congenital blindness and schizophrenia

February 26, 2020 7:12 AM

People Born Blind Are Mysteriously Protected From Schizophrenia (Vice): Over the past 60-some years, scientists around the world have been writing about this mystery. They've analyzed past studies, combed the wards of psychiatric hospitals, and looked through agencies that treat blind people, trying to find a case. [...] These findings suggest that something about congenital blindness may protect a person from schizophrenia. This is especially surprising, since congenital blindness often results from infections, brain trauma, or genetic mutation -- all factors that are independently associated with greater risk of psychotic disorders.

Congenital blindness is protective for schizophrenia and other psychotic illness. A whole-population study. (Schizophrenia Research abstract):

Congenital/early blindness is reportedly protective against schizophrenia. Using a whole-population cohort of 467,945 children born in Western Australia between 1980 and 2001, we examined prevalence of schizophrenia and psychotic illness in individuals with congenital/early blindness. Overall, 1870 children developed schizophrenia (0.4%) while 9120 developed a psychotic illness (1.9%). None of the 66 children with cortical blindness developed schizophrenia or psychotic illness.

Cognitive and neuroplasticity mechanisms by which congenital or early blindness may confer a protective effect against schizophrenia (Frontiers in Psychology full paper):

Several authors have noted that there are no reported cases of people with schizophrenia who were born blind or who developed blindness shortly after birth, suggesting that congenital or early (C/E) blindness may serve as a protective factor against schizophrenia. By what mechanisms might this effect operate? Here, we hypothesize that C/E blindness offers protection by strengthening cognitive functions whose impairment characterizes schizophrenia, and by constraining cognitive processes that exhibit excessive flexibility in schizophrenia.

No blind schizophrenics: Are NMDA-receptor dynamics involved? (Behavioral and Brain Sciences abstract)

Blindness, Psychosis, and the Visual Construction of the World (Schizophrenia Bulletin abstract)

posted by not_the_water (17 comments total)

Wow, this is super interesting. Thanks for posting.
posted by saturday_morning at 7:19 AM on February 26, 2020 [3 favorites]

Blindness, Psychosis, and the Visual Construction of the World (Sci-Hub Link)
posted by meehawl at 7:50 AM on February 26, 2020 [2 favorites]

Hmm. The Australian study doesn't seem too impressive, given the low numbers of blind children and the low incidence of schizophrenia/psychosis. You'd only expect a single incidence among the population on average anyway.
posted by tavella at 8:16 AM on February 26, 2020 [5 favorites]

It appears that people with schizophrenia may get fewer cancers. Humans, immune systems, and brains are interesting and not well understood.
posted by theora55 at 10:18 AM on February 26, 2020 [2 favorites]

Hmm. The Australian study doesn't seem too impressive, given the low numbers of blind children and the low incidence of schizophrenia/psychosis. You'd only expect a single incidence among the population on average anyway.

True, but it seems reasonable to note that it doesn't disprove the hypothesis that there are no people who are congenitally blind who also have schizophrenia, which (presuming it is otherwise methodologically sound) it had a pretty theoretical good chance of doing. In the context of an environment where many people are making what might seem, on the face of it, an extraordinary claim, this seems like a fairly sensible study to conduct, particularly given the fact that it was probably pretty cheap.

A single case in almost any cohort would, with appropriate reproduction, disprove what appears to be fairly settled agreement that cortical blindness is extremely strongly protective against schizophrenia. Given the low prevalence of both blindness and schizophrenia, and the issue that absence of evidence is not necessarily evidence of absence, it's always going to be challenging to confirm the hypothesis.

As ever...more studies are needed.
posted by howfar at 10:42 AM on February 26, 2020 [11 favorites]

On the other hand, people with schizophrenia are more likely to display photophilia, including dangerous sun gazing, than people with other psychiatric illnesses or the general population.
posted by jamjam at 10:58 AM on February 26, 2020

I suspect that somewhere at the intersection of the original post and jamjam's comment about photophilia lies a potentially fascinating sci-fi story.
posted by Godspeed.You!Black.Emperor.Penguin at 11:05 AM on February 26, 2020 [5 favorites]

Fascinating. Does anyone know if this only applies to schizophrenia/schizophreniform disorders or does it also apply to the other mental health conditions that can cause psychosis? I.e., have there been cases of people born blind with bipolar disorder I? Or maybe they don't experience the psychosis aspects of manic episodes?
posted by overglow at 11:07 AM on February 26, 2020 [1 favorite]

The question above about manic psychosis is darned near eponysterical...
posted by not_that_epiphanius at 12:23 PM on February 26, 2020 [1 favorite]

I suspect that somewhere at the intersection of the original post and jamjam's comment about photophilia lies a potentially fascinating sci-fi story.

Maximillian Cohen:
9:22, Personal note: When I was a little kid my mother told me not to stare into the sun, so once when I was six, I did. At first the brightness was overwhelming, but I had seen that before. I kept looking, forcing myself not to blink, and then the brightness began to dissolve. My pupils shrunk to pinholes and everything came into focus and for a moment I understood.
posted by doctord at 3:06 PM on February 26, 2020 [6 favorites]

I'm not surprised. I have aphantasia and seem to experience a lot fewer of the ordinary hallucinations most people have. For example, I have very prosaic, ordinary dreams that are generally not visual at all.
posted by saveyoursanity at 8:26 PM on February 26, 2020

Sun gazing among schizophrenics is common enough that that there have been epidemics of it in psychiatric hospitals.

