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- [00:02]
A
Hello, faithful listeners. Sam here to say a quick thank you for tuning in this week. I mean, clearly you love hearing us, but did you know we also love hearing from you? So go ahead, rate and review us on your favorite listening platform and tell us what science you want to learn more about these days. It's honestly way more fun that way, and it really helps us out. All right, on to the show. You might have seen some interesting headlines around recently, like these salmon got high on cocaine and scientists gave cocaine to salmon. Now, if you're anything like me, the first question you had reading those was like, why? Why would researchers do that? So we're asking them. We have one of the authors of that study on the show, Dr. Jack Brand. And let me tell you, going beyond the headlines, as we love to do here, there are some fascinating insights. How pharmaceuticals pollute our waterways and what the, ahem, downstream effects are on the wildlife who live there. Before that, we'll look into a recent study that says our brains struggle to make connections when we're stressed out. I mean, very relatable. And later, pcos, or polycystic ovarian syndrome, has a new name and for good reason. We'll talk about why and what it all means for the condition moving forward. Welcome to Curiosity Weekly. I'm your host, Dr. Samantha Yemin. Have you ever completely blanked on an answer to a question in a job interview? And then, like, the second you get home, you come up with the perfect response? Stress messes with our ability to think and even process memories, sometimes making them stronger, other times making it hard to remember anything at all. In a new study, researchers found that stress makes it harder to connect the dots between past memories and and new information. See, our memories are malleable. When we call upon a memory, they often get edited slightly. Our memories can evolve with time. Here's what the researchers did to investigate. They asked their 121 participants to memorize a series of paired images. One image was some kind of animal, and the second was either a face or a scene, for example, cat and forest. The next day, half of the participants were put under a high stress job interview and they had to solve complex math problems. Meanwhile, the other half just got to chill, talk about something of their choosing, and solve really easy math problems. Afterwards, both groups had to memorize another series of paired images, this time an animal again, along with a 3D shape. So, like cat and cube. Then everyone got into an FMRI machine. I mean, not all at once. One by one, the researchers showed them the 3D shapes. Again like the cube, and asked them to pick the matching face or scenes. But here's the trick. They were never shown shapes with faces or scenes before. So they had to remember the animal that was paired with the cube, like the cat, and then remember which face or scene was paired with the cat. In this made up example, it was forest. The researchers were testing whether stress affected that mental bridge to be able to remember cat paired with forest paired with cube. The clever thing about using shapes, faces or scenes and animals is that they all have distinct and really well characterized activation patterns in the brain. This means that the researchers could analyze the FMRI data to decode that activity. They saw that while the control participants were learning CAT plus cube, the brain was also quietly reactivating the memory of the forest to learn the association. In the stress participants. The FMRI showed that the forest memory was not firing as much at all. The researchers concluded that the stress blocked the brain from connecting those two memories, like the brain was purposely trying to keep the memories separate. They published their findings in the journal Science Advances. It reminded me of how the same thing makes me anxious again and again, and I have to actively try to remind myself that I've survived that same situation before. And it may help explain why we sometimes struggle to link the concepts learned in class during an exam. But there could be some benefits to all of this happening. Perhaps there's an advantage to keeping memories of stressful situations separate so we don't confuse details. So the next time you don't remember something till hours later, cut yourself some slack. Your memory might not have been failing you. You're probably just stressed and filing things separately. When thinking about ocean pollution, you might imagine something like the Great Pacific Garbage Patch or an oil spill. But there are a lot of other hidden pollutants making their way into our waters that don't have as obvious of origins. Think about this. Every medicine or drug you take goes through your body and turns into waste, which, depending on where you live, usually makes its way to your local sewage treatment facility. But those facilities aren't necessarily designed to filter out pharmaceuticals or drugs, leading to trace amounts ending up in our waterways. This can have a ton of effects on local wildlife behavior, so I've brought in an expert on the subject to tell us more. Take today, I'll be talking to Dr. Jack Brand, a researcher at the Department of Wildlife, Fish and Environmental Studies at the Swedish University of Agricultural Sciences. Welcome to the show, Jack.
