Depression - Our Intricate Brains

Excerpted from
The Chemistry of Joy : A Three-Step Program for Overcoming Depression Through Western Science and Eastern Wisdom
By Henry Emmons, M.D.

Of course, the idea of the tank is only a metaphor. But our brains really do require baseline levels of certain biochemicals to function properly. And when these levels get too low, or when our brains contain the wrong proportions of these chemicals, we often experience depression, anxiety, and even the urge to suicide.

Let's take a closer look. The brain is a vastly complicated web of nerve cells, or neurons, all poised to transmit mental messages as the brain communicates with itself. Moreover, chemical messengers-hormones and neuropeptides - can send signals from the brain to the rest of the body, instructing us via the bloodstream to feel strong and energized, calm and relaxed, or sluggish and bloated.

At the same time, chemicals produced in the gut, the heart, and our other organs also travel through the bloodstream, sending messages to the brain. Thus, when we feel agitated, we may have trouble digesting our food. On the other hand, when we eat a rich, hard-to-digest dinner, we might find it difficult to think clearly. Our bodies and brains affect each other, all the time.

Our brains are so elegant and complex that our understanding of them is still in its infancy. But we do know that thoughts, feelings, and sensations all work together; that the brain, gut, and other organs are continually interacting; and that your understanding of the world and of your own situation has an enormous impact on your mood, energy, and physical condition. Thus, understanding brain chemistry is one way of grasping how diet, exercise, genetics, and mental outlook all work together to create or overcome depression.

Mood Messengers: Neurons and Neurotransmitters

How does the brain communicate with itself.7 The answer lies in the billions of neurons within our brains. Each of these neurons is capable of producing a little electromagnetic charge that travels from the heart of the neuron out to its edge until it reaches the fatty membrane that surrounds the cell. In order for your nerve cells to function properly, these membranes must be healthy, flexible, and adaptable, nourished with the right kinds of fats and proteins. (In Chapter 4, we'll find out more about what exactly you've got to eat in order to sustain these vital portions of your brain.) If your cell membrane is healthy, the electrical charge passes along it easily-but then it encounters a new obstacle.

Although our billions of neurons all work together, each is also a discrete entity, separated from its neighbors by a microscopic space called a synapse. The electricity that can travel freely within each cell stops short when it reaches the empty space between the cells. For the brain to transmit messages from one neuron to another, it needs chemical messengers, known as neurotransmitters, to jump the gap.

So the electrical impulse of the first neuron stimulates the cell to release a bit of neurotransmitter, which floats across the synapse to the next neuron. That second neuron receives the chemical message-which stimulates a new electrical charge. This second electrical impulse travels across the second cell, stimulating a second burst of neurotransmitter, which then crosses the third synapse, setting off the same process in the next cell. This whole chain of communication-electricity traveling across nerve cells; chemical messengers floating across synapses-happens literally as fast as thought itself, and it's not really such a linear journey. Whenever you think, feel, or experience a physical sensation, neurons are firing simultaneously all over your brain, generating a host of new thoughts, feelings, memories, and physical responses. You need healthy neurons and a good supply of neurotransmitters to keep this process working smoothly.

Brain Chemicals and Types Of Depression

So what happens when one or more neurotransmitters is lacking? Then your brain will have difficulty sending and receiving messages. Likewise, if your neurotransmitters are out of balance-too much of some, not enough of others-your brain won't be able to process thoughts, information, and sensations the way it should. Symptoms of depression and anxiety-sleeplessness, hopelessness, worry, misery, and confusion-may be the result.

Thus, low levels of such neurotransmitters as serotonin, dopamine, and norepinephrine are the biochemical basis of anxiety and depression, whether the levels of these chemicals are naturally low, as for Jennifer, or have fallen in response to a series of crises, as for Dave. That's why a psychiatrist's first task is often to determine which chemicals are out of balance.

Unfortunately, no routine tests exist that can measure levels of brain chemicals-at least, not yet. But we can infer these levels by the types of depression and the clusters of symptoms that people manifest. Depending on which chemicals are imbalanced, you may tend toward anxious depression, agitated depression, or sluggish depression, each of which is a relatively distinct syndrome with its own behaviors and personality characteristics.

Serotonin and Anxious Depression

Serotonin is sometimes nicknamed the "well-being" chemical. Appropriate levels of this vital neurotransmitter help create feelings of peace, security, confidence, happiness, and joy. Imbalances are implicated not only in depression, but also in insomnia, migraine, premenstrual syndrome, and addiction, which may He why these conditions are often found in the same families, or, often, in the same people.

Serotonin sometimes operates like our brain's "responsible adult," helping us to "just say no" to impulsive behaviors such as aggression, binge eating, indiscriminate sexual activity, excessive gambling, and substance abuse. Studies have shown that people with low levels of serotonin may be more vulnerable to addictions and compulsive behavior, including alcoholism, drug addiction, compulsive shopping, and compulsive gambling. Likewise, a diet rich in serotonin-producing foods has been shown to help compulsive eaters resist the temptation to binge.

Besides being a "responsible adult," I also think of serotonin as our own personal "good parent," since whenever we feel worry, stress, or physical pain, our bodies release comforting levels of serotonin to help us cope. Thus, people with low levels of serotonin may have difficulty soothing or calming themselves, so that once a troubling thought or difficult event occurs, they may not be able to interrupt the anxiety or depression that results. Jennifer, for example, may have been unable to find relief from the misery of being left behind by her friends in part because of low serotonin levels. Once the blow occurred, she literally didn't have the resources to recover from it.

As with virtually every other aspect of our brains and bodies, serotonin levels are partly genetic, partly the result of early childhood experiences, and partly the outcome of our current choices in diet, exercise, and lifestyle. Children who grow up in warm, nurturing families, like Dave, may develop larger reserves of serotonin than people like Jennifer, with her divorced parents, depressed mother, and alcoholic father. Whenever Dave's mother or father soothed, comforted, or protected him, Dave experienced a rush of serotonin in response to the happy event. Thus he literally trained his brain to produce serotonin easily and often, which conditioned him to maintain high baseline serotonin levels. These high levels stood him in good stead throughout most of his life, enabling him to bounce back from stressful experiences and to maintain a generally high level of optimism and well-being.