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What is Depression? Types, Symptoms, Causes


Depression is a powerful opponent that millions of people worldwide grapple with. It’s more than just feeling down; it affects your mood, thoughts, and daily life.

Did you know that over 280 million people worldwide grapple with depression, according to the World Health Organization? Yet, for something so widespread, it often remains shrouded in misunderstanding and stigma.

So, what is depression? How does it creep into our lives, affecting us in ways beyond mere sadness?

Key Takeaways:

  • Depression, also known as major depressive disorder (MDD) or clinical depression, is a complex mental health condition that affects an individual’s mood, thoughts, and daily life.

  • There are various types of depression, including major depressive disorder (MDD), persistent depressive disorder (PDD), bipolar disorder, and postpartum depression, each with unique features.

  • Common symptoms of depression include persistent sadness, loss of interest or pleasure in activities, changes in appetite or weight, sleep disturbances, fatigue, difficulty concentrating, and thoughts of self-harm or suicide.

  • Depression can have biological factors like genetics, hormonal imbalances, neurotransmitter disruptions, inflammation, and environmental factors such as stressful life events, social isolation, and lifestyle choices.

  • Diagnosis of depression is based on specific criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), and it often involves a comprehensive assessment by a mental health professional.

  • Treatment options for depression include antidepressant medications, psychotherapy (talk therapy), and, in severe cases, brain stimulation therapies like electroconvulsive therapy (ECT) or transcranial magnetic stimulation (TMS).

  • Depression can significantly impact a person’s daily life, work, social relationships, and overall well-being, reducing productivity, increasing absenteeism, and challenges maintaining healthy connections.

  • Depression can co-occur with other mental health conditions, such as anxiety disorders, bipolar disorder, and substance use disorders, making it more complex to diagnose and treat.

  • Providing support, empathy, and encouragement for individuals with depression is crucial, and encouraging them to seek professional help can be a vital step toward recovery.

What is Depression?

Depression, often called major depressive disorder (MDD) or clinical depression, is a complex and debilitating mental health condition that profoundly affects an individual’s mood, thoughts, and daily life.

It is characterized by a persistent and pervasive sadness, hopelessness, and a loss of interest or pleasure in previously enjoyable activities. This condition is a medical illness requiring attention and treatment.

Fortunately, depression is highly treatable. Treatment options include psychotherapy (talk therapy), medication, brain stimulation therapies like electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), and lifestyle changes.

What Are the Different Types of Depression?

Depression doesn’t present itself in a one-size-fits-all manner. There are several types of depression, each with unique features and challenges. The most common types include major depressive disorder (MDD), persistent depressive disorder (PDD), bipolar disorder, and postpartum depression.

  • Major Depressive Disorder (MDD): MDD, often referred to as clinical depression or major depression, is characterized by profound and persistent sadness, loss of interest in daily activities, and difficulty in concentrating. It can affect people of all ages and backgrounds and is one of the most prevalent mental disorders globally.

  • Persistent Depressive Disorder (PDD): PDD, formerly known as dysthymia, is a form of chronic depression lasting at least two years. Persistent depressive disorder typically presents as a mild depression (at least in comparison to major depression), but it can still significantly impair daily life.

  • Bipolar Disorder: While not always classified as a type of depression, bipolar disorder is characterized by mood swings that include depressive episodes. People with bipolar disorder experience depression alternating with periods of mania (elevated mood).

  • Postpartum Depression: After childbirth, postpartum depression can affect new mothers, causing depression symptoms such as sadness, fatigue, and difficulty bonding with the newborn.

What Are the Common Symptoms of Depression?

Clinically, depression is defined by specific diagnostic criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). To be diagnosed with major depressive disorder, an individual must exhibit:

  1. Depressed Mood: A persistent sadness or a consistently low mood, lasting for most of the day and almost every day.

  2. Loss of Interest or Pleasure: A marked loss of interest or pleasure in activities that were once enjoyed, known as anhedonia.

In addition to these core symptoms, individuals with depression often experience a range of other emotional, physical, and cognitive symptoms, which may include:

  • Feelings of guilt, worthlessness, or self-blame.

  • Changes in appetite or weight (significant weight loss or weight gain).

  • Sleep disturbances, such as insomnia or hypersomnia.

  • Fatigue or loss of energy.

  • Difficulty concentrating or making decisions.

  • Psychomotor agitation or retardation (restlessness or slowed movements).

  • Recurrent thoughts of self-harm, death, or suicidal ideation.

