What Is Depression? 11 Variants of This Painful Mood Disorder

What is depression? The disorder is more than feeling a little down or “under the weather” on occasion. The dark cloud of depression lingers. Its persistent sadness, hopelessness, and despair include various types, causes, and brain changes that produce life-altering symptoms. Keep reading for all there is to know about depression.

Person with depression.
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The Definition of Depression

Depression is a mental disorder that affects the way an individual thinks, feels, and behaves. The disorder manifests as a persistent feeling of sadness and hopelessness occurring for two or more weeks. Although a mental condition, depression has an impact on the entire body. Its widespread symptoms impede daily functioning at work, home, and in personal relationships. According to the American Psychiatric Association, one in six people will experience one form of depression in their lifetime.

General Symptoms of Depression

While there are different types of depression, each type shares a set of general symptoms.

  • Feeling sad—Sadness, typically accompanied by a sense of hopelessness, occurs without reason.
  • Loss of interest in activities—Hobbies and activities that were once enjoyable become disinteresting, are viewed as worthless, etc.
  • Fatigue—Those with depression have a loss of energy without physical exertion and may sleep excessively.
  • Sleep disorders—Sleep disorders are common. Specifically, nightmares and insomnia, which is the inability to fall or stay asleep.
  • Changes in appetite—Appetite can increase or decrease with weight gain and/or loss.
  • Suicidal thoughts—Anyone with depression is at risk for thoughts of harming themselves.  

Cognitive Effects of Depression

The term cognition refers to the process of thinking. Cognition is how we take in and process information via the senses using key thinking skills called cognitive skills. In depression, cognitive dysfunction is known to occur. Researchers have noted deficits in cognitive skills such as attention, memory, visual and auditory processing, processing speed, problem-solving, and motor function (Lam et al., 2014).

Patients with depression exhibit these cognitive effects because the disorder’s symptoms impact thinking. For example, fatigue resulting from insomnia makes it difficult to concentrate, and a lack of motivation produces a diminished desire to learn. Furthermore, the side effect profile of antidepressant medications have implications on cognitive functioning.

Brain Changes Leading To Depression

The cognitive effects of depression stem from structural brain changes. Studies published in the British Medical Bulletin (2012) indicate that depression causes the brain to decrease in size. Shrinkage of brain matter takes place mainly in the hippocampus—the area of the brain responsible for learning and memory. The severity depends on the length of the depressive episode.

Depression also leads to widespread inflammation. As neurons (i.e. brain cells) are damaged, neurotransmitter levels critical for balancing moods, like dopamine and serotonin, decrease. The brain has reduced neuroplasticity and is unable to regenerate new neural connections with age. This is a major reason why cognitive dysfunction is noted in depression.

Causes and Risk Factors For Depression

Anyone can develop depression, but some are more susceptible than others. There are certain risk factors associated with the disorder. Females are more likely to be diagnosed with depression than males. One-third of women have an episode of depression in their lifetime. The teenage years through the mid-twenties is the primary age for depression symptoms to appear. Additionally, personality traits like pessimism and feeling easily stressed are related. Other causes and risk factors include:

  • Genetics—There are certain genes related to depression. Having a family member with depression increases the chances of developing the disorder.
  • Trauma—People who have experienced trauma, abuse, or neglect are at a higher risk for depression.
  • Death—Grief from the loss of a loved one is known to cause complicated grief, which contributes to depression.
  • Environment—Exposure to violence, toxic relationships, or poverty are a few environmental factors that can lead to a depressive mental state.   
  • Preexisting medical condition—Depression is common if the individual has an underlying mental disorder like anxiety, panic disorder, bipolar disorder, or chronic physical illness.
  • Medications—Medications like corticosteroids have depression as a side effect.

Types of Depression

Depression is a complex disorder that cannot be summed up into one or two types. There are many forms of depression. While similarities exist, they each display unique symptoms.

Major Depression

Major depression, also called clinical depression, is a severe form of depression characterized by persistent sadness with feelings of hopelessness. Someone with major depression experiences a loss of interest in activities that were once enjoyable like hobbies, sports, or sex. They suffer from anxiety, restlessness, and are easily agitated. Outbursts and sleep disturbances are not rare in major depression. Symptoms always interfere with work, school, and relationships.

Persistent Depressive Disorder

Major depression often precedes persistent depressive disorder. Persistent depressive disorder is characterized by a sad mood that is present most days for at least two years. The symptoms are lesser in severity than major depression. To receive a diagnosis of persistent depressive disorder, an individual has to display two or more of the following symptoms: low self-esteem, poor concentration, feelings of hopelessness, fatigue, changes in appetite, or insomnia or hypersomnia. Symptom-free periods do not last longer than 2 months.