- [05:22]
B
No worries. Thanks, Sam. Thanks for having me.
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A
Your recent paper garnered a ton of fascinating headlines. Before we get into that specific study, I'm wondering if you can explain why it's so important to understand how chemical pollutants can affect animal behavior.
- [05:38]
B
So a few different reasons. So animal behavior is fundamentally how animals interact with their environment. And this can determine things like what they eat or who eats them. So it's critical to their survival. But also in terms of chemical pollution, what we're finding is that these small sort of neuroactive chemicals that we're putting into the environment can have adverse effects on wildlife. And so these chemicals target neurological systems in your brain which are what we call evolutionarily conserved, meaning that they're also present in a variety of sort of non target wildlife species. And that means that fish and other animals can be equally susceptible to these drugs as you or I would be.
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A
And so understanding the way that they could act on wildlife would then change the way they behave in the wild, which could then have larger ecosystem impacts. Is that kind of, what's that called, Domino's effect, what you're looking at?
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B
Exactly. In one way, I think it can have effects at multiple different levels. So like I mentioned before with the example about altering foraging behavior or predation and things like that, so that can have immediate effects for the individual. So it can affect their survival or their reproductive success, et cetera. But then that can scale up as well to have broader population level effects. So there was a really famous study actually out of Canada by Professor Karen Kidding decades ago now, I think it was on how the key ingredient in the female contraceptive pill could actually feminize fish populations and lead to population collapses. And these were really, really, really tiny doses in the waterways as just sort of one example of how even very small levels of these drugs can have sort of drastic consequences for fish populations and indeed populations of other organisms as well.
- [07:30]
A
See, that's what I was going to say, because I would have assumed that these things are in such low concentrations, or at least they get diluted so much in the context of a large body of water. I was actually shocked that this would be a concern because I just assumed it's too little for it to do anything. But that doesn't seem to be the case.
- [07:50]
B
No, not at all. And a few points to raise there is that these are fairly small concentrations, but importantly, we're finding that even these small concentrations can have an effect. But I think what's more important is to think that these drugs are almost what we call pseudo persistent in our environment. That means they're sort of being continually discharged into our environment. And so there's constant, albeit low levels, but constant levels of these drugs throughout our environment. And also, there's not just one drug in our environment. There's multiple different types of drugs. And lots of fish and other aquatic organisms are really swimming through, at least near urban centers, sort of dilute cocktails of different pharmaceuticals and drugs in our waterways.
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A
Okay, so now I have to ask you about the cocaine study specifically. Can we start with why cocaine? Why was that I guess the molecule of choice? Yeah.
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B
Partly because cocaine is one of, if not the most commonly detected illicit compound in our waterways across the world. It's also present at fairly high concentrations in our waterways, particularly near urban centers, and also, you know, in places like downstream of music festivals or downstream of ski resorts in the wintertime, things like that. We also know that the. The neurological targets of cocaine, like I said before, are evolutionarily conserved, meaning that they're also present in a lot of other wildlife species, including fish, meaning that they're potentially susceptible to their effects.
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A
What behavioral effect were you expecting from this? And what did you find when salmon were exposed to cocaine versus the other metabolite that you studied?
- [09:39]
B
Exactly? Like you said, we exposed fish to either very, very low levels of cocaine. Its main metabolite, benzoylecanine, which I can never, ever pronounce. And so benzo lichenine.
- [09:52]
A
Is that right?
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B
That's right.
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A
Okay, I'll practice.
