Depression: What It Is, Types, Symptoms, Causes & Treatments

Depression: What It Is, Types, Symptoms, Causes & Treatments

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Life has many ups and downs, and it’s normal to feel the lows from time to time. However, for some people, this sadness may be more severe and longer lasting and is called depression.

Depression is common, and it’s not a character flaw or something you can just snap out of. In 2020, about 21 million adults in the United States experienced at least one major episode of depression, according to the National Alliance on Mental Illness (NAMI)

What is depression?

More than just a bout of the blues, depression doesn’t just go away on its own. It’s characterized by sadness and hopelessness that takes you away from the people you love and the things you typically enjoy. To be diagnosed with depression, the symptoms must be present for at least two weeks.

Types of depression

There are several different types of depression. The main ones include:

  • Major depression: Symptoms of major depression last for at least two weeks and interfere with your daily activities and quality of life.

  • Persistent depressive disorder: This is also called dysthymia or dysthymic disorder, and symptoms last for two years or more.

  • Perinatal depression: This is a specific type of depression that may occur during or after pregnancy. 

  • Seasonal affective disorder (SAD): With seasonal affective disorder, symptoms of depression come and go with the seasons. Depressive symptoms typically start brewing in the late fall and early winter and fade by spring and summer.

  • Depression with symptoms of psychosis: This type of depression travels with delusions, hallucinations and other psychotic symptoms.

Depression symptoms

Depression doesn’t look or feel the same in everyone.

Common depression symptoms may include:

  • Changes in sleep patterns—you may sleep too much or toss and turn all night long

  • Changes in appetite—you may overeat or have no appetite

  • Inability to focus 

  • Lack of energy

  • Irritability 

  • Fatigue

  • Lack of interest in activities you once loved

  • Hopelessness 

  • Aches and pains

  • Suicidal thoughts

These symptoms must be present for more than two weeks and interfere with your daily life, ability to socialize and work to be diagnosed as depression.

Depression causes 

There’s no one single cause for depression. It’s usually a result of a combination of genetics and the environment, according to the American Psychiatric Association.

For some people, depression may be triggered by a life crisis, such as the death of a loved one, a divorce, job loss, physical illness or something else altogether. Importantly, there’s not always a single traumatic event that precedes depression.

Other risks that may set a person up for developing depression include: 

  • Trauma early in life. People who experienced trauma when they’re young may experience long-term changes in their brains, which may increase the risk for depression.

  • Genetics likely play a role as well, as depression does run in families. 

There are also differences in certain brain chemicals found in people who are depressed compared to their counterparts who are not, and these differences may contribute to the risk for depression.

Other factors that may increase the chances of depression include:

Protecting against depression

Some factors are thought to help protect against depression by supporting the brain, cognition, immune system and metabolism.

Steps you may take to help reduce your risk of depression include:

  • Find social connections in your community or online

  • Gather and seek out family and friends

  • Get proper sleep

  • Exercise regularly, aiming for at least 30 minutes per day

  • Eat a healthy diet

  • Avoid excess alcohol, nicotine or drugs not prescribed for you

  • Avoid a sedentary lifestyle as much as possible

According to a 2020 study of more than 1,600 participants in Psychiatry Research, having a strong, supportive family and friend network and ties to the community may help stave off depression. In the study, people with higher levels of perceived social support had a 63% lower risk of depression. This study took place during the COVID-19 pandemic, when shelter-in-place orders were widespread.

Depression treatments 

There isn’t a one-size-fits-all treatment for depression, and something that works for your best friend or colleague may not work for you. The good news is that many options may be tried alone or in combination to help you get your life back. Be patient, and don’t give up hope. There may be some trial and error involved in the treatment process. 

Depression treatment mainstays include medication and therapy

Healthy lifestyle habits are also key to managing depression. The same things that may help lower your risk of depression are important during treatment, such as nutrition and physical activity habits.

In addition, when managing depression, give yourself grace, and be productive at your own pace. Prioritize and break down tasks into smaller tasks that need to get done each day, says the National Institute of Mental Health (NIMH), and wait to make big life decisions until you’re feeling better.

Depression medication


In general, antidepressants target brain chemicals related to mood. Several classes of antidepressants are commonly prescribed to relieve symptoms of depression. They include:

Selective serotonin reuptake inhibitors (SSRIs)

Target: The mood chemical serotonin

Available SSRIs include:

  • Citalopram

  • Escitalopram

  • Fluoxetine

  • Fluvoxamine

  • Paroxetine 

  • Sertraline

Common SSRI side effects may include:

  • Dry mouth

  • Nausea

  • Headaches

  • Sleeping difficulty 

  • Sexual problems

Serotonin and norepinephrine reuptake inhibitors (SNRIs)

Target: The mood chemicals serotonin and norepinephrine

Available SNRIs include:

  • Duloxetine

  • Venlafaxine

  • Desvenlafaxine

Common side effects of SNRIs may include:

  • Nausea, especially when starting the medication

  • Loss of appetite

  • Anxiety

  • Headaches

  • Sleeping issues

  • Dry mouth

  • Constipation

  • Lack of energy

  • Weight loss

  • Sexual difficulty

Atypical antidepressants

Target: Varies; multiple mechanisms of action are targeted

Available atypical antidepressants include:

  • Bupropion

  • Trazodone 

  • Mirtazapine

Each drug has different side effects, but the main ones are:

  • Nausea

  • Fatigue

  • Nervousness

  • Dry mouth

  • Diarrhea

  • Headaches

Tricyclic antidepressants

Target: Three brain chemicals—serotonin, norepinephrine and dopamine

Available tricyclic antidepressants include:

  • Amitriptyline

  • Clomipramine

  • Desipramine

  • Doxepin

  • Imipramine

  • Nortriptyline

  • Protriptyline 

  • Trimipramine

Common side effects may include:

  • Dry mouth

  • Blurry vision

  • Constipation

  • Trouble urinating

  • Cognitive issues

  • Fatigue

  • Worsening of glaucoma

  • Blood pressure effects 

These older antidepressants take longer to start working and have more side effects than SSRIs and SNRIs.