Bipolar Depression

Bipolar disorder is a mental disorder with mood fluctuations ranging from depressive lows to manic highs; therefore, bipolar depression describes the depressive intervals of the disorder. The symptoms of bipolar depression include a decrease in energy, a loss of interest in daily activities, and a lack of motivation. Suicidal thoughts may occur during episodes. A depressive phase is present for days to months at a time.

Postpartum (Perinatal) Depression

Postpartum (perinatal) depression refers to depression during or after pregnancy. Approximately 10 percent of women become depressed while pregnant and 15 percent develop depression after giving birth. Depression stems from the dramatic variations in estrogen, progesterone, and other hormones triggered by pregnancy and childbirth. Signs of postpartum (perinatal) depression are frequent crying, a lack of interest in the baby, thoughts of harming themselves or the baby, appetite changes, sadness, a loss of pleasure, and irritability. Symptoms subside once the body balances the hormone levels.

Premenstrual Dysphoric Disorder

Premenstrual dysphoric disorder is a type of depression affecting menstruating females. It causes debilitating emotional and physical symptoms seven to ten days before the start of a menstrual period. Premenstrual dysphoric disorder is similar to premenstrual syndrome (PMS) but more severe. Along with sadness, hopelessness, anxiety, and extreme moodiness, symptoms include fatigue, bloating, breast tenderness, headaches, difficulty concentrating, and changes in eating and sleeping habits that are relieved within the first two days of bleeding.

Psychotic Depression

Psychotic depression is depression with psychosis. An individual with psychotic depression is out of touch with reality. The disorder causes hallucinations, which is seeing or hearing things that are not there, and delusions, which is the belief in an untrue reality. This disruption in perception occurs along with the signs and symptoms of major depression. Aside from hallucinations and delusions, psychotic depression is characterized by intense feelings of guilt and worthlessness.

Situational Depression

Situational depression is a short term form of depression related to a stressful situation. Someone with situational depression cannot adjust after stressful life events like the loss of a loved one, a medical illness, relationship problems (i.e. divorce), abuse, natural disasters, and more. Frequent crying, excessive worry, avoidance of social situations, and neglecting responsibilities interfere with functioning.  

Seasonal Affective Disorder

Seasonal affective disorder is a type of depression that shares all of the symptoms of major depression, but only during a specific season. The symptoms present at the same time every year. In most cases, seasonal affective disorder begins in winter. Scientists assume seasonal affective disorder tends to arise in winter months because there is less natural sunlight available, which disrupts the circadian rhythm. The diagnosis is prevalent in northern regions.

Disruptive Mood Dysregulation Disorder

Disruptive mood dysregulation disorder is a depressive disorder of childhood that results in severe temper tantrums at least three times weekly. The outbursts are both verbal and behavioral. Symptoms of disruptive mood dysregulation disorder begin before age ten, are present for at least one year, and disrupt functioning in the home, school, and friends. These children are consistently angry.

Substance Induced Mood Disorder

Substance-induced mood disorder is a change in thoughts, feelings, or behavior caused by taking or discontinuing the use of a drug. Someone with substance-induced mood disorder may experience mania in which they feel anxiety, restlessness, and become irritable. They behave impulsively, speak quickly, and have an inflated sense of self-worth. Manic episodes lasting from days to weeks at a time are typically followed by depressive lows. Substances resulting in substance-induced mood disorder consist of alcohol, illegal drugs (i.e. cocaine, LSD, etc.), over the counter medications, or prescription medications (i.e. antidepressants, antianxiety medications, heart medications, and pain medication). Thoughts, feelings, and behavior are altered as the substances affect the levels of brain chemicals.

Atypical Depression

Atypical depression features symptoms identical to major depression but improves with positive events. The primary signs of atypical depression are weight gain, hypersomnia, a heavy sensation in arms or legs, and interpersonal rejection sensitivity. The onset of atypical depression is reported earlier in childhood or teenage years.

How To Diagnose Depression

Diagnosing depression involves multiple specialists. If a physician suspects depression, the first step is to perform a physical evaluation and family history to rule out conditions that mimic the same symptoms. This includes blood tests for thyroid disorders, vitamin deficiencies, or diabetes.

The individual must experience at least 5 out of 9 of the following symptoms, along with (1) a depressed mood or (2) a loss of pleasure that impairs social, occupational, and educational function and lasts more than two weeks.

  1. Depressed mood or irritable daily—indicated by either subjective report (e.g., feels sad or empty) or observation made by others
  2. Decreased interest—Loss of pleasure in most enjoyable activities, most of each day
  3. Marked weight change—(5%) or change in appetite
  4. Sleep problems—Insomnia or hypersomnia
  5. Change in activity—Psychomotor agitation or retardation
  6. Fatigue—Significant loss of energy
  7. Guilt or worthlessness—Feelings of worthlessness or inappropriate guilt
  8. Cognitive dysfunction—reduced ability to think or concentrate
  9. Suicidality—Thoughts of death or suicide, or has a suicide plan

Depression Treatment

There is no “one size fits all” for treating depression, nor is there a cure. What one person with depression responds to may differ from another. Treating the disorder consists of a combination of options: antidepressant medications, psychotherapy, lifestyle changes, and in rare cases, brain stimulation.

