Schizophrenia and Aberrant Salience

One of my special interests is psychosis/schizophrenia. I posted this infodump on Tumblr a few days ago, and it got a lot of notes and made its way over to some psychosis blogs, which was cool. (When I say psychosis blogs, I mean blogs run by/for people with psychotic illnesses or who experience psychosis on a regular basis. Sort of similar to autistic pride, psychosis pride/positivity doesn’t necessarily mean that people like being psychotic…it means they accept themselves for who they are and are just as valid and worthy of respect and kindness as people without psychosis.) Anyway, I was really happy that people found it helpful or interesting to read, and I thought I’d post it here, too. I also will give you a brief taste of the back-and-forth that goes on in my head when I’m trying to decide if a post is ready to be published or not:

Me: I’ve worked forever on this and I would kind of like to move on to something else…

Also me: But you could make it longer/better/more in-depth and why not say more about this and did you cite your sources on that and maybe hyperlink to this other thing you should include the data –

Still me: Yeah, but I have like, a million other things to do…

Increasingly agitated, hyperfixated me: NO. THIS IS THE ONLY THING. YOU MUST DO THIS THING UNTIL IT IS A MASTERPIECE.

Somewhat exasperated me: Or I could, like, not…

(And so on, ad infinitum.) Point is, I have a lot more to say about this, but without further ado, here’s the infodump, and you can expect more interesting information on schizophrenia and psychosis in the future!

Dopamine is a neurotransmitter (a chemical involved in brain function). It’s often associated with pleasure, and drugs like cocaine that make people feel intense pleasure act on dopamine.

Since around the 1950s, scientists have thought that schizophrenia is related to abnormal dopamine activity in the brain. So that’s a rough, oversimplified explanation for how schizophrenia occurs on a cellular level. 

But there are still a lot of questions about how exactly this translates to symptoms of schizophrenia, like hallucinations, delusions, disorganized thinking, and so on.

This is where dopamine comes back in. Dopamine is much more than just a “pleasure chemical” (neuroscience is waaaaay more complicated than that). Dopamine doesn’t just have to do with pleasure. It’s related to reward, anticipating reward, and goal-seeking behavior. Dopamine affects what you perceive as rewarding, or salient. And then that informs your behavior…not just what goals you work for, but what you pay attention to in your environment.

So when dopaminergic activity changes, this affects salience, meaning that certain stimuli are perceived as more important/meaningful than others. Here’s a visual metaphor for this. Let’s say this is how a typical person perceives this image:

[Image: four shelves of various cereal boxes, including Chex, Cheerios, Rice Squares, Life, Rice Krispies, Wheaties, and other off-brand ones. Except for a few gaps at the bottom, the shelves are mostly packed.]

But if there’s a change in your brain that means certain stimuli seem more important (salient) than others, the picture looks like this:

[Image: Same image as above, but with the coloring dramatically altered such that the warmer colors all appear a very bright yellow, the blues are intense, the greens are fluorescent, and many of the details on the cereal boxes, such as the words, the drawings, and the cartoon animals, are difficult to discern.]

(This is a visual metaphor. Psychosis isn’t actually associated with this kind of change in vision [at least not in most cases].)

And if your attention is then drawn to things that most people wouldn’t pay as much attention to, it makes sense, intuitively, that you might start to formulate unusual ideas about those things. If you’re focusing intensely on, say, people on the street who seem to be looking at you, that might evolve into the belief that people are talking about you or conspiring against you*. And then, because of how cognitive biases work, once you think people are out to get you, you might pay more attention to evidence that confirms this belief and dismiss evidence to the contrary. So you’re paying more attention to certain stimuli, which in turns fuels the delusion, and so on. Positive feedback loop.

To be clear, this is a really really really oversimplified explanation, and I’m by no means an expert, but this is just fascinating to me. And then it gets even more interesting: remember that part about how dopamine affects what we perceive as rewarding? Well, it’s been hypothesized that dopamine plays a role in the negative symptoms of schizophrenia (things like not talking much, social withdrawal, avolition, flat affect, etc.). If the dopamine in your brain is working differently and you’re not perceiving tasks as meaningful or rewarding, then you’ll be less motivated to do them. Less goal-seeking behavior.

There hasn’t been a treatment for negative symptoms in schizophrenia since the ‘90s, and negative symptoms are strongly correlated to poor prognosis – not just in schizophrenia, but in other brain illnesses like major depression and Alzheimer’s. But there is one chemical that seems to alleviate these symptoms: nicotine. So when people with schizophrenia smoke, it’s possible that part of why they’re doing so is because smoking alleviates these really awful debilitating symptoms that modern medicine doesn’t know what to do with.

Morals of the story: schizophrenia is complicated, science is cool, and let’s please stop moralizing illness. Having a sickness or a disability IS NOT A MATTER OF FAULT. There are so many factors outside of an individual’s control affecting health, so to equate bad health to personal failure is illogical, harmful, unkind, and just plain wrong. The nicotine example is especially powerful…like, if someone with schizophrenia gets lung cancer after smoking to alleviate profoundly debilitating symptoms of a disease that doctors still aren’t able to treat, that’s a reflection of systemic failures and the need for more research and better medicine. Not an individual’s moral failure.

*I had trouble finding a photo of people on the street to accompany this effectively.



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