Any condition that causes those experiencing it distress can become a pathology or the cause of a pathology. This 'condition' synesthesia is a perception based experience and is not a pathology in itself. Creative people tend to think in these patterns and it is possible to train the mind to do this.

The most common, if not necessarily adequate way to define pathology in thought processes is where those processes cause harm to the person afflicted or if the thoughts (delusions and hallucinations) are outside the range of human experience and distressing.

Synesthesia is far more common than schizophrenia and that in itself is an indicator that it should not be considered a disease but more of a variant in human thought processes. As ever we should be ultra vigilant against pathologising different thought processes as if there is a standard model that we all should adhere to.

The human mind is a wonderful thing and should not be regimented into normal and abnormal (healthy and diseased) . Some of the greats in human history thought 'differently' to the majority.

I think the auditory hallucinations of schizophrenia are triggered from a hyperactive inner ear. The vestibular end organs are also likely to be overactive, which I think can lead to visual illusions and hallucinations. The vestibular system has strong links with other senses, especially developmentally, so I suspect can cause hallucinations in them as well, though I am unsure of the exact mechanism. Synesthesia seems more likely to be due to some sort of cortical miswiring, and I don't think it fits into this scenario, or into schizophrenia for that matter.

Any condition that causes those experiencing it distress can become a pathology or the cause of a pathology. This 'condition' synesthesia is a perception based experience and is not a pathology in itself. Creative people tend to think in these patterns and it is possible to train the mind to do this.

The most common, if not necessarily adequate way to define pathology in thought processes is where those processes cause harm to the person afflicted or if the thoughts (delusions and hallucinations) are outside the range of human experience and distressing.

Synesthesia is far more common than schizophrenia and that in itself is an indicator that it should not be considered a disease but more of a variant in human thought processes. As ever we should be ultra vigilant against pathologising different thought processes as if there is a standard model that we all should adhere to.

The human mind is a wonderful thing and should not be regimented into normal and abnormal (healthy and diseased) . Some of the greats in human history thought 'differently' to the majority.

"The most common, if not necessarily adequate way to define pathology in thought processes is where those processes cause harm to the person afflicted"

By this definition, Solomon Shereshevsky, written up by Luria, had pathological synesthesia. So, for him, it was a disease.

Hi Dorothée,

you might want to contact Elias Tsakanikos. He is at Roehampton Uni (so quite close to you) and is doing research on the links between synaesthesia and schizotypy/schizophrenia, as far as I know.

I know this is not an answer in itself, but Tessa van Leeuwen at the Max Planck Institute for Brain Research (http://brain.mpg.de/?id=510) is an expert on Synaesthesia and is working on comparative neurophysiological studies between Schizophrenics and Synaesthetes using MEG. She might be the person to contact.

Michael Wibral

Thank you all for your answers and contributions!

Anthony, do you have any papers in support of your answer? I can't find adequate research to investigate it further. What about auditory hallucinations that are not triggered by inner ear hyperactivity?

Barry, I would agree with you, except I would also agree with Anthony to some extent. I've heard of some synesthetes not always finding their synesthetic experiences pleasurable (ex: http://sensanostra.com/color-sound-living-synesthesia). I have various forms of synesthesia myself, and if I'm in a state of anxiety or otherwise very tired, the experiences can be disruptive, unsettling, and distracting.

Phillip and Michael, thank you for the great links - very helpful and interesting! I'll definitely check out their work.

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One possible symptom of schizophrenia/element of schizotypy can be hypersensitivity or intensity of sense experiences. It would be interesting to research how schizophrenics who experienced synesthesia before their onset of schizophrenic symptoms experienced changes in their synesthetic experiences throughout the course of the disorder. (Or perhaps their synesthetic experiences remained the same - I don't know what would happen, although I would guess that their synesthetic experiences would be altered along with their other perceptual disturbances.)

