Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 8/30/2021
Major depressive disorder (MDD, or major depression) is a serious, widespread mood disorder that affects tens of millions of people every year.
In fact, according to data from the 2017 National Survey on Drug Use and Health, an estimated 17.3 million adults in the United States, or 7.1 percent of the US adult population, are affected by major depressive disorder.
Major depressive disorder can affect just about every aspect of your life, from your mood to your physical health and cognitive function.
Because the effects of major depression can be severe, it’s important to seek expert help if you feel worried that you could be depressed.
Below, we’ve discussed what major depressive disorder is, as well as the symptoms you could experience if you’re depressed and the factors that can cause or contribute to depression.
We’ve also explained what you can do to treat major depressive disorder, from medications to therapy, lifestyle changes and more.
Major depressive disorder is a mood disorder. It’s often referred to as major depression, MDD, or simply as depression.
MDD affects about one in every six adults at some point in life and is twice as common in women as it is in men.
If you have major depressive disorder, you may experience a variety of symptoms, including a depressed mood, reduced levels of energy, difficulty sleeping normally and a lack of interest in hobbies, activities and other tasks that you used to enjoy.
Major depressive disorder can take a serious toll on your life. It can affect your relationships, job performance and even your physical health.
Because its effects can be so debilitating, it’s important to recognize major depression and seek help if you think you’re affected.
Major depressive disorder can cause a range of mental and physical symptoms, some of which can have a major impact on your daily life.
It’s normal to occasionally feel sad, anxious or unhappy. It’s also normal to sometimes feel tired or less interested in life than you normally are.
However, when these issues continue for weeks or months at a time, they’re often signs that something isn’t right.
If you’ve experienced any of the symptoms below for a period of two weeks or longer, you may have major depressive disorder:
A persistent sad or “empty” mood. When you’re depressed, you may have persistent feelings of sadness, anxiety or an “empty” mood. This negative mood and outlook might persist regardless of day-to-day events.
Reduced interest in your hobbies. Things that normally make you feel happy, such as hobbies and other activities, might no longer interest you. You may no longer find certain activities pleasurable or enjoyable.
Pessimistic, guilty or hopeless feelings. You may feel hopeless and pessimistic about the future, or as if you’re not important or valuable. You may feel like there’s nothing that you can do to improve your situation or make life better.
Irritability and agitation. You may find that you get irritated easily, including by things or behaviors that previously won’t affect you. Men with depression often hide their emotions by displaying anger, irritability or aggressive behavior.
Difficulty falling asleep or staying asleep. You may find it harder to fall asleep or stay asleep during the night. Many people with depression wake up early in the morning or oversleep, affecting their ability to get out of bed the next day.
Fatigue and reduced energy. You may feel fatigued, or as if you have less energy than normal. People with major depression often feel excessively sleepy during the daytime, which may affect energy levels and physical performance.
Slow movement and speech. If you have major depressive disorder, you may speak or move at a slower pace. Some people with depression also have slower eye movement, facial expressions and changes in their posture.
An increase in needless physical movement. You may notice that you’re unable to sit still for long periods of time, or that you wring your hands, feel a need to walk around the room or make other purposeless physical movements.
Headaches, cramps, digestive issues and other acne and pains. You may develop pain, discomfort or digestive issues that don’t have an obvious cause. These may not improve, even with medication and other forms of treatment.
Changes in your appetite and/or body weight. You may experience changes in your appetite, such as increased or decreased hunger. These changes and their impact on your eating habits may cause you to experience weight gain or weight loss.
Difficulty concentrating or remembering. You may find it more difficult to concentrate on specific tasks, make decisions or remember information.
This can make performing your job or studying more challenging and mentally demanding.
The symptoms of major depression can vary from person to person. You may only develop one or two symptoms, or experience a wide range of symptoms.
Some of these depression symptoms may be more severe or persistent than others.
Major depressive disorder can affect people of all ages and backgrounds. It’s very possible for a person to develop depression even if their life appears to be comfortable, happy and fulfilling.
Although experts haven’t yet pinpointed an exact cause of depression, research suggests that a variety of genetic, personality, biochemical and environmental factors all potentially contribute to or cause major depressive disorder.
You may have a higher risk of developing major depressive disorder if you:
Have family members affected by depression. Depression can run in families. If you have a first-free relative with major depression(for example, your parent or sibling), you may have an increased risk of developing depression yourself.
Undergo a sudden, major life change. You may become depressed after a sudden or major change in your life, such as the loss of a job, a financial setback or the end of an important or significant relationship.
Experience a traumatic or stressful event. Depression often develops after stressful or traumatic events, such as diverse, the death of a loved one, or neglect or abuse that occurs during childhood.
Have certain personality traits. You may be more likely to develop major depression if you’re pessimistic, if you have low self-esteem or if you’re easily affected by issues such as chronic or severe stress.
Have a physical illness. Some physical illnesses are associated with an elevated risk of depression, including Parkinson’s disease, diabetes, cancer, chronic pain and heart disease.
Use certain types of medication. Certain medications, as well as substances such as alcohol and/or illicit drugs, may contribute to depression and other conditions that affect your mental health.
Major depressive disorder is treatable. By seeking expert help, it’s possible to overcome major depression and put your symptoms behind you.
According to the American Psychiatric Association, 80 to 90 percent of people with depression respond to treatment, with most people experiencing significant improvements.
