The Bizarre Link Between Blindness and Schizophrenia


[ ♪INTRO ] If you start reading pop-psychology listicles,
you might come across this statement: Supposedly, no one who was born blind has ever been diagnosed
with schizophrenia. We saw this so-called “fact,” too, and
it seemed so bizarre that we almost immediately dismissed it. After all, schizophrenia is
a mental illness with symptoms including delusions, disordered thinking, and hallucinations. How
is that closely related to being blind? Well, surprisingly, there is some truth behind
this idea. In the nearly 70 years they’ve been looking
— and despite the fact that it should happen statistically — researchers have found no
known cases of someone with a certain kind of blindness also being diagnosed with schizophrenia. It sounds unlikely, but some evidence suggests
these conditions are more closely related than you might think. In fact, some scientists
think this kind of blindness may even prevent people from developing schizophrenia in the
first place. First, it’s worth noting that this research
has only looked at small, limited sample sizes and is only based on correlations. That doesn’t
mean these studies aren’t useful, but it does mean it’s too early to say anything
for sure — especially since we still don’t know what causes schizophrenia. That being said, some researchers have made
pretty interesting observations here. Their work is specifically focused on congenital
or early cortical blindness, which we’ll call CCB for short. This is a condition someone
has at birth or develops in infancy, and it’s blindness caused by a dysfunction in the brain’s
occipital visual cortex. So if someone became blind as an adult or
was born blind because of something about their eyes, these studies don’t apply. At first glance, it might not seem like this
condition has anything to do with schizophrenia. But once you look at how the brain might cause
schizophrenia’s symptoms, the possible connection becomes a lot more clear. Take visual hallucinations, for example. They’re relatively common in people with
schizophrenia, and some evidence suggests they could happen when someone has trouble
integrating information from their senses — especially their sense of sight. The idea is that the brain would have trouble
getting the visual information it receives to line up with what it’s getting from the
other senses. And because of that — or in an effort to compensate — it could end up
producing hallucinations. Of course, if someone had never gotten any
visual input — like, say, if they had CCB — this couldn’t happen. There would be
nothing to overwhelm the brain, so this process couldn’t be triggered. This isn’t the only connection scientists
have noticed, though: They’ve also seen a similar relationship with auditory symptoms. People with schizophrenia tend to score lower
on measures of auditory processing, and they frequently report having auditory hallucinations
— two things that are likely related to the brain’s auditory cortex. It’s too early to say that these cortex
conditions cause those symptoms, but some experiments have found a correlation between
the two. In one published in 2017, for example, participants
with schizophrenia who had experienced auditory hallucinations tended to have thinner auditory
cortexes than those who hadn’t. But where does CCB come in? Well, many folks with this kind of blindness
have spent their lives relying more on their sense of hearing, so they tend to have greater
auditory perception than average. And brain scans have revealed structural changes that
reflect that. Most notably, their auditory cortexes have
likely expanded. So even if someone with CCB was born with
a thinner auditory cortex or was at risk of developing one, having to rely on their hearing could
have strengthened that brain region. And that could lower their risk for developing auditory
hallucinations. Relationships like this one have even been
observed on a larger, more brain-wide scale — although the consequences there are still
a bit fuzzy. In any case, though, this research is all
based on correlation, which means we can’t conclusively say CCB prevents schizophrenia.
But one thing we can say is that these studies are still significant. They’re super interesting on their own,
and on a larger scale, they can teach us more about how conditions like schizophrenia affect
the brain — and how we could treat them. Based on this kind of research, scientists
have suggested that people at high risk for schizophrenia might benefit from some kind
of cognitive training at a young age — training that works on things like sensory or perceptual
skills. We don’t know if that would be able to prevent
the condition from happening, but it would hopefully improve someone’s quality of life. Ultimately, this is another example of how
our brains are full of surprises, and how seemingly-unrelated systems are connected.
And by studying relationships like this, there’s a lot we can learn. If you want to learn more about schizophrenia
and how it might be different than what you’ve heard, you can watch our episode about it
after this. And as always, thanks for watching this episode of SciShow Psych! [ ♪OUTRO ]

63 thoughts on “The Bizarre Link Between Blindness and Schizophrenia”

  1. I'm glad you pointed out that correlations (especially with small sample sizes) say nothing…
    It's a mistake that many journalists and newspapers seem to make.
    Thanks guys!