Monoamine oxidase inhibitors (MAOIs)

Target:  A brain enzyme called monoamine

Available MAOIs include:

  • Isocarboxazid

  • Phenelzine

  • Selegiline

  • Tranylcypromine

MAOI side effects may be severe. They may include:

  • Weakness

  • Dizziness

  • Headaches

MAOIs can’t be used with other antidepressants and cold and flu medicines, as the combination may cause serotonin syndrome. Serotonin syndrome is marked by hallucinations, blood pressure fluctuations, fever and agitation.


Until now, ketamine has been mainly known as a "dissociative" anesthetic. It works by “disconnecting you” from your body for use in medical procedures and has been used this way for decades. It’s also used as a street drug with names like Special K.

The U.S. Food and Drug Administration (FDA) approved a form of the drug in 2019 called esketamine, a nasal spray, to treat one type of depression known as treatment-resistant depression. It’s given intranasally in a medical setting under close supervision.

Ketamine works rapidly, often in a few hours, by creating new neural pathways in mood centers of the brain.

Ketamine side effects may include:

  • Euphoria

  • Nausea

  • Dizziness

  • Vision changes

  • Headache

  • Mood fluctuations

  • Sensitivity to light or sound 

  • Feeling drowsy

It also has the potential to be misused, which is why it’s administered only in a healthcare office.

Brain stimulation therapy 

In a nutshell, brain stimulation activates or blocks brain areas via electricity directly through electrodes implanted in the brain or indirectly through electrodes placed on the scalp. The electricity may also be induced by applying magnetic fields to the head.

According to NIMH, approved brain stimulation therapies include:

  • Electroconvulsive therapy

  • Vagus nerve stimulation

  • Repetitive transcranial magnetic stimulation 


Talk therapy is still the cornerstone of treatment for depression.

There are many types of talk therapy, including:

  • One-on-one counseling

  • Group therapy

  • Family therapy 

  • Cognitive behavioral therapy (CBT)

CBT is a time-limited course of therapy designed to identify and change negative thought patterns and behaviors and improve the way you deal with challenging situations. Most other talk therapies stem from CBT with some variation. Today, many of these psychotherapies may be done online via telemedicine.

Light therapy

For people with seasonal depression, light therapy may help reset internal circadian rhythms (the “internal body clock”). Lack of sunlight may cause serotonin levels to dip, which may set the stage for seasonal depression.

Alternative treatments for depression

Many unapproved or alternative treatments are touted as potential depression cures, but it’s best to avoid these therapies, as none of these have the FDA’s stamp of approval. If you’re taking supplements such as St. John’s wort or SAMe, omega-3 fatty acids, 5-HTP or DHEA for depression, make sure to tell your healthcare provider, as these may interfere with your prescription medication.

Living with depression

Learning how to deal with depression may be challenging. It may help to remember that you’re not alone. Millions of people struggle with sadness and hopelessness, and help is available. 

It’s important to try to help yourself, too. This includes maintaining a regular sleep schedule, trying to eat regular, healthy meals and reaching out to loved ones and mental healthcare professionals for support. Self-medicating with alcohol, nicotine, drugs or illicit drugs will only worsen or prolong your symptoms. It's best to avoid them. Getting regular exercise—even just walking for 30 minutes a day—often boosts mood.

Self-care makes a big difference, too, according to the Substance Abuse and Mental Health Services Administration (SAMHSA). This includes taking steps to rein in stress, such as trying yoga, tai chi or deep breathing, or just making time to go for a walk each day.

Don’t be too hard on yourself. Give yourself the time and space to heal. This starts by setting realistic goals every day. It could be just showering and answering a few emails. Living with depression starts with baby steps. 

Never stop taking your antidepressants without discussing with your healthcare provider how, when and why you should stop, or if it makes sense to taper off the drug.

If you're experiencing depression symptoms and need to talk to someone, call 988, the Suicide & Crisis Lifeline. The Lifeline offers free and confidential emotional support across the United States, 24 hours a day, 7 days a week.


National Alliance on Mental Illness (NAMI): Depression.

National Institute of Mental Health (NIMH): Depression.

American Psychiatric Association: What Is Depression?

University of Cambridge: Healthy lifestyle can help prevent depression – and new research may explain why.

Psychiatry Research: The role of perceived social support on depression and sleep during the COVID-19 pandemic.

American Academy of Family Physicians: Types of Antidepressants.

U.S. Food and Drug Administration (FDA): FDA approves new nasal spray medication for treatment-resistant depression; available only at a certified doctor’s office or clinic.

National Institute of Mental Health (NIMH): Mental Health Matters Podcast: Depression: The Case for Ketamine.

University Hospitals: The Benefits of Ketamine Therapy for Depression.

National Institute of Mental Health (NIMH): Psychotherapies.

National Institute of Mental Health (NIMH): Brain Stimulation Therapies.

Cleveland Clinic: How Light Therapy Can Help With Seasonal Affective Disorder (SAD).

Substance Abuse and Mental Health Services Administration (SAMHSA): Depression.

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