Depression: Causes, Types, Symptoms, and Risk Factors

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- Updated by Judy Mullis, MS, RD, Nutritionist


At Longevity Box we believe that long-term health is about much more than longevity supplements like NMN. Mental health and how we think are critical factors when it comes to living long, healthy, vibrant lives. In this article, we look at depression, including risk factors and treatments.

Depression (major depressive disorder) is an illness that causes deep levels of sadness, hopelessness, worthlessness, and a loss of interest in favorite activities. Depression can affect a person’s body with changes in weight due to an increase or decrease in eating, oversleeping or not sleeping enough, and unexplained pains such as neck pain or headaches. There are several types of depression, including Premenstrual dysphoric disorder (PMDD), which is a more severe version of PMS, Persistent depressive disorder (PDD), which is a chronic version of depression; and Bipolar depression, which is depression marked with over-energetic episodes. Perinatal and postpartum depression is also a type of depression that affects mothers before or after childbirth. The symptoms of depression include a sense of deep sadness, persistent feelings of worthlessness or hopelessness, inability to concentrate, and challenges sleeping either too much or too little. The risk factors of depression include the death of a loved one, conflict in close relations, abuse or neglect, life events, medications, substance abuse, a lack of Vitamin D, and a person’s gender identity. The treatments for depression include medication, psychotherapy (talk therapy), and in the worst cases, electroconvulsive therapy (electric shock therapy).

What is Depression?

To learn what is depression (major depressive disorder), it’s essential to understand that depression is a medical illness that affects your feelings, your thoughts, and your overall behavior. Depression is marked by sadness, loss of interest, weight loss or increase, difficulty sleeping, an increase in ‘keeping busy’ (e.g., inability to sit still), and thoughts of suicide. Symptoms must last at least two weeks before they can be considered depression. Depression can cause a person to experience emotional and physical problems, limiting their ability to function in daily life.

How common is Depression?

Clinical depression is moderately common, affecting 8.1% of people in the USA over 20, according to the Centers for Disease Control and Prevention in 2018. Depression affects women twice as much as men, with depression being diagnosed in 10.4% of women, and 5.5% of men.

What are the types of Depression?

The types of depression are listed below, and help us understand depression definition.

  1. Premenstrual dysphoric disorder (PMDD) - PMDD affects women specifically and is marked by irritability, depression, mood swings, and physical signs such as breast tenderness and cramps.
  2. Persistent depressive disorder (PDD) - PDD is a long-term or continuous form of depression that doesn’t go away with time.
  3. Bipolar depression - Bipolar depression is when a person has manic (high energy) episodes followed by depressive episodes.
  4. Perinatal and postpartum depression - Perinatal and postpartum depression is when a mother has severe depression either before or after childbirth without improvement.
  5. Major depressive disorder (MDD) - MDD is a more severe form of depression, classified by a depressed mood, weight loss or gain, inability to concentrate, and recurrent thoughts of suicide.

1. Premenstrual dysphoric disorder (PMDD)

Premenstrual dysphoric disorder (PMDD) is a more severe premenstrual syndrome (PMS), the changes a woman undergoes before or during their period that affect their body and mental state. Premenstrual dysphoric disorder (PMDD) is marked by irritability and depression before the period starts, with symptoms disappearing a few days after the period ends, according to Women’s Health in 2021. More symptoms of PMDD include panic attacks, mood swings, crying, difficulty sleeping, and physical symptoms like breast tenderness, cramps, and headaches. PMDD differs from major depressive disorder symptoms (MDD), as PMDD only affects women, while MDD can affect both genders. A doctor will ask about your health history to diagnose PMDD and follow up with a physical examination.

2. Persistent depressive disorder (PDD)

Persistent depressive disorder (PDD) is one definition of depression as it is considered long-term or continuous depression, according to the Cleveland Clinic in 2021. Persistent depressive disorder is marked by sadness, lack of interest in activities, and difficulty concentrating. Feelings of hopelessness and low self-worth may also mark PDD. To diagnose PDD, a doctor may ask mental-health-related questions and ask for blood or urine samples to determine the cause of the symptoms.

3. Bipolar depression

Bipolar depression is a type of depression marked by days of hyperactivity and an upbeat attitude, then days of sadness, anxiety, and the lack of energy to do anything. Bipolar depression is split into three sub-types, Bipolar I, Bipolar II, and Cyclothymic disorder, and can help us understand is depression a disease, according to the NIH National Institute on Mental Health in 2022. 