  2. The other day I bumped into a blind person (correction: he bumped into me) and at first I thought he might have schizophrenia. He was acting a little, you know, different.
    But I was wrong. Turns out he was just blind drunk.

  3. Isn't looking at Statistics by definition coralation at best. If Statistics are politically ideologically motivated. Like crime Statistics. Or those trying pass laws .
    .

  4. Ok but what about this: I don't have schizophrenia
    I am also not blind.
    I have been vaccinated.
    So… checkmate science!
    /s

  5. So what would happen if a schizophrenic person was in total darkness for a period of time? What about schizophrenics in northern areas where the sun hardly shines in winter and barely sets in summer?

    I have severe, chronic migraine and occasionally, in the aura phase, have flashes of visual or auditory hallucinations. I always know these things do not exist and I am not mentally ill. Perhaps living most of my life free of any hallucinations allows me to reject unreal stimuli?

  6. because the harvard neurologist who had a stroke in her twenties describes the visual filter we are all using but unaware of.

  7. The link between the thinning of the auditory cortex and Schizophrenia should be easy to test for. There is one group of people who should have a thickening of the auditory cortex: Musicians. As part of learning how to sing or play a musical instrument is using your hearing as feedback. Especially for those who sing or play wind and string instruments, where note tuning can be done by change of airflow, position of fingers and/or instrument, or tightening/relaxing of the vocal cords, hearing is very important to the process of music performance. A study that compared symptoms experienced by musicians with Schizophrenia versus non-musicians with Schizophrenia should be enough to verify this. If thickening of the auditory cortex does reduce the chances that the person experiences auditory hallucinations, then musicians should experience less auditory symptoms than the average person.

    If this is true, then the next question is: Can learning a musical instrument or singing positively affect the auditory symptoms. There are studies out there that have shown changes to the brains of those who learned how to sing from a vocal coach, even in adults. These changes would have to include the Auditory Cortex. So, could someone with the auditory hallucinations of Schizophrenia be treated by teaching them how to sing or play an instrument? It wouldn't cure the disorder, but it might offer a measure of relief.

  8. Interesting, but couldn't it just be that when you're blind from birth, one has to learn to trust other people more? And can't secluded oneself?

    But the video also said that blindness related to eyes doesn't reduce the rate. Weird.

  9. Sooooo play video games ( requires both sharp visual and auditory senses to excel in ) I’ll just assume that’s the case!

  10. "Doctor! I think I'm schizophrenic!"
    "Why is that?"
    "I'm seeing things. Like, I think there's a tree outside the window."
    "There… is a tree outside the window."
    "Yeah, but I'm blind."

  11. You need to stop using the word "Listicles". Every time you do, it sounds like testicles… and then 12 year old me takes over, and you know how that goes.

  12. so make ppl with risk of schizophrenia rely more on their hearing at a young age to help lessen or reduce the symptoms might be an option

  13. So would the auditory correlation really have to be because of CCB? Anyone who went blind at a young enough age has spent their lives building that auditory sense the same way as anyone with CCB, regardless of specific condition. I wish I had brain scans of myself when I was born to compare to today. I was born with sight but lost it by age 2 due to detached retinas. I think it'd be really interesting material regardless of this particular topic.

  14. I had just been looking into the 'imprinted brain theory' that suggests in a percentage of cases that schizophrenia could be the opposite of autism – which is apparently supported by a list of symptoms associated more closey with either autism or schizophrenia such as chronic pain for example. I had also heard that 'williams syndrome' is apparently the opposite of autism to. All I know about schizophrenia and the brain is the reduced grey matter and increased ventrical size associated

  15. Finally! A study about blindness that takes into account the cause of the blindness itself! It’s so frustrating that cause is rarely noted and that lack invalidates a lot of results. Thank you for making not of it here!

