Depression is shockingly common — research suggests than over 10 percent of people with struggle with major depressive disorder at some point of their lives, but this diagnosis is far from the only kind of depression out there. You've also got persistent depressive disorder (a longer-lasting depression), postpartum depression, seasonal affective disorder, adjustment disorder (situational depression), premenstrual dysphoric disorder, and the list goes on.
Stress and trauma
The fact that exposure to stress or trauma places people at an increased risk of depression will surprise nobody — but the fact that research has revealed that over half of the population has suffered from some kind of trauma might. People who suffered trauma or other stressful events during childhood are more vulnerable to depression, especially if they've struggled through a series of rough circumstances, but people who experience traumatic or especially stressful things during adulthood are also more likely to suffer from major depressive disorder shortly following such events. Why? Trauma can literally rewire your brain and change your body chemistry, making it harder to cope with adverse events.
Whether it's genetic or environmental, you're much more likely to become depressed if a close relative or several also struggled with depression — your risk is two to four times higher, actually, and you're especially likely to become depressed earlier in life or suffer from recurrent episodes of depression if this is you. Genetics are, according to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (the DSM-5), responsible for about 40 percent of your risk of depression. Potentially heritable personality traits like neuroticism (basically, being a pessimist) explain some of this.
Women are nearly twice as likely as men to develop major depressive disorder, and depressed women are also at a higher risk of attempting suicide. In addition, you have two kinds of depression that only biologically female people can fall victim to — postpartum depression and menstrual dysphoric disorder. While depression is a complex illness and the reasons behind the fact that women get depressed more often aren't yet entirely clear, research indicates that:
- Hormonal fluctuations have got to have something to do with it — this is why depression is more common once a female enters puberty, in the days running up to a menstrual period, after childbirth, and during the perimenopause.
- The way females are socialized and expected to behave may also contribute to higher rates of depression in women. Women are, research found, more affected by the quality of relationships with people around them than men tend to be.
Could prescription medications be making you depressed? They could certainly contribute, as one study found that people taking various medications are more likely to suffer from depression. These include beta blockers (for heart conditions and high blood pressure), corticosteroids, the drug gabapentin (used for epilepsy and Parkinson's disease, among others), and proton pump inhibitors (for gastrointestinal issues). The study didn't, however, look at whether the participants were depressed before they started taking the medications. It is also possible, then, that the underlying illness had a greater impact on their depression than the medications.
Yes, it's true — research has demonstrated that around a third of depressed people also face a substance abuse disorder, meaning they are addicted to alcohol or drugs. That doesn't mean that substance abuse necessarily causes depression, though. Rather, people who are already depressed may turn to alcohol, drugs, or both in an attempt to feel better or just feel less (self-medication, in short). This isn't the most effective strategy, as depressed people who abuse alcohol and drugs are more likely to attempt suicide, and antidepressants are less effective in alcohol abusers as well.
Both other mental illnesses and physical conditions increase a person's risk of suffering from depression, and this includes anxiety, borderline personality disorder, diabetes, heart disease, and morbid obesity. This is, really, pretty logical; anything that robs you of your quality of life, leads to physical or emotional pain, or has you worrying whether you have a future at all is objectively depressing, yes? In these cases, the cause of depression may be found in the underlying illness itself — and rather than treating depression as a stand-alone illness, the patient is better served if the condition that triggered the depression is managed well.
Major depressive disorder seems to affect people in their twenties most often in the United States, though people of any age can become depressed for the first time. Data from the National Institute of Mental Health shows that 6.5 percent of US adults suffered from major depressive disorder in 2016, while 12.8 percent of adolescents aged 12 to 17 were clinically depressed — nearly double the rate of their adult counterparts.
We haven't covered all the possible contributing factors of depression. Ethnicity might play a role, for instance, but it's not clear to what extent because seeking medical help for depression is taboo in some cultures, and also because people belonging to some ethnic groups are more likely to live in poverty — another thing that contributes to depression.