Depression (major depressive disorder [MDD]) is a mental health disorder that is often undiagnosed and untreated in the US. MDD impacts how a person feels, how they think, and how they manage activities of daily living such as eating, sleeping, or working. It can cause severe mood changes and can occur at any age, but typically presents in young adulthood. Children that have high levels of anxiety may develop chronic mood disorders, including depression. Middle-aged or older adults may develop depression due to the chronic stress of serious illnesses or life events (National Institute of Mental Health [NIMH], 2018). This module will explore MDD and the healthcare provider's role in recognizing and managing this serious and often life-threatening condition.
Incidence and Prevalence
According to the World Health Organization (WHO, 2018), as many as 300 million people worldwide are affected by depression. In the US, there are an estimated 17.3 million adults who have had at least one major depressive episode (NIMH, 2019), and over 8% of adult Americans over age 20 reported depression in a given week from 2013-2016. In the US and worldwide, women are almost twice as likely to have depression as men (Brody et al., 2018; WHO, 2018). The prevalence of depression does not differ with age. There is a lower prevalence of depression among Asian adults (3.1%) compared to Hispanic adults (8.2%), European American adults (7.9%), and African American adults (9.2%). Of interest, the prevalence of depression decreases as family income level increases. Men with family incomes at 400% above the poverty level had the lowest prevalence of depression of all adult groups. Conversely, women with family incomes below the poverty level had the highest prevalence of depression at 19.8% (Brody et al., 2018). Depression leads to significant disability in adult patients and is characterized by a period of at least two weeks of sadness, loss of interest or pleasure, guilt, low self-worth, disturbed sleep, poor appetite, tiredness, and/or poor concentration. When it is severe, depression can lead to suicide (NIMH, 2018; WHO, 2018).
The exact cause of depression is not known and is likely the result of a combination of risk factors. While depression is a disorder of the brain, there are several causes that include environmental, genetic, and psychological or biochemical elements. Different chemicals in the brain can contribute to the symptoms of depression and are the focus of pharmacological treatments. Genetics play a role in depression, with identical twins having a 70% chance of suffering from depression in their life if one has had an episode. Personal characteristics, such as low self-esteem, pessimism, or poor stress management, can further lead to depression. Environmental factors that can lead to depression include continuous exposure to violence, neglect, poverty, or abuse (American Psychiatric Association [APA], 2017).
Depression typically presents between 15 and 30 years of age and can be persistent (persistent depressive disorder), part of bipolar disorder (bipolar depression), seasonal during the winter months (seasonal affective disorder), or during the postpartum period after the birth of a baby (postpartum depression) (US Department of Health & Human Services [USDHHS], 2017). A personal or family history of depression, major life changes, trauma, stress, misuse of alcohol or drugs, and certain physical illnesses along with their medications increases the risk of MDD (The Centers for Disease Control [CDC], 2018; NIMH, 2018).
Individuals who are middle-aged or older adults may suffer from depression in relation to chronic health conditions such as cancer, heart disease, diabetes, or Parkinson's disease. Depression can often make these conditions worse, and medications taken for these illnesses can trigger or exacerbate depression, making treatment of both depression and the illness complicated for the healthcare provider (NIMH, 2018).
Complications and Co-Morbidities
Depression is linked to many complications, the most significant of which is suicide. It was noted that during the lifetime of an individual suffering from MDD, over 46% voice a desire to die, and over 39% contemplate their suicide. This key study on MDD also found that people with a history of depression are more likely to have a history of substance abuse disorders as compared to anxiety or personality disorders. Over 57% of the 36,000 individuals with a diagnosis of MDD had a history that included drugs, alcohol, or nicotine abuse (Hasin et al., 2018). Smoking is higher among adults with mental health conditions, including depression and anxiety than the general population. The cause is unknown, yet the link to other health disparities from smoking should be noted, and mental health treatment should support smoking cessation (CDC, 2018).
Depression can adversely affect chronic diseases the individual may be suffering from and can decrease positive health outcomes along with increasing the cost of treating these conditions. Identifying and effectively managing depression can improve the other health conditions that co-exist. Some of those conditions are:
- Substance abuse;
- Lupus or other inflammatory conditions;
- Obstructive sleep apnea;
- Lyme disease or other infectious diseases including HIV;
- Chronic fatigue syndrome;
- Female hormonal disorders such as menopause or Premenstrual Dysphoric Disorder [PMDD] (NIMH, 2018).
