The Problem With the Average Patient
For more than a century, medicine has advanced by studying groups. Thousands of people enter clinical trials, researchers calculate what happens on average, and the resulting evidence helps determine which treatments should become standards of care. This approach has saved countless lives and remains essential to modern medicine. Yet hidden inside every average is an uncomfortable truth: almost no patient is actually average. Two people can share the same diagnosis while carrying different genes, eating different diets, sleeping different amounts, taking different medications, living in different environments, and possessing entirely different metabolic histories. Give them the same treatment and one may improve dramatically, another only modestly, and a third may experience an adverse effect. The National Institutes of Health describes precision medicine as an attempt to move beyond this limitation by considering individual differences in genes, environment, and lifestyle when making decisions about prevention and treatment. (National Institutes of Health (NIH))
The significance of that idea reaches far beyond genetics. Personalized medicine represents a shift in the fundamental question healthcare asks. Traditional evidence asks, What generally works for people with this condition? Personalized medicine adds another question: What is most likely to work for this particular person? The first question gives medicine its scientific foundation. The second may determine how precisely that science can be applied. The future of healthcare will depend upon learning how to do both.
A Diagnosis Is a Beginning, Not a Complete Description
Consider cancer, one of the fields in which precision medicine has advanced most rapidly. There was a time when identifying where a tumor originated provided much of the information available for choosing treatment. Today, molecular testing can reveal genetic characteristics within certain tumors that help physicians determine whether particular targeted therapies are appropriate. The FDA notes that molecular testing is already routinely used for a variety of cancers, allowing treatments to be selected according to specific biological characteristics rather than diagnosis alone. (U.S. Food and Drug Administration)
Something similar is occurring with medications. Pharmacogenomics examines how genetic variation can influence a person’s response to drugs. For certain gene-drug combinations, genetic information can help clinicians assess differences in metabolism, dosing, effectiveness, or the risk of adverse effects. The FDA maintains a table of pharmacogenetic associations for which it believes sufficient scientific evidence exists to indicate that particular genetic variants may influence drug metabolism or therapeutic effects, while also cautioning that inclusion does not automatically mean genetic testing is necessary before every prescription. (U.S. Food and Drug Administration)
That nuance is important because personalized medicine should not become another excuse to perform every available test. More data are useful only when they improve a decision. The promise is not a future in which everyone receives hundreds of exotic biomarkers and an impossibly complicated health plan. The promise is that medicine becomes better at identifying which information matters for which person at which moment.
Your Genome Is Only the Opening Chapter
The early excitement around personalized medicine understandably centered on DNA. Once the Human Genome Project demonstrated that the human genetic code could be mapped, it became tempting to imagine that disease would eventually become a straightforward exercise in reading genetic instructions. Sequence someone’s genome, identify the vulnerabilities, and design the perfect treatment. Biology turned out to be considerably more complicated.
Genes influence susceptibility, but they operate inside an environment. What we eat, how we move, what we are exposed to, how we sleep, the medications we take, our socioeconomic circumstances, and countless other variables interact with biology across a lifetime. The National Human Genome Research Institute therefore defines precision medicine broadly, incorporating genomic, environmental, and lifestyle information rather than genetics alone. (Genome.gov) Even the environmental component is expanding through the study of the exposome, the accumulated collection of chemical, physical, biological, and social exposures encountered throughout life. The National Institute of Environmental Health Sciences has emphasized that individualized medicine will require understanding these exposures alongside the genome because health is shaped by both. (NIEHS)
This changes the metaphor. DNA is not a complete prediction of the future. It is one layer of biological information. The person carrying that DNA continues changing every day.
From the Genome to the Living Biology
The next frontier is to understand those changes as they occur. Genomics can tell us about inherited or acquired genetic variation, but other technologies can examine different levels of biological activity. Proteomics measures proteins, the molecules carrying out much of the body’s functional work. Metabolomics examines the small molecules produced through metabolism. Epigenomics studies chemical modifications influencing how genetic information is regulated. Microbiome analysis examines microbial communities and their biological interactions. Wearable devices can continuously measure aspects of sleep, heart rate, physical activity, and other physiological signals.
Individually, each creates another window into the body. Combined, they may eventually allow medicine to see something it has rarely been able to observe: the trajectory of health rather than a single snapshot. The NIH’s All of Us Research Program illustrates this direction by integrating electronic health records, genomic information, surveys, physical measurements, biospecimens, environmental information, and wearable data across a very large and diverse population. Its purpose is to uncover patterns that smaller or less diverse datasets may miss and ultimately enable more individualized approaches to prevention and treatment. (National Institutes of Health (NIH))
The distinction between a snapshot and a trajectory may prove enormously important. A fasting glucose measurement of 95 mg/dL tells us something about today. Knowing that the same person’s fasting glucose has moved from 79 to 84 to 89 to 95 over several years tells us something else. Neither number alone diagnoses diabetes, but the pattern may prompt questions about metabolic direction. Personalized medicine has the potential to become increasingly longitudinal, concerned not merely with whether a value is abnormal but with where an individual’s biology appears to be heading.
