insights invite a reimagination of psychiatry’s future — one that embraces biological complexity, fosters diagnostic precision, and prioritizes prevention, ultimately aiming to alleviate the profound human burden of mental illness worldwide.

Subject of Research: People

Article Title: Bruce M. Cohen: An eclectic life and a multidisciplinary approach to the complex determinants and diverse presentations of psychiatric disorders

News Publication Date: 14 October 2025

Web References: http://dx.doi.org/10.61373/gp025k.0104

Image Credits: Bruce M. Cohen

Keywords: neuropsychiatric disorders, mitochondrial dysfunction, induced pluripotent stem cells, energy metabolism, psychiatric diagnostics, dimensional model, genomics, brain imaging, schizophrenia, bipolar disorder, Alzheimer’s disease, psychiatric research innovation

At the heart of this revelation lies the retinoic acid receptor-related orphan receptor beta (RORβ), a gene implicated in bipolar disorder susceptibility. Using cutting-edge induced pluripotent stem cell (iPSC) technology, scientists derived pancreatic islets from patients diagnosed with bipolar disorder. These specialized clusters of cells exhibited marked deficits in insulin secretion, a critical hormone for regulating blood glucose levels. Intriguingly, this dysfunction was directly linked to an aberrant overexpression of RORβ, underscoring the gene’s pivotal role not only in neural function but also in peripheral metabolic systems.

Delving deeper, the research team employed genetically engineered mouse models, manipulating RORβ expression specifically within pancreatic β cells. The results were nothing short of astonishing: mice with enhanced pancreatic RORβ expression displayed clear-cut alterations in behavior corresponding to the light and dark phases of their circadian cycle. During the light phase—when rodents typically rest—these mice exhibited depression-like behaviors characterized by reduced activity and diminished responsiveness. Conversely, as night fell and the dark phase commenced, these same animals switched to mania-like behaviors, manifesting hyperactivity and heightened exploratory actions.

This biphasic behavioral shift draws compelling parallels to the oscillating mood states seen in human bipolar disorder, providing a tangible biological substrate for such cyclic changes. Yet, the mechanisms mediating this phenomenon remained to be fully elucidated. To that end, the team explored the impact of pancreatic RORβ augmentation on insulin dynamics and hippocampal function across the circadian cycle. They discovered that overexpression of RORβ in the pancreas during the light phase suppressed insulin release from the islets. This reduction in circulating insulin triggered overactivity in the hippocampus, a brain region integral to mood regulation and cognitive processes. The hyperexcitable hippocampus, in turn, was associated with depression-like behavioral manifestations.

Perhaps most fascinating was the reciprocal portion of this feedback loop: the hippocampal hyperactivity driven by low insulin in the light phase set in motion a delayed response, enhancing insulin secretion from the pancreatic islets during the dark phase. This surge in insulin then dampened hippocampal neuronal activity, culminating in mania-like behaviors. This dynamic interplay between the pancreas and hippocampus highlights the elegance of a bidirectional communication pathway that synchronizes metabolic and circadian factors to shape mood states.

This pancreas-hippocampus feedback mechanism challenges conventional views that separate peripheral metabolic regulation from central nervous system function in neuropsychiatric conditions. Instead, it posits an integrated systemic network wherein circadian rhythms modulate both insulin secretion and neuronal excitability, ultimately influencing complex behaviors. Such insights pave the way for novel therapeutic targets aimed at disrupting maladaptive cycles in bipolar disorder by modulating peripheral metabolic signals.

The implications of these findings extend far beyond bipolar disorder. They suggest a generalizable framework wherein metabolic derangements could contribute causally to neuropsychiatric symptomatology via circadian-regulated hormonal and neuronal feedback loops. For clinicians, this underscores the importance of considering metabolic health and circadian rhythm therapies as adjunct strategies in managing mood disorders.

A notable aspect of this research is the utilization of human iPSC-derived pancreatic islets, which allowed for precise modeling of disease-relevant cellular phenotypes. By recapitulating patient-specific molecular alterations in vitro, the study bridges the translational gap between genetics and physiology, affording unprecedented insights into cell-type-specific pathophysiology.

Moreover, the circadian-dependent behavioral phenotypes uncovered in mice offer a biologically plausible explanation for the temporal mood fluctuations that define bipolar disorder. Unlike static models of mood regulation, this research highlights how dynamic metabolic processes intersect with neural circuitry in a time-dependent manner, providing mechanistic clarity to previously observed clinical rhythms.

The study also prompts intriguing questions about how environmental factors such as light exposure, feeding patterns, and sleep hygiene might influence the pancreas-hippocampus axis and, by extension, mood stability. It raises the prospect that lifestyle interventions targeting circadian alignment and metabolic control could have rapid and profound impacts on psychiatric outcomes.

From a molecular standpoint, RORβ emerges as a critical nexus linking peripheral and central pathology in bipolar disorder. Its dual role in regulating insulin secretion and modulating neural circuits opens new avenues for drug development. Pharmacological modulation of RORβ activity may offer a means to simultaneously recalibrate metabolic and mood disturbances, representing a paradigm shift in treatment approaches.

This research also underscores the value of interdisciplinary approaches that integrate neuroscience, endocrinology, and circadian biology. Such cross-cutting methodologies are essential for unraveling the complex etiologies of neuropsychiatric diseases, which do not recognize traditional boundaries between organ systems.

In sum, the elucidation of a pancreas-hippocampus feedback circuit governing circadian mood fluctuations represents a landmark advance in neuroscience and psychiatric research. It not only deepens our understanding of bipolar disorder but also sets the stage for innovative therapies that target systemic physiological rhythms to restore mental health. This work exemplifies the power of modern biomedical techniques to illuminate hidden biological connections with profound clinical implications.

As research continues to unravel these intricate links, the hope is that patients suffering from mood disorders may one day benefit from personalized treatments that harness the body’s own circadian and metabolic machinery to achieve sustained remission. The convergence of genetic, cellular, and behavioral data in this study offers a blueprint for such transformative breakthroughs.

Ultimately, this discovery serves as a potent reminder of the deep integration between mind and body, challenging us to rethink mental illness within a holistic physiological context. By advancing our grasp of how metabolic and neural systems interface through circadian rhythms, scientists are opening new frontiers in psychology, psychiatry, and medicine.

Subject of Research: Bipolar disorder, circadian rhythms, pancreas-hippocampus feedback mechanism, insulin secretion, neuropsychiatric and metabolic interactions

Article Title: A pancreas–hippocampus feedback mechanism regulates circadian changes in depression-related behaviors

Article References:
Liu, YN., Wang, QW., She, XY. et al. A pancreas–hippocampus feedback mechanism regulates circadian changes in depression-related behaviors. Nat Neurosci (2025). https://doi.org/10.1038/s41593-025-02040-y

Image Credits: AI Generated