A prospective patient recently asked me if her depression might involve some form of chemical imbalance. Like most Americans, she had seen hundreds of drug ads trumpeting the idea, but they filled her with a deep sense of helplessness. "I really don't want to take antidepressants," she explained. "And yet if there's truly something wrong with my brain chemistry, I'd pretty much have to get on meds, wouldn't I?"
She had aptly framed the conventional wisdom: Got chemical imbalance? Then you need to ingest some chemicals.
But the conventional wisdom is misguided. Yes, depression entails striking neurochemical abnormalities, but this fact - in and of itself - tells us nothing about how best to treat the disorder. That's because there are numerous ways of altering depressive brain function, and most of them have nothing to do with psychotropic drugs.
Consider the effects of exercise. Even moderate physical activity - brisk walking three times a week - has been shown in two landmark studies to fight depression as effectively as sertraline. Simply put: exercise changes the brain. It enhances the function of dopamine-based circuits that mediate our experience of pleasure, along with our ability to initiate activity. Likewise, physical exercise stimulates the brain's synthesis of BDNF, a growth hormone that guides the repair of damaged neurons and triggers the sprouting of new neuronal connections. Because BDNF levels plummet in depression, the disorder actually leads, over time, to atrophy of the brain's memory and reasoning centers. But exercise carries the potential to help reverse depression's neurotoxic imprint.
Neurological function is also critically affected by diet. For example, a deficiency of omega-3 fatty acids - key building blocks of brain tissue - has been strongly linked to depressive illness, in part because omega-3 fats facilitate the brain's use of "feel good" neurochemicals such as serotonin and dopamine. Omega-3s also serve as raw material for the body's construction of anti-inflammatory hormones, which help calm the cerebral inflammation that often characterizes depression. Accordingly, high-dose omega-3 supplements, typically in the form of fish oil, have been shown in multiple trials to exert a potent antidepressant effect.
Bright light exposure represents yet another proven strategy for altering brain chemistry. Specialized light receptors in the retina connect to circuits deep in the brain that regulate circadian rhythm. And sunlight - over 100 times brighter than typical indoor lighting - is the prime stimulator of the eyes' photoreceptors: it triggers a cascade of neurochemical reactions that help keep the "body clock" in synch. On the other hand, prolonged sunlight deprivation leads to depressive disruptions in biological rhythms that govern sleep, appetite, energy, and mood. Fortunately, regular bright light exposure - either via sunlight or specially designed light boxes - can restore healthy circadian function to the brain. Over a dozen published studies support its efficacy in the treatment of depression.
Then again, one of the most effective ways of changing the brain is simply to change the mind. This fact often surprises people, but it really shouldn't, because modern neuroscience has convincingly demonstrated that mind and brain are flip sides of the same underlying reality. In the oft-quoted words of Marvin Minsky, "the mind is what the brain does." Thus, by definition, any alteration of thoughts or feelings is reflected in corresponding shifts in brain activity.
Yet we in the West are the intellectual heirs of Cartesian dualism - a belief that mind and body are radically distinct, unrelated entities - and this legacy often renders the insights of neuroscience difficult to accept. Thus, it can be downright jarring to hear the psyche touted as a direct path to the inner workings of our neurochemistry. That's why so many were shocked by recent news accounts of changes in brain function among patients in psychotherapy for depression: if you're a dualist, there's no conceivable mechanism through which mere talking could possibly affect the brain.
Of course, pervasive mind-body dualism also helps explain why Big Pharma's mantra of "chemical imbalance" remains such an effective marketing strategy for the sale of its products. Too bad it's a strategy predicated on scientific illiteracy.
Stephen Ilardi is an associate professor of psychology at the University of Kansas and author of The Depression Cure: The Six-Step Program to Beat Depression without Drugs.