Depression is a common problem in the United States, affecting millions of people each year. Even though it’s common, it is a serious problem in the lives of people with depressive disorders. Depression is a mental health problem that affects your mood, but it can have consequences on multiple aspects of your life. It can impair your concentration, take away motivation, and make it hard to get out of bed. However, the condition can be treated with many different therapeutic approaches, depending on the depressive disorder you have. 

What is the scope of depression in the U.S., and who does depression affect the most? 

What Is Depression?

Depression is a mental health disorder characterized by low mood. But it’s more than just a sad feeling occurring from time to time. Rather, it’s a mental health problem that can get in the way of a healthy life and take some of the enjoyment out of everyday tasks and activities. It’s estimated that around 20% of people in the U.S. experience major depression at some point in their lifetime. Also, major depression represents only one of several mental health issues that can cause depressive issues. 

Depression is often used as shorthand to describe a diagnosis called major depressive disorder. Still, the broad term describes a very low mood brought on by one of several mental health disorders. Depression is most commonly associated with feelings of hopelessness, worthlessness, and sadness. However, it can also cause other common symptoms, such as losing interest in most activities or poor concentration. Depression may also come with physical symptoms like fatigue, hypersomnia, insomnia, and body aches.

Major depression involves periods of intense depression symptoms that last for about two weeks. These episodes can come and go randomly without treatment. However, other forms of depression may center around specific events or times of the year like seasons, menstruation, and pregnancy.

The Scope of Depression

After anxiety disorders, mood disorders are among the prevalent mental health threats. According to the 2020 National Survey on Drug Use and Health, 8.4% of adults age 18 or older had a major depressive episode in the past year in 2020. That accounts for more than 20 million people. According to the World Health Organization (WHO), depression represents the most common cause of disability globally. That means it’s a major cause of social and occupational impairment worldwide.  

Depression can be mild, but about 14 million adults had at least one major depressive disorder with severe impairment in 2020. Adolescents can also struggle with depression. Roughly 2.9 million people between ages 12 and 19 had a major depressive episode in 2020. 

Who Is Most Likely to Develop a Depressive Disorder?

statistics of depression

Depression can affect anyone, even those who may be mentally tough and resilient. There is still much to learn about what causes depression, but it’s likely several factors coming together at once. Genetics play a significant role, but brain chemistry, environment, and development can all play a role. In many cases, depressive disorders can cause quality-of-life problems or occupational or social functioning issues. 

While depression can affect anyone, certain risk factors may increase your likelihood of depression. For instance, women are more likely than men to have depression. Around 10.5% of women had depression in 2020, while only 6.2% of men had the disorder. Although, stigma may cause depression to go unreported and untreated in certain groups. 

Demographics data from the Substance Abuse and Mental Health Services Administration (SAMHSA) reveals that depression is high among White people, followed by Black or African American people. However, the highest rates of depression were among people of two or more races.

Beyond demographics, there are a few risk factors that can increase your likelihood of depression, including:

  • Having parents or grandparents with depression
  • Chronic health problems
  • Chronic pain
  • Sleep problems
  • Financial problems
  • Major life changes
  • Social isolation

What Are the Types of Depression?

Depressive or mood disorders are a class of mental health issues that cause low moods and other symptoms. In many cases, depressive disorders can cause quality-of-life problems or issues with occupational or social functioning. Depression most commonly causes mood symptoms that affect you mentally and emotionally. However, it can also cause physical symptoms like fatigue or body aches. Many mood disorders have similar symptoms with a few key differences, but a few have unique symptoms. 

While mood disorders can share some common symptoms, you must get the most accurate diagnosis for your needs. There may be different treatment options for each type of mood disorder. 

Here are the different types of depressive disorders:

Major Depressive Disorder

Major depressive disorder (MDD) is one of the most common depressive disorders in the United States. It was once classified as a mood disorder, but the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) reclassified it as a depressive disorder. MDD is diagnosed based on the occurrence of a major depressive episode, which involves five of nine common symptoms. One of the five symptoms must be either a low mood or a loss of interest in most activities. Low mood can involve feelings of sadness, hopelessness, or worthlessness. Loss of interest involves neglecting obligations and duties, but it can also mean not receiving pleasure from things you once enjoyed. 