- [09:55]
B
Or. We had a control group that received the implant, but no drug at all. And what we expected was sort of, as you'd imagine, we expected that cocaine would act in a similar way on fish brains as it does to loud brains and increase activity rates and hyperactivity and things like that. We. We did see signatures of that. So cocaine did slightly increase movement rates in fish, in particular in these salmon in the lake that we expose them to. But what sort of really surprised us was the effects of the metabolite. Now, what happens when people take cocaine is. Is your body partly breaks it down into this. This byproduct, this metabolite, benzoylecanine. When people then go to the toilet, they release a bit of cocaine and benzoalectinine into the wastewater system, and that gets flushed out into our rivers, streams, and coastal environments. Now, benzoalecanine is often present at higher concentrations than actually cocaine itself. But historically, we've always thought it's not very potent in humans, that it's not very biologically active in people, and therefore that it wouldn't be as great a environmental risk than when compared to cocaine. But Interestingly, in our study, we found that the metabolite was actually having a far greater effect on salmon movement and behavior than cocaine itself. And so we found that the metabolite actually almost doubled the movement rates of salmon and also made them disperse more across the lake. So they dispersed an extra 12 and a half kilometers, essentially across the lake, which. I don't know what that is in miles. I'm so sorry.
- [11:33]
A
No, well, I'm Canadian, so thank you for giving kilometers. Many of our listeners would know miles, so that's okay. You were able to measure that excess movement. I think you used some pretty cool tech to tag and track them. That was novel, I believe. Can you tell us more about that?
- [11:53]
B
Yeah. So what we did is we used what's called acoustic telemetry. And this is essentially a system where we surgically implant, under anesthesia, a small little acoustic tracking tag into the fish. We then stitch the fish up and then let it recover for a few days, and afterwards we release it into the lake. Now, in the lake, we had placed a number of what we call sort of hydrophones or underwater microphones. And now each of these tags emits a really unique acoustic signal. So they all have their own unique signal that they emit. And with this array of hydrophones, we can tell which fish is where and when in the lake. And then we pull all that data together after a few months, and we can reconstruct the sort of movement paths throughout the lake that the fish were taking.
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A
That's so cool. Had that been done before? Like, is that a well established way of tracking fish or was it new?
- [12:48]
B
No, that's a fairly well established way of tracking fish. The novel part of our experiment was actually using a technology developed by a Canadian collaborator of ours who was on the paper, Dr. Erin McCollum. So she sort of developed these slow release chemical implants. And so what these are is a small sort of fatty based implant which has some sort of drug in it, and it slowly releases the compound over time. So this means we can sort of individually expose fish themselves to a compound of interest rather than, say, you know, polluting the whole lake to see what happens.
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A
Since you were exposing the fish yourself through this slow release device, how realistic are the concentrations that they were exposed to compared to what you might expect naturally in the water?
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B
Yeah, so an important step in our research was actually validating that. And so what we did is we kept a portion of fish behind, we exposed them to the same slow release implants of these compounds, and then we took their brains and Measured the concentrations of these drugs in their brains. And we validated that the concentrations that we're achieving through our implants were approximately equivalent of what you'd see sort of downstream of major urban centers where cocaine is prevalent. And so the levels we achieved were environmentally realistic in that way.
- [14:11]
A
That's amazing. That's really cool. And tough work. Are we seeing more drugs besides cocaine in rivers and other waterways? Like, what's the, I guess, next one of concern now that you've figured out this one?
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B
There's many, to be honest. And so some of the recent figures for things like pharmaceutical drugs is almost 1000 different unique compounds or their transformation products are present in waterways across the globe, Plus a number of illicit substances like methamphetamine, mdma, cocaine, etc, and so we're finding lots and lots of different drugs in our waterways. Really interestingly, or at least what I think is really interesting, is the mixtures that we find. And so, for example, when you go to. When you go to a doctor, you know, your doctor might not prescribe medicine A and B together for you because they may have contradictions and that may lead to adverse effects. But of course, both of those drugs are still being prescribed to people and then entering our water systems. And so you can have aquatic animals like fish, being simultaneously exposed to combinations of drugs which actually have adverse chemical interactions, which we really don't understand well yet.