Another aspect that would be interesting to study is whether synesthetic experiences in schizophrenic patients is consistent the way it is in healthy synesthetes. Synesthesia is largely consistent across a lifespan (particular stimuli trigger the same synesthetic experience) so I wonder if schizophrenics with acquired synesthesia at the onset of their disorder also experience this consistency.

"Anthony, do you have any papers in support of your answer? I can't find adequate research to investigate it further.

You will find a list of my many publications on RG, though most are behind paywalls I'm afraid. I have generally confined myself to musical hallucinations, since the literature on MHs is of a manageable and finite size. MHs are clearly simpler than verbal hallucinations (voices), but as far as I can tell they lie on a continuum and have similar if not identical causes and correlates. If MHs cannot be explained, I don't see how voices possibly can be.

" What about auditory hallucinations that are not triggered by inner ear hyperactivity?"

A very pertinent question, but I knew of no such case. I have made repeated pleas over many years in the psychiatric, neurological and otological literature for any non-otological case of MH, but no one can or will produce one.

"I have various forms of synesthesia myself, and if I'm in a state of anxiety or otherwise very tired, the experiences can be disruptive"

Are you saying that the synesthesia itself fluctuates? If so, this is really very useful, since it should be possible to work out what is going on by monitoring changes in physiological variables, sensory systems and symptoms, however minor.

Thanks Anthony, I'll try to access some of your work.

Hm, I wouldn't use the word "fluctuates" as I'm not entirely sure what you mean by it and synesthesia normally doesn't fluctuate (or at least not according to what I understand by "fluctuate". When I used to experience panic attacks or was in an extreme state of anxiety, my senses were heightened (lights are brighter, sounds are more pronounced, etc.). The focus, enhanced by a highly intense emotional experience, is on the perceptual input. The resulting synesthetic experiences in themselves can therefore become overwhelming. So basically:

increased intensity of sensory experience --> increased intensity of synesthetic experience --> possibly perceived discomfort

I can't conclude whether it's this increased focus that causes variation in the intensity of the synesthetic experience or whether it's the intensity of the stimulus. It could also be that when one is in a highly anxious state, one focuses more on the terrifying stimuli and therefore on the more unsettling synesthetic experience.

I've come across more accounts of variations in intensity of synesthetic experiences but experiences do tend to vary quite a bit among synesthetes.

ex: http://www.ncbi.nlm.nih.gov/pubmed/9100340 (not specified as synesthesia, but similar nevertheless)

http://www.daysyn.com/rogowska_2011.pdf

http://books.google.de/books?id=mLTcmQ6q8N4C&printsec=frontcover#v=onepage&q&f=false

Emotions & Synesthesia:

http://www.jstor.org/discover/10.2307/1413908?uid=2&uid=4&sid=21104179404297

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3872781/

Plus some interesting comments on a drugs forum about alterations in natural synesthesia when on drugs (plus someone mentioning synesthesia as one of their schizophrenia symptoms):

http://www.bluelight.org/vb/archive/index.php/t-559314.html

Anyways, coming back to the original question, I can imagine that mirror-touch synesthesia could to some extent also be uncomfortable.

However, maybe I'm focusing too much on the synesthetic stimuli instead of the actual synesthesia and my reasoning is flawed here. Maybe we could break the question down:

Does anyone have experience with synesthesia subjects who experienced their synaesthetic experiences as discomforting? (ex: Solomon Shereshevsky, or a more simple example: I have a friend who hates the number 9 as to her that number is a scary man with a horrible personality.)

Anthony, in response to your hyperactive inner ear theory, how would you respond to transcranial magnetic stimulation "treatments" for auditory hallucinations?

http://psychiatry.yale.edu/research/programs/clinical_people/rtms.aspx

(See the list of references at the bottom) + a quick Google Scholar search also comes up with many papers

"Anthony, in response to your hyperactive inner ear theory, how would you respond to transcranial magnetic stimulation "treatments" for auditory hallucinations?"

