What you mean is called “the schizophrenia paradox”. Apart from using this as a search term, I advise you to read Timothy Crow (member of ResearchGate) who devised and defends the hypothesis the development of schizophrenia is ‘a mistake’ in brain development. I.e. the lateralization of the brain (which is needed for language development) which started with homo sapiens some 200.000 years ago.

I'm very curious who is the author of the idea schizophrenia started 300-400 years ago. Please tell me where you found this.

@ Flip, These are some of the references which suggest that schizophrenia is a recent phenomena. Including there is pdf file discussing this issue in detail.

http://www.ncbi.nlm.nih.gov/pubmed/3074859

http://www.ncbi.nlm.nih.gov/pubmed/3325024

http://ajp.psychiatryonline.org/article.aspx?articleid=98686

In the below pdf file please skip to pg 8 of the document to read about this issue.

I think schizophrenia is a developmental disorder that starts with ear infections in infancy, often a result of supine feeding. In the old days, such infants died, taking their genomes with them, nowadays they survive but impaired, especially with an oversensitive cochlea predisposing to auditory hallucinations. A recent epidemiological study in Belgium looking at the risk factors for hearing loss or ear infections in infants in the general populations has found the same risk factors as for schizophrenia, namely winter/spring births, male excess, urban residence, not breastfeeding, foreign born. See

http://www.kindengezin.be/img/SCRIPTIEEVKerschaver2012l.pdf

(Hopefully I now have the correct link!)

Thank you Tarun, I must confess I was unaware schizohrenia as a recent disease was a topic obviously taken seriousy by a few prominent scietntific journals.

Mayby, Anthony, the same is true for the ear infection-idea [bóth don't seem probable unless (paticular?) ear infections are recent phenomena]. Following your link leads me to a recipe for roasting duck, while I didn't think you were joking...

Anthony, thanks. Screened this PhD-thesis superficially, couldn't find 'schizophrenia', nor 'psychosis' in the text. In the summary, however, I see there's a correlation with a wide range of defects, reminiscent of perinatal oxygen shortage.

Just some loose, totally unscientific musings.

Google gives 1,45 million results for ‘ear infection schizophrenia’, which doesn’t mean a lot but signifies its a topic at least. In the Br. J of Psychiatry. I saw a case control study by Mason et al. which finds an OR for schizophrenia of no less than 4.15 (95% CI 2.08–8.29) associated with ear infection (EI) on the left side and seems to establish firmly EI precedes schizophrenia. I didn’t look at the etiological ideas, so for the time being I wouldn’t rule out a spurious correlation. The PhD-thesis you mentioned did say there’s a strong relationship between social deprivation and EI, so maybe there’s where one has to look.

Or maybe oxygen shortage?

Would a folic acid deficiency be a causal factor for EI? That would be something truly exhilarating!

One wonders about the enormous overrepresentation of schizophrenia among Dutch youngsters from Moroccan descent. I don’t think ear infection is a variable in that research.

Hovering around this subject I also saw a curious fact reported: there seem to be 231,724 posts by schizophrenia patients and 228,044 by EI-patients. Only 33 overlap, which, if it has any meaning, seems to indicate the connection is not a topic among the people directly concerned. Hardly a hard scientific fact, moreover: why would the people concerned know these things?

http://bjp.rcpsych.org/content/193/3/192.full

http://treato.com/Ear+Infection,Schizophrenia/?a=s

Thanks, Flip. The thesis was an excellent study on neonatal screening for hearing loss and its correlates, and does not mention schizophrenia. However, I noticed, as predicted in advance, that ear infections in infancy have the same ecological correlations as schizophrenia, and simply explain otherwise mysterious risk factors.

The Mason study was a replication of his previous study. An odds ratio of 10 (sic) was found for prior otitis media on the side of cerebral dominance in those with schizophrenia and auditory hallucinations. As far back as Kraepelin, it was accepted that at least some auditory halls were of otological origin. Whilst any single study is inconclusive, there are masses of similar bits of evidence, some of which I have reviewed, which add up to a simple coherent overall picture. If anyone knows of any other risk factor for schizophrenia with such high odds ratios (apart from family history, which does not get us very far), I think we should all be told.

I recall many years ago having a disagreement with Margaret Pollak, a distinguished pediatrician and Brixton GP. She said there was a high incidence of ear disease in Afro-Caribbean infants, whilst I maintained that otitis media was less common amongst older AC children and adults than the white British. I don't this discrepancy has been resolved.

It is quite possible that different organisms are involved in otitis nowadays. However, I think actual infection is a red herring, structural causes being more important, ie developmental trends in drainage of CSF into the cervical lymphatic system (as stressed by Hippocrates), any cranial bone disorder (these constrict lymph drainage channels), and feeding an infant on its back.