Signs and Symptoms/Diagnostic Features
There are multiple types of depression, and each has unique features and onset mechanisms. Yet, consistent signs and symptoms can be noted with MDD. The NIMH (2018) notes that the following behaviors and feelings that are experienced most of the day, nearly every day, for at least two weeks may indicate depression, particularly if symptoms are worsening or affect activities of daily life:
- Sadness, anxiety, "empty mood";
- Loss of interest in usually pleasurable things;
- Sleep disturbances including difficulty going to sleep, early-morning awakening, or oversleeping;
- Feelings of guilt, worthlessness, or hopelessness;
- Inability to concentrate, remember or make decisions, think clearly;
- Ongoing fatigue or decreased energy;
- Weight changes or appetite changes;
- Psychomotor agitation or retardation, noted by others;
- Suicide attempts or thoughts of death (CDC, 2018; NIMH, 2018).
MDD, also known as clinical depression, affects how the individual performs day-to-day activities, leading to feelings of hopelessness. Depression is different from sadness or bereavement and is outside the normal grieving process. While grief can be a trigger for depression, grief does not cause depression (APA, 2017).
Children suffering from depression have higher risks of developing MDD as adults. Children will present differently with depression than adults. Behaviors may include avoidance of others, refusal to attend school, pretending to be sick and remaining at the parent's side, mood swings, getting into trouble at school, or irritability. Since some of these behaviors are common in teens and adolescents, it can be challenging to diagnose depression in the child (Forman-Hoffman et al., 2016).
It can be equally challenging to diagnose depression in older adults. Signs and symptoms of dementia can mimic depression, such as agitation, irritability, fatigue, or even hallucinations or delusions. Those with dementia are less likely to have feelings of helplessness or hopelessness that a depressed individual would likely experience (Mayo Clinic, 2019a).
Types of Depression
See Table 1 for the various forms of depression that may impact an individual across the lifespan and develop under special circumstances (NIMH, 2018).
Forms of Depression
Examples of other depressive disorders include disruptive mood dysregulation disorder (diagnosed in adolescents and children) and premenstrual dysphoric disorder (PMDD); these have recently been added to the diagnostic classification of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5, 2013) (APA, 2016).
Screening for Depression
The US Preventive Services Task Force [USPSTF] suggests screening for depression in all adults based on a grade B recommendation (high certainty that the net benefit is moderate or moderate certainty that the net benefit is moderate to substantial; Siu & the USPSTF, 2016). Similarly, the USPSTF gives a grade B recommendation regarding the screening of adolescents aged 12 to 18 years for depression. Children aged 11 years or younger were given a grade of I, indicating that there was insufficient evidence to assess the benefits/harms of screening in this population (USPSTF, 2016). Rarely do patients present to their primary care provider complaining of depression. Patients are more likely to present with nonspecific symptoms such as headache, myalgia, or other pain, making diagnosis more difficult. Screening for depression is important for all patients, as they may not recognize their symptoms as components of a mental health condition. Without screening, many patients suffering from MDD may not be diagnosed. In a study by O'Byrne and Jacob (2018), it was noted that depression is associated with a lower quality of life, compromised interpersonal relationships, decreased work performance, and at its worse, loss of life through suicide; thus increasing the urgency for proper recognition and diagnosis. This systematic review identified 55 assessment tools for depression screening, including the Patient Health Questionnaire-9 (PHQ-9). This tool was recognized as having the most substantial literature and evaluation, including a robust performance across all studies. The PHQ-9 is short, simple, and free, increasing the accessibility and ease of use. The PHQ-9 is a nine-item survey based on the criteria for depression, as listed in the DSM-5. Each question has four answers: "not at all," "several days," "more than half the days," and "nearly every day" (Spitzer et al., 1999). The questions are as follow:
Over the last two weeks, how often have you been bothered by:
- Little interest or pleasure in doing things?
- Feeling down, depressed, or hopeless?
- Trouble falling or staying asleep, or sleeping too much?
- Feeling tired or having little energy?
- Poor appetite or overeating?
- Feeling bad about yourself or that you are a failure or have let yourself or your family down?
- Trouble concentrating on things, such as reading the newspaper or watching television?
- Moving or speaking so slowly that others could have noticed, or being so fidgety/restless that you have been moving more than usual?
