The percentage of U.S. adults who report having been diagnosed with depression at some point in their lifetime has reached 29.0%, nearly 10 percentage points higher than in 2015. The percentage of Americans who currently have or are being treated for depression has also increased, to 17.8%, up about seven points over the same period.

Over one-third of women (36.7%) now report having been diagnosed with depression at some point in their lifetime, compared with 20.4% of men, and their rate has risen at nearly twice the rate of men since 2017. Those aged 18 to 29 (34.3%) and 30 to 44 (34.9%) have significantly greater depression diagnosis rates in their lifetime than those older than 44.

Alarming rates of depression are not unique to the U.S. Globally, nearly four in 10 adults aged 15 and older either endure significant depression or anxiety themselves or have a close friend or family member who suffers from it. Clinical depression had been slowly rising in the U.S. prior to the COVID-19 pandemic but has jumped notably in its wake. Social isolation, loneliness, fear of infection, psychological exhaustion (particularly among front-line responders such as healthcare workers), elevated substance abuse and disruptions in mental health services have all likely played a role. While experiences of significant daily loneliness have subsided in the past two years amid widespread vaccinations and a slow return to normalcy, elevated loneliness experiences during the pandemic likely played a substantive role in increasing the rates of the longer-term, chronic nature of depression.

Depressive disorder (also known as depression) is a common mental disorder. It involves a depressed mood or loss of pleasure or interest in activities for long periods of time. Depression is different from regular mood changes and feelings about everyday life. It can affect all aspects of life, including relationships with family, friends and community. It can result from or lead to problems at school and at work.

Depression can happen to anyone. People who have lived through abuse, severe losses or other stressful events are more likely to develop depression. Women are more likely to have depression than men. An estimated 3.8% of the population experience depression, including 5% of adults (4% among men and 6% among women), and 5.7% of adults older than 60 years. Approximately 280 million people in the world have depression.

What causes depression?

Depression (major depressive disorder) is a common and serious mental disorder that negatively affects how you feel, think, act, and perceive the world. Depression is among the most treatable of mental disorders. Between 70% and 90% of people with depression eventually respond well to treatment.

During a depressive episode, a person experiences a depressed mood (feeling sad, irritable, empty). They may feel a loss of pleasure or interest in activities. A depressive episode is different from regular mood fluctuations. They last most of the day, nearly every day, for at least two weeks. Other symptoms are also present, which may include:

• poor concentration
• feelings of excessive guilt or low self-worth
• hopelessness about the future
• thoughts about dying or suicide
• disrupted sleep
• changes in appetite or weight
• feeling very tired or low in energy.

Depression can cause difficulties in all aspects of life, including in the community and at home, work and school. A depressive episode can be categorized as mild, moderate, or severe depending on the number and severity of symptoms, as well as the impact on the individual’s functioning. 

Depression results from a complex interaction of social, psychological, and biological factors. People who have gone through adverse life events (unemployment, bereavement, traumatic events) are more likely to develop depression. Depression can, in turn, lead to more stress and dysfunction and worsen the affected person’s life situation and the depression itself.

Depression is closely related to and affected by physical health. Many of the factors that influence depression (such as physical inactivity or harmful use of alcohol) are also known risk factors for diseases such as cardiovascular disease, cancer, diabetes and respiratory diseases. In turn, people with these diseases may also find themselves experiencing depression due to the difficulties associated with managing their condition.

Researchers don’t know the exact cause of depression. They think that several factors contribute to its development, including:

• Brain chemistry: An imbalance of neurotransmitters, including serotonin and dopamine, contributes to the development of depression.
• Genetics: If you have a first-degree relative (biological parent or sibling) with depression, you’re about three times as likely to develop the condition as the general population. However, you can have depression without a family history of it.
• Stressful life events: Difficult experiences, such as the death of a loved one, trauma, divorce, isolation and lack of support, can trigger depression.
• Medical conditions: Chronic pain and chronic conditions like diabetes can lead to depression.
• Medication: Some medications can cause depression as a side effect. Substance use, including alcohol, can also cause depression or make it worse.

The American Psychiatric Association’s classifies depressive disorders as the following:

• Clinical depression (major depressive disorder): A diagnosis of major depressive disorder means you’ve felt sad, low or worthless most days for at least two weeks while also having other symptoms such as sleep problems, loss of interest in activities or change in appetite. This is the most severe form of depression and one of the most common forms.
• Persistent depressive disorder (PDD): Persistent depressive disorder is mild or moderate depression that lasts for at least two years. The symptoms are less severe than major depressive disorder. Healthcare providers used to call PDD dysthymia.
• Disruptive mood dysregulation disorder (DMDD): DMDD causes chronic, intense irritability and frequent anger outbursts in children. Symptoms usually begin by the age of 10.
• Premenstrual dysphoric disorder (PMDD): With PMDD, you have premenstrual syndrome (PMS) symptoms along with mood symptoms, such as extreme irritability, anxiety or depression. These symptoms improve within a few days after your period starts, but they can be severe enough to interfere with your life.
• Depressive disorder due to another medical condition: Many medical conditions can create changes in your body that cause depression. Examples include hypothyroidism, heart disease, Parkinson’s disease and cancer. If you’re able to treat the underlying condition, the depression usually improves as well.

There are also specific forms of major depressive disorder, including:

• Seasonal affective disorder (seasonal depression): This is a form of major depressive disorder that typically arises during the fall and winter and goes away during the spring and summer.
• Prenatal depression and postpartum depression: Prenatal depression is depression that happens during pregnancy. Postpartum depression is depression that develops within four weeks of delivering a baby.
• Atypical depression: Symptoms of this condition, also known as major depressive disorder with atypical features, vary slightly from “typical” depression. The main difference is a temporary mood improvement in response to positive events (mood reactivity). Other key symptoms include increased appetite and rejection sensitivity.

