DID Underdiagnosis Series — Article 4 of 5
The previous articles in this series established that DID is far more common than its diagnosis rate suggests, and that the gap between expected and diagnosed prevalence is large enough to constitute a systemic problem. This article addresses what to do about it — specifically, what tools exist, what evidence supports them, and what a reliable assessment sequence looks like in clinical practice.
The core finding from the structured-assessment literature is straightforward: when clinicians use dissociation-specific tools, they find dissociation. When they rely on generic psychiatric intake formats, they miss it. That is not a subtle effect. A 2021 meta-analysis of SCID-D studies found that the structured interview robustly differentiated dissociative from non-dissociative disorders with a very large overall effect size, with especially strong differentiation on amnesia and identity alteration. The problem is not diagnostic validity. The problem is diagnostic application.
The Four Primary Assessment Instruments
1. Dissociative Experiences Scale (DES)
The DES is a 28-item self-report questionnaire that asks patients to rate the frequency of dissociative experiences on a 0–100% scale. It takes approximately five minutes to complete and five minutes to score. It is best understood as a screening tool rather than a diagnostic instrument.
A DES score above 30 is generally considered the threshold for further structured assessment. However, the DES has both false positive and false negative limitations — some patients with DID score below 30, and some without DID score above 30. A negative DES screen does not rule out dissociative pathology, particularly in patients who present with a covert, high-functioning dissociative structure. The DES is valuable for identifying patients who warrant a second look; it is not sufficient to make or exclude a diagnosis.
2. Structured Clinical Interview for Dissociative Disorders (SCID-D / SCID-D-R)
The SCID-D-R is the gold standard for structured dissociation assessment. It is a 277-item clinician-administered interview that evaluates five core dissociative symptom domains: amnesia, depersonalization, derealization, identity confusion, and identity alteration. Administration typically requires 45 to 180 minutes or more, depending on clinical complexity.
The 2021 meta-analysis by Mychailyszyn and colleagues found that SCID-D interviews produced very large effect sizes in differentiating dissociative from non-dissociative disorders. The instrument performs particularly well on amnesia and identity alteration — the two domains most central to DID diagnosis. The SCID-D-R requires formal training and clinician familiarity with dissociative phenomenology to administer reliably.
3. Dissociative Disorders Interview Schedule (DDIS)
The DDIS is a shorter structured interview that covers dissociative disorders while also assessing borderline personality disorder, somatic symptoms, Schneiderian first-rank symptoms, substance use, trance states, and childhood abuse history. Its inclusion of Schneiderian symptoms and BPD features makes it particularly useful in differentials where those conditions are on the table.
The DDIS takes less time than the SCID-D and may be more practical in clinical settings where full SCID-D administration is not feasible. It does not provide the same granularity on severity and frequency of individual dissociative symptoms.
4. Multidimensional Inventory of Dissociation (MID)
The MID is a 218-item self-report questionnaire that assesses a wide range of dissociative experiences across multiple subscales and includes validity indicators designed to detect response distortion. It can generate diagnostic impressions including DID and PTSD and provides a more detailed phenomenological picture than the DES alone.
The MID requires clinical corroboration — self-report instruments are influenced by patient knowledge of DID, suggestibility, and symptom presentation variability across states.
The Practical Assessment Sequence
A clinically grounded sequence for assessing potential DID moves through several steps. The sequence is not rigid — clinical judgment governs the pace and depth of each step — but the overall logic reflects the evidence base.
| Step | Action | Clinical Rationale |
|---|---|---|
| 1 | Ask directly about dissociation during intake | DID symptoms are rarely volunteered; direct questioning is the sine qua non of identification (ISSTD, 2011) |
| 2 | Clarify voice phenomenology if voices are present | Internal vs. external location, personification, and relationship to self-states help distinguish DID voices from psychotic hallucinations |
| 3 | Administer DES when dissociation is clinically plausible | Captures frequency estimates quickly; identifies patients who warrant structured follow-up |
| 4 | Follow elevated DES or clinical suspicion with structured interview | SCID-D-R or DDIS provide diagnostic-level differentiation that DES cannot offer alone |
| 5 | Consider MID for comprehensive phenomenological mapping | Useful when interview access is limited or as a supplement to clinical interviewing |
| 6 | Assess childhood trauma history with appropriate care | Trauma history is central context; dissociative amnesia may render it incompletely recalled |
| 7 | Complete differential diagnosis for comorbidities | DID is frequently comorbid with PTSD, depression, BPD, and substance use; comorbidities should be identified, not used to foreclose DID assessment |
The Questions That Should Be Routine
The following questions require no specialized training and no formal instrument. They take two to four minutes. They are appropriate for any patient presenting with a significant trauma history, treatment-resistant symptoms, “complicated” presentations, self-harm, or unexplained symptom variability:
- “Do you ever lose time or come to somewhere without knowing how you got there?”
- “Do you ever feel like someone else took over and said or did things you wouldn’t have said or done?”
- “Do you hear voices inside your head that seem separate from your own thoughts?”
- “Do you ever find yourself in the middle of something with no memory of how it started?”
- “Do other people tell you that you said or did things you have no memory of?”
- “Do you ever feel like you are a very different person at different times — more than just mood?”
The goal of these questions is not to confirm DID. It is to determine whether structured assessment is warranted. A patient who answers affirmatively to two or more of these questions has given the clinician sufficient reason to proceed with formal dissociation assessment before finalizing any other diagnosis.
Addressing the Time Barrier
The most common objection to dissociation assessment is time. The SCID-D-R can take up to three hours. The answer to this objection is not that time is irrelevant — it is that the time investment is proportionate to the clinical stakes.
A patient with undiagnosed DID who is treated for BPD, depression, or schizophrenia for five years accumulates considerably more clinical time, at considerably greater cost, with considerably worse outcomes, than a patient who receives appropriate assessment and targeted treatment.
Not every patient who might have DID requires a full SCID-D-R. The DES and the six direct questions above can identify patients who warrant the additional investment. For the majority of patients, routine assessment will not suggest DID. For the subset who screen positive, the structured interview is not an indulgence — it is the only reliable way to determine whether DID is present.
References
- Mychailyszyn MP et al. Differentiating Dissociative from Non-Dissociative Disorders: A Meta-Analysis of the SCID-D. J Trauma Dissociation. 2021;22(1):19-34.
- ISSTD. Guidelines for Treating DID in Adults, Third Revision. J Trauma Dissociation. 2011;12(2):115-187.
- Steinberg M. Structured Clinical Interview for DSM-IV Dissociative Disorders — Revised (SCID-D-R). Washington DC: American Psychiatric Press; 1994.
- Dell PF. The Multidimensional Inventory of Dissociation (MID). J Trauma Dissociation. 2006;7(2):83-109.
- Pietkiewicz IJ et al. Revisiting False-Positive and Imitated DID. Frontiers in Psychology. 2021;12:637929.