I am waiting to see if it works, and, if so, how it works. I find the brain stimulation literature on hallucinations very hard to interpret in general, as it is not clear if the brain and/or ear is being stimulated. This goes right back to when the electrical action of the brain and its motor areas were first discovered by Hitzig, who thought he was stimulating the auditory nerve while investigating vertigo.

"When I used to experience panic attacks or was in an extreme state of anxiety, my senses were heightened (lights are brighter, sounds are more pronounced, etc.)."

So basically:

increased intensity of sensory experience --> increased intensity of synesthetic experience --> possibly perceived discomfort"

This is what I had in mind about fluctuation in synesthesia or its triggers. I have shown that audiosensitivity, whatever its supposed cause or correlates, is of peripheral origin, as shown by abnormal middle ear muscle reflexes. The likely physiological mechanism is reduced perilymph pressure leading to inner ear hypersensitivity. I cannot find any evidence at all that anxiety causes inner ear symptoms (dizziness, tinnitus, audiosensitivity, etc), unless there is hyperventilation, which lowers CSF/perilymph pressure. See my related RG question.

This supports the idea that the vestibular system drives and organises other sensory systems, as in does in development, and is involved in sensory integration, and in regulating the autonomic nervous system.

Can synesthesia be a prodrome of Schizophrenia? Living with it and never decompensating does not invalidate the possibility neither does functioning with it make it less prodromal!

I'm not really an expert on synesthesia, but after following this discussion for a while, I would like to way in nontheless :-)

I believe that we may have a case of "shared variance", so to speak. I would maybe even assume that, e.g., hearing colours in synesthetes and hearing colours in psychotic patients may actually be different phenomena with regards to their respective causes/pathomechanisms. So, while either group may experience similar phenomena, I would not go as far and call one the prodrome of the other (at least not as a general rule, even though some cases may obviously exist). I little, albeit oversimplified, like headaches in common cold vs. brain tumor. Both clinical pictures may (and do so more often than not) present with headaches - and in individual cases, persons may have both a common cold as well as a brain tumor - but I would go easy on "lumping" both clinical entities together, solely because they share symptoms (and, also in headaches as may be in synesthesia, the same thing can actually be fundamentally different but merely similar on the "phenomenological" side).

With respect to the question of whether synesthesia can at times be considered a disease, a play on this topic is running at the Young Vic in London. Here is an extract from the theatre review by Henry Hitchings in the Evening Standard, June 24th, 2014:

"Kathryn Hunter plays Sammy Costas, whose profound synaesthesia means numbers resemble people and words kick up little splashes as they dance through her mind. Able to perform extraordinary feats of memory, she turns this to professional advantage yet complains that it's so hard to forget things that her head feels as if it may burst. Hunter's quirkily expressive performance conveys both the wonders and horrors of sensory overload and is the heart of the production, which Brook has created with Marie-Helene Estienne."

I am not so sure now as I was here 13 days ago that synesthesia must be due to cortical miswiring, and had nothing to do with a very common cause of sensory overload, Meniere Spectrum Disorder due to bouts of inner ear hypersensitivity. The most indicative symptom of MSD is a feeling of fullness or pressure in the ear(s), or that the head might burst.

It seems science looks at things in isolation rather than as complex interactions and consequences. When I get stressed my ears buzz more and I become more creative but I now know what to do about it. I simply increase my suppliments, especially zinc and B6 due to my condition of Pyroluria. I have to balance my desire to be creative with my need to be balanced, functioning and well. 

Its a simple system really.... stress depletes minerals, anti-oxidents and vitamins as does infection. Stressed bodies also produce stress chemicals which cause hyperviligance as a common survival mechanism. As do recreational drugs including many natural psychodelics such as magic mushrooms etc. However chronic stress causing ongoing hyperviligance is exhausting, depletes appitite and the ability to sleep so further nutritional deficit occurs.

The common nutritional factor between synesthesia, inner ear hypersensitivity and psychosis appears to be very low zinc, magnesium and B vitamins. The consquence of low B3, folic acid, Vit C and B12 either on their own, and often together, is psychosis. Low B1, B5, B6, magnesium, manganese and zinc all have effects such as depression, anxiety, lack of focus, dizziness etc. low zinc causes a loss of appitite as it is depleted during digestion and the body tries to conserve it. Zinc is used in over 200 processes in the body so is vital to wellbeing. 