Bipolar I is the most severe of bipolar depression and is marked by extreme manic episodes (uncontrolled high energy) that last at least a week. Bipolar I is then followed by depressive episodes that last at least two weeks, marked by sadness, trouble sleeping, and lack of interest. Bipolar II is similar to Bipolar I; however, the episodes are either shorter or less severe. Cyclothymic disorder also consists of manic or depressive symptoms, but are not severe enough or last long enough to be considered episodes. To diagnose bipolar depression, a doctor will complete physical and mental health examinations and may refer you to a psychiatrist for treatment.

4. Perinatal and postpartum depression

Perinatal and postpartum depression is a type of depression that may affect a woman before and after childbirth. Perinatal and postpartum depression symptoms include extreme sadness, anxiety, lack of energy, and the inability to perform basic tasks. Perinatal and postpartum depression is different compared to major depressive disorder as it typically revolves around a mother and their child, a feeling of being overwhelmed, and other factors such as life stress and environmental factors. To diagnose perinatal and postpartum depression, a doctor will run a health and mental examination and may refer you to a trained mental health specialist.

5. Major depressive disorder (MDD)

Major depressive disorder (MDD), according to the NIH National Library of Medicine in 2022, is when a person has a continuous depressed mood, a feeling of guilt or lack of self-worth, an inability to concentrate, an inability to sleep, and suicidal thoughts. Major depressive disorder can help us better understand is depression a mental illness in its statistics, affecting over 280 million people worldwide, according to WHO in 2021. To diagnose MDD, a doctor may run a physical and mental examination and lab tests to determine the best course of action.

What are the Causes of Depression?

The causes of depression, which can help us understand what is depression are listed below.

  • Chemical imbalances - chemical imbalances in the brain, such as low dopamine levels, can affect a person’s mood and contribute to depression.
  • Trauma - Trauma, abuse, or neglect are all factors that can affect a person physically and emotionally.
  • Chronic health issues - Chronic health issues, or long-lasting chronic pain, can affect a person severely over time and may contribute to depression.
  • Substance abuse or addiction - Substance abuse (such as alcohol) or addiction can affect a person’s ability to feel in control, and may contribute to feelings of low self-worth and depression.
  • Grief and social isolation - Grief caused by the passing of a loved one, and social isolation or relationship issues, can all contribute to a persistent depressed feeling.
  • Financial troubles - Having debt, or the loss of a job, can all contribute to depression.
  • Genetics - Genetics, and history in the family of having depression can all contribute to a person developing depression.

It should be noted that depression is usually caused by several factors, not by any single factor.

What are the Symptoms of Depression?

The symptoms of depression that allow us to define depression are listed below.

  1. Hopeless outlook - A hopeless outlook can cause a person to feel overwhelmed, worsening the symptoms of depression.
  2. Lost interest - A loss of interest in familiar activities is a mark of depression due to a change in brain chemistry.
  3. Increased fatigue and sleep problems - Increased fatigue and sleep problems
  4. Anxiety - Anxiety
  5. Irritability in men - Irritability in men is usually a symptom where men try to hide their feelings with excessive anger or aggression.
  6. Changes in appetite and weight - Changes in appetite and weight are caused by low energy levels and mood changes and can contribute to depression.
  7. Uncontrollable emotions - Uncontrollable emotions, such as tears or anger, can be a symptom of depression as people have less control over their feelings when they are overwhelmed.
  8. Looking at death - Looking at death and having suicidal thoughts is a symptom of depression, as people may consider death as a way to be free from their feelings.

1. Hopeless outlook

A hopeless outlook (feeling helpless and hopeless about one’s future) is a symptom of depression because depression can alter a person's perspective and make them feel overwhelmed. This can result in a negative, pessimistic outlook. This hopeless outlook can worsen the symptoms of depression and can give insight into is depression real.

2. Lost interest

A lack of interest or pleasure in activities once enjoyed is a common symptom of depresion (also known as anhedonia). This is due to changes in brain chemistry and a lack of energy and can contribute to feelings of hopelessness, sadness, and fatigue, further increasing the symptoms of depression.