Can certain foods make depression worse?

Talk therapy and medication are the two primary treatment options for people with depression. But self-care measures can be highly beneficial, too. While these may include getting good sleep, exercising regularly, and practicing meditation, there’s another element you might not have considered: diet.

If you’re experiencing depressive symptoms, such as sadness, overwhelming emotion, or lack of energy, you may sometimes look to food as a pick-me-up — perhaps a bag of chips for comfort or a sugary snack to quickly boost your energy. However, there’s plenty of scientific research affirming the link between diet quality and depression. While some foods may alleviate symptoms, others may make them worse.

Fast food is cheap, convenient, and tastes good (most of the time). However, researchers believe there’s a link between depression and levels of inflammation in the body, and inflammation is exacerbated by ingredients commonly found in large quantities in fast food dishes, like artificial trans fats, refined carbs, sodium, and sugar.

One large study found that people who eat fast food regularly are at a 40% greater risk of developing depression, and researchers suggest that the high amounts of trans fats in fast food products were a primary contributing factor. Meanwhile, other researchers discovered that people who frequently eat fast food were less resilient to depressive symptoms.

For those with depression, drinking alcohol could have the opposite effect, as studies suggest higher intake may lead to increased symptoms. This is sometimes called “alcohol-induced depressive disorder,” which occurs only shortly after you drink alcohol or while you go through withdrawal.

As the National Institute on Alcohol Abuse and Alcoholism reveals, alcohol affects different pathways in the brain, in turn affecting mood and behavior. What’s more, drinking alcohol may make antidepressant medication less effective.

Despite what some diet plans suggest, there’s generally nothing wrong with eating grains like rice and wheat. However, during the process to make them refined (e.g., turning brown rice into white rice), much of their beneficial nutrition is lost.

Plenty of research supports the link between unrefined grains and depression. For example, one study in women postmenopause saw that those who ate refined grains had a greater risk of new-onset depression. Meanwhile, researchers analyzing the diets of over 1,600 adults noted those who ate unrefined grains had a lower risk of depressive symptoms.

Refined sugar negatively influences an array of physical health conditions, from diabetes and heart disease to obesity and some types of cancer. But high intake has been shown to affect mental well-being, too.

Some research indicates a potential association between sugar intake and depression, and researchers believe this ingredient has several negative long-term effects on the body that encourage this link.

These include:

• increased inflammation and hormone imbalance, both of which are linked to mood
• a potential impact on the growth and development of brain cells and proteins
• influence on neurotransmitters in the brain

A lot of barbecue, picnic, and quick-meal staples like sausages, ham slices, corned beef, and jerky are classed as processed meats. While they’re easy to prep and bring into meals if you’re not in the mood to cook, these ingredients have the potential to encourage signs of depression.

Myriad studies have found significant links between red and processed meat consumption and increased risk of experiencing depression and its symptoms. As with fast food, scientists believe this is due to their trans and saturated fat content, which encourages higher inflammation levels in the body.

Can food help to improve depression?

One factor that may contribute to depression is a person’s dietary habits, which will determine the nutrients that they consume. A 2017 study found that the symptoms of people with moderate-to-severe depression improved when they received nutritional counseling sessions and ate a more healthful diet for 12 weeks.

The improved diet focused on fresh and whole foods that are high in nutrients. It also limited processed refined foods, sweets, and fried food, including junk food. Depressive symptoms, including mood and anxiety, improved enough to achieve remission criteria in more than 32% of the participants. The researchers concluded that people could help manage or improve their symptoms of depression by addressing their diet.

Some scientists have suggested that increasing selenium intake might help improve mood and reduce anxiety, which may help make depression more manageable.

Selenium is present in a variety of foods, including:

• whole grains
• Brazil nuts
• some seafood
• organ meats, such as liver

Vitamin D may help improve the symptoms of depression, according to a 2019 meta-analysis. People obtain most of their vitamin D through sun exposure, but dietary sources are also important.

Foods that can provide vitamin D include:

• oily fish
• fortified dairy products
• beef liver
• egg

Vitamins A (beta carotene), C, and E contain substances called antioxidants. Antioxidants help remove free radicals, which are the waste products of natural bodily processes that can build up in the body. If the body cannot eliminate enough free radicals, oxidative stress can develop. A number of health problems can result, which may include anxiety and depression.

The results of a 2012 study suggested that consuming vitamins that provide antioxidants may reduce symptoms of anxiety in people with generalized anxiety disorder. Fresh, plant-based foods, such as berries, are good sources of antioxidants. A diet that is rich in fresh fruits and vegetables, soy, and other plant products may help reduce the stress-related symptoms of depression.

Vitamins B-12 and B-9 (folate, or folic acid) help protect and maintain the nervous system, including the brain. They may help reduce the risk and symptoms of mood disorders, such as depression.

Sources of vitamin B-12 include:

• eggs
• meat
• poultry
• fish
• oysters
• milk
• some fortified cereals

Foods that contain folate include:

• dark leafy vegetables
• fruit and fruit juices
• nuts
• beans

Diet may play a role in depression. Following a diet that is low in processed foods and provides plenty of fresh, plant-based foods and healthful fats may help improve symptoms.

Other tips that may help include:

• getting at least 150 minutes of physical exercise each week
• spending time outdoors
• avoiding the use of alcohol and other substances
• getting 7–8 hours of sleep in every 24 hours