Women are diagnosed with depression twice as often as men are. Women have been taught from an early age to express their feelings, whereas men are taught to deal with their feelings internally. Possibly depression is just as prevalent in both sexes, but women are the ones seeking help. Underweight women have twice the incidence of depression compared to overweight women; the reason for this is unknown. Depression could also be hormonally related. Depression is commonly seen in early teenagers and perimenopausal women, when their hormones are fluctuating drastically. Depression is also common in menopause, during the second half of the menstrual cycle (luteal phase), and postpartum, when there are drastic hormone changes. There also could be some anatomical differences between men and women. Research has shown that women store both emotion and memory in the same parts of their brain, whereas men store them in separate areas.

It is unclear what exactly causes depression, but research shows that it is most likely related to our inherited genes plus a triggering environmental effect. It is felt that heredity may account for as much as 80% of the risk for depression. Researchers have isolated a gene that is responsible for regulating serotonin function. People with the short arm of the gene are twice as likely to develop depression after a triggering environmental effect. Symptoms of depression are prolonged sadness, inability to feel pleasure, sleeping too much or too little, difficulty eating and suicidal thoughts. Approximately twenty million Americans are affected, with 30,000 committing suicide each year.

Brain cells communicate with one another via neurotransmitters. A deficiency of the neurotransmitters, serotonin, dopamine, norepinephrine, and glutamate is involved in depression. Signs of serotonin deficiency are depression, over eating, and being overwhelmed. An excess of dopamine causes excitement, whereas low dopamine causes fatigue. Newer evidence is pointing towards unhealthy nerves in the part of our brains that control emotion, not the lack of neurotransmitters, is what is causing us to be depressed. The stress hormone, cortisol, is elevated in people with depression. Overexposure to cortisol has been shown to inhibit the growth of nerve cells in the brain. Part of the reason why antidepressants work is that they stimulate the growth of new nerve cells. Drugs in the future will probably focus on repairing damaged nerves in the part of the brain that controls emotion. Drugs that diminish the stress response are currently being studied. From what we learned about cortisol in the last chapter, it is apparent that depression can have serious effects on our health. Depression is a serious risk factor for heart disease.

The treatment of depression is centered upon making the neurotransmitters, especially serotonin, available for use. Neurotransmitters are mostly made from amino acids, the building blocks of proteins. Tryptophan, an amino acid, is a direct precursor of serotonin. Tryptophan is available by prescription only, but supplemental 5-hydroxytrptophan will increase serotonin levels as well. The amino acids phenylalanine and tyrosine are precursors of dopamine, epinephrine, and norepinephrine. Brain chemistry is still not completely understood, but it is believed that by increasing individual amino acids in the diet, levels of neurotransmitters will increase as well, preventing or relieving depression. There are some theories indicating that the longer one is depressed, the harder one is to treat. It is important to seek treatment sooner than later. There is some evidence that prolonged severe depression can result in early ovarian decline.

Initially the treatment of depression was with psychoanalysis thanks to the work performed by Sigmund Freud. Ever since the tricyclic antidepressant drugs became available in the 1960's, psychoanalysis has been used less and less. The tricyclics increase the activity of serotonin and norepinephrine, thus increasing euphoria. The side effects are blurred vision, dizziness, and sleepiness. In 1987 Prozac was the first selective serotonin reuptake inhibitor (SSRI) available in the U.S. SSRIs only increase the availability of serotonin and not norepinephrine, so side effects were less severe. The SSRI's include Prozac, Celexa, Luvox, Paxil, and Zoloft. Side effects from these medicines include insomnia, loss of sex drive, nausea, and restlessness. Lexapro is the newest SSRI and it has been touted to relieve anxiety as well as depression. The monoamine oxidase inhibitors (MAOIs) are less commonly used than the SSRIs because they have more dangerous side effects. Marplan, Nardil, and Parnate are MAOIs and they can cause a hypertensive crisis, dizziness, weight gain, constipation, and headaches. MAOIs cannot be used with other medications to treat depression and people must eliminate the amino acid, tyramine from their diet. The use of MAOIs might be back on the rise, because the FDA just approved an MAOI patch. This will result in fewer side effects because most of the serious side effects from MAOIs were secondary to oral administration. Wellbutrin is another commonly prescribed drug for depression, but its exact mechanism of action is unknown. There seems to be less sexual dysfunction on Wellbutrin, and Wellbutrin SR (sustained release) is the same drug as Zyban, used for smoking cessation. Some of the above antidepressants have increased suicidal thoughts in teenagers, as well as adults. It is important to watch for signs of increased irritability, anxiety, hostility, or restlessness, especially in the first few weeks of treatment. When antidepressants are stopped it is important to decrease the medication slowly. Stopping cold turkey can cause dizziness, fatigue, nausea, headaches, anxiety, and depression.

There are also natural agents which are used for depression. St. John's Wort has been used for hundreds of years and it is one of the most studied herbs. The studies show that it is as effective as standard drugs for treating mild depression. Omega-3 fatty acids are being extensively studied. The nervous system cannot grow and regenerate without omega-3 fatty acids. Docosahexaenoic acid (DHA), an omega-3 fatty acid, is the main component of cell membranes in the brain. GABA and glutamate are natural occurring molecules, which can also be taken as a supplement. They are the primary neurotransmitters in the brain, and as a result they can affect all activities in the brain. Testosterone supplementation has been shown to improve mood in a study involving men, so the same hormone may have the same effect on women. DHEA, an over the counter hormone, has been used for depression and mood elevation as well. SAMe, ginkgo biloba, phenylalanine, and 5-HTP are also used to treat mild depression. Adequate levels of vitamin B12 have been shown to be important in treating depression. People who respond best to medical treatment have higher concentrations of vitamin B12. Exercise is also important because of the release of natural endorphins, which elevate mood.

When the above treatments are unsuccessful the next step would be electroshock therapy. It involves using a small electrical current to induce a mild seizure, resetting the electrical state of the brain. Though the exact mechanism of action is poorly understood, it is a very effective treatment for depression. More recently, magnetic resonance imaging (MRI) is being looked at as a possible cure for depression. Small studies have shown that moods improved following an MRI of the brain.