Not everyone who has depression experiences the same symptoms. Some people may have more severe symptoms than others.

Some people may experience depression-related physical illnesses like headaches, stomachaches, or chronic pain. Some people may have other mental health conditions like anxiety, bipolar disorder, or substance use disorders.

What Emotional Symptoms Are Typically Associated with Depression?

Emotional symptoms are a hallmark of depression and play a central role in its diagnosis and impact on an individual’s well-being.

Following are some emotional symptoms often associated with major depressive disorder, some of which are included as DSM-5 criteria, but also others that can still be common related signs of the condition:

  • Persistent feelings of sadness and hopelessness

  • Loss of interest or pleasure in most or all normal activities, such as hobbies, sports, or sex

  • Angry outbursts, irritability, or frustration, even over small matters

  • Feelings of worthlessness or guilt, fixating on past failures or self-blame

  • Trouble thinking, concentrating, making decisions, and remembering things

  • Frequent or recurrent thoughts of self-harm or death (e.g., suicidal thoughts, suicide attempts, or suicide ideation)

  • Anxiety, agitation, or restlessness

  • Feeling tearful, empty, or numb

  • Having low self-esteem or confidence

These emotional symptoms can vary in severity and duration. Depression affects different aspects of your life, such as your relationships, work, school, or hobbies. They can also make you more vulnerable to physical illnesses and other mental health problems.

Are There Physical Symptoms Linked to Depression?

Depression isn’t just a mental health problem. It can also cause physical signs that may interfere with your daily functioning. Some of the physical symptoms of depression include:

  • Changes in appetite or weight (eating too much or too little)

  • Changes in sleep patterns (sleeping too much or too little, insomnia, or restless sleep)

  • Fatigue and lack of energy

  • Headaches, backaches, or other pains

  • Digestive problems, such as nausea, constipation, or diarrhea

  • Slowed movements or speech

  • Restlessness or agitation

If you have any of these symptoms for over two weeks, you may have depression and should seek professional help.


What Causes Depression?

The exact causes of depression are not fully understood. However, researchers believe that biological factors and environmental factors play a role in the development of depression.

How Do Biological Factors Contribute to Depression?

Biological factors refer to the changes in the brain chemistry, structure, and function that affect mood and behavior. Some of these risk factors are:

  • Genetics: A family history of depression may increase your risk of developing it.

  • Hormones: Changes in hormone levels due to pregnancy, childbirth, menopause, or thyroid problems may trigger or worsen depression.

  • Neurotransmitters: These are chemical messengers that help the brain cells communicate with each other. Imbalances in neurotransmitters such as serotonin, dopamine, and norepinephrine may contribute to depression.

  • Inflammation: Chronic inflammation in the body may affect the brain and cause depression.

  • Medical conditions: Some conditions such as diabetes, heart disease, cancer, stroke, Parkinson’s disease, Alzheimer’s disease, and HIV/AIDS may cause or worsen depression.

What Is the Role of Environmental Factors?

Environmental factors are external events and situations that affect your mood and well-being. Some of these factors are:

  • Stressful life events: Stressful events like losing a loved one, going through a divorce, losing a job, having financial problems, experiencing trauma or abuse, or facing a severe illness may trigger or worsen depression.

  • Social isolation: A lack of social support, feeling lonely, or being rejected by others may increase your risk of developing depression.

  • Lifestyle factors: Poor sleep habits, eating an unhealthy diet, being physically inactive, smoking, drinking alcohol excessively, or using recreational drugs may contribute to depression.

How is Depression Diagnosed?

Depression is diagnosed based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria, the standard reference for mental health professionals.

According to the DSM-5, a person must have at least five of the following symptoms for at least two weeks, and one of them must be depressed mood or loss of interest or pleasure:

  • Depressed mood most of the day, nearly every day

  • Markedly diminished interest or pleasure in all or almost all activities most of the day, almost every day

  • Significant weight loss or gain, or decrease or increase in appetite

  • Insomnia or hypersomnia nearly every day

  • Psychomotor agitation or retardation almost every day

  • Fatigue or loss of energy almost every day

  • Feelings of worthlessness or excessive or inappropriate guilt almost every day

  • Diminished ability to think or concentrate, or indecisiveness almost every day

  • Recurrent thoughts of death, suicidal ideation, or a suicide attempt

The depressive symptoms must cause significant distress or impairment in social, occupational, or other important areas of functioning.

What Tests and Assessments Are Commonly Used?