- Thoughts you would be better off dead, or of hurting yourself (Spitzer et al., 1999)?
The response for each question is scored between 0 and 3 (0 for "not at all" to a 3 for "nearly every day"), with a total possible score of 0-27. The scoring system for evaluation is:
- 5-9 = mild depressive symptoms;
- 10-14 = moderate symptoms;
- 15-19 = moderately severe symptoms; and
- Greater than 20 = severe symptoms. (O'Byrne & Jacob, 2018)
While false positives are possible with this screening tool due to its high sensitivity, nurses should recognize the risk-benefit of determining possible depression in the patient. A positive result on the screening tool does not equate with an actual diagnosis of depression. Further to note is the PHQ-9 was funded by a pharmaceutical company. With this knowledge, a prudent healthcare provider will use the tool in tandem with a thorough health assessment and evaluate the need for appropriate treatment of depression over time (O'Byrne & Jacob, 2018). Adolescents between 12 and 18 years of age should be screened for major depression and provided psychotherapy and follow-up. For children between 7-11 years of age, there is not sufficient evidence to evaluate the effectiveness of screening at this time (Forman-Hoffman et al., 2016).
Other screening tools that are frequently used in primary care are listed in Table 2 below:
Diagnosis and Differential Diagnosis
Once screening has been completed with risk identified, the healthcare provider will determine a diagnosis of depression through further assessment. No definitive diagnostic test exists for depression; it, therefore, must be determined through exclusion (Forman-Hoffman et al., 2016). The DSM-5 outlines the required criteria for making a diagnosis by the healthcare provider. The first step in diagnosing any mental health condition is ruling out underlying medical conditions. Conditions such as hypothyroidism, a brain tumor, or vitamin deficiency could mimic depression and should be ruled out prior to initiating treatment (APA, 2017).
A complete blood count (CBC), B12 level, metabolic panel including glucose, renal and hepatic functions, antinuclear antibody (ANA), erythrocyte sedimentation rate (ESR), and thyroid screening should be obtained. Providers may also recommend a urine or serum toxicology screening before and during treatment for depression. Imaging studies may be indicated to rule out intracranial pathology. For a patient to be diagnosed with MDD, they should have a minimum of five out of the nine criteria listed in the DSM-5, with one of the five being a depressed mood or loss of interest in otherwise pleasurable things. These symptoms are also knowns as Criteria A in the DSM-5. Nurses often remember these signs/symptoms by the mnemonic "SIG E CAPS" for sleep, interest, guilt, energy, concentration, appetite, psychomotor, and suicidal ideation. Table 3 illustrates the further criterion for the diagnosis of MDD (DSM5, 2016; Najera, 2015).
Diagnostic Criterion for Diagnosis of MDD
The physical examination may be unremarkable in a depressed patient, but some features may be noted, including poor personal hygiene, a flat affect, slowed speech, or psychomotor agitation or retardation. Mental status should be checked, particularly in the older patient to rule out cognitive decline. The exam should include assessment for delusions, hallucinations, or mood swings (DSM5, 2016; Najera, 2015).
A previously accepted theory that depression stems from a chemical imbalance in the brain regarding the monoamines serotonin, norepinephrine, and dopamine has shifted in the last 15 to 20 years. Theories regarding alterations in brain architecture and complex circuitry have led researchers to question if the neurotransmitters are not simply a messenger of information or symptom as opposed to the cause itself. Advancements in the fields of genetics and functional neuroimaging have opened new and exciting investigational possibilities and altered the way depression is viewed in the last 20 years, hopefully leading to changes in treatment down the road (Goldberg, 2018). Current management focuses primarily on non-pharmacological and pharmacological treatments. Psychotherapy or pharmacotherapy can successfully treat depression based on the individual situation. The length of a depressive episode and the severity of symptoms can be decreased through successful therapy, medications, or both (CDC, 2018).
Psychotherapy, also known as counseling or simply therapy, is usually short-term and has a focus on thoughts, feelings, and concerns within the individual's daily life. Psychotherapy may also delve into the past and consider how it could be impacting current issues, as well as help the patient to develop coping mechanisms for the future. The therapist and patient work together to find coping skills and prepare for future challenges. The patient should be encouraged to talk about their feelings openly and honestly to have the highest success with treatment (CDC, 2018). Common therapy goals may include:
- Improving health;
- Smoking cessation;
- Stopping drug or alcohol abuse;
- Stress management;
- Identifying triggers for depressive episodes;
- Improving family relationships;
- Understanding painful events in one's past;
- Understanding negative feelings and how to cope (CDC, 2018).
