Depression Overview

Medically reviewed by Andrea Brant, LMHC
Updated July 12, 2024by BetterHelp Editorial Team

The World Health Organization (WHO) estimates that 3.8% of the population (approximately 280 million people) lives with depression. The experience of depression may vary from person to person, as each human being has a unique set of contributing circumstances, body chemistry, and other factors that impact their experiences.

While the definition of depression by psychologists may vary, the American Psychological Association defines it as “extreme sadness or despair that lasts more than days. [Depression] interferes with the activities of daily life and can cause physical symptoms such as pain, weight loss or gain, sleeping pattern disruptions, or lack of energy.” 

Experiencing symptoms of depression?

Overview of depression

Depression is a serious mental health condition characterized by low mood, feelings of hopelessness, loss of interest, and sleep disruptions. The term depression encompasses several mental disorders, including major depressive disorder (MDD), seasonal affective disorder (SAD), persistent depressive disorder (PDD), and perinatal depression. Additionally, certain mental health conditions can feature depression symptoms; for example, bipolar disorder is typically marked by periods of depression. 

Major depression is one of the most common mental health conditions in the US. Depression can significantly affect an individual’s mental health, physical well-being, and ability to function. Despite its prevalence and potential complications, though, depression is a treatable condition, and its symptoms can be managed through proper mental health care. 

If you believe you’re living with depression, a medical or mental health professional can provide you with screenings and determine whether further testing, a diagnosis, and treatment are necessary. Treatment for depression typically involves medication, psychotherapy, and lifestyle changes. Electroconvulsive therapy (ECT) may also be utilized when depressive symptoms are treatment resistant.  

Symptoms of depression

While depression is a mental health condition, the symptoms of depression are not limited to mental or emotional symptoms. The following are some possible physical symptoms that a person with clinical depression might experience:

  • Fatigue
  • Changes in sleeping patterns
  • Poor appetite
  • Weight loss
  • Weight gain
  • Chronic pain

Depressive symptoms can range from mild to severe and may or may not include the presence of a low or depressed mood. Other common signs of major depression include feelings of emptiness or sadness, loss of interest in normally enjoyed activities, restlessness, and withdrawal from others. 

According to a systematic review of evidence from observational studies, depression may also cause someone to have a lower quality of life (though the review also showed that QoL improved after depression went into remission.) Many adults and adolescents who experience depression may also have difficulty with concentration and low self-esteem. People with depression may also experience thoughts of death, self-harm, or suicide, which can be addressed by experts at a crisis lifeline.*  

If you are experiencing suicidal thoughts or urges, contact the National Suicide Prevention Lifeline at 988. Support is available 24/7.

Potential causes of depression

There can be multiple risk factors for depression. That being said, children and adolescents (and even older adults) who live with one or more of the following risk factors do not automatically experience a major depressive episode.

Understanding the causes of depression can make a significant difference for some when it comes to preventive measures and clinical treatment.

Current literature suggests that individuals with families who have experienced depression may be more vulnerable to this mood disorder.

The quality of a person's lifestyle and upbringing can also be a common causal factor of depression. Someone who is constantly under stress or pressure or who is exposed to environments that are unhealthy may develop depression over time. Traumatic experiences that a person has not yet resolved can also cause symptoms of depression.

Finally, a clinical illness or specific medication (like a psychoactive drug) can alter an individual's brain chemistry and be a contributing factor to depression. This specific risk factor may vary according to the individual's brain chemistry and circumstances.

Types of depressive disorders

There are several types of depressive disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), including major depressive disorder (MDD), seasonal affective disorder (SAD), postpartum depression, and premenstrual dysphoric disorder (PMDD).

Unipolar depressive disorders are characterized by depressive episodes alone, whereas bipolar disorders are characterized by manic and depressive episodes. This list focuses on unipolar depressive disorders.

Depending on the signs and symptoms that a person exhibits, they may be diagnosed via a set of criteria that correlate to a specific depressive diagnosis.

