What Is Depression? Symptoms, Causes, Diagnosis, Treatment, and Prevention

illustration of a black woman covering her face in sadness
Depression is one of the most common mental health conditions among Americans.Adobe Stock

While everyone has experienced sadness, not everyone has experienced depression. In fact, if you’ve never been depressed, chances are that you don’t have a real grasp on what living with this complex mental illness is like.

Depression is insidious. It affects not only your mood, but also your ability to feel, think, and function. It blunts sensations of pleasure, closes off connectedness, stifles creativity, and, at its worst, shuts down hope. It also often causes deep emotional pain not only to the person experiencing it, but to that person’s close family and friends.

Common Questions & Answers

How do I know if I’m depressed?
Typical signs of depression in adults include persistent feelings of sadness or emptiness, feeling irritated, overwhelming feelings of guilt, anxiety, frustration, or anger, changes in appetite, an inability to concentrate, and loss of interest in previously enjoyed activities, among other symptoms.
What causes depression?
The exact cause of depression isn't yet known, but researchers believe factors including genetics, brain chemistry, and hardship may play a role.
Can depression go away on its own?
Depression can come and go, but treatment or therapy can help reduce symptoms. Depression can recur, sometimes triggered by the same problems that led to it in the first place. Some people can stop treatment once symptom-free for several months, while others require ongoing treatment.
How long does it take antidepressants to work?
Some people experience benefits shortly after starting an antidepressant, but research suggests it takes about six to eight weeks for antidepressants to take full effect.

Signs and Symptoms of Depression

If sadness alone isn’t a good gauge of depression, what is? According to the American Psychiatric Association’s (APA) current Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is the diagnostic guide used by most mental health professionals, if you’ve experienced at least five of the following symptoms most of the day, nearly every day, for at least two weeks, you may be diagnosed with major depressive disorder (MDD), also known as clinical depression.

  • Tearfulness, emptiness, or worthlessness
  • Little interest or pleasure in your work, hobbies, friends, family, and other things you once enjoyed
  • Dramatic changes up or down in your appetite or your weight not related to dieting
  • Feelings of listlessness or fatigue for no obvious reason
  • Trouble concentrating or making decisions
  • Anxious restlessness that manifests in ways like pacing or wringing your hands — or the opposite, moving or speaking more slowly than usual
  • Insomnia or sleeping too much
  • Recurrent thoughts of suicide or death

Causes and Risk Factors of Depression

No one knows for sure why some people become depressed and others do not. Depression can occur spontaneously, without any obvious cause. And it’s well documented that once you’ve had one depressive episode, your risk of having another later in life increases.

Psychiatrists today generally look at depression in “bio-psycho-social” terms, meaning that they see it as a complex disorder most likely triggered by overlapping biological, psychological, and social (also referred to as environmental) factors, according to a study published in August 2019 in Psychiatric Times.

Among the potential contributors to depression are:

  • Genetics Many studies suggest that depression can spring from a genetic predisposition, including one international study involving more than 807,000 people, published in the February 2019 issue of the journal Nature Neuroscience, that linked 269 genes to depression. Genes alone are not believed to write your destiny, however. Scientists think that while some genes may increase risk, other factors are needed to trigger symptoms.
  • Neurotransmitters The long-held idea that depression is caused by low levels of certain neurotransmitters (chemical messengers that communicate between neurons) has been debunked, according to a systematic review published in July 2022 in Molecular Psychiatry. But, it’s clear that neurotransmitters play a role, at least for some people. Experts’ current belief is that the relationship between depression and neurotransmitters is complex and may be related to nerve cell connections, nerve cell growth, or the functioning of nerve circuits, Harvard Medical School states.
  • Inflammation Multiple studies indicate that disease-related or stress-related inflammation may create chemical changes in the brain that can trigger or worsen depression in certain people and influence how a person responds to drug therapy, according to a study published May 2018 in Psychiatric Times.
  • Hardship There’s growing evidence, according to the World Health Organization, that psychological and social factors like a history of abuse, poor health and nutrition, unemployment, social isolation or loneliness, low socioeconomic status, or stressful life events (divorce or money worries, for example) can play a decisive role in the onset of depression. For example, adults with MDD have double the rate of childhood trauma compared with people without MDD, a study published May 3, 2016, in the journal Translational Psychiatry showed.
  • Traumatic Brain Injury (TBI) Another all-too-common cause of depression is TBI. In 2019, more than 223,000 people were hospitalized for TBIs (aka concussions) following a bump or blow to the head from things like falls, assaults, car accidents, and workplace and sports-related injuries, according to the Centers for Disease Control and Prevention. And more than half of those patients will meet the criteria for major depression three months after their injury, suggests a study published November 30, 2017, in the journal Brain Injury.