3. Increased fatigue and sleep problems

Increased fatigue and sleep problems (low energy levels and trouble falling asleep) are common symptoms of depression because depression can disrupt the normal sleep-wake cycle of the body. A depressive episode may lead to a decreased ability to fall asleep or feel rested, further contributing to fatigue and sleep problems.

4. Anxiety

Anxiety is a symptom of depression, characterized by a general sense of unease, fear, or panic about a situation. Anxiety goes hand in hand with depression, as depression is an illness. People who have depression usually have another mental health issue, such as an anxiety disorder, according to the Centers for Disease Control and Prevention in 2022. 

5. Irritability in men

Irritability in men is a specific symptom of depression meaning, as men tend to hide their feelings more than women. Irritability in men occurs when men hide their sad feelings with anger, irritation, or aggression, while women may instead express sadness, according to the NIH National Library of Mental Health in 2017.

6. Changes in appetite and weight

Changes in appetite and weight, such as a decrease in eating, or less weight, despite not doing any dieting regimens, can indicate one of many severe depression symptoms. Changes in appetite and weight are symptoms of depression, as depression can alter a person’s mood and energy levels, which can change a person’s eating habits. Some may find they eat less, and not enjoy what they eat, while others will overeat, which can increase weight gain. Changes in appetite can be a physical example of internal depression and anxiety.

7. Uncontrollable emotions

Uncontrollable emotions, such as crying or angry outburst, are a symptom of depression as depression can affect a person’s ability (or lack thereof) to control their emotions. A feeling of worthlessness, sadness and a hopeless outlook can all cause a person to feel not in control of their feelings. This can result in intense mood swings and shed light on what is major depressive disorder.

8. Looking at death

Looking at death, being obsessive over death, or thoughts of suicide are all symptoms of depression, according to Mental Health America in 2022. Looking at death can give us some insight into what does it mean to be depressed, as those with severe depression may be looking for an ‘out’, and considering death as an option.

When do Depression Symptoms Usually Occur?

Depression symptoms usually occur in a person’s teens, when they reach 20, or 30; however, depression symptoms and depression definition psychology can affect anyone at any age, according to the Mayo Clinic in 2022. Depression symptoms are typically reported more in women than men; however, this may be due to women being more likely to ask for help than men.

What are the Risk Factors of Depression?

The risk factors of depression that can give insight on what does depression mean are listed below.

  1. Genetics - Genetics, in some cases, may be linked to depression and may be inherited in families with a depression disorder history
  2. Death - Death or the passing of a loved one can affect a person’s ability to cope, and is a significant risk factor for depression.
  3. Conflict - Conflict, as in fights or arguments with friends or family, may cause depression.
  4. Abuse - Abuse, such as physical, sexual or emotional abuse can all contribute to depression.
  5. Life events - Life events, such as a graduation or a new job, can cause depression due to their sudden change and impact on a person’s life.
  6. Medications - Medications can cause depression as they alter the chemical levels in the brain.
  7. Substance abuse - Substance abuse can cause depression, or be a person’s attempt to cover up depression, which can aggravate the condition.
  8. Vitamin D Deficiency - Vitamin D Deficiency has been linked to depression due to a chemical imbalance in the body.
  9. Gender identity - Gender identity, as in a person identifying with another gender, can cause a person to be discriminated against, which may lead to depression.

1. Genetics

What is genetics in relation to depression can help us better understand how genetics factor into depression, as a paper by the American Journal of Psychiatry in 2011 found a gene that may be linked to depression. What is genetics, as a risk factor, may be summed up by chromosome 3p25-26. 3p25-26 is a gene found in families with recurring depression disorders, giving us the link between genes and some cases of depression, and what is the definition of depression.

2. Death

Death, as in the passing of a loved one, can significantly contribute to depression as the situation causes sadness, and grief, and may make a person feel worthless or unable to cope. Death as a risk factor can help us in understanding depression as grief is a normal reaction to death; however, thoughts of suicide and lack of self-worth are not, and are more closely related to depression.

3. Conflict

Conflict, as in personal struggles or fights with family or friends, may cause a person to develop depression. Conflict can make a person feel unsafe, withdraw from close relations, and create too much of a mental burden so that a person feels overwhelmed, and it can be a risk factor in what causes depression.

