Multidimensional Inventory of Dissociation – 60-item version (MID-60)

Scores for each item range from zero (never) to 10 (always). The MID-60 mean score represents the percentage of time the person self-reports having dissociative symptoms and experiences. Hence, a person with dissociative identity disorder may have dissociative symptoms and experiences around half the time (51%) whereas for a university student this may be 13% of the time. A mean score of more than 21% indicates clinically significant symptoms.

Interpretation of MID-60 mean scores is consistent with the 218-item MID. Specifically:

• 0–7: Does not have dissociative experiences
• 7–14: Has few diagnostically significant dissociative experiences
• 15–20: Mild dissociative symptoms and experiences. PTSD or a mild dissociative disorder (such as dissociative amnesia, depersonalisation / derealisation disorder) are possible
• 21–30: May have dissociative disorder and/or PTSD
• 31–40: May have a dissociative disorder (such as OSDD-1 or DID) and PTSD
• 41–64: Probably has DID or a severe dissociative disorder and PTSD
• 64 +: Severe dissociative and post-traumatic symptoms. High scores may also reflect neuroticism, attention seeking behaviour, exaggeration or malingering of symptoms, or psychosis

Subscales
The MID-60 provides information on subscales relevant to different diagnoses. This enables the clinician to form an impression about the likely diagnosis. For example, a score of 27% is clinically significant, but does not indicate the most likely diagnosis. If the subscales of PTSD and depersonalisation/derealisation are both above the clinical threshold, this can indicate the person has the dissociative subtype of PTSD, whereas if the memory-related subscales are above the clinical threshold this can indicate dissociative amnesia. Another example is a person who scores 45%, which would seem to indicate dissociative identity disorder. Yet, if the subscale score for amnesia (for recent events) is not elevated, this points towards a more severe case of other specified dissociative disorder. The subscales are:

• DID: Amnesia (for recent events) – items 42, 45, 48, 58. Clinical cutoff = 10
• DID / OSDD-1: Subjective awareness of alter personalities and self-states – items 3, 36, 39, 49, 57. Clinical cutoff = 20
• DID / OSDD-1: Angry intrusions – items 28, 33, 35, 46, 60. Clinical cutoff = 18
• DID / OSDD-1: Persecutory intrusions – items 22, 37, 44, 56, 59. Clinical cutoff = 18
• Derealisation/Depersonalisation – items 2, 7, 9, 13, 25, 47, 50, 53. Clinical cutoff = 20
• Dissociative Amnesia: Distress about severe memory problems – items 1, 8, 20, 38, 43, 52. Clinical cutoff = 30
• Dissociative Amnesia: Loss of autobiographical memory – items 16, 19, 24, 29, 34. Clinical cutoff = 34
• PTSD: Flashbacks – items 4, 15, 31, 40, 54. Clinical cutoff = 16
• Conversion Disorder: Body symptoms – items 5, 10, 14, 18. Clinical cutoff = 10
• Conversion Disorder: Pseudo-Seizures (Psychogenic non-epileptic seizures) – item 26. Clinical cutoff = 10
• General Subscales: Trance – items 21, 27, 30, 32, 41, 51. Clinical cutoff = 11.7
• General Subscales: Self-confusion – items 6, 11, 12, 17, 23, 55. Clinical cutoff = 33.3

The MID-60 is for screening purposes, is not designed to be the sole determinant of a diagnosis and should always be used in conjunction with clinical expertise. Further evaluations can be conducted with the Structured Clinical Interview for DSM-5 Dissociative Disorders (SCID-D) or Dissociative Disorders Interview Schedule (DDIS).

The MID-60 is a short version of the 218-item Multidimensional Inventory of Dissociation, a diagnostic instrument (Dell, 2006). The MID-60 was derived from the five items with the highest pattern matrix loading for each of the MID’s 12 factors (Dell & Lawson, 2009). The MID-60 has a nearly identical factor structure to the full MID, excellent internal reliability (α = .97) and content and convergent validity (Kate et al., 2020).

Normative sample
The mean score for both males and females in an Australian university sample (n = 313) was 13.0 (SD = 13.8; Kate et al., 2021). Age did not moderate mean scores MID-60. However, younger participants aged 24 or under had significantly higher scores on the subscales of self-confusion (19.3 vs. 14.6) and angry intrusions (10.0 vs. 6.6).

Clinical samples
Females with a dissociative disorder diagnoses (N = 30) had a mean MID-60 score of 56.8 (SD = 18.8) and the two males had a mean score of 53.4 (SD = 4.7; Kate, Jamieson & Middleton, 2021; 2022). This is consistent with the mean for the 218-item MID, i.e., DID (N = 76, M = 51.3, SD = 18.7) and OSDD-1 (N = 40, M = 39, SD 19.4; Dell et al., 2017). The MID mean has been calculated in people with schizophrenia experiencing a relapse (N = 20, M = 27.0, SD = 20.6) and in remission (N = 20, M = 18.4, SD = 19.2; Laddis & Dell, 2012) and in a clinical group with a borderline personality disorder diagnosis (N = 21, M = 25.4, SD = 18.1, Korzekwa et al., 2009).

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