alongside those of depression in the past two decades. And so have the rates of obesity, which is also correlated with increased inflammatory markers. Studies show that obesity is associated with a 55 percent increased risk of depression, and it cuts the other way too: depression is associated with a 58 percent increased risk of developing obesity.21 In the cogent words of a group of Australian researchers in a 2013 paper: “A range of factors appear to increase the risk for the development of depression and seem to be associated with systemic inflammation; these include psychosocial stressors, poor diet, physical inactivity, obesity, smoking, altered gut [function], [allergies], dental [cavities], sleep and vitamin D deficiency.”22
In 2014 Scottish researchers addressed the gap between what the science says about the causes of depression and what patients experience when they find themselves caught in the default web of psychiatric care. In their paper they highlight the value of what I practice: psychoneuroimmunology.23 Indeed, it’s a mouthful of a word, but it simply refers to examining (and respecting) the complex interplay between various systems and organs of the body, especially those that syncopate the nervous, gastrointestinal, and immune systems in a brilliant dance that in turn affects mental well-being. These researchers point out that many patients who are told they have psychiatric conditions originating in their head or related to some (fictitious) brain chemical deficiency actually share real biological imbalances related to their immune-inflammatory pathways. These patients show elevated levels of inflammatory markers in their blood, signs that their body is on the defensive, activating processes that can result in unexplainable physical symptoms and that are diagnosed as psychiatric rather than biologic. And rather than treating the underlying biology, they are instead relegated to a lifetime of therapy and medication, to no avail.
The conditions examined by these researchers were depression, chronic fatigue, and “somatization,” the latter of which is what we call the production of symptoms with no plausible organic cause. These diagnoses have a lot in common in terms of symptoms: fatigue, sensitivity to pain, inability to concentrate, flu-like malaise, and cognitive issues. Isn’t it interesting that each of these conditions is often diagnosed as a separate illness and yet they share so much in common from a biological standpoint? As the authors state: “If psychiatry is to rise to the challenge of being a science, then it must respond to the [existing] data in reconceptualizing boundaries. As such, the data reviewed here challenge the organizational power structures in psychiatry.”24
Personalized lifestyle medicine that accounts for the role of the environment in triggering inflammation and the manipulation of the immune and endocrine systems is the most sensible way to approach those individuals who would otherwise be candidates for multiple medications. It turns out that it may not all be in your head—but rather in the interconnectedness among the gut, immune, and endocrine systems.
In upcoming chapters, we’re going to be exploring all of these connections—the indelible links between your gut and its microbial inhabitants, your immune system, and the orchestra of hormones that course through your body in sync with a day-night cycle. These connections influence the state of your entire physiology and, as important, your mental health and overall sense of well-being. While it may seem odd to talk about the gut-based immune system in terms of mental health, the latest science reveals that it may be the body’s—and mind’s—center of gravity. Just as I write this, yet another new study has emerged that overturns decades of textbook teaching about the brain and immune system. Researchers at the University of Virginia School of Medicine have determined that the brain is directly connected to the immune system by lymphatic vessels we didn’t know existed.25 That we had no idea about these vessels given the fact that the lymphatic system has been so thoroughly studied and charted throughout the body is astonishing on its own. And such a discovery will have significant effects on the study and treatment of neurological diseases, from autism and multiple sclerosis to Alzheimer’s disease and, yes, depression. It’s time we rewrite the textbooks. And it’s time we treat depression for what it really is.
So if depression isn’t a disease, then what is it? As I briefly mentioned in the introduction, depression is a symptom, a vague surface sign at best that doesn’t tell you anything about its root cause. Consider, for a moment, that your toe hurts. Any number of things can cause a toe to hurt, from physically injuring it to a bunion, blister, or tumor growing inside. The hurting is a sign that something is wrong with the toe, simple as that. Likewise, depression is the hurting; it’s an adaptive response, intelligently communicated by the body, to something not being right within, often because things are also off in our environment.
Depression doesn’t always manifest with feelings of serious melancholy and sadness or the urge to sit on the couch all day brooding. I can’t even remember the last patient I saw who was like the person you see on a TV commercial for an antidepressant. All of my patients experience anxiety—an inner kinetic discomfort, restlessness, unease, and a lot of insomnia. In fact, most cases of depression involve women who are very much on the go and productive, but they are also anxious, scatterbrained, overly stressed out, irritable, forgetful, worrywarts, unable to concentrate, and feeling “wired and tired” at the same time. And many of them have been dismissed by the medical system; their psychiatric problems were created by mistreatment as they fell into the vortex of endless prescription medications.
Take, for another example, a forty-two-year-old patient of mine we’ll call Jane, who fell into this black hole after being treated for irritable bowel and acne with drugs, including the now discontinued Accutane (isotretinoin). Jane experienced a depressed mood, a common side effect of Accutane, and was then put on an antidepressant as she stopped the medication (isotretinoin is a retinoid, a strong medication used to treat severe acne; it causes birth defects in babies born from mothers who take it during pregnancy, so it’s carefully regulated and only available in its generic form under a special program). After the death of her parents, which triggered more symptoms of depression, Jane was diagnosed with a thyroid problem, and her doctor at the time prescribed radioablation therapy, which destroys thyroid tissue with radioactive iodine 131. This led to her having acute panic attacks, and she soon began taking Xanax. Symptoms of more thyroid problems, including brain fog, extreme fatigue, and physical pain, culminated in a diagnosis of fibromyalgia. Jane was then treated with birth control pills and an antibiotic and soon developed chronic yeast infections, bloating, and abdominal pain. By the time she came to me, Jane had a twenty-four-hour home health aide.
Jane’s experience reflects that of so many people labeled as depressed and sent away with yet another prescription. The system creates patients who are otherwise healthy and just need to recalibrate their bodies using simple lifestyle interventions, mostly around diet—not drugs. After all, it is through diet that we communicate with our environment. It’s a dialect that we’ve forgotten how to speak.
AN EVOLUTIONARY MISMATCH
Take a look around you and appreciate the world we live in today with its technologies and conveniences: computers, cars, cell phones, and supermarkets. But also consider the mismatch between this scenario and the days when we had to forage for our food and sleep under the stars. Our caveman days are still very much a part of our DNA because evolution is slow; what seems like ages in cultural time (20,000 years ago) is but a blink of an eye in biological time. Which brings me to ask the question: Is all this depression simply a sign of an evolutionary mismatch?
This is the term that encompasses the source of most modern ills. We are engaged in lifestyles that are not compatible with what our genome has evolved over millions of years to expect. We eat a poor diet, harbor too much stress, lack sufficient physical movement, deprive ourselves of natural sunlight, expose ourselves to environmental toxicants, and take too many pharmaceuticals. Our wayward departure is marked by two specific revolutions in the history of mankind: the Neolithic, or agricultural, Revolution and the Industrial Revolution. For 99 percent of our existence, we followed the so-called Paleolithic diet, which is devoid of inflammatory and “insulinotropic” foods like sugar, grains, and dairy. Our body’s microbial ecology has been one of the primary victims