Thank you so much, Heather. After reading through all the above scientific discussions, I find your practical observation of commonality of symptoms to be a refreshing light at the end of the tunnel. 

Meaning no disrespect to the scientific investigators, as the mother of a schizophrenic adult child, what is helpful to me is what might work. I know when his therapeutic team put my son on a regimen of some of the above listed supplements (don't know all the specifics as I'm not privy to that info) he improved in his ability to function in the world in ways we non-schizophrenics call "normal." The problem with schizophrenic folks is that they don't like to take regimens of anything!

I am grateful for those in the scientific/academic community who take on the investigation of this neurological disorder. You are our lifeline to "sanity." Many blessings!

" When I get stressed my ears buzz more and I become more creative but I now know what to do about it."

I would be very interested if Heather or anyone else can explain any physiological link between stress and inner ear conditions like tinnitus (other than hyperventilation which lowers inner ear pressure and oversensitises the ear).   It is constantly stated and believed that stress causes conditions like Meniere's disease, but in the absence of a definite mechanism, it seems much more likely that it is the very distressing auditory and vestibular symptoms that induce stress and fear.  Chemicals and hormones may well be involved, but this will only ever be a partial explanation.

I think there are several findings that may be of help here:

Firstly, Meniére's is clearly related to genetic predisposition, as is shown by the high concordance-rates in genetically related individuals. Obviously, there is GxE-interaction, so not every person from a "risk-family" will develop the disease; also, through genetic emergence, the disease can obviously also present in patients without a family history.

Secondly, in line with my previous argument, tinnitus and Meniére's should not be treated as synonymous. Meniére's presents with tinnitus, but the core-symptom of Meniére's is vertigo, and a number of Meniére's patients present without tinnitus as well as, more importantly, tinnitus presents with higher prevalence not-related to Meniére's.

Thirdly, tinnitus is commonly believed to be related to synaptic plasticity (in this case faulty plasticity). Synaptic plasticity is strongly influenced by stress-hormones and heavily dependent on "continuity". Thus, I find it hardly surprising that chronic but rarely acute stress may bring on tinnitus and exacerbate it in tinnitus patients. In those cases where a presumed "single stressor" brings on tinnitus, if would strongly assume that this stressor will, in fact, actually be a "second hit"; meaning that other stressors or even (more or less subliminal) chronic stress precede it.

Finally, allthough I still maintain that one should be cautious about "lumping" synesthesia and psychotic(-like) experiences together, I would state that the actual perception of both will be linked to schizotypic features; i.e., both are based on external stimuli that are (probably in fundamentally different fashions) misinterpreted by the brain. The capacity for, basically, overly attributing salience to stimuli is a function of schizotypy and has been shown repeatedly to be intrAindividually influenced by percieved stress. Thus, when stress increases both the tinnitus-perception as well as creatvity, I find this highly interesting but also beautifully in line with my suggested line of reasoning. :-)

Looking forward to your comments!

For the benefit of the person who downvoted my comment 19 days ago on how hard it is to distinguish whether brains, ears or audiovestibular nerves are being electrically stimulated, here is an extract from J Applied Physiol 2004;96:2301:

"galvanic vestibular stimulation (GVS) has been used for over a century as a means to discover and then look at the function of the vestibular system. In his 1820 dissertation, Bohemian physiologist Johann Purkyne (81) reported that a galvanic current flowing through the head upset balance and equilibrium. Eduard Hitzig (46), starting his experiments as an army doctor during the Franco-Prussian war, noted that nystagmus was one consequence of applying an electric current to the brains of dogs and humans, including the exposed brain of one wounded soldier. Thus we have the first evidence that the two motor outputs of the vestibular system can be driven by a galvanic stimulus. It was Josef Breuer (8) who finally demonstrated the vestibular origin of these phenomena by combining galvanic stimulation with labyrinthectomy in animals. The first description of its perceptual output may have come much earlier, in 1790, from Alessandro Volta himself (103). In between putting the electrodes of his newly invented battery in his ears and his subsequent collapse, he briefly experienced the sensations of an explosion inside his head, spinning, and the sound of boiling tenacious matter. The spinning was likely the manifestation of vestibular stimulation and the boiling either auditory stimulation or the sound of flesh boiling. The explosion needs no further explanation: a pile of 30–40 Zn/Ag elements generates ∼30 V! Hitzig and Breuer also came across the perceptual phenomenon, but they were more specific about their experiences. Camis (10) reported that these gentlemen put “the two electrodes to the two mastoid processes, and experienced a sensation of falling towards the side of the cathode.”

" tinnitus and Meniére's should not be treated as synonymous. Meniére's presents with tinnitus, but the core-symptom of Meniére's is vertigo"

Patients with Meniere's Disease will end up in an ENT clinic, and the main symptom may well be vertigo.  Which is why I delineate the broader condition but with the same causes, Meniere Spectrum Disorder.  I think the core symptoms of MSD in order of relevance are pressure/fullness in head or ear(s);  audiosensitivity;  vertigo;  abnormal hearing; tinnitus.  MSD is common, misunderstood and misdiagnosed, and most sufferers will end up nowhere near an ENT clinic.

"Thirdly, tinnitus is commonly believed to be related to synaptic plasticity (in this case faulty plasticity). Synaptic plasticity is strongly influenced by stress-hormones and heavily dependent on "continuity". Thus, I find it hardly surprising that chronic but rarely acute stress may bring on tinnitus"

As with any medical symptom, finding the cause for tinnitus should start with known knowns, ie ear disease.  Then check for unknown knowns, ie ear disease only shown on special testing.  In my experience, confirmed by checking the literature, there is no need for unknown unknowns, eg synaptic plasticity.  If anyone knows of any case of tinnitus not originating in ear disease, please could they quote a reference.   A fundamental defect of any stress or plasticity theory is that it can only explain bilateral tinnitus.  MSD is a fluctuating condition, and Meniere's disease starts with violent attacks,  so if stress is involved, it must be an acute stress.

"I think the core symptoms of MSD in order of relevance are pressure/fullness in head or ear(s); audiosensitivity; vertigo; abnormal hearing; tinnitus."

I think one should define the word "relevance" here. After having spoken intensively to many Meniére's patients, I would state that the symptom which causes most distress to the patient is the sudden and usually completely incapacitating attack of vertigo. This is in line with primary treatment aims: "Nevertheless, there are numerous conservative and surgical measures available to otolaryngologists that are aimed principally at abolishing the frightening and disabling vertigo with which patients present." (Saeed, BMJ 1998;316:368). This is, however, not a thread about Meniére's but synesthesia and psychosis, so I think we should not stray too far.

"In my experience, confirmed by checking the literature, there is no need for unknown unknowns, eg synaptic plasticity. If anyone knows of any case of tinnitus not originating in ear disease, please could they quote a reference."

Try this one: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297194/

To quote from it: "The evidence that tinnitus originates from single synapses in the periphery of the auditory system does not, however, contradict the involvement of central parts of the auditory system. Sensory messages originate from the peripheral organs, but perception itself is a phenomenon subserved by system activity, i.e., sub-cortical and cortical neural networks." Thus, otitis (for example) may be the distal cause, but the persistence of tinnitus (after otitis has been successfully treated) is believed to be due to rewiring of central "auditory" networks.

"Meniere's disease starts with violent attacks, so if stress is involved, it must be an acute stress."

This, I am afraid, is a non sequitur. A rapid onset is of itself not necessarily an exclusion for a chronic cause. Furthermore (and incidentally, I was talking about tinnitus, not Meniére's), as I mentioned in the part of my post you didn't cite, an acute stressor preceding rapid-onset tinnitus is, more often than not, itself preceded by chronic stress or at least many other acute stressors; not to mention genetic vulnerability.

