Major Depressive Disorder: Symptoms, Risk Factors & Treatment

Introduction

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) defines major depressive disorder (MDD) as a period of at least two weeks during which an individual experiences a depressed mood or loss of interest, along with several other symptoms including sleep disturbance and lack of concentration (American Psychiatric Association, 2013). However, the symptoms should not be attributable to another medical condition or substance use (APA, 2013). The National Institute of Mental Health (NIMH) categorizes MDD as one of the most common psychiatric disorders in the United States (NIMH, 2019). Data from the 2017 National Survey on Drug Use and Health indicates that 17.3 million American adults—representing 7.1 percent of the U.S. adult population—had MDD in 2017 (NIMH, 2019).

The prevalence of MDD is higher among females (8.7 percent) than males (5.3 percent) (NIMH, 2019). Furthermore, prevalence is highest among young adults between the ages of 18 and 25 at 13.1 percent, and among individuals from ethnic minorities at 11.3 percent (NIMH, 2019). This paper analyzes the symptoms and risk factors of MDD, the theoretical and neurobiological foundations of the disorder, evidence-based interventions, and diversity issues related to the diagnosis and treatment of MDD.

Symptoms of Major Depressive Disorder

The DSM-5 criteria categorize the symptoms of MDD into five classes (Criteria A through E). Criterion A includes nine symptoms, of which a client must exhibit at least five over the same two-week period. One of those symptoms must be either a depressed mood or a loss of pleasure or interest in significant activities (APA, 2013). To count toward an MDD diagnosis, a symptom must either be newly present or have clinically worsened from pre-illness status (APA, 2013).

A1 – Depressed mood: The individual experiences a depressed mood for most of the day, nearly every day. They will often report feeling sad, discouraged, hopeless, or "down in the dumps" (APA, 2013). Some clients deny feeling sad or anxious, yet a clinician may still infer depressed mood from their demeanor and facial expressions during a clinical interview. Rather than demonstrating sadness, some clients exhibit high irritability evidenced by exaggerated frustration over minor matters, outbursts, persistent anger, or a tendency to blame others (APA, 2013). For children and adolescents, depressed mood often presents as an irritable or cranky mood experienced most of the day, nearly every day.

A2 – Loss of interest or pleasure: The individual may lose interest in almost all activities for most of the day (APA, 2013). They may report losing interest in hobbies, no longer enjoying activities that were once pleasurable, or simply "not caring" anymore. Family members may also report social withdrawal and loss of pleasure—for example, a football enthusiast who no longer plays, or a child who enjoyed sports finding excuses not to attend (APA, 2013).

A3 – Weight and appetite changes: The client may experience significant unintentional weight gain or loss, or a sudden increase or decrease in appetite nearly every day. Some individuals report craving specific foods, while others are completely unable to eat and must force themselves (APA, 2013). Clinically significant weight loss is defined as a change of at least 5 percent in body weight over a one-month period. In children, this criterion may be indicated by failure to gain weight as expected for their developmental stage (APA, 2013).

A4 – Sleep disturbances: One may also experience hypersomnia, insomnia, or other sleep difficulties nearly every day. Insomnia may present as initial insomnia (difficulty falling asleep), terminal insomnia (waking too early and being unable to return to sleep), or middle insomnia (waking during the night and being unable to return to sleep). Hypersomnia may present as increased daytime sleep and prolonged nighttime sleep (APA, 2013).

A5 – Psychomotor changes: Also common is psychomotor retardation or agitation presenting as hand wringing, pacing, inability to sit still, slowed speech and movements, or long pauses before answering questions. The retardation or agitation must be noticeable to others—not merely based on self-report (APA, 2013).

A6 – Fatigue or loss of energy: A depressed individual may report fatigue or a loss of energy experienced most of the day, nearly every day. The time needed to complete tasks may increase significantly from pre-illness levels, and tasks such as washing and dressing may require substantial effort (APA, 2013).

