”Is there an association between the use of heeled footwear and schizophrenia?” [1]. The human mind has an almost infinite capacity to come up with unlikely ideas and connections. From the Department of Lateral Thinking in Sweden, comes a hypothesis by Jarl Flensmark that’s so crazy, it could just be true… can high heels cause schizophrenia?

Normally when reviewing a scientific paper, it’s sensible to start with the background, and explain how the idea originated as a result of hints given in a variety of previous studies and speculations. In this case I can’t, because I honestly can’t figure out what inspired Flensmark, what piece of wiring in his head made him come up with the connection between high-heeled shoes and Shizophrenia. He may be right, he may be completely wrong, but I don’t care – the man is a genius.

Schizophrenia is a tricky disease for researchers to get a handle on. As with many conditions like autism, diagnosis has improved in recent times, making the analysis of trends more complicated (is the disease affecting more people, or are we just better at spotting it?). No correlation has been found between the condition and any hypothesized cause, nor has any underlying disease process been found to explain it [2][3]. Really, we don’t have a clue.

If there really was a link, how would it work? Flensmark believes the key lies in signals from mechanoreptors in the lower legs – sensory cells that feed information about mechanical forces acting on your body to the brain. The brain of a person walking normally receives a barrage of signals as the ankle and foot move through their range of movement, but this movement – and therefore the signal – is altered by high-heeled shoes. The area of the brain that receives this signal has been implicated in Schizophrenia studies before:

"Heath found that electrode stimulation of the anterior parts of the cerebellum could improve functioning in schizophrenia. These parts are normally stimulated by impulses from stretch receptors in the lower extremities. Bicycling reduces depression in schizophrenia and this is probably due to the improved lengthening contractions of the triceps surae."

If this is really true, then there should be some sort of correlation between shoe-use and Schizophrenia across time and cultures. In particularly, we should see some interesting links between the history of footwear, and the history of Schizophrenia. This is quite an ambitious area to tackle, but the Swede races us through the two stories over a few pages.

Bipedal walking evolved about ten million years ago, but it was a long time before we had shoes. Once they emerged, a continual pattern appears whereby heeled shoes are introduced to an area, and mental illness swiftly follows. Shoes first appeared in the Middle East, followed by mental institutions, and then both spread into Europe. An increase in the use of footwear after the English civil war is followed by an apparent increase in schizophrenia cases. Greater shoe production in Massachusetts after the American Revolution is followed by an increase in schizophrenia cases 30 years later. Indeed, throughout the world mass production of heeled shoes seems to lead to a rise in cases.

Flensmark notes several subtler trends. As schizophrenia spreads to a new area it seems to be more prevalent in the upper classes to begin with, notably in India, perhaps due to earlier adoption of heeled shoes. Western Ireland had a greater number of cases than East Ireland, and has substantially more rain, again possibly resulting in more shoe-wearing. There are trends linking time of year of birth to schizophrenia, which Flensmark suggests could be due to the fact that babies who reach walking age during the summer are less likely to wear shoes in that important period. A dizzying array of statistics are presented on everything from rates of immigration to the prevalence of shoe use vs. schizophrenia in warm vs. cold countries, and nothing contradicts the basic premise, that the use of heeled shoes and the prevalence of the illness are linked.

This is far from a proven theory though. While none of the evidence so far contradicts the idea, a lot of it is quite vague, and open to interpretation. For example, the apparently earlier emergence of the disease in the upper classes could simply be due to their access to better medical diagnosis, or for a variety of work or diet related reasons. The rise in the mass production of shoes in a country was probably linked to hundreds of other commercial and social trends as the industrial revolution kicked off, and links with climate and season could be, well, just that. Really, the evidence presented proves nothing – but while on the one hand it means the hypothesis isn’t that well supported, on the other it shows that neither has it been shown to be false.

To be fair, Flensmark himself observes that while “many data suggest an association between the use of heeled footwear and schizophrenia”, it is clear that “they could probably be questioned in many instances.” Indeed, his idea covers so much ground that there are a hundred and one null hypotheses that could be generated. However, relying on sketchy historical data is going to be a non-starter I feel – for a start, there’s no real way of knowing what kind of illness somebody living centuries ago really had. There is of course one concrete thing that Flensmark points out would demolish the theory - "the existence of young patients not being able to use their legs during many years and yet having schizophrenia".

Failing that, clinical experiments would be one way to find out; “The effects of the use of heeled and flat shoes during shorter or longer periods of time on cortical excitability [54], and on connectivity in cerebellar and basal ganglia loops [52,55] could be studied in patients with schizophrenia. A normalization of patterns would indicate the importance of the proposed neural pathways in the pathophysiology
of schizophrenia. Patients could be recruited to clinical trials of the effects of using only flat shoes as long as possible on symptoms and cognitive deficits.”

The data presented is, frankly, sketchy and circumstantial at best, and many would argue that the paper lacks focus. However, Flensmark is presenting a hypothesis, not a theory, and it would be slightly unfair to judge it too harshly. The idea is an interesting one, and certainly testable. Above all though, I have great admiration for a man whose imagination can suddenly conjure up a link between sexy shoes and schizophrenia. If he were right, it would be the coolest result ever. Hopefully we’ll see some results soon.

[1] Flensmark, J. (2004). Is there an association between the use of heeled footwear and schizophrenia?. Medical Hypotheses , 63(1), 740-747. DOI: 10.1016/j.mehy.2004.05.014

[2] Weinberger DR, McLure R., 2002. Neurotoxicity, neuroplasticity,
and magnetic resonance imaging morphometry – what is happening in the schizophrenic brain? Arch. Gen. Psychiat., 59:553–8.

[3] Andreasen N.C., Nopoulos P., O’Leary D.S., Miller D.D., Wassink T., Flaum M., 1999. Defining the phenotype of schizophrenia: cognitive dysmetria and its neural mechanisms. Biol. Psychiat., 46:908–20.