Medicine May Become More Preventive Because It Becomes More Precise
Healthcare today is often extraordinarily effective once disease becomes unmistakable. A blocked coronary artery can be opened. An infection can be treated with the appropriate antimicrobial. A damaged joint can be replaced. A tumor can be removed, irradiated, or treated systemically. These achievements should not be minimized. But the next great advance in medicine may come from becoming better at identifying risk before catastrophe requires intervention.
Precision medicine could help make prevention more specific. Instead of telling everyone that they possess some generalized risk of cardiovascular disease, clinicians can already integrate age, blood pressure, cholesterol, smoking status, diabetes, family history, and other information to estimate risk. Future models may incorporate increasingly sophisticated molecular, genetic, imaging, environmental, and longitudinal data. Rather than merely asking whether disease exists, healthcare may become better at estimating which biological trajectory a person is following and where intervention would have the greatest value.
This is not science fiction, but neither is it fully realized medicine. A 2024 Nature Medicine editorial described precision health as a natural evolution of increasingly data-driven healthcare while emphasizing the considerable challenges required to make its benefits broadly accessible. (Nature) Those challenges include cost, data quality, privacy, equitable representation, clinical validation, interoperability, and the enormous computational problem of transforming oceans of information into decisions that genuinely improve health.
More Data Can Still Produce Bad Medicine
There is an important danger hiding inside this technological optimism. The ability to measure something does not automatically make it clinically meaningful. A person can now generate enormous quantities of health information through consumer wearables, genetic tests, continuous glucose monitors, microbiome sequencing, biological-age tests, imaging, and specialty laboratory panels. Without careful interpretation, this abundance can produce false alarms, unnecessary interventions, anxiety, and the illusion of precision without the evidence to support it.
Personalized medicine therefore requires something technology cannot replace: judgment. A biomarker must be interpreted within the patient’s history. A genetic variant must be understood in terms of its actual clinical significance. A sophisticated laboratory result is useful only if it changes what should reasonably be done. Even multi-omics, despite its extraordinary research potential, is still developing, and relatively few multi-omic models currently outperform established clinical approaches sufficiently to justify routine use across medicine.
The future is therefore unlikely to be a machine producing a perfect protocol from a blood sample. It will be a partnership between increasingly sophisticated information and increasingly thoughtful interpretation. Technology can reveal patterns. Clinical reasoning must determine what those patterns mean.
The Return of the Individual
There is a fascinating irony in all of this. Medicine is becoming more technologically sophisticated in order to rediscover something physicians have always known: the patient in front of them is an individual.
The difference is that we are becoming better equipped to measure that individuality. Genetics can reveal variations invisible during a physical examination. Molecular profiling can distinguish diseases that once appeared identical. Wearables can capture physiology outside the clinic. Longitudinal laboratory data can reveal movement before a threshold is crossed. Environmental information can provide context for biology. Large datasets can uncover patterns no individual physician could recognize alone.
This is also where personalized medicine and a thoughtful functional medicine approach can intersect. Both begin with the recognition that a diagnosis does not tell the entire biological story. A systems-oriented assessment can examine how nutrition, metabolism, sleep, stress physiology, gastrointestinal function, hormones, medications, environmental exposures, genetics, physical activity, and medical history interact within one person. The objective should never be complexity for its own sake. It is to determine which variables are actually relevant and which interventions have the strongest rationale.
Healthcare After the One-Size-Fits-All Era
The future of medicine will not require abandoning population-based evidence. In fact, personalized medicine depends upon it. We need large, rigorous studies to know which treatments work, which tests are reliable, and which associations are meaningful. What will change is how that evidence is applied. Instead of assuming that the average response describes every patient, medicine will become increasingly capable of identifying subgroups and, eventually, individual characteristics that alter risk, diagnosis, prevention, or treatment.
The National Institutes of Health has already built one of the world’s largest precision-medicine research efforts around precisely this idea. The All of Us Research Program aims to include one million or more participants and combine many different forms of health information so researchers can understand why people experience disease and respond to treatment differently. (National Institutes of Health (NIH)) The scale of the project reveals something about where medicine is heading. To understand the individual more precisely, science first needs to understand human variation more deeply.
Perhaps this is the paradox that will define twenty-first-century healthcare. Medicine will collect information from millions of people so that it can become better at treating one.
The ultimate promise of personalized medicine is not that every patient will receive a different treatment. Sometimes the standard treatment will remain exactly the right one. The promise is that the treatment will be chosen because it makes sense for the individual rather than simply because it works for the statistical average. Prevention can become more targeted. Diagnosis can become more precise. Treatments can be selected more intelligently. And healthcare can begin moving from asking, What disease does this person have? toward the much richer question: What is happening within this particular person, why is it happening, and what does the evidence suggest we should do about it?
That is not merely personalized medicine.
It is medicine becoming more precise about the person it was always meant to serve.
If you are interested in understanding your health beyond isolated symptoms or individual laboratory values, a personalized functional medicine assessment can help bring your medical history, metabolism, nutrition, hormones, lifestyle, and other relevant factors into a more complete picture. Book your 15-minute complimentary discovery call today to explore how a more individualized approach may help you better understand your health and the factors shaping your long-term trajectory.
References
- National Institutes of Health: The Promise of Precision Medicine
- National Human Genome Research Institute: Precision Medicine
- U.S. Food and Drug Administration: Precision Medicine
- Nature Medicine: What Will It Take to Make Precision Health a Global Reality?