4. Abuse

Abuse in various forms, such as physical, sexual, or emotional abuse (including neglect), can all contribute to depression, according to WebMD in 2021. Abuse contributes to our depression understanding as abuse can cause a person to feel unsafe, overwhelmed, and isolated, which can create a mental burden.

5. Life events

Life events, such as graduation or a new job, can make a person feel depressed. Life events may cause depression due to the extreme and sudden changes they bring about in a person’s life, even if these life events are interpreted as positive. Life events causing depression can be diagnosed using the dsm 5 depression criteria, according to MD+ Calc in 2023.

6. Medications

Medications have been known to increase a person’s likelihood of developing depression. Certain medications are more likely to cause or be linked to depression, such as isotretinoin (a medication for acne), according to WebMD in 2021, and can tell us what is -0 in relation to depression. Medications can affect brain chemistry, leading to feelings of gloom, despair, and lack of self-worth.

7. Substance abuse

Substance abuse, including drugs and alcohol, can be linked to depression. Some people use substances when they don’t feel good, leading to substance abuse, while others use substances too much, which can create feelings of guilt and depression. Using substances to escape bad feelings may, in turn, cause more bad feelings, which can perpetuate depression and give us a better understanding on what is depression mean.

8. Vitamin D deficiency

Vitamin D deficiency has been linked to patients with depression, according to PubMed in 2018. Vitamin D deficiency is necessary for healthy body functions, so a lack of this can cause a chemical imbalance in the body, which has been linked to a higher risk for depression. 

9. Gender identity

Gender identity, identifying with another gender (also known as gender dysphoria) may lead to depression as people who identify with another gender are often discriminated against, teased, and do not have access to experienced healthcare providers. Without gender-affirming treatment, those with a different gender identity may be at high risk for depression and suicide.

What are the Complications of Depression?

The complications of depression, as described in a depression paragraph according to WebMD in 2022, include heart disease, pain, sexual performance, and sleep. Those who have experienced a heart attack are at risk for complications of depression, with up to 65% of patients developing depression. Pain is also a complication of depression, as those who experience depression may also experience unexplained headaches, cramps, and neck pain.

How does Depression affect the Body?

Depression affects the body in several ways, including sleep cycle, weight, restlessness, and fatigue. Depression can cause a person to get too much or too little sleep and affect their weight, either gaining or losing weight despite not taking a diet. Depression can also make a person restless, doing menial movements (such as pacing) and being unable to sit still. Deep depression can also affect the body so that a person feels fatigued or lacks energy.

How does Depression affect the Brain?

Depression affects the brain through depressive episode symptoms, where a person may have decreased brain activity in the hippocampus, according to a study done by the NIH National Library of Medicine in 2018. Depression may also affect the brain via reduced gray matter and a higher level of cortisol (the stress hormone), inhibiting neuron growth.

Can depression cause long-term brain damage?

Yes, depression can cause long-term brain damage, according to WebMD in 2022, helping make depression explained. People with long-standing cases of depression have been known to have less gray matter volume than a healthy person, despite not having depression for years. Less gray matter means less neural activity and development, which can cause chemical imbalances and feelings of sadness.

How does Depression affect Lifestyle?

Depression affects lifestyle in many ways, including social isolation, negatively impacted relationships, substance abuse, and financial consequences. Depression can cause a person to withdraw from friends and family, increasing loneliness. Depression can also cause a person to be less patient in close relationships, causing arguments and negatively impacting these relationships. Depression can also cause a person to use substances excessively to escape feelings. Depression can also cause a person to work less, impacting them financially. However, in understanding is depression curable, it’s essential to know that there are many ways depression is being diagnosed and treated.

How is Depression Diagnosed?

Depression is diagnosed, according to the NIH National Library of Mental Health, by a person exhibiting at least five depression symptoms almost all day for at least two weeks. Healthcare providers will look for symptoms of a depressed mood and lack of interest as the two key symptoms a person must have to be diagnosed. Healthcare providers know what does depressed mean and will rule out other causes for depression with lab tests and physical examinations before diagnosing a person with depression.

How is Depression Prevented?

There are many ways to prevent depression and lower the risk of developing depression, such as regularly exercising, eating healthy, and being connected with family, friends, and the community. Other ways to prevent depression include learning to manage stress, seeking professional help if you cannot cope with difficult emotions, learning about the disorder from depression articles and other web sources, getting enough sleep, and avoiding substance abuse.

