What kind of things make it more likely that a person will suffer from depression during their lifetime? Let's take a look at the known risk factors.
First things first: The true meaning of 'risk factors'
After thinking it over, I've decided to include a semi-random story here. A good friend of mine has had bunions since she was a child, but they've only recently started giving her trouble — real trouble. The pain and inflammation was so bad that she could hardly walk, and after doing some Googling, she started toying with the idea that gout might be the cause. "But I don't have any of the risk factors," she said, "exception hypertension." Her conclusion? "That can't be it, then, can it?" Yes, it can, and it turned out that it was.
Having said that, let's take a look at the factors associated with a higher risk of depression.
Genetic factors have a huge impact on a person's risk of developing depression. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which your healthcare provider will use to determine whether you meet the diagnostic criteria for depression, points out that people who have immediate relatives who suffered from depression have a two to four times higher risk of becoming depressed themselves. Research quite shockingly shows that people whose identical twins have suffered from depression or currently do have a 70 percent risk of developing major depressive disorder, too.
Your inherent personality, too, has an affect on your risk of depression. There are those who literally "always look on the bright side", and then there are people who tend more towards the pessimistic. One way of being isn't necessarily better than the other — pessimists may be more likely to avoid social and other risks, as they're more likely to dwell on them, for instance. It does seem, however, that these pessimists, or people with "negative affect", are more vulnerable to depression, the DSM-5 says.
Female people are about twice as likely to develop depression than males, statistics show, and they're also at a higher risk of attempting suicide if they do become depressed. This may be down to a few factors — hormonal fluctuations like those associated with the menstrual cycle, pregnancy, and the menopause have been implicated, as has the way in which women are socialized to relate to the world. Depression may, of course, be highly underdiagnosed in men, as well, because they are less likely to seek medical attention for mental health struggles.
In addition, transgender people have been found to suffer from depression in higher numbers than the general population, something that can be attributed to a combination of body dysphoria and the social struggles trans people encounter.
4. Stress and trauma
Experiencing extreme stress, trauma, or abuse — especially in childhood, but also later in life — is another risk factor for depression. In some cases, stressful events or trauma can trigger an episode of depression, but that is not always true. Having a history of adverse experiences is, unfortunately, enough to be at a higher risk. We'll include living in poverty, another known risk factor for depression, here, as poverty is essentially a constant state of stress.
5. Chronic or serious illness
Research shows that rates of depression are high in people who suffer from chronic or serious illnesses, such as heart disease, cancer, Parkinson's disease, fibromyalgia, diabetes, and HIV. In some cases, the reason can be found in the impact the illness has on the person's quality of life over time, whether because of pain, worries about life expectancy, or social implications. In others, such as Parkinson's disease and Alzheimer's, the underlying illness contributes to some of the brain changes that are also associated with depression. Having another mental illness, such as anxiety or borderline personality disorder, also places a person at a higher risk of depression — as does having suffered from depression before.
6. Substance abuse and medications
Research has shown that around 30 percent of depressed people also have a substance abuse disorder — an addiction to drugs or alcohol. This correlation makes substance abuse an important risk factor for depression, but that doesn't mean depression is necessarily caused by a drug or alcohol addiction; it can also be the other way around.
Certain medications, like some beta blockers, gabapentin (an anti-epilepsy drug also used to treat some other conditions), and corticosteroids, have also been associated with a higher risk of depression.
Numerous different studies have investigated possible links between depression and ethnicity or racial group, and a lot of them contradict each other. To take a closer look at this, one study that look at rates of depression among different ethnic and cultural groups in the US found that depression was more common in African Americans and Hispanics than Caucasians. After adjusting for other factors, such as health and poverty, however, their findings looked a lot different. Depression was now about equally common in Hispanic and white people, and seen less often in black people.
When looking at studies like that one, you also have to remember that someone has to be diagnosed with depression in order to be included in research. Not only is it more taboo to seek medical attention for depression in some cultures, the DSM-5 also notes that the way in which depression express itself can depend on a person's cultural background.