There is no one cause of depression. It’s thought that biological processes, psychological factors, major events in a person’s life and personal circumstances can all play a role. Some examples of the many causes of depression include:
- traumatic experiences
- unresolved emotional problems
- certain medications
- medical conditions (such as cancer, stroke, heart attack or an underactive thyroid)
- substance abuse
- lack of sunlight
- neurotransmitter imbalance
- hormonal imbalance
- nutrition deficiencies
- toxicity from mold and metals
Over the years, researchers have found that more cases of depression are characterized by the accrual of multiple chronic mild stressors. These include work-related stress, homemaking demands and financial trouble, than by major losses such as divorce or the loss of a job. We can dive deeper into some of these common causes of depression in order to better understand how some environments, personal circumstances and decisions, and physical conditions can increase the risk of developing depression.
About half a million Americans, mainly from northern climates, suffer from seasonal affective disorder (or SAD), a form of clinical depression that comes and goes in a seasonal pattern. It is believed that a vitamin D deficiency and a lack of sunlight keeps a part of the brain, the hypothalamus, from working properly, leading to a disruption of circadian rhythms. When our circadian rhythms are out of whack, it can increase our levels of melatonin. These melatonin increases make us feel sleepy and lethargic, and decreases our serotonin levels, affects our mood and appetite.
Our diet can be a major contributor to the development of depression as well. Our bodies are interconnected systems. Everything we put in them, expose them to or do to them affects the whole person, not just one area. The foods that we eat will not only affect our digestion and energy, but also alter the neurochemistry of our brains, specifically the neurotransmitters.
The neurotransmitters dopamine, norepinephrine and serotonin affect mood and behavior. When there is an imbalance, this can lead to signs of depression. In fact, serotonin eases tension and dopamine and norepinephrine raise alertness. The foods commonly consumed in the Western diet have the ability to alter the balance of our neurotransmitters. The high levels of omega-6 and 9 fatty acids in refined and processed foods, for example, have been found to cause dramatic problems in the production of serotonin.
Hypoglycemia (low blood sugar) is a commonly overlooked commonality in depression. Consuming sugar and simple carbohydrates such as white rice, white bread and white flour, causes a rapid and dramatic rise in blood sugar. This then produces an exaggerated insulin response. A 2013 study conducted at the University of Washington Medical School involved over 4,000 patients with diabetes. Researchers found that depressed patients (compared with non-depressed patients) had a significantly higher risk of severe hypoglycemic episodes and a greater number of hypoglycemic episodes.
Alcohol lowers serotonin and norepinephrine levels, it depresses the brain and nervous system and blunts the action of stress hormones. According to a 2011 study published in Addiction, there a link exists between alcohol use disorders and major depression. Researchers found that increasing involvement with alcohol also increases the risk of depression. Potential mechanisms underlying these linkages include neurophysiological and metabolic changes resulting from exposure to alcohol.
Toxic mold exposure is another cause of depression that sometimes isn’t taken seriously enough. Research published in The American Journal of Public Health indicates that there is a link between homes with mold and residents with signs of depression. This data comes from more than 6,000 European adults and it proves that toxic mold causes depression.