What are the Treatments available for Depression?

There are several common treatments for depression that a healthcare provider may prescribe to a person that has been diagnosed with depression, which includes antidepressant medication, psychotherapy, and in extreme cases, electroconvulsive therapy, according to WebMD in 2021. 

Antidepressant medication, such as Lexapro or Prozac, helps rewire the brain’s circuitry, which may help elevate a person’s mood and improve depression symptoms. Psychotherapy (also known as talk therapy) is when a person talks with a trained mental health care provider about improving their mindset, feelings, and the challenges of depression, which can give a person soft skills for managing their feelings better. Electroconvulsive therapy is given in worst-case scenarios where other forms of treatment aren’t working. Electroconvulsive therapy is where a doctor puts a person to sleep and sends electrical currents through the brain, inducing a seizure, which may activate the neurons and alleviate signs and symptoms of depression.

What are the Natural Treatments available for Depression?

There are several natural treatments available for depression, such as herbal remedies, acupuncture, reflexology, exercise, and meditation, according to the Cleveland Clinic in 2020. However, few studies have been done to see if they work, meaning you should talk to your healthcare provider before trying them. Of the herbal remedies, ginkgo biloba is one of the most common plants used for treating depression. Acupuncture and reflexology are similar in that they work with the body's pressure points to help alleviate symptoms. Exercise is a straightforward natural treatment where some physical activity can help elevate a person’s mood. Meditation is also suitable for stress management, where a person sits and focuses on their breaths for a set period, which may decrease overall depressed feelings.

How does Therapy help with Depression?

Therapy can help with depression in several ways, including pinpointing life events that contribute to a person’s feelings of depression, setting goals to feel better, and developing skills to better deal with depression symptoms. There are two common types of therapy used to treat depression, which are Cognitive Behavioral Therapy (CBT), and Interpersonal Therapy (IPT). CBT is where a person learns to identify and deal with the negative thoughts behind their symptoms. IPT teaches a person how to express emotions better and solve problems in a better way, which can help a person cope with depress o and alleviate symptoms better.

What to Expect in a Depression Condition?

A person can expect a persistent feeling of sadness while in a depressed condition, along with difficulties thinking, eating, sleeping, and a lack of enjoyment in once-loved activities. An example of depression is when a person feels hopeless about a situation for an extended period, coupled with fatigue and unexplained pain in the body, such as headaches.

How Long Does Depression Last?

Depression has variable lengths of time that it lasts, with the average description of depression lasting as long as 6 months, according to Wiley Online Library in 2017. The mean duration of depression for some people was 107 months, while 12% of people in the study had depression even after 36 months. The cases with the longest depression usually also had antidepressants, psychotherapy, and suicidal behavior involved.

Can you completely recover from depression?

Yes, you can completely recover from depression in most cases. Mild cases usually see improvement in weeks or months; however, more severe cases or relapses cause 20-30% of people to experience depression mean that it never truly goes away, according to WebMD in 2022.

Is depression considered a serious illness?

Yes, depression is considered a serious illness as it affects how a person feels, thinks, acts, and their overall physical health. If a person is diagnosed with depression using the depression DSM 5, they should talk with their healthcare provider for treatment. Being diagnosed with depression and not treating it right away can cause long-term effects, such as higher cortisol levels and less gray matter in the brain.

Does depression affect vision?

Yes, depression can affect vision as stress can affect a person’s eyesight through increased blurred vision. Depression may cause a person to see things less clearly due to the higher cortisol levels in the body, which can affect a person’s vascular and nervous systems.

What is the difference between Depression and Anxiety?

The difference between depression vs. anxiety is that depression is more about a localized feeling of sadness, while anxiety revolves around excessively worrying or stressing about a situation’s outcome. Another difference between depression vs. anxiety, and determining if anxiety and depression is real, is in their symptoms. People with anxiety described physical symptoms such as a high heart rate and muscle tension. People with depression described physical symptoms such as sadness, hopelessness, loss of interest, lack of energy, and trouble sleeping. Both conditions are also treated differently, as depression is treated with medication such as antidepressants and therapy (depression psychology). On the other hand, anxiety is treated with anti-anxiety medications (also known as benzodiazepines), therapy, and relaxation techniques.