- [15:28]
A
When I was reading about some of your work, that was what struck me as well, is the combinatorial effects. Our waterways are essentially a soup of all of these things that end up through our sewage systems. And if I'm thinking a pharmacist, their expertise is required just to understand what one person is taking in when they're on multiple medications. How do you do that for a waterway that has an entire population's waste in it?
- [15:58]
B
Very difficult. It's a very difficult task and one that we're struggling with. But historically, and this is the approach we're still taking, is exposing animals to, say, a single compound of interest and seeing their effects. And. But new sort of modeling techniques is sort of trying to bring all that together and understand, you know, what concentrations are causing hazards for fish and what are their effects of all these multiple different types of drugs. But it is a very, very difficult task, Especially when you throw in things like increasing temperatures of lakes and rivers and things like that. Understanding all these processes simultaneously is extraordinarily difficult.
- [16:39]
A
I also thought it's interesting that you're focused on the behavior aspect, and a lot of people might Wonder what about health outcomes like how chemicals affect different population numbers and the bigger ecosystem effects? What about what happens when we then eat those salmon, for example? Is that part of your work too? Or is there a reason why you think behavior is the key thing to focus on?
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B
It's not part of my work per se, but it's a very, very large part of the field. And so actually I think the story is almost flipped in that what the field traditionally focused on was exactly those sort of measures that you're talking about. So what concentrations of these drugs affect survival or reproductive failure and things like that. What we were finding is that fish that were exposed to concentrations below those, those dangerous levels were still seeing effects of these, these pharmaceuticals. And so they're what we call sort of sublethal effects. They include things like behaviour. And so historically we didn't really consider behaviour that much in ecotoxicology, but we're now sort of understanding and discovering that all of these subtle sub lethal changes in behavior can actually scale up to affect things like survival, affect things like population sizes, reproductive success, which have cascading impacts on the ecosystem.
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A
Wastewater treatment facilities, they're not really designed to filter out pharmaceuticals or these types of everyday chemicals, let's say.
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B
That's right.
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A
Do you think there's a world where that changes as the problem gets more severe? And what does that even look like?
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B
Yeah, and so exactly as you said, most sort of wastewater treatment techniques aren't really designed or weren't set up to sort of remove these products from our rivers and streams and things like that. But there are sort of advanced wastewater techniques. So things like activated charcoal, which can help filter out large portions of these substances, things like ozonation, which, which break down some of these products. The main issue is the cost involved and scaling that up at cost. And for some countries that may be easier. So you can find some European countries which have fairly advanced wastewater treatment techniques across the board. However, when you move into sort of lower income countries, these facilities are minimal or often lacking entirely, which can be huge problems for the animals that inhabit those ecosystems in those countries. And so, yeah, there's lots of different things that can be done, but it's a question of cost and scalability. There's also some things we can do in terms of designing drugs from the outset with the idea that they're going to end up in the environment. And so some of my colleagues have sort of been spearheading this sort of greener pharmacy movement, so sort of advocating for designing pharmaceuticals and drugs from the outset with the idea that they're going to end up in the environment. So how do we minimize their impact or maximize their breakdown once they enter our aquatic environments? So there's a range of different things we can do. And the solution I think will likely be sort of multi pronged. It won't be a simple sort of one size fits all. But there is hope I think moving forward.
- [20:05]
A
Is there a certain chemical pollutant affecting wildlife today that you're most concerned about or that you think is most urgent for these solutions?