Understanding the different types of depressive disorders may help those experiencing symptoms to understand their condition better. Below are some of the most statistically common forms of depression:

  • Major depressive disorder (MDD): Also called major depression, major depressive disorder can lead to feelings of sadness, low energy, fatigue, physical pain, sleep disruptions, and weight fluctuations. According to the National Institute of Mental Health, for an individual to be diagnosed with major depressive disorder, they must experience symptoms of depression “most of the day, nearly every day, for at least 2 weeks”. 
  • Dysthymic disorder: This condition is generally categorized as a continuous, long-term form of mild depression. The less severe signs and symptoms can occur sporadically and may come and go over a period of years.
  • Seasonal affective disorder (SAD): Seasonal affective disorder typically comes and goes with seasons. For many, seasonal affective disorder occurs in late fall and early winter, and it may be less noticeable during spring and summer.
  • Postpartum Depression: This condition may occur when a person experiences major depression during pregnancy or after delivery. If symptoms of depression are experienced exclusively after birth, clinicians may designate the diagnosis as postpartum depression. This condition may occur when a person experiences major depression during pregnancy or after delivery. If symptoms of depression are experienced exclusively after birth, clinicians may designate the diagnosis as postpartum depression.
  • Premenstrual dysphoric disorder (PMDD): PMDD typically arises a week or two before a person’s period begins, and symptoms often dissipate a few days after their period begins.  PMDD is generally associated with symptoms such as a depressed mood, irritability, and tension. Premenstrual syndrome (PMS) is similar to PMDD; however, PMS generally involves fewer and less severe symptoms than PMDD.

Experiencing symptoms of depression?

Treatment options for depression

Major depressive disorder can seriously affect a person’s quality of life. However, many people can find symptomatic relief with proper treatment (though it is also possible to experience treatment-resistant depression.) Below are several methods that have been shown to be effective in the treatment of depression.


Psychotherapy or talk therapy is one of the leading treatment options for depression. This treatment involves an individual working with a therapist who can get to know them and learn about their symptoms. At this point, the psychotherapist can then begin helping them develop an action plan with techniques that may help to reduce their symptoms and the severity of their condition.


Individuals who are experiencing depression may also be prescribed antidepressant medication. The specific medication that is prescribed can vary from person to person, especially when there is an underlying medical condition, such as heart disease. Always consult with a health care provider prior to starting or stopping any medication. A medical or mental health professional can discuss the efficacy, side effects, and treatment duration of a specific medication. 

Brain stimulation treatment options

If other treatment options do not reduce the occurrence of symptoms of depression, brain stimulation therapies may be an option to explore. Brain stimulation therapies used to treat severe depression include repetitive transcranial magnetic stimulation (rTMS) and electroconvulsive therapy (ECT). Electroconvulsive therapy is a medical procedure that is performed under anesthesia, and it has generally been reserved for patients with intense major depression who have not yet responded to other treatments.

How can online therapy support those living with a mental health condition?

When an individual faces depression or another challenge, they may experience feelings of isolation. This feeling, along with physical manifestations of depression, can make it challenging for a person to leave home. If you don’t feel comfortable with in-office therapy at this time, you might try online therapy, which research has shown to be effective for depression and anxiety. 

Online therapy can be a helpful mental and emotional support option that can be received from the comfort of your own home or anywhere where you feel comfortable. With some therapy platforms, such as BetterHelp, you can also contact your therapist 24/7 via in-app messaging, and they’ll respond as soon as they can.


Depression and related disorders can look different on an individual basis. Strategic supportive methods can help to reduce symptom intensity in some individuals. Online therapy has been found to be effective for those experiencing symptoms of depression. With BetterHelp, you can be matched with an online therapist with training and experience treating people with depression. Take the first step to addressing depression and reach out to BetterHelp today.
Depression is treatable, and you're not alone
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