The new biology of depression
The old story is that depression is caused by a deficiency of neurotransmitters like serotonin. This ‘serotonin model’ led to widespread treatment using selective serotonin reuptake inhibitors (SSRIs) such as Zoloft and Prozac. If you’ve been diagnosed with depression, your doctor may have said that you’re “just born that way.” And you may worry that having a depressed family member means that you’ll get depression too.
However, gamechanging science is showing that our destinies are not written in our genes. Further, data revealing that SSRIs don’t work (and create dangerous side effects!), along with a mountain of research studies, have debunked the deterministic serotonin model of depression. Instead, we’re finding that depression is often a symptom of chronic inflammation.
We are all at risk for chronic, silent inflammation because we are living at a time of evolutionary mismatch. That is, our modern lifestyles create incompatibilities between what our genes expect of us and what our world demands. We eat foods that are processed beyond recognition, are sitting inside offices and cars most of the day, and are exposed to thousands of modern chemicals. Inflammation is the result of these types of conflicts.
Science is showing that chronic inflammation is at the root of nearly every disease (1). Inflammation is linked to everything from metabolic disorders, like obesity and diabetes, to neurodegenerative diseases and cancer (2-4). I’ve personally treated hundreds of patients diagnosed with depression whose bodies were on fire with chronic inflammation. My clinical success rates are so high because I recognize that depression is a symptom, not a disease, and I treat the cause: inflammation.
Inflammatory markers are associated with depression
Usually we recognize inflammation, a signal that something is wrong, by pain. For instance, babies quickly learn to avoid hot stoves because of the sharp pain associated. However, because the brain does not have pain receptors, it’s difficult for us to know when our brains are inflamed.
Researchers identify brain inflammation by quantifying levels of inflammatory proteins, such as C-reactive protein. New research is showing that markers of inflammation are elevated in depressed patients. In one study, researchers found that when depressive symptoms resolved, these signs of inflammation also decreased to normal levels (5). In another study, researchers measured C-reactive protein levels in over 1000 women for several years. They found that increases in C-reactive protein triggered the onset of depression (6). When inflammation was triggered, depression was triggered.
Furthermore, when inflammation is created in healthy people, they develop depressive symptoms (7). On the flip side, anti-inflammatory treatments effectively resolve depression (8). That’s right: treatments that lower inflammation, not reset serotonin, are the real “antidepressants.”
These studies, that show that body inflammation creates brain symptoms, support the exciting concept of psychoneuroimmunology. Psychoneuroimmunology, which reveals that all systems and organs are connected, is literally rewriting the book on psychiatric disorders like depression (9). This inclusive framework expands the one-gene, one-ill, one-pill perspective that has stymied effective treatments.
Psychoneuroimmunology helps us understand that no one is “just born with it” when it comes to disease. We have the power to heal ourselves.
The most powerful path to our brain is through our gut
The intestinal wall is our border with the outside world. Because the gut is where things from the outside (like food) are absorbed inside our bodies, the intestinal wall is designed to handle a many types of interactions with foreign matter. Considering the functions of our gut, it makes sense that most of our immune cells are located in the gut (10). Further, the gut is home to our microbiome, the trillions of beneficial microbes that live inside our gastrointestinal tract. When a potential threat is sensed in the gut, large, far-reaching inflammation occurs (11). This inflammation can travel directly from your gut to your brain (12), especially through the vagus nerve.
The vagus nerve is the longest nerve stemming from the brain. This nerve is connected to several parts of the gut, including the stomach and intestines. The vagus nerve also touches other organs important for digestion, like the pancreas.
The vagus nerve is a two-way information highway that connects 200-600 million nerve cells between our intestines and brain (13). Many of us have felt this gut-brain link. Have you ever been too stressed to eat or felt butterflies in your stomach? Interestingly, this perceived stress, anxiety, and nervousness isn’t just in your head; it can lead to inflammation in your gut and beyond (14, 15). While it’s best to manage stressors to reduce stress-related symptoms, like depression, I’ve found that one of the most direct and quick ways to calm the vagus nerve is through dietary change. Just as emotions send messages to your gut, food sends messages to your brain.
How does food create inflammation?
There are many drivers of gut inflammation that leads to depressive symptoms. Processed foods, which often are the bedrock of the Standard American Diet (SAD), are foreign to our bodies. When we eat highly processed foods, our gut cells set off the alarm of inflammation. Further, many people are unknowingly eating inflammatory foods like gluten and dairy that cause allergenic reactions too mild for most people to notice. Sugar, artificial sweeteners, and casein proteins (found in dairy) have been shown to activate inflammation.
The SAD can also cause nutrient deficiencies, as people are filling up on bagels and granola bars instead of nutrient-rich foods. Beyond food, many people pop pills without thinking about what they do to their bodies. Often, patients come to psychiatrists like me after they’ve been dosed with a cocktail of ‘harmless’ drugs like Tylenol, statins, antibiotics, acid blockers, and birth control pills.
Consuming processed, nutrient-poor foods and pharmaceuticals can radically change the gut microbiome. Alterations in the microbiome, called dysbiosis (or “wrong living”), can lead to intestinal permeability, or leaky gut. Leaky gut fans the flames of inflammation and depression.
Several studies have shown that a healthy microbiome is essential for a healthy brain (16). A gastroenterology research team revealed that certain types of microbial ecosystems are linked to anxiety and impaired brain function (17). In one study, researchers treated mice with a probiotic bacteria called Bifidobacterium longum. Dosing mice with probiotics reduced their anxiety-like behavior (18). Interestingly, they created a mouse model of anxiety by inducing inflammation, further evidence that inflammation causes depression.
How can you resolve inflammation and depression?
For many people, committing to stop eating the top gut bombs that drive inflammation is an effective start to resolving depression. For others, it is useful to help the gut microbiome by supplementing with probiotics.
Curcumin, the active ingredient of turmeric, has been extensively researched as a superior anti-inflammatory and antidepressant. Studies have shown that curcumin is better than Prozac for depression. In fact, I encourage all my patients to try this turmeric latte and rethink breakfast.
It can be overwhelming and difficult to change ingrained habits like eating. Because I cannot accommodate all the people that I’d like to in my private practice, I created the Vital Mind Reset program. This program serves as a guide and vibrant community to help people resolve all sorts of diagnoses like depression. The importance of a supportive community cannot be overstated, especially as research has shown that loneliness drives inflammation that triggers or compounds depression. I’ve been amazed and humbled by the remarkable stories of committed people who have successfully tapered off their medications through diet and stress reduction. Starting by mindfully choosing what you eat, you too can reclaim health and vitality.