Psychotherapy can have several underlying evidence-based approaches, including cognitive behavioral therapy (CBT), interpersonal therapy (IPT), and problem-solving therapy. There is no one-size-fits-all approach, and a combination of approaches may prove successful. CBT helps to change thought patterns and consequently improve mood; it is based on the theory that the way one thinks and behaves may contribute to depression. CBT may be used alone or in adjunct with medications to treat depression. CBT has been noted to have a long-term benefit of protection against subsequent relapse or recurrence of depressive episodes. While there is not a consensus on whether CBT can be curative for depression, there seem to be lasting effects that provide coping skills and mental health resources the patient can use for future episodes. During therapy sessions, the patient will most often read about their problem, maintain behavioral or mood records between sessions, and complete homework assignments that focus on treatment and behavioral skills practice. Benefits are typically seen within 12-16 weeks, and the patient is active in their recovery (Anxiety and Depression Association of America [ADAA], 2018). See Figure 1 for additional information regarding CBT.
What is CBT?
IPT helps patients with relationships that may influence their depression. This type of therapy is very effective with groups of individuals with similar issues and with mild to moderate depression. In severe depression, the patient may need to be stabilized on medications before implementing IPT. Adolescents do particularly well with a combination of IPT and medications (ADAA, 2018).
There are numerous additional non-pharmacological treatment options such as acupuncture, mindfulness training, transcranial magnetic stimulation (TMS), and electroconvulsive therapy (ECT) that may be explored and discussed with patients that wish to avoid medications or are searching for adjunctive therapy (NIMH, 2018). A small 2016 pilot study found a decrease in depressive symptoms amongst women undergoing a 12-week mindfulness yoga program (Schuver & Lewis, 2016). Moderate improvements in depression/anxiety symptoms were seen throughout 47 studies, including more than 3,500 patients who underwent mindfulness interventions for the management of their depression. Mindfulness is thought to alter the prefrontal cortex and anterior cingulate cortex activity, leading to significant increases in electroencephalographic studies (ECGs). Mindfulness concepts are often combined with cognitive therapy into mindfulness-based cognitive therapy (MBCT). Research indicates that this may be as effective and cost-effective, as antidepressant medications to prevent a depressive relapse. There are limitations, as experienced providers for this therapy are scarce, and there is an extended amount of time required to see benefits from mindfulness therapy. Mindfulness should not be considered appropriate as first-line therapy for severe depression, but rather as an adjunct or complementary therapy or an alternative for mild symptoms in motivated patients (Maxwell & Duff, 2016).
ECT uses controlled electric currents to provoke a brief period of seizure-like activity. This is done in a series of four to six treatments before an improvement can be expected, with a total of six to twelve treatments over two to six weeks; maintenance treatments on a monthly basis are sometimes required. The patient is placed under general anesthesia for the treatments and able to resume normal activity in about an hour. ECT can have significant adverse effects, such as headaches, muscle pain, nausea, confusion, and memory loss. It is only utilized in severe depression, depression with psychosis, or bipolar disorder patients that have not responded to medication and psychotherapy with more conventional methods. In uncomplicated severe depression, ECT has been shown to lead to improved mood in 80% of patients. TMS creates rapidly alternating magnetic fields using a large magnetic coil placed on the patient’s forehead. Four to five 40-minute sessions per week may be required over the course of four to six weeks in order to see improvement. TMS is not recommended in patients with psychotic symptoms, bipolar disorder, or at high risk of suicide. TMS is contraindicated in patients with pacemakers or metal objects in their heads. The patient is awake and alert throughout the treatment, and general anesthesia is not required. Patients with a history of seizures should be warned that TMS may induce a seizure. Mild adverse effects may include muscle contractions or tingling in the face/jaw, headache, or lightheadedness. Vagus nerve stimulation (VNS) is FDA-approved for resistant depression only after attempts with four different medications and ECT treatment. Originally developed to treat seizure disorders, its use in depression treatment is controversial and rare. Adverse effects include voice changes, hoarseness, sore throat, cough, difficulty swallowing, neck pain, and breathing difficulty while exercising. Similarly, the FDA has approved deep brain stimulation (DBS) for the treatment of obsessive-compulsive disorder, and it is currently being studied for use in patients with Tourette's syndrome and MDD. It is more commonly used in the treatment of Parkinson's disease, and its safety and effectiveness for depression have yet to be determined. Both VNS and DBS involve surgically implanted stimulators. ECT, TMS, VNS, and DBS may be costly procedures for the patient, depending on the details of insurance coverage for each individual (McDonald & Fochtmann, 2019; National Alliance on Mental Health, n.d.).