How Is Depression Diagnosed?

To be diagnosed with MDD, one of your symptoms must be a persistent low mood or a loss of interest or pleasure, the DSM-5 states. Your symptoms must also not be due to substance abuse or a medical condition, such as thyroid problems, a brain tumor, or a nutritional deficiency.

Of course, it’s normal to have any or all of these symptoms temporarily (for hours or even days) from time to time. The difference with depression is that the symptoms persist and make it difficult to function normally.

If you suspect you may be depressed, the best first step is to reach out to your primary care doctor, a psychiatrist, or a psychotherapist. Also, know that depression screenings may now be a part of routine checkups. As of June 2023, the U.S. Preventive Services Task Force (USPSTF) recommends that primary care providers screen all adults for depression, including pregnant and postpartum people and older adults.

If you’re reluctant to consult a professional, type “depression” or “clinical depression” into Google on your cellphone or computer and you’ll find links to a clinically validated depression test known as the PHQ-9 patient health questionnaire. Although designed to be administered by a healthcare professional, this test is short and straightforward. Take it and you can immediately see if your score indicates you may have depression.

Important: If you suspect you have depression, or if you’re feeling troubled by your symptoms, have suicidal thoughts, just need to talk, want some advice, or need a referral for treatment, call the Suicide and Crisis Lifeline (formerly known as the National Suicide Prevention Lifeline) at the three-digit code 988, or the National Substance Abuse and Mental Health Services Administration Helpline at 1-800-662-HELP (4357). Both are free and available 24/7, 365 days a year.

Learn More About Depression Symptoms

What Are the Different Types of Depression?

In addition to MDD, there are several other kinds of depression, including:

  • Persistent depressive disorder (PDD), previously known as dysthymia, is diagnosed in people who have at least two of the symptoms of major depression for at least two years at a time, according to Cleveland Clinic. It’s possible to fluctuate between severe and less-severe symptoms, and to have both PDD and MDD at the same time, a condition called double depression. People with PDD are often perceived as cranky, sullen, changeable, or pessimistic rather than being recognized as having a treatable disorder.
  • Bipolar disorder, formerly called manic depressive disease, is characterized by moods that cycle between extreme highs (mania) and lows (depression), often with periods of normal mood in between, according to the American Psychiatric Association. Bipolar disorder affects 2.8 percent of U.S. adults, according to the National Institute of Mental Health.
  • Seasonal affective disorder (SAD) is depression that occurs at the same time each year, usually beginning in fall and persisting through winter, according to Mayo Clinic. SAD is associated with changes in sunlight, and is often accompanied by increased sleep, weight gain, and cravings for foods high in carbohydrates.
  • Premenstrual dysphoric disorder (PMDD) is a more serious form of premenstrual syndrome (PMS). PMDD usually develops a week or two before a woman’s period and passes two or three days after menstruation starts, according to the Office of Women’s Health.
  • Postpartum (or perinatal) depression (PPD) is diagnosed in mothers who experience symptoms of major depression shortly after giving birth (or during pregnancy), the American College of Obstetricians and Gynecologists states. PPD is usually related to a combination of factors, including sharp changes in hormone levels following childbirth. Feelings of intense sadness, anxiety, or exhaustion are much stronger, and last longer, than the “baby blues” — the relatively mild symptoms of depression and anxiety that many new mothers experience in the first few days after childbirth.

