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What Causes Depression?

Grace Ogren
 April 11th, 2024|   Clinically Reviewed by 
Dr. Malasri Chaudhery-Malgeri, Ph.D.

Key Points

  • Depression has multiple causes that vary person-to-person.
  • Genetics, trauma, substance use, and abuse can cause depression.
  • Multiple therapies and medications treat depression.

Multiple causes and factors contribute to depression. It can vary between two siblings, and certainly between people all over the world. As clinicians and the general public gradually become more and more aware of what causes depression, more identified causes have come to light—as have treatments. 

Depression is characterized by feelings of low mood, hopelessness, and sadness1 affecting your daily life for 2+ weeks. Some people experience severe symptoms, like suicidality, while others may experience persistent but low-level symptoms. Some types of depression correlate with the seasons. It’s always best to seek a diagnosis from your doctor to determine the type of depression.

Arguably, there’s a treatment solution for every type and cause of depression. Whether it’s caused by genetics, environment, situations, or anything else, you have resources to heal. 

Is Depression Caused by Chemical Imbalance?

Sometimes, yes. An imbalance of neurotransmitters in the brain can poorly affect your mood2 and cause clinical depression. But, this popular “cause” of depression is becoming less and less validated. 

Harvard Medical School2, for example, says, “…depression doesn’t spring from simply having too much or too little of certain brain chemicals. Rather, there are many possible causes of depression, including faulty mood regulation by the brain, genetic vulnerability, and stressful life events.”

Chemicals and neurotransmitters are part of the picture, but not nearly all of it. For example, antidepressant medications raise neurotransmitter levels immediately2, but it takes weeks to see results. This suggests the issue goes much deeper than an imbalance; instead, research finds new nerve connections must form2 and strengthen in the brain to bring relief. 

What Is the Leading Cause of Depression?

Everyone reacts differently to life events, adversity, and abuse. Similarly, everyone has their own unique levels of neurotransmitters and nerve connections in the brain. That’s why a leading cause of depression can’t be identified. 

Some events and predispositions can better predict the onset or likelihood of depression. For example, 80% of those who experienced a major negative life event developed an episode of major depression3. A negative life event could include abuse, loss of a loved one, job loss, and homelessness. 

Pregnancy can cause postnatal depression3, due to a sudden change in hormones, stress, and sleep deprivation after birth. Between 10-20% of new mothers develop depression. Like trauma and abuse, pregnancy can make the likelihood of depression higher, but not guarantee its development.

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Causes of Depression

The causes of depression can exist independently or overlap. For example, someone with depression may be genetically predisposed to it and experience abuse. The causes will vary for each person. Some people will also experience the causes but not develop depression. 

Family History/Genetics

Depression runs in families4. Children with a depressed parent are 1.5-3% more likely to develop depression than other populations. Bipolar depression has particularly high chances of affecting immediate family members. Identical twins, for example, are 60-80% likely to share their diagnosis of bipolar with the other.  

Several genes affect how we respond to stress4, which can increase or decrease the likelihood of developing depression. Genes turn off and on to help you adapt to life, but they don’t always adapt helpfully. They can change your biology enough to lower your mood and cause depression, even if it doesn’t run in your family.


Depression and medical illnesses commonly co-occur5, which led researchers to wonder if medications could cause depression (unrelated to the distress of medical conditions). They found that to be the case in some situations.

Medications like barbiturates, corticosteroids, flunarizine, and topiramate5 were found to potentially cause depressive symptoms and clinical depression. Medications can also cause symptoms like fatigue, sleepiness, or low appetite, which can progress into depression. 


Physical, psychological, and sexual abuse can cause depression6. Abuse can change how you see yourself and the world around you, which can lead to feelings of sadness, low self-worth, and hopelessness. Those feelings can then contribute to, or solely cause, depression.

Victims of abuse may also isolate themselves and shut down, which can make depression more likely to develop. Emotional abuse and childhood abuse tend to correlate strongly with adult depression6. Largely, any kind of abuse makes the development of depression more likely. 


Depression is more common in those with physical illnesses7 like diabetes, autoimmune diseases, and other chronic conditions. Feeling hopeless, unwell, and discouraged because of a health condition contributes to depression developing. Short-term illness, like being hospitalized and immobile after an accident, can also cause an episode of depression. Those with chronic illnesses may experience more frequent and long-lasting depressive episodes. 

Depression can reduce normal functioning, and even life expectancy7, in those with co-occurring physical illnesses. Treatment for depression can improve symptoms of physical ailments, too.

Drugs and Alcohol

Drugs and alcohol can cause physical and emotional symptoms that lead to depression8. For example, feeling dependent on a substance may cause discouragement and hopelessness, which can then progress into depression. Plus, coming down from a substance-induced high mood can make low moods even more profound. Losing relationships due to addiction can erode support systems and lead to isolation. Sickness and ongoing effects of substance use can make you feel physically ill, which also connects to depression.

Effective treatment for substance use and depression addresses each disorder: detox and therapy for addiction, therapy and medications (as prescribed) for depression.

Death Or A Loss

Grief can be a powerful catalyst. The loss of a loved one, sudden or not, can cause low mood, hopelessness, and intense emotional pain. Though healthy grief cycles do include pain and depression, these emotions can become severe9 and interfere with your ability to function. 

Sometimes, those in grief need professional help to navigate the loss and feelings associated with it. This is especially true for anyone with thoughts of suicide or experiencing severe loss of function (can’t get up in the morning, can’t work, can’t eat).

Can You Develop Depression?

Anyone can develop depression. It’s most common in young adults10, but anyone of any age, sex, and race can become clinically depressed. You don’t need a history of depression, nor get depression by a certain age, to develop it. 

Depression can come on suddenly, or as a gradual build-up of symptoms. For example, the loss of a loved one could spur a quick onset of depression. On the other hand, stress and anxiety can more slowly progress into depression. In these cases, depression isn’t always noticeable until it’s glaring.  

Sometimes, catching stress, grief, and anxiety early-on can prevent them from progressing or contributing to depression. Other times, situations completely beyond your control can contribute to and cause depression. Examples include genetics, hormones, and simply how your unique brain works.  

Find Additional Help for Depression

Navigating clinical depression isn’t something you have to do on your own. You can begin your journey by talking with your primary care provider, who can refer you to 1:1 and group therapy. They may also prescribe antidepressants to work in tandem with therapy. 

Your therapist may use therapies like cognitive behavioral therapy (CBT), which aims to improve unhealthy thought patterns. You may also try dialectical behavioral therapy (DBT), which focuses more on managing emotions and thoughts in a healthy, productive way. 

You can also attend rehab for depression. Browse our collection of depression rehabs to find a center that fits your needs–see what insurance they accept, reviews, photos, and more.

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