According to research, which is most consistently a risk factor for depression?

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A risk factor is something that increases your chances of developing a disease or condition. For example, smoking is a risk factor for heart disease, cancer, and stroke.

When it comes to depression, several factors may play a role, including a variety of genetic, psychological, and environmental contributors.

Several factors can make depression more likely. These may include:

• family history and genetics
• chronic stress
• history of trauma
• gender
• poor nutrition
• unresolved grief or loss
• personality traits
• medication and substance use

Do risk factors differ for different types of depression?

There are various types of depression, including:

• major depressive disorder [MDD]
• seasonal affective disorder [SAD]
• persistent depressive disorder [PDD]
• postpartum depression

Do all of these types of depression have different causes? The short answer is no.

Most cases of depression are the result of various risk factors coming together, rather than just a single cause. Plus, certain factors may weigh more heavily on different people. For example, stress may play more of a role in one person, while poor diet may significantly affect others.

In other words, depression is a complex disorder with multiple factors weighing in.

Overall, a large majority of the risk factors discussed below can contribute to most types of depression to varying degrees.

Family history and genetics

Genetics are known to play a significant role in depression. If you have a close family member, such as a parent or sibling with depression, you have a 2 to 3 times greater risk of developing depression than a person without a family history.

One way researchers know this is through twin studies. Identical twins share 100% of their genes, while fraternal twins share 50% of their genes. So if genes play a role in depression, we would expect that if one twin has depression, an identical twin would have a much higher chance of having it than a non-identical twin.

Through studies like this, researchers have found that heritability for major depression may be as high as 40–50%.

Chronic stress

While a little stress can be a good thing — as it can keep us motivated — chronic stress can wear down the body’s healthy stress response, leading to depression in some people.

Long-term stress results in overactivity of the brain’s HPA axis, which refers to the interaction between the hypothalamus, pituitary gland, and adrenal glands. The HPA axis plays a vital role in how our body handles stress.

When the HPA is overactive, it results in the release of too much epinephrine [an adrenal hormone involved in the fight, flight, or freeze response] and cortisol, the body’s “stress hormone,” which can cause all kinds of health problems, including depression.

Research shows that dysfunction of the HPA axis is seen in about 70% of people with depression.

History of trauma

Individuals with a history of trauma and abuse, particularly during early childhood, may be at greater risk of developing depression. Those who’ve experienced childhood trauma also seem to be more likely to experience treatment-resistant depression in adulthood.

One study found that adults with MDD had experienced significantly more childhood trauma than adults without depression. Specifically, 62.5% of the participants with MDD reported more than 2 traumatic events, compared with 28.4% of participants in the healthy control group.

Those with MDD had much higher rates of sexual, physical, and emotional abuse than those without MDD. They also had experienced much more neglect, bullying, or rejection, and had witnessed more domestic violence.

The study also showed that people with a history of childhood trauma before the age of 7 — including sexual, physical, or emotional abuse — didn’t respond as well to antidepressant treatments.

Racial trauma may also put a person at a higher chance of depression — this may affect adults and adolescents alike.

Gender

Being female may increase your chances of developing depression. In fact, major depression is the leading cause of disease burden in women around the world.

Women are twice as likely as men to experience major depression. They also have higher rates of:

• depressive symptoms in bipolar disorder
• persistent depressive disorder
• seasonal affective disorder

Around 1 in 8 women will experience depression in their lifetime.

There are a few theories as to why this is the case. Women report experiencing more stress and higher rates of trauma [both risk factors for depression] than men.

Female hormones, such as estrogen, may also play a role. Gender differences in depression rates emerge in puberty, with girls reporting more depression starting in their preteen years. Women are also vulnerable to depression after childbirth and during menstruation, when hormones are more prone to fluctuation.

Besides women, research also shows that people who are transgender or nonbinary are more likely to experience depression — which may be due to various factors, including abuse, discrimination, and gender minority stress.