Light therapy typically utilizes a lightbox with fluorescent tubes, a reflector, and a diffusing screen. Patients are instructed to sit in front of the light daily, typically in the morning, for 30- 60 minutes. It is thought to activate the suprachiasmatic nucleus, the circadian pacemaker of the brain. It has been used as an effective and safe treatment for seasonal affective disorder, but a recent systematic review and meta-analysis in patients with non-seasonal depression found a beneficial effect despite the poor quality of evidence (Perera et al., 2016).
While mild to moderate depression can often be treated with therapy alone (CBT or psychotherapy), moderate to severe cases of depression often require the addition of medication (WHO, 2018). There are a few over-the-counter medication options, such as St John’s wort, omega-3 fatty acids, and s-adenosylmethionine (SAMe). These options have been approved by the FDA for the treatment of depression and remain under study. They can also have significant adverse effects and drug interactions (never take St John’s wort with a prescription antidepressant) despite being sold over-the-counter without a prescription (NIMH, 2018).
In terms of prescription medication, the bulk of medications currently FDA-approved for the treatment of depression target the three neurotransmitters traditionally associated with depression: serotonin, norepinephrine, and dopamine. They usually take two to four weeks to work, and symptoms such as sleep, appetite, and concentration often improve before mood. Most need to be tapered up slowly when starting and down when stopping. There exists a current FDA warning that patients, especially those under the age of 25, may experience an increase in suicidal thoughts or behaviors during the first few weeks of taking an antidepressant, and all patients should be monitored for this effect (NIMH, 2018).
Selective serotonin reuptake inhibitors (SSRIs) are usually the safest initial choice and cause the least side effects. As their name would suggest, they work by selectively blocking the reuptake of serotonin, thereby increasing the amount of serotonin available within the brain. This includes medications such as citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), fluvoxamine (Luvox CR), paroxetine (Paxil), and sertraline (Zoloft). Serotonin-norepinephrine reuptake inhibitors (SNRIs) include duloxetine (Cymbalta), venlafaxine (Effexor), desvenlafaxine (Pristiq), and levomilnacipran (Fetzima) (Mayo Clinic, 2018).
Tricyclic antidepressants (TCA) and tetracyclics, which is an older class of medications including clomipramine (Anafranil), nortriptyline (Pamelor), imipramine (Tofranil), and amitriptyline (Elavil), inhibit norepinephrine and serotonin reuptake but with significantly more adverse effects (sedation, weight gain, anticholinergic effects, hypotension, cardiac effects, and even seizures) (Mayo Clinic, 2019b). Mirtazapine (Remeron) is an atypical tetracyclic antidepressant that antagonizes alpha-2 adrenergic and serotonin receptors. Monoamine oxidase inhibitors (MAOIs) such as tranylcypromine (Parnate), phenelzine (Nardil), isocarboxazid (Marplan), and selegiline (Emsam) are rarely used except when other medications have failed due to serious adverse effects, drug interactions, and even dangerous food interactions. There are also a few uncategorized atypical antidepressants. Bupropion (Wellbutrin), blocks the reuptake of norepinephrine and dopamine and can be used for depression as well as seasonal affective disorder and smoking cessation (Mayo Clinic, 2018; NIMH, 2016).
Vortioxetine (Trintellix) is also a newer medication for depression which works by inhibiting serotonin reuptake, but also as a mixed antagonist/agonist of specific serotonin receptors. Vilazodone (Viibryd) acts as a selective serotonin reuptake inhibitor, as well as a partial serotonin receptor agonist. Trazodone (Oleptro) antagonizes serotonin and alpha-1 adrenergic receptors and blocks the reuptake of serotonin. Similarly, nefazodone (Serzone) antagonizes serotonin receptors, as well as blocking the reuptake of norepinephrine and serotonin (Mayo Clinic, 2018).