Here in the shade thrown by this FPP, I think that raises a possibility that some schizophrenics have learned to deal with their disease by damaging their own retinas because something their retinas do or produce makes schizophrenia worse on an ongoing basis. Schizophrenics also have elevated rates of retinitis pigmentosa, but that could be because they tend to stare at the Sun, I suppose.
posted by jamjam at 1:09 AM on February 27, 2020 [3 favorites]

Schizophrenics also have elevated rates of retinitis pigmentosa, but that could be because they tend to stare at the Sun, I suppose.

Looking directly at the sun cannot and will not cause retinitis pigmentosa. It can cause solar retinopathy, which has a different cause entirely (looking at the sun, or in some cases very bright artificial light sources without protection, as in welding). a Retinitis pigmentosa is a genetic condition (I'm married to someone with RP).
posted by mandolin conspiracy at 10:47 AM on February 27, 2020 [3 favorites]

Can an understanding of cognition and neuroplasticity in C/E blindness be used to reduce the likelihood of schizophrenia? At first glance, the answer seems to be “no” since: (1) only C/E blindness (but not blindness acquired after the first few months of life) is associated with a protective effect; (2) it is difficult to identify most people who will develop schizophrenia during the first year of life; (3) it is not clear what type of training could be given to people less than 1-year old, given limited attention span and undeveloped verbal abilities; and (4) the presence of vision is likely to reduce the extent of developmental neuroplasticity. However, the ultimate answer to this question may not be this simple. For example, much remains to be learned about biological and computational changes associated with C/E, and later-developing, blindness, and so further investigation into these issues may reveal clues for intervention development.

This is all a ridiculously fascinating line of inquiry. Thanks for posting this.
posted by mandolin conspiracy at 11:15 AM on February 27, 2020

Looking directly at the sun cannot and will not cause retinitis pigmentosa. It can cause solar retinopathy, which has a different cause entirely (looking at the sun, or in some cases very bright artificial light sources without protection, as in welding). a Retinitis pigmentosa is a genetic condition (I'm married to someone with RP).

I think you may be referring to non-syndromic retinitis pigmentosa, mandolin conspiracy.

According the the Wikipedia article:

Causes

RP may be: (1) Non-syndromic, that is, it occurs alone, without any other clinical findings, (2) Syndromic, with other neurosensory disorders, developmental abnormalities, or complex clinical findings, or (3) Secondary to other systemic diseases.[6]

•RP combined with deafness (congenital or progressive) is called Usher syndrome.[7]

•Alport's syndrome is associated with RP and an abnormal glomerular-basement membrane leading to nephrotic syndrome. It is inherited as X-linked dominant.

•RP combined with ophthalmoplegia, dysphagia, ataxia, and cardiac conduction defects is seen in the mitochondrial DNA disorder Kearns–Sayre syndrome (also known as Ragged Red Fiber Myopathy)

•RP combined with retardation, peripheral neuropathy, acanthotic (spiked) RBCs, ataxia, steatorrhea, and absence of VLDL is seen in abetalipoproteinemia.[8]

•RP is seen clinically in association with several other rare genetic disorders (including muscular dystrophy and chronic granulomatous disease) as part of McLeod syndrome. This is an X-linked recessive phenotype characterized by a complete absence of XK cell surface proteins, and therefore markedly reduced expression of all Kell red blood cell antigens. For transfusion purposes these patients are considered completely incompatible with all normal and K0/K0 donors.

•RP associated with hypogonadism, and developmental delay with an autosomal recessive inheritance pattern is seen with Bardet–Biedl syndrome[9]

Other conditions include neurosyphilis, toxoplasmosis and Refsum's disease.

A friend of mine developed mild RP secondary to MS, and another friend developed a bad case in the last year of his life after 3 decades of very severe rheumatoid arthritis.
posted by jamjam at 3:41 PM on February 27, 2020 [2 favorites]

I think you may be referring to non-syndromic retinitis pigmentosa

What I was getting at is that it's not caused by staring at the sun.

The syndromic versions as well are almost all caused by larger inherited syndromes.
posted by mandolin conspiracy at 9:18 PM on February 27, 2020

I'd add that RP sometimes gets diagnosed when it's not exactly the thing that's happening but it's close, e.g.,

Secondary Retinitis Pigmentosa (Syphilis)

This paper presents four cases of syphilitic chorioretinitis that meet the criteria generally used in the diagnosis of retinitis pigmentosa (RP): namely, suppressed electroretinogram (ERG), abnormal electrooculogram (EOG), constricted fields, nightblindness, and pigmentary degeneration. Findings that can help to differentiate syphilitic chorioretinitis from true retinitis pigmentosa are discussed.

Then there's cases of RP that get misdiagnosed as something else, etc. The eye is a weird thing!
posted by mandolin conspiracy at 9:24 PM on February 27, 2020 [1 favorite]