Philip, the link did not work.   This discussion can be easily circumvented by citation of any non-otological case of tinnitus due to a proven central lesion.  I cannot find a single one.

Otitis is a risk factor for endolymphatic hydrops and Meniere's disease (known known).  So any case of post-otitic tinnitus is more likely due to undetected hydrops (unknown known) than to any unknown unknown.

Tinnitus in Meniere's disease is likely to be episodic, concomitant with other symptoms in a Menieriform attack.  A stress explanation needs to explain not only the sudden acute onset, but the resolution of the attack despite the continued chronic stress.

Sorry, here's the link again:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297194/

Should it not work again, try the DOI (10.3389/fnsys.2012.00012) or the bibliography: Guitton, M.J. (2012). Tinnitus: pathology of synaptic plasticity at the cellular and system levels. Front Syst Neurosci, 6:12.

Regarding your other comments, I spent some time deciding whether and how to respond. I do not want to come across as petty or self-opinionated, but - although it is in no way my intent to prove you wrong (or to prove anything, for that matter) - your arguments, with all due respect, are Straw Men and, additionally, filled with a number of other logical fallacies. Thus, even though I thoroughly enjoy this discussion, I think we should maintain a certain level of "good form".

I would like to reiterate, however, that this is NOT a thread about Ménière's but about synesthesia and psychosis, so I suggest sticking to this topic.

Sorry, RG keeps incorporating the rest of my post into the link. So, again, it does not work. I'll try the following option this time :-)

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297194/

Hurray, ca marche! :-)

Here is an extract from a post by Tommasina on Perfume Posse on Mar 21st, 2009, confirming that the inner ear can be involved in changes in synesthesia:

" I’m a classical musician (but will do Gershwin, etc., when necessary / in the mood~), but had somehow not realized that I ‘saw’ musical notes as colors and shapes. Then, when I was (TG, apparently mis-) diagnosed with Menieres disease, about 3 years ago, I had all sorts of distortions and boomings in my head, and most of the time felt very nauseous and off-balance – both literally and metaphorically – so I didn’t want to sing: I couldn’t properly hear what I was singing. I went to one lesson anyway, and I freaked out when my friend / voice teacher suggested I start warming up with a run of 5 notes, bcs when she played them on the piano, they were the wrong shape and color! And, as I said, I hadn’t realized that I ‘saw’ these things. I guess you could compare it to knowing that your shadow is there in bright light, but never paying any attention to it unless someone says, “Hey, look at your shadow!” I couldn’t for the life of me tell you what color and shape those notes should have been, but they were extremely elongated, dark-orange-brown isosceles triangles, and no way could I sing them!"

On the basis of her above symptoms, she was indeed unlikely to have been diagnosed with Meniere's Disease or any other serious ear condition in an ENT clinic. Unfortunately, she will have been told or got the impression that there is therefore nothing wrong with the ear, which is why I formulated the condition of Meniere Spectrum Disorder to cater for the large number of persons like this. 

The reason for mentioning Meniere Spectrum Disorder here is that it is intimately involved in the schizophrenia prodrome, at least as far as auditory hallucinations are concerned. 

See also:

Manic-depressive disease: clinical and psychiatric significance

 John Duval Campbell

Lippincott, 1953 - Manic-depressive illness - 403 pages

There are many case descriptions of patients with clear Meniere Spectrum Disorder in it.  Try searching for  "ears", "wooziness", "noises",  "dizzy" on Google Books.

Thank you very much all for interesting discussion. A lot of new ideas. Synesthesia is not a sign of the coming of schizophrenia. More often - synesthesia is one of mental development. We are talking about the mind, which is peculiar to gifted, often artistically, personalities. Since the high degree of talent often correlates with psychopathology, the simultaneous manifestation of synesthesia and psychopathology is quite possible. But I believe that there is no causal relationship.