To qualify as a major depressive episode, you have to experience these symptoms for two weeks or more. If you have a major depressive disorder, these episodes may come and go over time, and symptoms don’t typically last more than a few weeks at a time. You may experience a few each year that vary in severity. In some cases, symptoms can be severe, causing deep despair with suicidal thoughts or actions. 

Major depression can be progressive, worsening over time and affecting more areas of your life. 

Bipolar Disorder

Bipolar disorder was once classified as a mood disorder, and the DSM-5 puts it in a class called bipolar and related disorders. Still, it shares similarities with major depression. Shifts between high and low moods characterize bipolar disorder. Low moods can involve major depressive episodes similar to what you might experience with a major depressive disorder. However, the disorder will also cause periods of very high moods called manic episodes. 

Manic episodes involve feelings of excitement, high energy, inflated self-importance, and increased distractibility. To qualify as a manic episode, you must experience three or more of the seven symptoms noted in the DSM. You also have to experience these episodes for a week or longer. 

Bipolar disorder is split into two major subtypes called Bipolar I and Bipolar II. Bipolar I involves a mood that meets the diagnostic criteria of a manic episode. A manic episode immediately qualifies the disorder as bipolar I. However, bipolar II will involve major depressive episodes with hypomanic episodes, which are high moods that don’t meet the criteria for a full manic episode. 

It’s possible to experience high and low moods that don’t meet major depression or manic episodes criteria. In that case, you may have another disorder in the bipolar category called cyclothymia. 

Persistent Depressive Disorder

Persistent depressive disorder (PDD) is a mental health disorder that’s also in the category of depressive disorders. It’s also called dysthymia, and it can involve many of the same symptoms as major depression. However, it doesn’t cause symptoms that are as numerous or severe as major depressive disorder. But PDD does cause symptoms that last much longer than MDD before disappearing. 

PDD symptoms can last for two years or longer. While the symptoms aren’t as severe as other mood disorders, a long period of low mood can lower your quality of life. It can also impair your sleep, concentration, and energy levels. People with PDD also often experience low self-esteem and low motivation levels. 

If PDD isn’t treated, it may last for a very long time. However, with treatment, symptoms may be reduced or go away entirely. 

Perinatal Depression

Perinatal depression is a disorder centering around pregnancy. It includes depression symptoms that occur after birth, which is called postpartum depression. It also includes depression that occurs during pregnancy, which is called prenatal depression. Perinatal depression is a blanket term that includes women who experience depression symptoms during and after pregnancy or in just one or the other. 

Perinatal depression is more severe than the common “baby blues,” which are routine changes in mood associated with pregnancy, major life changes, and the stress of new parenthood. While “baby blues” are manageable, perinatal depression can hinder your functioning or your quality of life. Common symptoms include irritability, sadness, guilt, and intrusive thoughts about harming your baby or yourself. Perinatal depression may occur in around 20% of women between pregnancy and three months after birth. 

Premenstrual Dysphoric Disorder

Premenstrual dysphoric disorder (PMDD) is a mood disorder that occurs during menstruation. Menstrual cycles can commonly come with mood changes that emotional and psychological symptoms cause. However, the typical irritability, stress, and mood shifts that come with menstruation aren’t necessarily depressive disorders. PMDD is typically more intense than PMS (premenstrual syndrome). It may involve symptoms like very low mood, mood swings, anger, anxiety, hopelessness, and panic attacks. 

Like PMS, it can affect women a few days or weeks leading up to before their periods. Symptoms fade after menstruation ends. The most significant difference between PMS and PMDD is the level of impairment your experience because of symptoms. PMDD can cause severe symptoms that make it difficult to function at home or work, and it may take the enjoyment out of your life. 

Seasonal Affective Disorder 

Seasonal affective disorder (SAD) is depression tied to a specific time of the year. It’s most commonly associated with the winter months, but rare instances of SAD in spring or summer can occur. SAD in the winter is thought to be linked to light exposure and your body’s circadian rhythm. It’s more common to experience SAD symptoms in northern regions that see long, dark winters. 

In order to be diagnosed with SAD, you will need to experience depression symptoms around the same time each year for two years in a row. SAD symptoms usually appear in late fall and last until spring. 

