Depression affects people of every age, economic situation, and race. Even though depression is common — especially in teens — some people get depressed but others don't. Why?
Lots of things influence whether a person gets depressed. Some of it is biology — things like our genes, brain chemistry, and hormones. Some is environment, including daylight and seasons, or social and family situations we face. And some is personality, like how we react to life events or the support systems we create for ourselves. All these things can help shape whether or not a person becomes depressed.
Research shows that depression runs in families. Some people inherit genes that contribute to depression. But not everyone who has a family member with depression will develop it too. And many people with no family history of depression still get depressed. So genes are one factor, but they aren't the only reason for depression.
Chemicals called neurotransmitters (pronounced: nur-oh-TRANZ-mit-urs) help send messages between nerve cells in the brain. Some neurotransmitters regulate mood. When a person is depressed, these neurotransmitters might be in low supply or not effective enough.
Genes and brain chemistry can be connected: Having the genes for depression may make a person more likely to have the neurotransmitter problem that is part of depression.
Things like stress, using alcohol or drugs, and hormone changes also affect the brain's delicate chemistry and mood.
Some health conditions may cause depression-like symptoms. For example, hypothyroidism is known to cause a depressed mood in some people. Mono can drain a person's energy. When health conditions are diagnosed and treated by a doctor, the depression-like symptoms usually disappear.
Getting enough sleep and regular exercise often has a positive effect on neurotransmitter activity and mood.
Daylight affects how the brain produces melatonin and serotonin. These neurotransmitters help regulate a person's sleep–wake cycles, energy, and mood. When there is less daylight, the brain produces more melatonin. When there is more daylight, the brain makes more serotonin.
Shorter days and longer hours of darkness in fall and winter may lead the body to have more melatonin and less serotonin. This imbalance is what creates the conditions for depression in some people — a condition known as seasonal affective disorder (SAD). Exposure to light can help improve mood for people affected by SAD.
The death of a family member, friend, or pet sometimes goes beyond normal grief and leads to depression. Other difficult life events — such as when parents divorce, separate, or remarry — can trigger depression.
Whether or not difficult life situations lead to depression can depend a lot on how well a person is able to cope, stay positive, and receive support.
For some people, a negative, stressful, or unhappy family atmosphere can lead to depression. Other high-stress living situations — such as poverty, homelessness, or violence — can contribute, too. Dealing with bullying, harassment, or peer pressure leaves some people feeling isolated, victimized, or insecure.
Situations like these don't necessarily lead to depression, but facing them without relief or support can make it easier to become depressed.
Life is full of ups and downs. Stress, hassles, and setbacks happen (but hopefully not too often). How we react to life's struggles matters a lot. A person's outlook can contribute to depression — or it can help guard against it.
Research shows that a positive outlook acts as a protection against depression, even for people who have the genes, brain chemistry, or life situations that put them at risk for developing it. The opposite is also true: People who tend to think more negatively may be more at risk for developing depression.
We can't control our genes, brain chemistry, or some of the other things that contribute to depression. But we do have control over how we see situations and how we cope.
Making an effort to think positively — like believing there's a way around any problem — helps ward off depression. So does developing coping skills and a support system of positive relationships. These things help build resilience (the quality that helps people bounce back and do well, even in difficult situations).
Here are three ways to build resilience:
Being positive and resilient isn't a magic shield that automatically protects us from depression. But these qualities can help offset the other factors that might lead to trouble.
Reviewed by: D'Arcy Lyness, PhD
Date Reviewed: Aug 14, 2016
