the 4:1 diagnosis ratio - a story of historical bias

Tourette Syndrome supposedly is four times more likely to affect males than females. Yet, support groups are full of women.

Why?

The question is often brushed off with an answer such as these: “Women are more likely to seek help when they do have a problem.” “Women are more vocal.” “Support groups are always full of mothers whose children are the ones who actually have the problem.”

And sure, these might be true. They probably all are, to an extent.

But the dismissal of big questions with small answers has never sat right with me, so I decided to dig a bit further.

What I found was this:

Women with Tourette Syndrome aren’t necessarily rarer than men with the same condition; instead, they remain unidentified due to flawed conceptualizations of what neurodevelopmental disorders look like.

I’ve written before about the problems with much early research about Tourette Syndrome in the context of how it mis-characterized the prognosis for people with TS so as to result in the invisibility of afflicted adults.

Similarly, early research entirely missed key components of TS in terms of differences in its manifestation across various demographics. Recent studies have identified differences in the types of symptoms commonly displayed by males and females. Girls and women, for example, are more likely to display severe obsessive-compulsive symptoms, while boys and men are more likely to have worse hyperactivity. It is also thought by some that due to differences in socialization of boys and girls, girls may be more likely to direct more effort earlier on towards tic suppression. Young boys, on the other hand, may not feel as much pressure to suppress due to innately held expectations that they will be generally louder and more restless than their female counterparts.

There is not adequate research into these topics to be able to say for sure which differences do and do not exist or to what degree they affect an individual’s experience with their symptoms and with receiving a diagnosis. But what is clear is that there is ample reason to expect that males and females with TS have different experiences with the disorder.

Yet, the model of TS taught to clinicians does not take any of these potential gender differences into account. It treats what is beginning to appear as a severely male-weighted model of TS as default.

Adding insult to injury, the idea that TS is mainly found in males establishes a bias against diagnosing females even with clear symptom patterns. So when a female appears with an “atypical” symptom presentation, her chances of receiving a diagnosis become significantly lower than if clinicians did not have the idea that females usually do not develop TS. And in a cyclical pattern, the more females with female-typical symptom profiles that go undiagnosed, the more male-weighted the model of TS remains.

Therefore, the current system is set up to fail girls and women presenting with TS symptoms.

Research into other areas of medicine has shown time and again that when the male model is extended to women without consideration for potential differences, women’s health suffers. Under-diagnosis, mis-diagnosis, and less successful treatment tend to result from these cases, as opposed to those where sex based differences are taken into account. A 2009 study in the International Journal for Equity in Health highlighted this issue, concluding that assumptions about women’s health are often derived from established male models, leading to less timely and lower quality healthcare for women (Rinsberg et. al., 2009). Studies in heart disease (Biddle et. al., 2018), stroke (Giralt et. al., 2012), and chronic pain (Hamberg et. al., 2002) all demonstrate specific areas where this bias and its devastating results can be observed.

If this is true for heart disease, stroke, chronic pain, etc., what possible reason would there be to assume the same phenomenon is not also occurring with the diagnosis and treatment of neuro-developmental disorders?

And it looks like it is.

I took a look at gender distribution statistics for a range of neurological disorders. I found something that was shocking to me even despite my prior suspicion - in almost every disorder I read about, many of which are not related to each other at all, there is a significant skew towards diagnosis in males such as is demonstrated in Gould’s 2017 study on Autism in women and Quinn’s 2005 analysis of cross sectional issues in women with ADHD. The same finding held true even for arachnoid cysts, which aren’t a neurodevelopmental disorder at all but instead are technically classified as a sub-type of brain tumor which result from a birth defect or injury to the lining of the brain (Rare Diseases Database).

How could it be that all these disparate conditions share the same tendency to affect males more? From a biological perspective, it makes no sense.

Could it be that instead, males experiencing neurological symptoms are more likely to receive an accurate diagnosis?

A group of fellow volunteers had the same idea and conducted an analysis of support group membership and gender. Members of online tic disorder support groups were screened and sorted into categories based on whether they had a diagnosed or suspected tic disorder and their gender. Members there to get information for a child were sorted based on the gender of the child, as an effort to mitigate the potential data skew caused from mothers’ membership. Statistical analysis revealed that males and females with tic disorder symptoms are roughly equally represented in these groups. While this was not a controlled scientific study, it is certainly cause for further scrutiny. The numbers aren’t publishable in a scientific journal but they do hold enough water that their drastic difference from official numbers of TS gender distribution ought to be re-examined in a controlled study.

Without further research it’s impossible to draw a firm conclusion here. For now, I’m just a blogger, and these are just suggestions for though. But I think the questions are worth considering.

But one thing is certain. Somewhere, somehow, we are missing neurodivergent women. We should pay more attention to where they might be, because I am convinced that they exist.

Sources:

Rinsberg, G., Johansson, E. E., & Hamsberg, K. (2009). A theoretical model for analysing gender bias in medicine. International Journal for Equity in Health, 8(28). https://doi.org/10.1186/1475-9276-8-28

Caitlin Biddle, James A. Fallavollita, Gregory G. Homish, Heather Orom,Gender bias in clinical decision making emerges when patients with coronary heart disease symptoms also have psychological symptoms, Heart & Lung, 2018, ISSN 0147-9563, https://doi.org/10.1016/j.hrtlng.2018.11.005.

Katarina Hamberg, Gunilla Risberg, Eva E. Johansson, and Göran Westman. Journal of Women's Health & Gender-Based Medicine. 2002.http://doi.org/10.1089/152460902760360595

Giralt, D. , Domingues‐Montanari, S. , Mendioroz, M. , Ortega, L. , Maisterra, O. , Perea‐Gainza, M. , Delgado, P. , Rosell, A. and Montaner, J. (2012), The gender gap in stroke: a meta‐analysis. Acta Neurologica Scandinavica, 125: 83-90. doi:10.1111/j.1600-0404.2011.01514.x

Judith Gould (2017), Towards understanding the under-recognition of girls and women on the spectrum. Autism. 21(6): 703-705. https://doi.org/10.1177/1362361317706174

Patricia O. Quinn (2005), Treating adolescent girls and women with ADHD: Gender-Specific issues. Journal of Clinical Psychology. 61(5): 579-587. https://doi.org/10.1002/jclp.20121

Arachnoid Cysts. (n.d.). Retrieved from Rare Diseases Database: https://rarediseases.org/rare-diseases/arachnoid-cysts/