Scientists estimate 15 percent of people will suffer an episode of major depression during their lifetimes. Because depression affects so many patients, future health care professionals will inevitably encounter it. No matter what degree they’re earning, they should seek out programs that train them to recognize and treat the disorder. For example, someone who wants to learn more about a Master of Science in Nursing program should always check to see whether depression and other common mental health disorders are part of the curriculum.

Because of the stigma surrounding mental health issues, many people think people with clinical depression should just “snap out of it.” However, conquering depression is more complex than willing a patient to be in a good mood. The disorder has complex biological and psychological components. Biologically, it’s a three-headed monster involving neurotransmitters, hormones and genetics.

Classic Signs of Depression

While no two cases of depression are alike, people suffering from the disorder deal with certain common symptoms:

• Anhedonia. Anhedonia, the opposite of “hedonism,” is the inability to feel pleasure. People with depression have a hard time being happy even in the best of circumstances.
• Grief and guilt. Depression often correlates with feelings of sadness and excessive guilt. Patients may obsess over circumstances so much that their sadness or guilt takes on an almost delusional quality.
• Self-injury. Sometimes, people with depression hurt themselves by cutting. They may also attempt suicide because they view life as hopeless.
• Psychomotor retardation. When a patient is depressed, every action seems to require tremendous effort. They lack energy for even common tasks, like bathing, preparing meals and housekeeping.
• Vegetative physical symptoms. Scientists have discovered depressed patients often have irregular circadian rhythms. A telltale sign of depression involves waking up long before the alarm clock goes off and having difficulty getting back to sleep. In addition to sleep disruption, many also suffer from decreased appetite.

Neurotransmitters

Nerve cells, or neurons, in the brain transmit signals to one another using neurotransmitters. Neurons release neurotransmitters to carry these signals across the gap between cells, or the synapse.

When the signal has passed, the nerve cells recycle the neurotransmitter. Alternatively, it’s broken up by enzymes and flushed into the blood, urine or cerebrospinal fluid.

Most antidepressant medications inhibit either the recycling of neurotransmitters or the production of enzymes that break them down. Doctors have discovered three major neurotransmitters associated with depression:

1. Dopamine. Dopamine is essential to helping the body feel pleasure. A dopamine shortage is thought to be a major cause of anhedonia.
2. Norepinephrine. Doctors associate norepinephrine shortages with psychomotor retardation.
3. Serotonin. Serotonin shortages create an environment for perseverating on grief and guilt. Doctors sometimes give depressed people the same medications that treat obsessive-compulsive disorder to treat the symptom that both illnesses share obsessiveness.

Hormones

Researchers suspect an imbalance between estrogen and progesterone in the female body could explain why women suffer from depression twice as often as men. These hormones are often disordered during certain events in a woman’s reproductive lifecycle, such as when she begins her period, gives birth and starts menopause. Doctors think the estrogen/progesterone imbalance reduces the number of neurotransmitter receptors and may inhibit the recycling process.

Doctors also estimate that 20 percent of depression cases could actually be hypothyroidism, or a shortage of thyroid hormone. Additionally, about half of depressed patients have elevated cortisol levels, which indicate a massive physical stress response. In many cases, a first major depression is triggered by a stressful life event. After four or five stress-induced depressions, the body can sink into cyclical periods of depression even without encountering major stressors.

Genetics

People who have a short variation of the 5-HTTLPR gene, which is a serotonin transporter, may be predisposed to depression. The gene variation correlates highly with depression in people who experience traumatic events before the age of 10. Interestingly, cortisol, which the body generates as part of its stress response, also regulates the function of the 5-HTTLPR gene.

Even with all that is known about the biology of depression, antidepressant medications alone only help 30 to 40 percent of patients. One thing is certain: With so many biological components involved in depression, no patient has the ability to simply “snap out of it.”

About the Author: Reilly Mahan is a freelance medical journalist.