Dr. Mark D'Esposito

And that's why acetylcholine doesn't boost your working memory, but dopamine does and vice versa.

Right.

Well, most people probably have optimal dopamine, but there's a significant percentage that probably have too little or maybe too much.

And unfortunately, we can't measure it in the blood.

There isn't a blood test that I'm aware of that can measure dopamine because it's stuck in the brain.

Peripheral dopamine in the blood is not a good readout.

It's not a good readout, yeah.

and especially when you're talking about dopamine in areas like prefrontal cortex.

So we don't have a good readout there.

There's invasive procedures like positron emission tomography where we can inject a radioisotope that tags dopamine, and then we can do a scan that actually shows us how much dopamine.

This scan was originally developed to show Parkinson's disease, that you can diagnose Parkinson's disease by showing that there's less dopamine in patients that have Parkinson's disease by looking at this scan.

Obviously, it's invasive.

You're injecting an isotope.

It's expensive, and it's not something we could all do.

But we had used it to show that it correlates very strongly with your working memory capacity.

So how much information you can hold online, if you can hold four or five or six letters when I do a –

span task correlated with how much dopamine we can see in the PET scan.

So that would be a way that we could do it.

Yeah, it's a very strong proxy for dopamine.

So if your working memory capacity is seven letters or numbers, when I say 4, 3, 7, 1, 5, 0, 6, if you get them all back to me very quickly, you probably have more baseline dopamine than someone who has five.