Learn More About Perinatal Depression

Learn More About SAD

Learn More About Bipolar Disorder

Learn More About Postpartum Depression

Depression: Recognizing Unusual Symptoms

One reason depression can be hard to identify is that its signs can vary widely from person to person and sometimes be masked by atypical symptoms. For example, some people who are depressed may show it by acting disgruntled, resentful, or irritable. In fact, aggression — including outright acts of violence — can be indicative of “hidden” depression, according to a report published in February 2017 in Psychiatric Times. Depression masquerading as anger may seem surprising at first, but not when you consider that several underlying factors, including alcohol or substance abuse and childhood trauma, have been linked to both.

Similarly, although it’s not clear why, a person who experiences anxiety is at high risk for developing depression, and vice versa. The National Alliance on Mental Illness reports that as many as 60 percent of people with anxiety will also have symptoms of depression; the same goes for people with depression having symptoms of anxiety. Experts say there is often a genetic predisposition for these co-occurring disorders, according to Hartgrove Behavioral Health System.

Depression may also manifest psychosomatically, meaning that instead of presenting first and foremost as a mood disorder, the dominant symptom may be things like vague aches, dizziness, headaches, digestive problems, or back pain, according to a review published in the Journal of Clinical Psychiatry. Complicating matters is that it’s often hard to know whether depression is causing the physical symptoms, or if the physical symptoms are causing depression.

Duration of Depression

How long depression lasts varies from person to person, but according to the DSM-5, a depressive episode lasts at least two weeks.

Untreated depressive episodes appear to last 6 to 12 months, according to StatPearls. Depression also tends to be chronic, with episodes happening again in about half of people who’ve experienced one depressive episode, 70 percent of people who’ve had two episodes, and 90 percent of people who’ve had three episodes. But some people never experience another episode after the first one.

How Do I Know if My Antidepressants Are Working?

Not sure if your antidepressant is helping? Here are some questions to ask yourself, according to psychiatrist Allison Young, MD.
How Do I Know if My Antidepressants Are Working?

Treatment and Medication Options for Depression

If you suspect that depression is interfering with your life, talking about what you’re experiencing and discussing treatment options with a medical professional is essential. As actress Taraji P. Henson, who describes her depression as “suffocating” darkness, recently explained in an interview with Self, “When you’re quiet, things aren’t fixed. It gets worse.”

The good news is that there’s abundant evidence that people with depression who seek treatment will find significant relief from talk therapy (psychotherapy), medication, lifestyle changes, or a combination of all efforts, according to the Anxiety and Depression Association of America.

Which Types of Talk Therapy Work Best for Depression?

The Society of Clinical Psychology rates several types of psychotherapy as highly effective treatments for depression:

  • Behavioral Activation Therapy The aim of this type of therapy is to reverse the downward spiral of depression by encouraging you to seek out experiences and activities that give you joy.
  • Cognitive Behavioral Therapy (CBT) CBT focuses on changing specific negative thought patterns so that you are able to better respond to challenging and stressful situations.
  • Interpersonal Therapy This very structured, time-limited form of therapy focuses on identifying and improving problematic personal relationships and circumstances directly related to your current depressive mood.
  • Problem-Solving Therapy This therapy is a form of CBT that teaches take-charge skills that help you solve real-life problems and stressors, big and small, that contribute to depression.
  • Self-Management or Self-Control Therapy This type of behavioral therapy trains you to lessen your negative reactions to events and reduce your self-punishing behaviors and thoughts.

What Are the Different Antidepressants and How Do They Work?

The most commonly prescribed antidepressants cause changes in brain chemistry that affect how neurons communicate. Exactly how this improves mood remains somewhat of a mystery, but the fact that they do often work is well-established. If you’re thinking about trying antidepressants, talk to your doctor about whether these treatments could be right for you.

All antidepressants can have side effects, but some may be more problematic than others. You may need to try several different medications, or a combination, guided by your doctor, before you find what works best for you.

In addition, it may take some patience before you see results. The full benefits of the drugs may not be realized until you’ve taken them for as long as three months, according to the the STAR*D trial, the largest, longest study on antidepressant treatment, which ended in 2006.

