The Beck Depression Inventory (BDI, BDI-II), created by Dr. Aaron T. Beck, is a 21-question multiple-choice self-report inventory that is one of the most widely used instruments for measuring the severity of depression. The most current version of the questionnaire is designed for individuals aged 13 and over and is composed of items relating to depression symptoms such as hopelessness and irritability, cognitions such as guilt or feelings of being punished, as well as physical symptoms such as fatigue, weight loss, and lack of interest in sex. There are three versions of the BDI—the original BDI, first published in 1961 and later revised in 1978 as the BDI-1A, and the BDI-II, published in 1996. The BDI is widely used as an assessment tool by healthcare professionals and researchers in a variety of settings.
Throughout his work, Beck drew attention to the importance of "negative cognitions": sustained, inaccurate, and often intrusive negative thoughts about the self. In his view, it was the case that these cognitions caused depression, rather than being generated by depression.
Beck developed a triad of negative cognitions about the world, the future, and the self, which play a major role in depression. An example of the triad in action taken from Brown (1995) is the case of a student obtaining poor exam results:
The development of the BDI reflects that in its structure, with items such as "I have lost all of my interest in other people" to reflect the world, "I feel discouraged about the future" to reflect the future, and "I blame myself for everything bad that happens" to reflect the self. The view of depression as sustained by intrusive negative cognitions has had particular application in cognitive behavioral therapy (CBT), which aims to challenge and neutralize them through techniques such as cognitive restructuring.
When the test is scored, a value of 0 to 3 is assigned for each answer and then the total score is compared to a key to determine the depression's severity. The standard cut-offs are as follows: 0–9 indicates that a person is not depressed, 10–18 indicates mild-moderate depression, 19–29 indicates moderate-severe depression and 30–63 indicates severe depression. Higher total scores indicate more severe depressive symptoms.
Some items on the BDI have more than one statement marked with the same score. For instance, there are two responses under the Mood heading that score a 2: (2a) I am blue or sad all the time and I can't snap out of it and (2b) I am so sad or unhappy that it is very painful.
However, this version retained some flaws; the BDI-IA only addressed six out of the nine DSM-III criteria for depression. This and other criticisms were addressed in the BDI-II.
Items involving changes in body image, hypochondria, and difficulty working were replaced. Also, sleep loss and appetite loss items were revised to assess both increases and decreases in sleep and appetite. All but three of the items were reworded; only the items dealing with feelings of being punished, thoughts about suicide, and interest in sex remained the same. Finally, participants were asked to rate how they have been feeling for the past two weeks, as opposed to the past week as in the original BDI.
Like the BDI, the BDI-II also contains 21 questions, each answer being scored on a scale value of 0 to 3. The cutoffs used differ from the original: 0–13: minimal depression; 14–19: mild depression; 20–28: moderate depression; and 29–63: severe depression. Higher total scores indicate more severe depressive symptoms.
One measure of an instrument's usefulness is to see how closely it agrees with another similar instrument that has been validated against clinical interview by a trained clinician. In this respect, the BDI-II is positively correlated with the Hamilton Depression Rating Scale with a Pearson r of 0.71, showing good agreement. The test was also shown to have a high one-week test–retest reliability (Pearson r =0.93), suggesting that it was not overly sensitive to daily variations in mood. The test also has high internal consistency (α=.91).
The cognitive subscale contains eight items: pessimism, past failures, guilty feelings, punishment feelings, self-dislike, self-criticalness, suicidal thoughts or wishes, and worthlessness. The somatic subscale consists of the other thirteen items: sadness, loss of pleasure, crying, agitation, loss of interest, indecisiveness, loss of energy, change in sleep patterns, irritability, change in appetite, concentration difficulties, tiredness and/or fatigue, and loss of interest in sex. The two subscales were moderately correlated at 0.57, suggesting that the physical and psychological aspects of depression are closely related rather than totally distinct.
The instrument remains widely used in research. A search on Pubmed returns 3,209 peer-reviewed articles that have used the inventory in the measurement of depression, and it has been translated into multiple European languages as well as Arabic, Japanese, Persian, and Xhosa.
Another serious limitation is that in participants with concomitant physical illness, it has been suggested that the BDI's reliance on physical symptoms such as fatigue might artificially inflate scores due to symptoms of the illness, rather than of depression. In response to this criticism, Beck and his colleagues have developed a measure called the "Beck Depression Inventory for Primary Care" (BDI-PC). This is a short screening scale consisting of seven items from the BDI-II considered to be independent of physical function. Unlike the standard BDI, the BDI-PC produces only a binary outcome of "not depressed" or "depressed" for patients above a cutoff score of 4. Researchers and clinicians who work with medically ill populations might also consider using the Center for Epidemiologic Studies - Depression Scale (CES-D) or the Hospital Anxiety and Depression Scale (HADS) as alternative measures.
The BDI provides a measure of severity of symptoms, rather than a diagnosis. Some may consider it inappropriate to make a diagnosis of depression solely on the basis of a self report inventory.