Life can throw many types of obstacles in our path. As we attempt to navigate these challenges, it’s normal to experience feelings of helplessness, sadness or even depression. Depending on the situation, these feelings may linger for a few hours or even a few days. That’s not typically cause for concern. But when the depressed mood hangs on for two weeks or more, it may be a sign of depression.
What Causes Depression?
For a long time, it was assumed that most cases of depression were caused by either a “chemical imbalance” or a lack of positive thinking. Thanks to important research, we’ve learned much more about the causes of clinical depression and what can be done to help people with mood disorders. Researchers have identified five main causes of depression:
- Brain and biology
- Stressful life events
- Other medical conditions
- Depression, the Brain and Biology
An important discovery regarding a possible cause of depression has been the role of new cell growth and connections in the brain. We know that the brain can create new nerve cells called neurons. The area of the brain where many of these new cells are produced is called the hippocampus. The hippocampus plays a central role in helping us learn and retain information in memory.Researchers have found an association between sluggish production of neurons in the hippocampus and low mood. In fact, studies have shown that the hippocampus tends to be smaller in people with depression. Stress may also be a factor that’s responsible for a smaller hippocampus because stress hormones are known to suppress the production of neurons in the brain.Current antidepressant medications work to increase the amount of chemical messengers (neurotransmitters) exchanged between neurons. But conventional antidepressants don’t directly create more neurons. While antidepressants do increase the chemical communication in the brain, it typically takes weeks before the potential benefit of an antidepressant medication kicks in to help lift mood. Armed with the recent discovery that depression may be directly related to low production of new neurons, researchers are working to develop a new type of medication that helps facilitate cell growth in the brain, which could produce quicker results in the treatment of depression.
- Depression and Genes
Your genes affect every part of your body, including your mood. We know that depression and bipolar disorder have a genetic link because they tend to run in families. For example, about half of people with bipolar disorder also have a family member with a mood disorder. The genetic link is even stronger between identical twins who share the same genetic makeup. If one identical twin has bipolar tendencies, the other is up to 80 percent likely to also have a bipolar disorder. But in fraternal twins, who don’t share the same genes, a diagnosis of bipolar disorder in only one twin only poses about a 20 percent risk for the other twin.Researchers have also identified a particular gene called 5-HTT that’s been shown to increase the risk of depression in some people, especially when they’re exposed to stressful life events. Genes come in pairs (one from each parent) and are either short or long in length. Studies have shown that people with one short 5-HTT gene are at higher risk of depression, and are significantly more likely to experience depression if both genes are short when accompanied by stress. Those with two long 5-HTT genes are less prone to depression in similarly stressful situations.
- Depression and Stressful Life Events
We all encounter stress in our lives, but it’s the heavy stressors — the death of a loved one, loss of a job, a divorce, or financial ruin — that can have lasting emotional consequences and lead to depression. Most people are resilient to the daily stress they encounter because these situations tend to be short-term. For example, if you have a tense conversation with someone at work, by the end of the day it seems to have resolved or doesn’t seem as important any longer. But when the stressor is long-term, such as dealing with a failing marriage or worry over financial matters, the continual flow of stress hormones — called the fight or flight response — wears you down and lowers your ability to be emotionally and physically resilient to stress. This constant worry increases your risk of depression.Another significant source of stress is early childhood trauma. Studies have shown that experiencing trauma such as abuse, neglect or abandonment early in life greatly increases the risk of both depression and substance abuse as an adult.
- Depression and Other Medical Conditions
Some medical conditions, especially chronic illnesses, are known to increase the risk of depression. Thyroid hormone imbalances, for example, are well-known for their effect on mood. Too much thyroid hormone (hyperthyroidism) can result in manic behavior. Too little thyroid hormone (hypothyroidism) can lead to feelings of fatigue and depression. Other conditions that may trigger depression include diabetes, stroke, heart disease, kidney disease, Alzheimer’s disease, multiple sclerosis, cancer and lupus.
- Depression and Medications
Although most people who take prescription medication won’t experience symptoms of depression, some drugs have this as a possible side effect. These include:
- Barbiturates (used to treat anxiety and seizures)
- Benzodiazepines (used to treat anxiety and insomnia)
- Beta blockers (used to treat heart conditions and high blood pressure)
- Estrogens (used to treat menopause symptoms)
- Opioids (used to relieve pain)
- Statins (used to lower cholesterol)
Getting Help for Depression
Depression can have many causes. If you’re at risk for any of these, empower yourself by learning as much as you can about depression, how it’s treated, and how to manage it. If symptoms persist for more than two weeks, seek help to keep your depression from worsening. Your doctor and an experienced mental health counselor can work together to help you learn to manage your moods effectively.