Sometimes, other medications may be added to your regimen, depending on the form of depression, severity of your symptoms, and your response to other therapies. These might include a mood stabilizer, such as lithium (sold under several brand names) or valproic acid (Depakene, Depakote). If symptoms of psychosis (having delusions or seeing or hearing voices that are not real, for example) are present, a doctor may prescribe an antipsychotic medication, such as haloperidol (Haldol), risperidone (Risperdal), ziprasidone (Geodon), aripiprazole (Abilify), and olanzapine (Zyprexa).

Some experts believe that using an antipsychotic in combination with an antidepressant may be more effective for depressive disorders than antidepressants alone, according to a review published in Shanghai Archives of Psychiatry.

Learn More About Depression Treatment

Lifestyle Changes for Depression

Lifestyle changes, such as making art, journaling, exercising more, and practicing yoga or mindfulness, can also alleviate depression and the stress that can heighten it. Alternative treatments like massage, acupuncture, and light therapy may also help.

Diet changes, too, can uplift your mood by reducing inflammation and helping to ensure your brain gets the nutrients it needs to function at its best.

One small randomized controlled study, published October 9, 2019, in the journal PLoS One, found that self-reported symptoms of depression dropped significantly in just three weeks in young adults who changed from a highly processed, high-carbohydrate diet to a Mediterranean diet focused on vegetables, whole grains, lean proteins, unsweetened dairy, nuts and seeds, olive oil, and the spices turmeric and cinnamon. In contrast, the depression scores didn’t budge in a control group of people who didn’t change their diet.

Should You Worry About Antidepressant Withdrawal?

No, but it’s easy to see why some people might think so, because of a medical condition called antidepressant discontinuation syndrome (ADS), which can occur if you abruptly stop taking medication rather than tapering off as is generally advised. ADS is marked by a wide range of responses, including but not limited to flu-like symptoms, insomnia, worsening mood, and stomach distress, according to a report published March 11, 2019, in Psychiatric Times.

Current estimates are that up to 40 percent of patients who’ve taken an antidepressant for at least a month will experience ADS symptoms if they abruptly stop their medication instead of lowering their dose gradually, according to a study published December 2018 in The American Journal of Psychiatry. (Conversely, more than 60 percent of patients who stop taking an SSRI will have no significant symptoms.) Tapering under the care of a doctor can prevent ADS by allowing the brain to adjust to changes in neurotransmitter levels.

More to the point, while you should slowly stop your antidepressant with the help of your doctor, antidepressants do not cause dependence and withdrawal like other substances. Unlike substances that are known to cause addiction, such as alcohol, opioids, and barbiturates, people don't crave antidepressants. You don’t get “high” from them, and they aren’t intentionally or compulsively overused. Serious reactions like the seizures and agitation that can follow sudden withdrawal from addictive substances are “unheard of when these antidepressants are tapered gradually,” note the authors of the Psychiatric Times report.

What Is Treatment Resistant Depression and Is There Any Help for It?

If you’ve tried at least two different antidepressants and your depression hasn’t improved, you may be diagnosed with treatment-resistant depression (TRD). TRD is a serious condition that has been highly associated with suicidal ideation and suicide attempts. Thirty percent of people with TRD attempt suicide in their lifetime, more than double the rate of their treatment-responsive peers, according to a review published in April 2018 in the Journal of Affective Disorders. It is not, however, a hopeless condition. A number of alternative treatment approaches are available, including:

  • Esketamine A nasal spray marketed under the name Spravato, esketamine won FDA approval on March 5, 2019, as a new treatment for TRD. It is derived from ketamine, a veterinary anesthetic best known as the street drug “Special K.” Because of safety concerns, Spravato must be administered in a medical office and should be taken along with an oral antidepressant.
  • Electroconvulsive Therapy (ECT) ECT is the modern-day version of electroshock therapy. It involves a brief electrical stimulation of the brain while the patient is under anesthesia. According to the APA, ECT rapidly provides substantial improvement in approximately 80 percent of patients with severe, uncomplicated major depression. Like any medical procedure, ECT is associated with side effects — most commonly, issues with memory. In most cases, this is short-term; however, some people can experience permanent gaps in memory, per the APA. Nevertheless, current ECT has far fewer side effects than electroshock therapy of the past.
  • Transcranial Magnetic Stimulation (TMS) TMS uses rapidly alternating magnetic fields to change activity in specific areas of the brain. Although researchers don’t fully understand how exactly TMS affects the brain, it appears to influence how the brain is operating and, in turn, improve mood and decrease depressive symptoms, according to Mayo Clinic.
  • Vagus Nerve Stimulation This therapy involves implanting a tiny device in the chest that provides regular mild electrical pulses to the longest of the nerves that arise from the brain. A study published on August 21, 2018, in the Journal of Clinical Psychiatry involving nearly 600 patients with TRD found that vagus nerve stimulation significantly improved quality of life for many patients.
  • Psychedelic Drugs While not yet FDA approved, microdosing with psychedelic drugs to produce a more positive mood in people with chronic depression is the focus of a flurry of research worldwide, including at the Johns Hopkins Center for Psychedelic and Consciousness Research. The possibilities appear vast and promising. For example, one of the latest Johns Hopkins studies, published March 1, 2019, in The American Journal of Drug and Alcohol Abuse, found that a synthetic form of a psychedelic derived from the venom of certain toads provided fast-acting relief from depression and anxiety. However, according to a July 2022 position statement from the APA, there’s not enough evidence yet to endorse the use of psychedelics for the treatment of any mental health condition except during approved investigational studies, and more research is needed in this field.

Prevention of Depression

If you’re wondering how to prevent depression, unfortunately there’s no surefire way. But according to Mayo Clinic, these steps could help:

  • If you suspect you have depression, get professional help early on to keep it from getting worse.
  • Lean on your family or friends for support.
  • Consider long-term treatment to prevent your depressive symptoms from coming back even after you feel better.

Try your best to curb stress in your life.

Complications of Depression

Depression can worsen and take a significant toll on your mental and physical health if it’s not properly treated, according to Mayo Clinic. Potential complications of depression include:

  • Misuse of alcohol or drugs
  • Anxiety disorders
  • Social isolation
  • Family or relationship difficulties
  • Work or school issues
  • Excess weight, which can lead to diabetes or heart disease
  • Pain
  • Self-harm or suicide
  • Early death from other medical conditions

Research and Statistics: How Many People Have Depression?

Unfortunately, there are plenty of people who know exactly what it means to be depressed. In 2020, an estimated 21 million, or 8.4 percent, of adults in the United States had at least one major depressive episode in the past year, according to the National Institute of Mental Health, making it one of the most common mental illnesses in the United States.

What’s more, a recent report from Mental Health America, a nonprofit founded in 1909, offers startling statistics pertaining to one of depression's most disturbing symptoms: thoughts of suicide.

According to its 2023 State of Mental Health in America report, suicidal ideation among adults has reached 4.84 percent (more than 12.1 million people).

There is a bright side. Although there is no one-size-fits-all cure for depression, there are many effective treatment options, one of which is bound to help you heal if you’re struggling with the illness. This cannot be emphasized enough, given that roughly two-thirds of people living with depression do not receive the care they need, according to a report published online February 22, 2019, in the journal Neuropsychiatric Disease and Treatment.

Depression and Gender: Is It Different in Men and Women?

When it comes to depression, there is a distinct gender gap. Depression is nearly twice as common in women as in men, according to data from the National Center for Health Statistics. Hormonal and other biological factors play a role in this disparity. After all, only cisgender women and people with a uterus can have premenstrual or postpartum depression. The same is true of antepartum (or perinatal) depression — depression during pregnancy — which the American College of Obstetricians and Gynecologists estimates affects 1 in 10 pregnant women.

   Poll

Have You Ever Experienced Antidepressant Withdrawal?

How Are People of Color Affected by Depression?

Research on depression within communities of color has revealed a number of differences in the symptoms, diagnosis, and treatment between people of color and white communities.

The symptoms of depression may appear differently among people of color compared with white people, according to the study from February 2019 in Neuropsychiatric Disease and Treatment. For instance, while white people are more likely to have acute depressive episodes, African American people are more likely to experience depression that’s more chronic, prolonged, and debilitating.