Common treatments for major depressive disorder include antidepressants, psychotherapy and changes that you can make to your habits and lifestyle.
The first step in treating major depressive disorder is undergoing a diagnostic evaluation with a licensed mental health provider.
You can do this by talking to your primary care provider about your symptoms, reaching out to a mental health professional locally, or remotely using online psychiatry.
Depression is often treated with antidepressants — medications that can improve your feelings, thought processes and behavior.
Antidepressants work by changing the levels of certain chemicals, called neurotransmitters, in your brain and body.
Common neurotransmitters targeted by antidepressants include serotonin, norepinephrine and dopamine.
Several different types of antidepressants are used to treat major depressive disorder, including:
Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine (available under the brand name Prozac®), citalopram (Celexa®), escitalopram (Lexapro®), fluvoxamine (Luvox®), paroxetine (Paxil®), sertraline (Zoloft®) and others.
Serotonin-norepinephrine reuptake inhibitors (SNRIs), such as venlafaxine (Effexor XR®), duloxetine (Cymbalta®), levomilnacipran (Fetzima®) and desvenlafaxine (Pristiq®).
Tricyclic antidepressants (TCAs) and tetracyclic antidepressants (TeCAs), such as desipramine (Norpramin®), imipramine (Tofranil®), nortriptyline (Pamelor®), mirtazapine (Remeron®), doxepin and others.
Monoamine oxidase inhibitors (MAOIs), such as phenelzine (Nardil®), isocarboxazid (Marplan®), selegiline (Emsam®) and tranylcypromine (Parnate®).
Other antidepressants, such as trazodone (Desyrel®), bupropion (Wellbutrin® SR and XL), esketamine (Spravato®) and others.
For most people, selective serotonin reuptake inhibitors (SSRIs) are used as the first option for treating major depressive disorder.
Most antidepressants take several weeks to start working. You may notice that your ability to fall and stay asleep, mental focus and appetite start to improve before you experience any changes in your mood.
If you’re prescribed antidepressants, make sure to keep using your medication as directed even if you don’t notice any changes.
Your healthcare provider may adjust your dosage or switch you to a different antidepressant if you don’t experience improvements after several months.
Our full list of antidepressants provides more information about the medications above and how they work to treat depression.
Major depressive disorder often improves with psychotherapy, either on its own or alongside the use of antidepressants.
Psychotherapy, or talk therapy, involves talking with a psychiatrist, psychologist or other mental health professional about your moods, feelings, behaviors and the specific mental health issues you’re currently facing.
Therapy can take several forms, including online counseling or a support group with others.
Different forms of therapy used to treat depression include cognitive-behavioral therapy (CBT), interpersonal therapy (IPT) and a variety of other science-based approaches used to deal with the specific problems that you may face as part of your depression.
Our full guide to therapy for depression goes into more detail about how psychotherapy works, as well as the numerous benefits it can have for your moods, behaviors and life outlook.
It’s often possible to reduce the symptoms of major depressive disorder by making changes to your habits and lifestyle.
Your healthcare provider may suggest lifestyle changes to implement while you use medication or take part in therapy.
Try the following lifestyle changes to ease your symptoms and recover from major depressive disorder:
Avoid isolating yourself. When you’re depressed, it’s common to withdraw from social activity. Try to avoid isolating yourself by taking part in meetups, events, group activities and other social activities.
Reach out to friends and family members. Spending time with friends and members of your family is a great way to keep yourself socially active. Your friends and family are also valuable sources of help and support.
Avoid making major life decisions while you’re depressed. Because depression can affect your thoughts and behavior, it’s best to avoid making decisions about your career, relationships or other important parts of your life until after you’ve recovered.
Stay active and exercise regularly. Exercising can trigger the release of neurotrophic factors that improve your brain function and mood. These may help to make depression symptoms less severe and improve your recovery. Try to keep yourself active. Even a short walk or bike ride around your neighborhood is often enough to improve both your physical and mental health.
Focus on making steady, gradual progress. Recovering from major depression takes time. Instead of expecting immediate improvements, focus on making small, measurable progress towards your goals. As you move forward, pay attention to the progress you’ve made. You may notice that a small amount of daily or weekly progress can add up to much larger improvements over the course of several months.
Most of the time, a combined approach involving antidepressants, therapy and lifestyle changes can reduce the severity of depression and help you make progress towards recovery.
When these treatment approaches aren’t effective, your healthcare provider may recommend a different form of treatment, such as electroconvulsive therapy (ECT).
Electroconvulsive therapy is typically used to treat severe depression that doesn’t improve with conventional treatments.
It’s safe and effective for the vast majority of patients but can cause side effects such as confusion and memory issues.
In certain cases, your healthcare provider may suggest other types of brain stimulation therapy, such as vagus nerve stimulation (VNS) or repetitive transcranial magnetic stimulation (rTMS).
Major depression is a common mental disorder that can affect your mood, feelings, relationships and countless other aspects of your daily life.
If you’re experiencing the symptoms of major depressive disorder, it’s important to reach out for help by talking to a mental health professional, or by contacting a close friend or family member for assistance.
Major depressive disorder is treatable, and options such as online mental health services make it easier than ever to get the expert help you need to make progress towards recovery.
You can learn more about treating depression in our full guide to depression treatments, or with our free online mental health resources.