Changing the gut microbiota through fecal microbiota transplantation (FMT) is an innovative approach for treating mental health issues.
Several years ago, a decision was announced by a controversial surgeon to perform the first human head transplant, igniting intense media attention. This groundbreaking procedure brought forward numerous philosophical and ethical questions. Among these, perhaps the most profound centered on the concept of ownership over the new hybrid being: Would the identity belong to the donor of the head or to the body? In essence, this debate touches on whether the essence of self and identity is rooted in the brain or extends to other parts of the body.
Who we are?
The origins of the sense of self have long puzzled philosophers and scholars. Historically, many believed the self resided within an immaterial entity known as the soul, thought to be immortal and enduring beyond the body’s death. In various cultures, the idea persists that souls may transfer from one body to another after death. Followers of major religions often hold that the soul ascends to an eternal afterlife.
Even today, the notion of a mobile self capable of transferring between bodies and realms has retained a place in contemporary thought. Yet, modern perspectives have adapted this concept, envisioning mind-uploading into supercomputers to replicate an individual in cyberspace or transferring consciousness through technology, as often portrayed in movies and media. Emerging research reveals that mind and body form a deeply integrated whole, shaped by social environments to develop each individual’s personality.
What is the brain – gut axis?
Foreign guests within the body quietly influence emotions and behaviors in ways previously unimaginable. Through the rise of media and the internet, awareness has grown about the impact of the body’s resident microbes, collectively known as the microbiome, on brain functions and cognitive health. Beyond influencing physiological processes like inflammation and immunity, the microbiome exerts a significant effect on the mind. Research has increasingly shown that these microbes play a role in psychological conditions, such as depression and anxiety. Studies involving the transfer of gut microbiota between animals and humans have revealed that stress-related behaviors and psychological distress can, in fact, be passed to new hosts.
Intriguingly, research indicates that the microbiome might also shape desires, decisions, and beliefs. Although the brain plays a central role in these functions, it does not act alone. Factors such as gut microbes communicate with the brain through the gut-brain axis, though the precise extent of their influence remains an open question.
Each person’s microbiome is unique, shaped by factors like nutrition, social connections, mental well-being, and medications such as antibiotics. The cumulative mental impact of this microbial diversity is complex, depending on a host of known and unknown factors. As Robert M. Sapolsky argues in Determined: A Science of Life Without Free Will, individual decisions and behaviors are shaped by a web of influences—prenatal factors, early life experiences, socioeconomic conditions—often beyond what is traditionally considered free will. This view may indeed find support in the nuanced ways microbes contribute to the health and function of the mind.
Changing personality
Transplantation may, in certain cases, transfer cognitive or personality traits from donors to recipients. Limited evidence suggests that nearly half of heart transplant recipients report shifts in cognition post-surgery, with similar accounts from kidney and liver transplant recipients. Although these observations are largely self-reported and lack robust scientific validation, they raise intriguing questions about how transplants may impact identity.
While the precise influence of the microbiome on cognitive functions and personality remains uncertain, recent discoveries underscore its critical role in shaping personality and identity. When former NASA scientist Josiah Zayner conducted an unapproved fecal microbiota transplant (FMT) on himself to address gut issues, unexpected changes were noted beyond gastrointestinal health. After the FMT, he reported new cognitive inclinations, such as a newfound desire for sugary foods—a preference of the fecal donor.
Psychological changes associated with FMT have been observed in both animals and humans, indicating potential for its therapeutic application in psychiatric conditions like depression, anxiety disorders, schizophrenia, substance use disorders, and childhood disorders. Notably, recent research reveals that individuals with schizophrenia exhibit microbiome differences, particularly in microbes responsible for metabolizing tryptophan, compared to non-affected individuals. Similar studies highlight differences in microbiota involved in synthesizing neurotransmitters such as glutamate, butyrate, serotonin, and gamma-aminobutyric acid (GABA) among individuals with and without depression.
Beyond its philosophical implications in understanding self and identity, FMT presents an opportunity to address psychological disorders through microbiome modulation. Nonetheless, the potential for infectious disease transmission through fecal matter requires further research to establish safer, optimized methods, possibly as an adjunct intervention for managing psychiatric conditions.
https://doi.org/10.1186/s12888-020-02654-5
https://doi.org/10.3390/transplantology5010002