In another study, published in December 2022 in Nursing Research, which was focused primarily on Black and African American mothers, participants were more likely to report self-blame, irritability, difficulty sleeping, and an inability to experience pleasure than some of the hallmark symptoms of depression, such as feelings of hopelessness or sadness.

Importantly, the authors of the study noted, traditional depression screening tools may not capture these symptoms, meaning depression may go undetected in some Black and African American women.

Among Black and Hispanic people, major depression goes undiagnosed and is undertreated at a much greater rate than among white people, according to a report published in May 2022 by Blue Cross Blue Shield. When these communities do receive treatment, prescription medication and counseling are utilized less often than in white communities, the report noted.

When it comes to treatment, Asian American and Pacific Islander (AAPI) communities are the least likely racial group to seek professional mental health services, according to Mental Health America. That’s often due to factors like a lack of accessible resources, language barriers, and cultural stigmas surrounding mental health issues.

Learn More About Suicide Risk and Prevention

Related Conditions

When your provider evaluates you for depression, it’s important that they rule out any other potential conditions that could be causing your symptoms. Conditions that may overlap with MDD, according to StatPearls, include:

Importantly, some people may have at least one of the above conditions in addition to depression, according to research published in February 2015 in the Journal of Medical Internet Research. Having multiple mental health conditions at the same time is what’s known as psychiatric comorbidity.

Suicide Discussion

Suicide Discussion

Resources We Love

Favorite Organizations for Depression

American Psychiatric Association (APA)

The APA offers a wealth of information and resources for people who have depression. We love that you can easily locate a doctor who specializes in treating your condition on their Find a Psychiatrist page.

National Institute of Mental Health (NIMH)

The NIMH is the largest research organization in the world committed to understanding the treatment and prevention of mental disorders. Their site offers information about depression and also lets you search for clinical trials in your area.

Favorite Online Support Networks

Anxiety and Depression Association of America (ADAA)

If you’re looking for support, the ADAA can help you find it. Search for a support group near you or start your own.

Depression and Bipolar Support Alliance (DBSA)

This organization provides hope, support, and inspiration to those battling depression and bipolar disorder. DBSA chapters offer support groups around the country. Most are volunteer-run and allow participants to meet with others who might have similar struggles.

Families for Depression Awareness

Families need support, too. This organization caters to family members, friends, and caregivers of those who have depression. Their free webinars cover ways to spot depression and intervene with those who are affected.

Favorite Apps, Products, and Gadgets

7 Cups App

If you’re feeling sad, lonely, or stressed, the 7 Cups app could provide you with online therapy and emotional support, allowing you to speak to someone 24/7 in a confidential setting.

Happify

This app offers activities and games to overcome negative thoughts. You’ll receive a “happiness score” that you can improve each time you play. It’s based on effective, evidence-based psychological strategies. The company says 86 percent of those who use the app report feeling better about their lives after just two months.

Bright Light Therapy Lamp

If you have seasonal affective disorder (SAD), bright light therapy may help improve your symptoms. We like the Verilux HappyLight Lucent 10,000 Lux LED Bright White Light Therapy Lamp. It’s compact and portable, so you can use it on the go. And it received an average of 4.6 stars on Amazon reviews. The cost is around $45.

Favorite Annual Meetings

American Psychiatric Association’s Annual Meeting

The APA’s annual conference covers some of the biggest research breakthroughs in the field of psychiatry, including those related to depression.

Anxiety and Depression Association of America (ADAA Conference)

The ADAA sponsors an annual conference that brings together clinicians and researchers from across the United States and the world. The focus of the meeting is to highlight improved treatments and new data on anxiety, depression, and related disorders.

Favorite Retreat

Sierra Tucson

Sierra Tucson, located in Tucson, Arizona, is a recognized retreat and rehab center for those battling addiction and certain mental health concerns like depression. We like that their comprehensive program is based on individual needs and proven treatment modalities. They also work with insurance companies to try to keep your costs down.

Additional reporting by Leona Vaughn and Christina Vogt.

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Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.

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