Perinatal hypoxia is related in some way with sensorineural deafness (not otitis media), just as it is related to schizophrenia.

Patients that go to psychiatrists to thinking they will be able to convince them that their schizophrenia has been caused by ear infection really would need to have their heads examined! Even in much clearer cases of musical hallucinations due to ongoing ear disease, patients keep quiet for fear of being thought crazy.

Hi Taurun,

Urbanicity, social isolation, social dislocation, and repeated social defeat are all highly significant environmental risk factors for psychotic disorders.

It is highly likely that the only reason schizophrenia might appear to be a recent phenomenon is because it has become more visible. During the last 400 years very large populations have congregated in urbanised, industrialised cities, in which there are little psycho-social supports for the disadvantaged. At the same time, advancing industrialisation of our societies has dismantled the protective social factors (especially large extended family networks) that were common to pre-industrial societies.

Even in cultures that actively encourage altered states of consciousness and belief in spirits and/or magic, there are still words to describe what we would call "psychosis".

For example in Yoruba the word "were" describes a "disease" that encompasses; "hearing voices, trying to get others to hear or see something that isn't there, smelling seeing tasting hearing or feeling things that other say aren't there, laughing for no reason, talking too much or not at all, piling sticks for no reason, fear of JuJu (ie witchcraft) when no-one else believes there is any JuJu".

Amongst Inuit people the term "nuthkavihak" means "talking to oneself, answering oneself, talking to people who are not there, believing a child or partner was killed by magic when no-one else believes this, believing oneself to be an animal, not talking at all, running away for no reason, getting lost, hiding in strange places, drinking urine, becoming strong and violent for no reason, killing dogs or threatening people for no reason."

These are not concepts imported into these cultures by western psychiatrists. Psychosis, and individual's who are more prone to it than others, are identified in all traditional human cultures. The fact that the per-capita rate of schizophrenia falls within a narrow range no matter where you go in the world strongly suggests these tendencies evolved a very long time ago.

Paul.

The evolutionary persistence of a genetic-loading towards psychotic disorders might be explained in many ways. Three possible theories;

Firstly;

There are many gene variants associated with increased risk of schizophrenia, but none that are necessary or sufficient causes in themselves. Many of the identified genes affect the metabolism of dopamine and other monoamines, or of the endocannabinoids that interact with dopamine regulation.

(Analogy- Dexamphetamine elevates dopamine, serotonin and (nor)adrenaline levels. 5mg of dexamphetamine is performance-enhancing in 99% of humans, as rated by neurocognitive tests.

However 500mg can produce a psychotic break in an otherwise healthy individual).

It is quite possible that some of these gene variants that modulate dopamine are performance enhancing in isolation, but performance degrading in company with some of the other risk genes and/or in company with other, non-genetic, risk factors, (insult or injury in utero, trauma in childhood, social dislocation or defeat, cannabis or amphetamine use, etc).

I think it was William James (in the late 1890s) who first pointed out a puzzling fact about the heritability of psychotic disorders. When he was researching family histories of people suffering what we would now call Schizophrenia and Bipolar Disorder, he found not only that the disorders were far more common in some families, but that these same families also seemed to have a higher instance of writers, artists, political leaders and scientists.

So it may be that these genetic risk factors persist because they are neutral or increase fitness in most individuals who possess them, but are disastrous for a few individuals who are unlucky enough to have the wrong combinations of them...

Second Theory;

The symptoms of schizophrenia that we think of as disastrous may have actually been useful in some pre-industrial, pre-scientific societies. An increased tendency to trance or magical thinking, or the ability to extemporously compose and relate mythical stories, etc may have led to higher social status in some places and times. As only 1% of the population suffer psychotic disorders, in most pre-industrial societies any village, band, or kin group would probably only contain one or two such individuals at any time. Extremely problematic or dangerous individuals would likely be persecuted, abandoned, driven away or killed. But most would simply be viewed as spiritually gifted or as eccentric, and accommodated into the group.

In some cultures a tendency towards these behaviours may have been adaptive most of the time. And in other societies, under extreme and unusual situations, a tendency toward psychosis may sometimes prove adaptive.

Third Theory;

Evolutionary biology teaches us that it is not how significantly impairing a mutation is, but how prevalent it is, that decides whether it persists in the population.

Recent research: 

Schizophrenia emerged after humans diverged from Neanderthals

https://www.sciencedaily.com/releases/2016/08/160815064944.htm

Another update:

https://www.sciencedaily.com/releases/2016/10/161019160035.htm