15.2: Measurement of Major Depressive Disorder and Depressive Symptoms

Depression is characterized by substantial symptom heterogeneity, which makes its assessment difficult. For example, combinations of the nine DSM-5 criteria required for a MDD diagnosis results in 227 unique depressive symptom profiles (Fried & Nesse, 2015). Furthermore, Fried (2017) assessed content overlap of the seven most commonly used depression scales in scientific research and found 52 disparate symptoms, with little symptom overlap across instruments. Therefore, it is important to note that measurement of depression is a challenging endeavor because there is no single measure that can account for its complexity. MDD diagnoses are made using well-validated clinical interviewing instruments, while depression symptom severity is measured using self-report rating scales. Researchers often combine clinical interviews with rating scales to provide insight into the presence and nature of an individual’s depression. For the purposes of this chapter, we provide a brief overview of some of the most prevalent diagnostic interviews and rating scales used in research to measure MDD and depressive symptoms.

15.2.1. Diagnostic Interviews

15.2.1.1. Structured Clinical Interview for DSM-5 (SCID-5)

The SCID-5 is the most widely used structured diagnostic interview for assessing the DSM-5 disorders (First et al., 2015). Clinical psychologists and psychiatrists and other trained mental health professionals use the SCID-5 to assess for the presence of lifetime and current depressive disorders and other psychiatric disorders such as anxiety disorders (see Chapter 16; Schuch et al., 2021), psychotic disorders (see Chapter 17; Fibbins et al., 2021), substance use disorders, somatic symptom disorders, externalizing disorders and trauma-and stressor-related disorders. Research suggests that the SCID-5 has excellent reliability, sensitivity, and specificity for most of the psychological disorders with high prevalence, even when the clinical interview is conducted over the telephone (Osório et al., 2019). Due to its popularity, the SCID-5 has been translated into other languages and has been used in a variety of cultures.

15.2.1.2. Mini International Neuropsychiatric Interview (MINI)

The MINI is a short, structured diagnostic interview developed jointly by clinicians in the U.S.and Europe that follows diagnostic criteria outlined in the International Classifications of Disease and DSM-5 (Sheehan et al., 1997). The MINI is typically used in research to reduce the amount of time it takes to assess and diagnose depression. Research suggests that the reliability and validity of the MINI is on par with the SCID (Sheehan et al., 1997). The MINI can be conducted within 15 minutes and can serve as a short and accurate assessment of psychopathology.

15.2.2. Dimensional Measures of Depressive Symptoms

Depressive symptoms have been measured using a variety of self-report rating scales. Three commonly used rating scales of depressive symptoms are described below. These rating scales assess current depressive symptoms severity over a specified time interval and aid in determining whether treatments are effective in reducing depressive symptoms.

15.2.2.1. Beck Depression Inventory, Second Edition (BDI-II)

The BDI-II assesses the presence of depressive symptoms during a two-week period using 21 items scored on a 4-point Likert scale ranging from 0-3. Higher scores indicate greater severity of depressive symptoms (Beck et al., 1996). A score of 13 or higher on the BDI-II is generally an indication of the presence of a depressive disorder and the BDI-II has shown high sensitivity and specificity when utilized as a screening tool (Lasa et al., 2000). The BDI-II has shown good internal consistency and validity across different settings and populations (Steer et al., 1999, 2000).

15.2.2.2. Hamilton Rating Scale for Depression (HRSD)

The HRSD is a reliable assessment of the severity of depressive symptoms using 17 items scored from 0-4 (Trajković et al., 2011). A total score is obtained by summing all the items together. The HRSD provides categories that indicate the severity of depressive symptoms based on the total score. For example, a total score from 0-7 indicates normal levels of depressive symptoms, 8-16 suggests mild depression, 17-23 suggests moderate depression, and a score ≥24 indicates severe depression (Sharp, 2015).

15.2.2.3. Center for Epidemiologic Studies Depression Scale (CES-D)

The CES-D was originally developed to assess the number and frequency of depressive symptoms in the general population (Radloff, 1977). The CES-D exhibits strong psychometric properties, including high internal consistency and good divergent and convergent validity (Van Dam & Earleywine, 2011). The CES-D has also been validated for use in a variety of age groups, including adolescents and young adults (Roberts et al., 1990). The CES-D has 20 items scored from 0-3. A total score is computed by summing all the items together, with possible scores ranging from 0-60. Higher scores indicate more symptoms and are weighted by frequency of occurrence during the past week. CES-D scores that are at least 16 or greater have been shown to identify individuals at risk for clinical depression (Lewinsohn et al., 1997).

In 2004, the original CES-D was revised by Eaton et al. to reflect depressive symptoms more accurately as indicated by the DSM. The CESD-R (i.e., Center for Epidemiologic Depression Scale Revised; Eaton et al., 2004) is also 20 items, with each item scored on a scale of 0-3. Higher scores reflect greater severity of depressive symptoms. Based on scoring, participants can be categorized into one of five possible depressive categories: meets criteria for major depressive episode, probable major depressive episode, possible major depressive episode, subthreshold depression symptoms, or no clinical significance. An advantage of using the CESD-R compared to other instruments is that it is free and accessible as a part of the public domain (see https://cesd-r.com/).