  16. Can we talk about how Brit got her hair done and she looks AMAZING? (I mean she always does, but God I'm jealous of her hair right now lol)

  17. You had me until the auditory part; I thought you were going to say that people who were born deaf also don't have schizophrenia. Instead you said just said the auditory part is the opposite of the visual part. The whole thing fell apart. 😕

  18. Why then are people blind from birth from none brain causes not be included in this 'conclusion'…they also relie heavily on tneir auditory ability, so could also have this protection against schizophrenia…or else, something else is helping, not only the blindness. A function of the occipital lobe, maybe, that is damaged in these types of blindness?

  19. I think if that wheat enzyme the breachs the gut. Similar blood brain lock and key issues could be the culprit
    Theres studys if correlation between high fever and strep throat,? If you lay on your back For visual hallucinations , Courtesy of your oxsipitel lobe geting the action of blood on brain conflict
    or sleep Was a high fever and strep throat on the left side like me and the blood goes to the Frontal parietal rear frontal cortex damage evrey thing on the way. We do know? What causes of hallucinations the question is how many ways can You hallucinate i have 3 ways

    Sencery over lode to much info in chemical form geting passed down strem ?? As seen in Autism spectrum and (hsd)( spd) Hypostases

    Breach of the spinal fluid
    Clover whole Leaching In to the brain??? Because the fiser being a week point in the folds ot could reach the porriol and rear frontal cortex?? Hypothesis

    Pinel spasm Short release in to the blood as seen in death Near death Other traumatic incidents (fact)
    (thats why heaven is what we believe In our native Tongue
    With a finle bow from are Favorite cast …

    Say Hi To the green brothers For me They're my favorite YouTube demigods O if only we had pudi pie followers
    the world wold be a better place
    👨‍🏫🤷‍♂️👨‍🏫

  20. Today i saw a big dog and a woman, and then they've dissappeared as I desided to look at them again. Is SciShow spying on me?!

  21. I would guess that knowing you were at risk fot schitzophrenia and having someone help you work with that from a young age would be helpful even without a unique cognitive training regimen. Like a medical dula, kind of. I remember reading that other cultures with ways of codifying schitzophrenia as something other than mental illness tended to have better results with folks, and I wonder if expectation of disease progression plays a role there.

  22. This is making me wonder if my symptoms would've been as intense if I had the kinda training/conditioning you were talking about towards the end when I was a kid

  23. But schizophrenia doesn’t just include hallucinations. What about delusions, olfactory or tactile hallucinations, flat affect, etc. This study talked about Positive cluster of symptoms but no Negative or Disorganized ones. How would being born blind of deaf stop any of those?

  24. You should do an episode on autism with the 60% more neurons than average brain.
    https://i.postimg.cc/DzQz9m7d/autistic-neurons.png
    23:00 – 24:00
    https://youtu.be/3pIeBEWcsyM

  25. My eye sight is getting worse because
    of elevated adrenaline in my body
    from a continual panic disorder
    It makes my pupils dilate largely even in inappropriate environments so exposing my retina to excessive light which is damaging
    Because I can’t see well I sometimes suffer with visual psychosis
    when affected by other issues as well as I have difficulty hearing from injury that’s minute enough that it causes no other issues other than disrupting my experience in my surroundings, once again added to other issues can cause some other symptoms of psychosis

  26. this is an extremely proscribed and artificial way of defining the experiences associated with a psychiatric diagnoses.

    The positive and negative symptoms scale which is a staple for treatment, does not define one organic disorder and most recent research has shown that this diagnoses is far from 'one thing'.

    More likely, there is a bias in the way we investigate positive and negative symptoms related to our sightedness and others experiencing problems might experience them in different ways.

    Note: schizophrenia research used to study "multiple personalities", then a focus on delusion, today auditory hallucinations are focused on, it's also true that many meta-analyses have confounded various incarnations of diagnoses…actually a problem with the DSM in general, compounding from generation to generation.

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