Antidepressant Medications

Antidepressants are medications that exert effects on the brain by altering levels of brain chemicals called neurotransmitters, which communicate messages between the brain’s nerve cells. There are many types of antidepressant medications frequently prescribed for depression.

  • Selective Serotonin Reuptake Inhibitors (SSRIs)—SSRIs are the most common antidepressants prescribed. They increase the availability of the serotonin by preventing the neurotransmitter from “reuptake” or the process of replacing serotonin.  
  • Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)—SNRIs are similar to SSRIs, but target both serotonin and norepinephrine.
  • Tricyclic Antidepressants (TCAs)—When other antidepressants fail, TCAs increases the levels of serotonin, norepinephrine, and multiple other neurotransmitters.
  • Monoamine Oxidase Inhibitors (MAOIs)—Monoamine oxidase is an enzyme in the body that removed neurotransmitters. MAOIs inhibit monoamine oxidase, which increases the levels of neurotransmitters available to the brain.


Psychotherapy is an effective adjunct to depression treatment along with other depression therapies such as medication and lifestyle adjustments. Psychotherapy, also referred to as “talk therapy,” is when someone speaks with a mental health professional to applies various techniques to identify triggers contributing to depression and other mental health conditions.

Cognitive behavioral therapy is the most common psychotherapy for depression treatment. The goal of cognitive behavioral therapy is to discover unhelpful patterns of behavior and distorted thought processes underlying the depression. The therapist teaches skills to change those behaviors.

Therapy can be with the individual or it can include family members, a spouse, or a group of two or more patients.

What Is Depression? 11 Variants of This Painful Mood Disorder
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Symptoms of depression can be reduced by a healthy diet. Avoid processed foods high in sugar. While foods such as soda, candy, and pastries provide a spike in energy, they lead to a crash later. Instead, whole grains, lean meats, and green leafy vegetables benefit depression. Consuming these foods have a balanced amount of protein, carbohydrates, fat, vitamins, and minerals—and contain antioxidants that prevent cellular damage to the brain.

Examples of healthy foods for depression are vegetables such as broccoli, spinach, carrots, and sweet potatoes, fruits like peaches and berries, nuts and seeds, poultry, fish, soy products, and yogurt.


Exercise is an important component of depression treatment. Physical activity stimulates the production of feel-good endorphins that boost mood. Exercising regularly also increases levels of neurotransmitters, like serotonin, which are low in some people with depression. The elevations in neurotransmitters are crucial for regulating mood and for cognition.

Experts recommend 30-minutes of aerobic activity daily. In studies of thirty men and women with depression, the group who was assigned to walk 20 to 40 minutes three times per week for six weeks had more improvement in depression than the group with social support interventions (Craft et al., 2004).

Electroconvulsive Therapy (ECT)

Electroconvulsive therapy (ECT) is a treatment for severe depression that has not responded to other therapies. ECT is electrical stimulation of the brain. The patient undergoing ECT is given anesthesia so that they will not feel anything during the procedure. Electrodes placed on the scalp deliver an electrical current that induces a seizure. The seizure is controlled with medications. Studies by researchers at John Hopkins conclude the electrical stimulation encourages the growth of new brain cells. Neurons in the brain regenerate in areas like the hippocampus. For the best effectiveness, 2-3 sessions of ECT weekly for several weeks treats depression.

Repetitive Transcranial Magnetic Stimulation (rTMS)

Repetitive transcranial magnetic stimulation (rTMS) is a form of brain stimulation that uses magnetic pulses to target areas of the brain thought to be responsible for depression symptoms. Firstly, a magnetic coil is placed on the patient’s scalp to test their motor threshold to determine the correct amount of brain stimulation for the individual. A magnetic coil is then placed on the patient’s forehead to target the front regions of the brain. rTMS is painless, but patients are given earplugs to protect their hearing from the clicking noises from the magnet. Each session typically lasts 30 to 40 minutes five times a week for four to six weeks.


Craft, L. L., & Perna, F. M. (2004). The Benefits of Exercise for the Clinically Depressed. Primary care companion to the Journal of clinical psychiatry6(3), 104–111. https://doi.org/10.4088/pcc.v06n0301

Lam, R. W., Kennedy, S. H., Mclntyre, R. S., & Khullar, A. (2014). Cognitive dysfunction in major depressive disorder: effects on psychosocial functioning and implications for treatment. Canadian journal of psychiatry. Revue canadienne de psychiatrie59(12), 649–654. https://doi.org/10.1177/070674371405901206

Palazidou, E. (2012). The neurobiology of depression. British Medical Bulletin, (101)(1), 127–145. https://doi.org/10.1093/bmb/lds004

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