In general, antidepressants should not be abruptly stopped, as this can cause withdrawal as well as a return of depression symptoms. The most common adverse effects seen with antidepressants include nausea/vomiting, weight gain, diarrhea, sleepiness, and sexual dysfunction. A drug interaction with other medications that increase serotonin levels, such as triptans used to treat migraines, can cause a condition called serotonin syndrome (agitation, hallucinations, high temperature, and severe blood pressure changes). Women of childbearing age should be warned that most antidepressants were previously considered pregnancy category C (risk cannot be ruled out) with the exception of paroxetine (Paxil, category D) and bupropion (Wellbutrin, category B), with slight variations between the medications’ safety in lactating mothers (Mayo Clinic, 2018; NIMH, 2016).
A systematic review and meta-analysis published in Lancet in 2018 reviewed 522 double-blind, randomized controlled trials, involving 116,477 patients diagnosed with MDD and 21 different antidepressants. Unfortunately, this analysis only recorded outcomes at or around eight weeks, which is a rather short period of time, especially for such long-acting medications. The authors noted that 426 of the 522 (81%) reviewed trials were deemed to be a moderate- or high risk of bias. Despite these limitations/shortcomings, the results showed all antidepressants were more effective than placebo. Agomelatine (Valdoxan), amitriptyline (Elavil), escitalopram (Lexapro), mirtazapine (Remeron), paroxetine (Paxil), venlafaxine (Effexor), and vortioxetine (Trintellix) were among the most effective, while fluoxetine (Prozac), fluvoxamine (Luvox), reboxetine (Edronax), and trazodone (Desyrel) were among the least effective. Agomelatine (Valdoxan) is a novel antidepressant that acts as a melatonin agonist and serotonin antagonist. It has been marketed in Europe since 2009 and in Australia since 2010 but is not currently available/approved for use in the US. Reboxetine (Edronax) is a norepinephrine reuptake inhibitor that is not approved for use in the US. Regarding tolerability, agomelatine (Valdoxan), citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), sertraline (Zoloft), and vortioxetine (Trintellix) had the lowest dropout rates, while amitriptyline (Elavil), clomipramine (Anafranil), duloxetine (Cymbalta), fluvoxamine (Luvox), reboxetine (Edronax), trazodone (Oleptro), and venlafaxine (Effexor) had the highest dropout rates. Overall, when evaluating effectiveness as well as tolerability, the authors determined that the best options for the treatment of depression appear to agomelatine (Valdoxan) and escitalopram (Lexapro) and the worst options appear to be fluvoxamine (Luvox), reboxetine (Edronax), and trazodone (Oleptro) (Cipriani et al., 2018).
Depression may be resistant to standard treatments, with up to 67% of patients failing to respond to first-line therapy. Many times, the resistance is not related to the medication or treatment but rather a compliance with administration by the patient. Failure can also be due to an incorrect dose, or an inadequate amount of time to develop a therapeutic blood level. When treating resistant depression, the healthcare provider should re-evaluate the diagnosis to ensure accuracy and consider co-morbidities such as anxiety, substance abuse, or psychosis. Assure consistency in medication administration. Upon assurance, the medication is being properly administered; an increase in dosage should be considered if appropriate. A change in medication may be warranted, such as changing from an SSRI to an SNRI or adding an additional medication to the current treatment regime. CBT can be added if not already part of the treatment, and ECT can be considered. Despite the fact that most depression is managed in primary care, consultation with a psychiatrist should be considered in the following circumstances:
- Suicidal ideations;
- Resistant depression;
- Severe depression;
- ECT considerations (Hasin et al., 2018).
MDD discriminately affects females and is a serious and costly health problem in the US and worldwide. All forms of depression are underdiagnosed and undertreated, even though the disease impacts the daily functioning of the individual. An increase in depression is noted in vulnerable populations, and particularly in those of low income. Depression may lead to a lower earning potential, and a lack of income is correlated to increased depression. This link to socioeconomic conditions creates more questions for future research (Hasin et al., 2018). The economic impact of all types of depression is high. The costs include the direct cost of healthcare services and treatments, along with indirect costs associated with lost employment days/opportunities, productivity, and daily functioning. The burden of depression to both the individual and those around them cannot be overlooked (McCormick et al., 2015).
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