A7 – Feelings of worthlessness or guilt: It is common for depressed individuals to experience feelings of excessive or inappropriate guilt or worthlessness nearly every day. The individual often demonstrates unrealistic self-evaluations or increased rumination over past failures (APA, 2013). These feelings must be excessive—not merely self-reproach about failing to meet ordinary interpersonal or occupational responsibilities (APA, 2013).

A8 – Cognitive difficulties: Indecisiveness and a diminished ability to concentrate or think are also common, manifesting nearly every day. The individual may complain of memory difficulties or increased distractibility (APA, 2013). Children may present with an inability to concentrate in school and a sudden drop in grades, while elderly clients may report memory difficulties resembling dementia. This criterion may be based on either subjective reports or observations by others close to the patient (APA, 2013).

A9 – Suicidal ideation: Recurrent thoughts of death, suicidal ideation, suicide attempts, and plans for committing suicide are also common among depressed individuals. The individual might present with beliefs that the world would be better off without them, or with recurrent thoughts of suicide (APA, 2013). In some cases, the individual may have a concrete suicidal plan, such as updating their will, settling debts, or acquiring materials such as poison or rope. Suicide may be motivated by a wish not to burden family members, an intense desire to end seemingly unending pain, or a sense of giving up following a series of failures (APA, 2013).

Criterion B: The symptoms must cause clinically significant distress or impairment in occupational, social, or other important areas of functioning (APA, 2013). Impairment may manifest in various ways, including job loss, declining academic performance, difficulty maintaining friendships, or inability to meet financial obligations.

Criterion C: The symptoms are not attributable to another medical condition or the physiological effects of a substance (APA, 2013).

Criterion D: The occurrence of MDD symptoms is not better explained by delusional disorder, schizophreniform disorder, schizoaffective disorder, or another specified or unspecified schizophrenia spectrum or psychotic disorder (APA, 2013).

Criterion E: The client has never experienced a hypomanic or manic episode (APA, 2013). This criterion does not apply, however, if any previous hypomanic or manic episodes were attributable to the physiological effects of another medical condition or substance use (APA, 2013).

Prognostic and Risk Factors

Studies have found that negative affectivity (neuroticism) is a significant risk factor for MDD (Fanous et al., 2007). Individuals with higher neuroticism scores are more likely than the general population to develop MDD when faced with stressful life events. Fanous et al. (2007) conducted a study analyzing the risk of MDD among 1,733 female-female and 1,862 male-male pairs of twins. The findings showed that an increase of one standard deviation in neuroticism increased the odds of developing MDD by 90 to 100 percent for women and 85 percent for men (Fanous et al., 2007). This further supports the finding that women are more vulnerable to major depressive episodes than men.

Individuals exposed to adverse experiences in childhood are at greater risk of developing MDD later in life than those who have a typical childhood (APA, 2013). Stressful life events in adulthood—such as the death of a child or spouse—can also increase the risk of developing MDD.

Individuals whose first-degree relatives have suffered from MDD are three to four times more likely to experience a major depressive episode than the general population (APA, 2013). According to the American Psychiatric Association, heritability for MDD is approximately 40 percent (APA, 2013).

The risk of MDD increases with a prior history of non-mood disorders such as borderline personality disorder, substance use disorders, and anxiety disorders (APA, 2013). Furthermore, risk is higher among individuals with chronic illnesses such as cardiovascular disease and diabetes (APA, 2013).

Conclusion

A crucial insight from this review is that diversity influences both the presentation of symptoms and the course of treatment for MDD patients. It is therefore essential that social workers understand the diversity issues surrounding symptom presentation in different clients to ensure they select the most appropriate and culturally informed treatment plan. Recognition of gender- and ethnicity-related differences in suicide risk, somatic symptom expression, and treatment response is fundamental to effective, person-centered care for individuals living with MDD.