Depression Causes

Depression is a common mental health problem, but how can you recognize its risk factors? The condition is like other mental health issues in that various factors can cause it. This means it is unlikely for you to pinpoint a single cause. A mix of biological, developmental, and environmental factors can contribute to your overall risk of developing a substance use disorder. 

Family History and Genetics

Genetics make up a significant portion of your risk factor for mental health disorders, including depression. If a parent or grandparent experiences depressive disorders, you have a higher risk of depression as well. In fact, genetics may make up as much as 40% of your risk factor for mood disorders. 

Genetic variables in mental health disorders are challenging to determine, but researchers use twin and adoptions studies to differentiate between genetic and developmental factors. Twins share the same genetic makeup, but their developmental and environmental factors can be different. When twins share the same diseases and disorders at high enough rates, it suggests a genetic component to the disease’s risk factor. 

Adopted children get genetics from a set of parents, but they develop in a separate environment from their biological parents. If they share diseases and disorders with their biological parents, it suggests genetics were at play. Twin and adoption studies of depression have found that genetics do play a role in depression. However, the exact genetic variations that cause disease have been discovered for some illnesses, but not for depression. In other words, genes play a role, but we don’t know exactly how yet. It’s likely that more than one gene is involved in the development of mood disorders. 

It can double your risk of depression if you have a parent with depression. Still, having a parent with the disorder doesn’t mean you are guaranteed to struggle with depression. Genetics increases your risk, but other risks and protective factors can influence you.


There may be physiological issues in your brain or body that contribute to the development of depression. These anatomical and brain chemistry variables may be present from birth or developed over time. 

A potential cause for mental health issues like depression is a chemical imbalance in the brain. Neurotransmitters are a part of your brain’s chemical messaging system. They are passed between nerve cells throughout your body. An imbalance of chemicals may occur for various reasons. An imbalance of chemicals related to mood like serotonin and dopamine could cause mood disorders like depression. 

According to this potential cause for depression, having too much or too little of key neurotransmitters could cause depression symptoms. Neurotransmitters work by binding to chemical receptors on each nerve cell. If there are too few receptors, that could also cause uncomfortable depression symptoms. 

It’s possible that diet, lifestyle, and genetic predispositions can cause these neurochemical problems that predispose you to depression. However, chemicals may be just one factor that contributes to mood disorders. 

Still, even though chemical imbalances are often cited as the cause of depression, it’s a theory that hasn’t yet been definitively proven. It may not fully explain mood disorders. But many medications used to treat depression address this issue. For instance, SSRIs (selective serotonin reuptake inhibitors) are the first-line treatment for depression. They work by increasing serotonin levels in the brain. Other medications include monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs).

Medical Conditions 

Several medical conditions may increase your likelihood of developing depression. Chronic medical conditions, worrying diagnoses, and permanent changes—like the loss of a limb—can significantly impact mental health. Other medical issues, like sleep problems or thyroid conditions, can directly influence your mood.

Chronic pain can also influence depression rates. Other common chronic conditions like diabetes, multiple sclerosis, and cancer are associated with high rates of depression and other mental health issues.

Medical problems can increase your stress levels and cause you to worry about day-to-day challenges or the prognosis of your disease. However, some medical problems can cause mental health issues directly. Even some vitamin deficiencies can lead to low mood and fatigue. When you’re asking a doctor about a potential mental health problem, it’s important to go through a medical exam and blood work as well. 

Treating Depression

While depression is a major challenge, it can be treated. Around 66% of adults and 41% of adolescents who experienced major depressive episodes in 2020 received treatment. As noted earlier, the first-line treatment option for depression is SSRI medication. Other pharmacotherapies can include SNRIs (serotonin and norepinephrine reuptake inhibitors) and anxiolytics. Other drugs can be used in specific circumstances based on your needs. 

If you experience severe moods that cause delusions or hallucinations, you may take antipsychotics. People with bipolar disorder may take mood stabilizers like lithium to treat manic episodes. 

Often, the best treatment is a mix of medication and psychotherapies. Generally, talk therapy can be helpful, along with group therapy, behavioral therapy, mindfulness, trauma-based therapy, and other options. Ultimately, your treatment plan will depend on what you need.

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