How to Measure Depression: Assessing for Symptoms

How Do You Measure Depression?

Major depression impacts approximately 5%-6.7% of the world’s adult population each year, but the majority of depression likely goes undiagnosed. Steps can be taken—such as understanding how to measure depression more frequently and effectively—in clinical care settings to better identify individuals needing depression treatment. Brief assessments are efficient measures of depression symptoms in clinical settings. While these depression tests are not designed to diagnose depression, they can screen for symptoms, clarify symptom severity, measure symptoms after treatment, and detect depression symptoms occurring together with other disorders, such as substance use disorders.

Read on to learn about depression and how it is diagnosed. Then review the importance of depression measures, with a focus on the Beck Depression Inventory (BDI), as well as other assessment tools.

how to measure depression

What is Major Depression?

Major depression is a mood disorder marked by ongoing, deep sadness (or irritability) and a lack of ability to feel pleasure. Individuals with depression often withdraw from others, feel miserable, and have a negative view of their life. For an official diagnosis to be considered, these and other depression symptoms must last at least two weeks, indicating that their mood change is persistent.

Patients with depression must also meet the following criteria:

  • Loss of interest in activities that they normally enjoy.
  • Persistently low mood.
  • Experience at least three additional depression symptoms affecting them most of the time.
    • Mood: Sadness, loneliness, irritability.
    • Cognition: Trouble thinking clearly and making decisions, low confidence, thoughts of death or self-harm.
    • Physical Well-being: Body aches, headaches, psychomotor retardation (moving slowly), stomach aches.
  • These changes interfere with daily functioning, relationships, and major life areas such as work, school, and home.

How Is Depression Diagnosed?

Depression is diagnosed primarily through a clinical interview conducted by a primary medical or health care provider. Clinical depression—the threshold above which depressive symptoms may be considered an official depressive disorder— includes a variety of symptoms that can present in many ways, underscoring the importance of a thorough evaluation interview.

Clinicians wanting to learn more about a patient’s symptoms often use standardized depression tests, with the most widely accepted being the Beck Depression Inventory (more on that later). Primary care clinics are often the first point of contact for individuals with depression, and routine depression screening helps normalize conversations about depression in healthcare settings. And while depression assessments are not designed to diagnose depression, clinicians frequently use brief screening tools to identify depression symptoms that may need further exploration.

The Clinical Interview

Clinicians conduct a standardized interview with patients to assess for depression symptoms experienced in the past two weeks, the duration of each symptom, and the impact symptoms have had on daily life activities. Using guidelines from the American Psychiatric Association’s (APA’s) Diagnostic and Statistical Manual of Mental Health Disorders, 5th Edition (DSM-V), clinicians then determine if an individual’s symptoms meet the criteria for a depressive disorder. These inquiries help clinicians understand the severity of symptoms and identify depression subtypes, both of which can affect treatment options and outcomes.

Assessment for Depression

Many clinicians rely on assessments to measure depression symptom severity more thoroughly. And some use these measures as screening tools when clarifying a complex diagnosis or when multiple disorders may be occurring at the same time.

Several self-report and clinician-administered depression measures are available, but the Beck Depression Inventory (BDI) is the most widely used tool today. And while the information gleaned from using the BDI can be crucial for generating an accurate diagnosis, this depression measure is not designed to diagnose depression.

The Beck Depression Inventory (BDI)

The Beck Depression Inventory (BDI) is a widely used assessment for measuring depression symptoms among adults. It can be used to monitor symptoms at the time of the evaluation, throughout treatment, and as a follow-up after the treatment has concluded.

What Is the Beck Depression Inventory?

The Beck Depression Inventory (BDI) is a self-administered assessment protocol designed to measure the severity and characteristics of depression symptoms in individuals ages 13-80. It was developed based on observations of symptoms that frequently occurred for individuals with depression, with the second edition (BDI-II) being revised to align more closely with current diagnostic criteria.

The BDI consists of 21 items about psychological and physical symptoms associated with major depression. Individuals are asked to recall their experience over the last two weeks as they rate each item on a 4-point scale, ranging from zero (little to no problem with that symptom) to three (severely bothersome).

After rating all 21 items, individuals compile their scores to generate an overall score.

Score Severity Ranges:

1-10 Considered normal

10-16 Mild

17-20 Borderline clinical depression

21-30 Moderate

31-40 Severe

Over 40 Extreme

measuring depression

Using the Beck Depression Inventory in a Clinical Setting

Clinicians frequently rely on the BDI when evaluating an individual for a depressive disorder, as a key advantage of the DBI is its ability to generate a more detailed picture of how depression symptoms impact a patient’s life. The perspective it can provide also helps inform treatment choices, not only at the initial assessment but also at follow-up points throughout treatment. As valuable as the BDI is for evaluating symptoms, though, it is not intended for use as a stand-alone diagnostic tool or instead of a clinical evaluation. A completed BDI can provide valuable information for clinicians, but it is not a shortcut or substitute for a clinical evaluation.

Beck Depression Inventory-Fast Screen

Many individuals with significant medical conditions, such as multiple sclerosis and end-stage renal disease, often develop depression at the same time. However, the standard BDI includes screening questions for somatic (physical) symptoms, some of which may overlap with symptoms of their condition and lead to false positive results for depression.

The Beck Depression Inventory-Fast Screen (BDI-FS), a self-report assessment based on the standard BDI, reduces this risk by only screening for seven psychological symptoms. It is also an efficient measure that takes less than five minutes to complete, a welcome feature for individuals who already spend a lot of time in medical appointments.

Additional Depression Assessments

The BDI is a standard assessment for clinicians evaluating for depression, but other measures of depression are available for screening and recording symptoms.

Ecological Momentary Assessment

Standard assessments, like the BDI, are typically designed to use information recalled and self-reported by patients. However, this information is impacted by recall bias, when individuals recall memories in a distorted way based on their state of mind. Individuals with depression tend to have negative recall bias, which can affect the accuracy of standard depression measurement tests.

Ecological Momentary Assessments (EMAs) take a different approach, utilizing smartphone apps to capture individuals’ symptoms in the setting where they occur close to the time they emerge. While only a few of these have been studied to date, their potential for providing more accurate assessments of depression symptoms is promising.

Physical Health Exams

Because of how common physical symptoms are with depression, clinicians may also recommend a physical exam to rule out other conditions. Some conditions, such as fibromyalgia, chronic fatigue syndrome, diabetes, and thyroid disease have symptoms that may appear similar to depression. Because some clinicians may discuss medication options, obtaining up-to-date health information during the diagnostic process also helps individuals and clinicians make safe, effective choices.

Measuring Depression for Positive Health Outcomes

20% of individuals are believed to have a major depressive episode at some point during their lifetime, and early symptom detection plays an important role in facilitating a positive outcome in these cases. Utilizing depression measurement tests, such as the Beck Depression Inventory, can improve the odds of getting timely treatment, when symptoms eventually surface.