humanist + humorist

The bad news: if I had bet money on that plurality stat from the other day, it looks like I would’ve lost.

The good news: LB Lee came through with the citations, and between us I think we’ve nailed it down for real this time. Also, brought my list of relevant studies up to 5 — which is still tiny, but hey, still better than one.

So, consider the previous mini-vent a trailer for this full-length dissection.

The big one, probably the actual Ground Zero source for the statistic, from 1991:

• Ross, C. A. (1991). Epidemiology of multiple personality disorder and dissociation. Psychiatric Clinics of North America, 14(3), 503–517. 10.1016/S0193-953X(18)30286-7

The abstract flat-out says “multiple personality disorder related to childhood abuse affects about 1 % of the adult population.”

(MPD was renamed to DID in the fourth edition of the DSM, released in 1994. This research straddles the year of the name change, so you’ll see both terms come up.)

I don’t have access to the full text, but Ross discusses the study in the second edition of his book, Dissociative identity disorder : diagnosis, clinical features, and treatment of multiple personality (1997). Sample was 502 people in Winnipeg, screened with the Dissociative Experiences Scale, then later re-evaluated with the Dissociative Disorders Interview Schedule.

From the book:

There are a number of serious methodological limitations to the DDIS portion of this study: No validating clinical interviews were conducted; the validity of the DDIS in nonclinical populations is unknown; the sample size is too small; the data come from only one city; and no other standardized interview was administered. Because of these limitations, the data from the study, shown in Table 5.2, must be regarded only as first approximations. The 1% prevalence of DID is a conservative interpretation of the data, because over 3% of respondents endorsed DSM-III-R criteria for multiple personality disorder. I excluded most of these people as false positives because they reported neither trauma histories nor the rest of the DDIS symptom profile for DID. It is clear that the DID cases detected in this study are far milder in symptom severity than clinically diagnosed cases, including their DES scores.

Several other interpretations of the data are possible. First, the prevalence of severe DID may be less than 0.2% because no such cases were detected in a sample of 502 respondents. Second, these data provide the strongest existing scientifically based (as opposed to ideologically based) argument in favor of the iatrogenic amplification of DID. If cases existing in the general population are mild, and those diagnosed clinically are severe, it is possible that symptom levels get amplified during recruitment into the mental health system in a substantial proportion of cases.

Much more research and more advanced methodology are required before any firm conclusion can be reached about the epidemiology of DID in the general population. (109)

So! Bunch of thoughts here:

• Wow, that’s a lot more softpedaling and caveats than he presents in the study itself, huh
• Spoiler alert, the next few studies have the same “methodological limitations”
• The way 2% of this group managed to “endorse DSM-III-R criteria” for MPD without having trauma histories or severe dissociation…this 2014 literature review pins it on the early criteria not involving amnesia at all, which was added in later versions of the DSM
• Again, the DDIS is a screening tool, it doesn’t give you a diagnosis (which Ross would know, since…he developed it)
• Which means, again, the 1% number appears to be “people whose DDIS results say DID is a possibility to look into,” not “people who definitely have DID”
• This number comes with even more caveats, but: “less than 0.2%” is a possible, preliminary estimate for the general-population rate of “people who have clinically-diagnosable DID”
• It’s unnerving to see a doctor present “people who seek mental-health treatment have worse symptoms than people who don’t” as an argument for treatment making the symptoms worse

A lot here depends on what exactly Ross means by “symptom severity.” Is he saying his DID patients have more disruptive/debilitating symptoms, while the study is flagging people who might be plural systems, but more healthy and well-adjusted about it?

Or does he just mean symptoms that are farther outside the norm — say, the study is flagging systems who only report 2 alters, while his patients all have at least 20? Or what?

(average system has 0 alters, Headmates Georg is an outlier and should not have been counted–)

Two more studies by Ross’s students, 1991 and 1994:

• Ross, C. A., Ryan, L„ Voigt, H., & Edie, L. (1991). High and low dissociators in a college student population. Dissociation, 4, 147-151.

Sample of 345 college students in Winnipeg, 8 of them (about 2.3%) came up as “people whose DDIS results say DID is a possibility to look into.”

• Murphy, P. E. (1994). Dissociative experiences and dissociative disorders in a non-clinical university group. Dissociation, 7, 28-34.

Sample of 415 students at the University of Idaho, 4 of them (about 1%) came up as “people whose DDIS results say DID is a possibility to look into.”

The study I found earlier, from 2007:

• Sar V, Akyuz G, Dogan O, 2007. Prevalence of dissociative disorders among women in the general population. Psychiatry Res. 149, 169–176. 10.1016/j.psychres.2006.01.005

Sample of 628 women in Sivas, Turkey, 7 of them (1.1%) came up as “people whose DDIS results say DID is a possibility to look into.” (I found another study from 2014 by the same people, but it appears to be a different evaluation of the same sample group.)

Some digging turned up one more, from 2006:

• Johnson JG, Cohen P, Kasen S, Brook JS. Dissociative disorders among adults in the community, impaired functioning, and axis I and II comorbidity. J Psychiatr Res. (2006) 40:131–40. 10.1016/j.jpsychires.2005.03.003

Sample of 658 people in New York State. This is the only one that didn’t use the DDIS; apparently it used a bespoke combination of items from the DES and the Structured Clinical Interview for DSM-IV Dissociative Disorders. 1.5% came up as “people whose results on this custom setup say DID is a possibility to look into.”

I found that cited in Dissociative identity disorder: An empirical overview, a 2014 literature review. It was the only mention of a specific “trying to measure the rate in the general population” study that hadn’t already been scrounged up by either me or LB.