There is no single test that can diagnose depression. However, some tests and assessments can help rule out other possible causes of the symptoms, such as thyroid problems, anemia, vitamin deficiencies, infections, or brain tumors.

Some of these tests include:

  • Blood tests: These can check for levels of hormones, electrolytes, glucose, and other substances that may affect mood and energy.

  • Urine tests: These can screen for drugs, alcohol, or toxins that may contribute to depression.

  • Physical examination: This can check for signs of illness, injury, or infection that may cause depression.

  • Neurological examination: This can assess for any problems with the brain or nervous system that may affect mood and cognition.

  • Brain imaging: This can include computed tomography (CT) scan, magnetic resonance imaging (MRI), positron emission tomography (PET) scan, or single-photon emission computed tomography (SPECT) scan.

  • Psychological tests: These can include questionnaires, interviews, rating scales, or inventories that measure the severity and type of depressive symptoms, as well as other aspects of mental health such as personality traits, coping skills, cognitive abilities, and social support.

What Is the Process for Diagnosis?

The process for diagnosis usually involves several steps:

The first step is to consult with a primary care provider (PCP), who can perform a general health evaluation and refer the person to a mental health professional if needed.

The second step is to see a mental health professional (MHP), such as a psychiatrist, psychologist, counselor, social worker, or nurse practitioner. The MHP can conduct a comprehensive mental health assessment and diagnosis based on the DSM-5 criteria and other clinical information.

The third step is collaborating with the MHP to develop a treatment plan that suits the person’s needs and preferences. The treatment plan may include medication, psychotherapy, or both.


What Are the Treatment Options for Depression?

The main treatment options for depression are antidepressant medications and psychotherapy. Sometimes, they are used together in combination therapy.

How Effective Are Antidepressants?

Antidepressant medications are drugs that work by altering the levels of certain chemicals in the brain called neurotransmitters. These chemicals regulate mood, emotion, cognition, and behavior.

Antidepressants are effective for many people with depression, but not for everyone. Some people may respond better to one type of antidepressant than another or may need to try different doses or combinations to find the best fit.

Some people may not respond to any antidepressant or experience intolerable side effects. This is called treatment-resistant depression.

What Therapies Are Used for Treating Depression?

Psychotherapy, or talk therapy, involves talking to a trained mental health professional about your thoughts, feelings, and experiences.

This can help you understand the causes of your depression, cope with stress and negative emotions, change unhealthy patterns of thinking and behavior, and improve your relationships and self-esteem.

Different types of psychotherapy can be used to treat depression, such as cognitive-behavioral therapy (CBT), interpersonal therapy (IPT), problem-solving therapy (PST), dialectical behavior therapy (DBT), acceptance and commitment therapy (ACT), and others.

Each type has its own goals and techniques, and different people may benefit from other types of psychotherapy.

For severe depression, especially when other treatments have not worked, brain stimulation therapies may be an option. These therapies use electrical currents or magnets to stimulate specific brain areas involved in depression.

Some examples of brain stimulation therapies are electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), vagus nerve stimulation (VNS), and deep brain stimulation (DBS).

How to Help Someone with Depression?

Support from friends and family is invaluable for individuals with depression. Here are some ways to provide meaningful support:

  • Be empathetic: Listen actively and show understanding of their feelings and struggles.

  • Encourage professional help: Encourage them to seek assistance from a mental health professional who can provide expert guidance and treatment.

  • Stay connected: Maintain regular contact and offer companionship, even when they feel uncomfortable engaging with others.

  • Educate yourself: Learn more about depression to understand their experiences and challenges.

How Does Depression Affect Daily Life?

Depression can cause emotional and physical problems that interfere with daily life, work, and social settings. It can also affect relationships, both with oneself and with others.

Symptoms of depression can make it hard to function normally in daily life. For example, people with depression may have trouble getting out of bed, taking care of themselves, or fulfilling their home, school, or work responsibilities.

They may also isolate themselves from others, avoid social situations, or lose interest in hobbies or friends. Depression can also affect one’s self-esteem, confidence, and motivation.

What Are the Challenges in Work and Social Settings?

Depression can also harm work and social settings. People with depression may experience:

  • Reduced productivity, performance, or quality of work

  • Increased absenteeism, tardiness, or turnover

  • Difficulty meeting deadlines, following instructions, or collaborating with others

  • Conflict, misunderstanding, or dissatisfaction with coworkers, supervisors, or clients

  • Decreased creativity, innovation, or problem-solving skills

These challenges can affect one’s career prospects, income, and job satisfaction. They can also create stress and anxiety that worsen the symptoms of depression.