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B
Not a single one. I think, I think we still don't know how many of these drugs actually affect different organisms. And it's likely that some of these substances have already had catastrophic effects for local populations in different parts of the world that we haven't even registered and we're not even aware of. I think there's been some highly publicized cases like for example the Indian Vulture crisis. Back through the 90s and early 2000s, essentially what was happening is with farmers were giving their livestock an anti inflammatory drug, Diclofenac. And basically when these livestock would pass away, if they passed away in the field, they'd be scavenged on by local vultures. But what we didn't know at the time was that know this chemical can cause sort of kidney failure and death in vultures and, and that ended up wiping out. I think the recent estimates were between sort of 95 and 98% of the vultures in, in that country. It was a major sort of ecological crisis and we're only sort of really understanding the last sort of 10 years, the, the scale of it and the consequences it had both in terms of local ecosystems, but also for the local human populations and disease spread amongst local communities as well.
- [21:36]
A
In your dream world, how do we address this problem of chemical pollutants going forward?
- [21:41]
B
There is still fairly little systematic monitoring over time of all the different substances that are in our waterways and what the safe and tolerable levels for organisms in those ecosystems are. And so in my ideal world we'd have a wider spread systematic monitoring efforts, probably with somewhat stricter regulatory requirements for polluting in those systems. We'd also have a greater understanding of how these substances are affecting the local organisms and be investing more money into sort of broader advanced wastewater treatment techniques, not just in sort of high gdp, high income countries, but across the board.
- [22:19]
A
Thank you so much for joining us Jack. Dr. Jack Brand is a researcher at the Department of Wildlife, Fish and Environmental Studies at the Swedish University of Agricultural Sciences. Thanks for being on the show.
- [22:29]
B
Cheers. Thanks, Sam. Thanks for having me.
- [22:36]
A
After years involving an international consortium of doctors, thousands of surveys of patients and healthcare professionals, and dozens of organizations from around the globe, Polycystic ovary syndrome has officially been renamed. As of May 2026, PCOS was officially renamed to PMOS, or Polyandocrine Metabolic Ovarian Syndrome. The full transition will play out over the next three years, but it's a landmark decision that researchers and healthcare professionals alike hope will usher in a new era of more accurate diagnoses, increased funding for research, and the end of fragmented care for patients. PMOS affects 10 to 13% of people who were assigned female at birth and are now of reproductive age. In pmos, the body struggles to respond to insulin, and that insulin resistance drives the overproduction of androgens. Those are hormones that are present in all bodies. But in people with ovaries, when they spike, they can disrupt everything from metabolism to skin to fertility. Simply put, it's an imbalance of hormones that causes a bunch of different dysfunctions all around the body. People with PMOS can have symptoms like irregular periods, hair loss, pelvic pain, excess body hair infertility, weight gain, skin problems, skin sleep apnea, and psychological issues like depression and anxiety. Insulin resistance can also lead to high cholesterol and increase the risk of type 2 diabetes and cardiovascular disease. And because the condition encompasses so many different systems, it's been thought of as difficult to diagnose and treat. Previously, the name polycystic ovary syndrome created this powerful misconception that ovarian cysts were the defining feature of the condition. The problem with that is not everyone with PMOS has ovarian cysts. Not everyone with PMOS has gynecological symptoms at all. In fact, it's primarily a hormone disorder, so misclassifying it has led to problems with diagnosis. Not only that, there are specific drawbacks in research funding and educational opportunities because of the way it was previously categorized. When a condition's labeled strictly gynecological, it becomes siloed from other fields. Research grants become funneled exclusively towards reproductive outcomes, leaving cardiovascular, metabolic, and mental health impacts understudied. And medical specialists in very relevant areas like endocrinology, cardiology, and metabolic health might not recognize the disorder in patients who lack the non gynecological symptoms. Experts have been advocating for a name change for a long time, but past efforts had issues gaining traction on international scale. With this change, the hope is that we're moving in a direction toward better and more accurate care for those who are suffering. For warner Bros. Discovery Curiosity Weekly is produced by the team at Wheelhouse DNA. The senior producer and editorial correspondent is Teresa Carey. Our producer is Chiara Noni. Our audio engineer is Nick Karisimi. And head of production for Wheelhouse DNA is Cassie Berman. And I'm Dr. Samantha Yamin. Thanks for listening.