Poor nutrition

Eating a nutritious diet is important for brain function. When we don’t get the necessary nutrients our body needs, we’re at greater risk of developing physical and mental health problems.

Research suggests that eating a lot of processed foods may increase someone’s risk of depression. Similarly, consuming too many simple carbs is linked to symptoms of depression, especially in women.

Studies have also found that people with depression may be more likely to have low blood levels of:

• vitamin B9 [folate / folic acid]
• vitamin B12
• vitamin D
• zinc
• copper
• manganese

So eating foods rich in these nutrients or taking a supplement may help ease depression symptoms.

One group of nutrients considered to be a protective factor against depression is omega-3 fatty acids, found for example in fatty fish, algae, walnuts, and chia seeds.

Evidence suggests that people who usually consume a diet rich in omega-3-fatty acids are at lower risk of developing:

• major depression
• prenatal depression
• bipolar depression

Other research suggests that diets rich in antioxidants may help reduce symptoms of depression. Plus, evidence indicates that magnesium may be helpful for people with mild to moderate depression.

Unresolved grief or loss

Grieving the loss of a loved one is a natural part of the human experience, and recovering from such a loss takes time.

In a natural bereavement process, the intense feelings of emptiness and sadness typically start to decrease over time. But in some cases, due to a variety of factors, healing becomes more difficult. This unresolved or “complicated” grief can lead to depression in some people.

About 1 in 10 bereaved adults experience prolonged grief. For some, this can lead to grief-related major depression.

Personality traits

Can your personality make you more susceptible to depression? Some research suggests it can.

One study found that the following personality traits are linked to depressive symptoms:

• high neuroticism
• high harm avoidance
• low self-directedness
• low cooperativeness

Another analysis also found that people with depression scored higher in neuroticism but lower in extraversion and conscientiousness. This study was based on the “Big Five” personality traits. What the study results mean is that a person with depression may be more likely to:

• feel vulnerable or insecure
• get stressed more easily
• experience mood episodes
• find it difficult to make small talk or introduce themselves
• feel drained after socializing
• avoid big groups
• be more reserved
• be less organized
• be impulsive
• finish things at the last minute

Medication and substance use

In most cases, people use substances or alcohol in an effort to feel better. But sometimes the substance can have the opposite effect, making the person feel worse.

When substances — including prescribed medications — lead to depressive symptoms, it’s known as substance-induced depression. This may occur when you actively use a substance, or when you experience intoxication or withdrawal.

Studies suggest that nearly half of these depressive episodes occur through heavy alcohol use. Other substances commonly associated with substance-induced depression include cocaine and opioids, particularly heroin.

Medications more commonly associated with substance-induced depression include:

• interferons [medications that attack viruses and cancer cells]
• corticosteroids [medications that reduce inflammation]
• digoxin [used to treat heart failure]
• antiepileptic medications

Researchers suggest that these substances alter neurotransmitter communication in important brain circuits.

Some symptoms of depression include:

• low mood most of the day
• reduced interest or pleasure in activities
• notable weight loss or gain without trying; decrease or increase in appetite
• fatigue or low energy
• sleep disturbances: insomnia or sleeping too much
• recurrent thoughts of suicide or death
• feelings of worthlessness or inappropriate guilt
• poor concentration
• slowing down of thoughts or physical movements; agitation or restlessness

If you experience any of these symptoms for a period of several weeks, it might be time to seek help. Consider reaching out to a healthcare professional, therapist, or a depression hotline.

Even if you have a few risk factors, it doesn’t mean you will definitely develop depression. But it’s always a good idea to do what you can to protect yourself when it’s in your power to do so.

While we have no control over some risk factors, like genetics or childhood trauma, we can control other contributors such as diet and alcohol use.

It also helps to develop stress-coping skills — such as meditation and exercise — to help reduce the chance of depression through chronic stress.

If you do develop depression, just know that it’s highly treatable and there are many supportive services available to help.

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