How Does Depression Affect Relationships?

Similarly, depression can affect one’s social life and relationships. People with depression may experience:

  • Reduced social support, connection, or intimacy

  • Difficulty communicating, expressing emotions, or resolving conflicts

  • Increased irritability, anger, or frustration

  • Withdrawal from family, friends, or community activities

  • Loss of trust, respect, or empathy from others

These issues can affect one’s mental health and well-being. They can also make it hard to form healthy and fulfilling relationships with others.

They can also increase the risk of other mental health issues such as anxiety, substance abuse, or eating disorders.

Can Depression Co-Exist with Other Mental Health Conditions?

Depression can co-exist with other mental health conditions, such as anxiety disorders, bipolar disorder, schizophrenia, and substance use disorders.

When depression and another mental health condition occur, it is called comorbid depression. Comorbid depression can make both conditions worse and more challenging to treat.

What Is Comorbid Depression?

Comorbid depression is when people experience depression and other mental illnesses simultaneously. For example, a person may have depression and an anxiety disorder, such as generalized anxiety disorder, panic disorder, or social anxiety disorder. Anxiety is the most common mental illness that co-occurs with depression.

Comorbid depression can also occur with other types of mental health conditions, such as:

  • Bipolar disorder

  • Schizophrenia

  • Substance use disorders

  • Eating disorders

  • Personality disorders

How Does Depression Interact with Anxiety Disorders?

Depression and anxiety disorders can have similar or overlapping symptoms, such as:

  • Feeling sad, hopeless, or worthless

  • Having trouble sleeping or sleeping too much

  • Losing interest in activities you used to enjoy

  • Having difficulty concentrating or making decisions

  • Having low energy or fatigue

  • Having changes in appetite or weight

  • Having thoughts of death or suicide

  • Feeling restless, irritable, or on edge

  • Having panic attacks or avoiding certain situations

  • Having intrusive thoughts or compulsions

  • Having flashbacks or nightmares

However, depression and anxiety-related disorders can also have different or opposite symptoms. For example:

  • Depression can make you feel numb or empty, while anxiety can make you feel overwhelmed or flooded with emotions.

  • Depression can make you feel sluggish or slow down your movements, while anxiety can make you feel jittery or speed up your actions.

  • Depression can isolate you from others, while anxiety can make you seek reassurance or support.

The interaction between depression and anxiety can vary from person to person. Some people may have more symptoms of one condition than the other. Some people may have episodes of both conditions at the same time.

Some people may have one condition that triggers the other. For example:

  • A person with major depression may develop an anxiety disorder due to feeling hopeless about their future or fearing the consequences of their actions.

  • A person with an anxiety disorder may develop major depression due to feeling exhausted from their constant worry or avoiding the things they love.

  • A person with perinatal depression may develop postpartum anxiety due to feeling overwhelmed by the demands of caring for a newborn or worrying about their baby’s health.

  • A person with seasonal affective disorder may develop generalized anxiety disorder due to feeling depressed during winter or anxious about changing seasons.

Discover Hope and Healing at Lucid Wellness Center with Transcranial Magnetic Stimulation (TMS)

If you or a loved one are battling depression and seeking an effective treatment option, don’t lose hope. Lucid Wellness Center specializes in Transcranial Magnetic Stimulation (TMS), a cutting-edge therapy that offers new possibilities for those with treatment-resistant depression.

Experience the transformative power of TMS and take the first step towards reclaiming your life.

Contact Lucid Treatment Center today to learn more about our personalized treatment plans and how TMS can make a difference in your journey to recovery.


Adams, Mark J., et al. “Genetic stratification of depression by neuroticism: revisiting a diagnostic tradition.” Psychological Medicine 50.15 (2020): 2526-2535.

Kessler, Ronald C., and Evelyn J. Bromet. “The Epidemiology of Depression across Cultures.” Annual Review of Public Health, vol. 34, 2013, p. 119, Accessed 6 Oct. 2023.

Reddy, M. S. “Depression: The Disorder and the Burden.” Indian Journal of Psychological Medicine, vol. 32, no. 1, 2010, pp. 1-2, Accessed 6 Oct. 2023.

Van Praag, H. M. “Can stress cause depression?.” Progress in Neuro-Psychopharmacology and Biological Psychiatry 28.5 (2004): 891-907

World Health Organization. “Depression.” WHO, Accessed 6 Oct. 2023.

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