Looking at “related research” for any of these brings up a lot of studies about dissociative disorders overall, or dissociation in general as a symptom. So it’s possible some of those tried to get rates of DID along the way (and if it was since 2014, that one group of reviewers wouldn’t have found it). But I didn’t go paging through them to check.

That makes 5 studies, done in 3 countries, across 2 continents, being fairly consistent about “at least 1% of the general population has serious-enough dissociative symptoms to rate follow-up evaluation for DID.”

Obviously we should have more research. And I don’t know if this number would bear out under more studies. But you know, I wouldn’t be surprised or skeptical if it did? In my personal, non-medical, non-expert opinion, this sounds credible! The vibes check out.

And it’s still not the same as saying “1% of the general population has for-sure diagnosable DID.” There are, to date, zero (0) studies where the data support that.

(Sidenote: none of these studies have even looked for “people who have the experience of being plural, whether or not they qualify for a DID diagnosis.” So the prevalence of that could, conceivably, be higher. Based on vibes alone, I suspect it’s not a lot higher.)

A section I have to put in here somewhere:

Colin Ross is a Problem Guy.

That doesn’t mean he’s wrong 100% of the time — some patients have reported amazing and helpful therapeutic experiences with him. And of course, some critics want to discredit anyone who acknowledges DID at all. (Along with, you know, anything that involves confronting the long-term effects of serious child abuse.)

But other critics, including patients, accuse Ross of committing serious medical abuse. In a broad and depressingly-plausible range of ways — including plenty of things that would’ve been abusive from any doctor, with any patient, unrelated to whether they should have gotten an MPD/DID diagnosis or not.

This harrowing interview with an ex-patient, who ended up suing him for malpractice, starts with “he diagnosed me with MPD after 15 minutes of conversation” and vaults all the way to “he convinced me I had been abducted by aliens and gave birth to a half-alien baby.” It’s not good!

So maybe it’s not surprising that this particular guy massaged his “1% of the population” statistic until it said the more-dramatic thing he wanted it to say.

We know he did not invent DID, previously MPD, previously [doctor’s multi-paragraph explanation of how their patient has this strange dissociation-based experience of being more than one person in the same body]. Other medical professionals were already documenting that 40+ years before Ross was born.

But he did develop the DDIS! Which is used in 4 of these 5 studies! It’s widely used in good faith by doctors who I hope are mostly not-terrible, it does well when tested on patients with already-diagnosed dissociative disorders, and I haven’t seen any studies (or callout posts) that discredit it…but I wouldn’t blame anyone for worrying, just from the Colin Ross of it all.

And even if the DDIS is rock-solid, and hugely useful for the thing it was actually designed to do (help rule in/out possible diagnoses for a person who came in actively seeking mental-health support)…nobody has done a study big enough to say “of the 1% of average people this interview flags for DID follow-up, how many of those get the diagnosis when you do the follow-up?”

(Since it rules out 99% of people, if you want to end up with a sample of at least 100, you need to start by running the interview on a group of at least 10,000.)

The DID rate could turn out very close to 1% of the general population. It could also be 0.01%. We just don’t know.

So that’s the deal. If you’re reading this and you know of any relevant studies I missed (or if new ones have come out since I posted), drop a comment, I’ll add it to the list.

And if any DID Youtubers come across this post and want to use the history/research as a jumping-off point for a video…go for it. The platform could really use somebody to bring it up there.

September 30: “Alabama is shrinking under the onslaught of Covid-19, its chief medical officer said, as deaths in the state outnumber births for the very first time.”

October 4: “18% of health care workers have quit their jobs during the COVID-19 pandemic, while another 12% have been laid off. Among health care workers who have kept their jobs during the pandemic, 31% have considered leaving.”

October 7: “…the model projected the risk of reinfection under endemic conditions — in which everybody has either been infected by or vaccinated against the virus. In these conditions, unvaccinated individuals should expect to be reinfected with COVID-19 every 16 to 17 months on average.”

October 21: “A WHO paper on Thursday estimated that out of the world’s 135 million health staff, “between 80,000 to 180,000 health and care workers could have died from Covid-19 in the period between January 2020 to May 2021”.”

October 25: “Sixty-eight years later, an iron lung is still keeping Lillard alive — she sleeps in it every night. While many people who had polio or post-polio syndrome either weaned themselves off the machines or switched to another form of ventilator, Lillard never did.”

The legacy of polio — and of its vaccines. (It is amazing how this went from “a constant, overwhelming threat” to “a nearly-eradicated nonissue” in, what, a generation or two?)

October 27: “It’s true that of all members of our population, 5–11 year-olds actually have the lowest risk of hospitalization due to COVID-19 according to COVID-NET data published in the MMWR. However, even if you look at this fact, based on historical estimates, COVID-19 would be the 8th leading cause of death in this age group.”

Children are at low risk, but they’re not at no risk.

“As far as the vaccine, with the pediatric dose, there are 0.06 mg tromethamine and 0.4 mg tromethamine hydrochloride. [The generic product warning antivaxxers are up in arms about] describes a 500 mL solution of tromethamine containing, in total, 18 g of tromethamine (3.6 g per 100 mL), or 60,000 times as much tromethamine.”

So if the Secret Nefarious Medical Cabal snuck this into the vaccine formula to prevent Secret Undisclosed Heart Problems…they skipped the step where they tell us to give every kid 60,000 doses.

Non-COVID-related bonus:

“Unwanted, intrusive visual memories are a core feature of stress- and trauma-related clinical disorders such as posttraumatic stress disorder (PTSD) […] even once intrusive memories have been laid down, playing a visually-demanding computer game after reactivating the memories may reduce their occurrence over time.”

In other words, if you or someone you know get caught up in a traumatic event? Once they’re safe, have the survivor get out their phone and play Tetris for a while. It’ll make a long-term difference.