Funded by the Institute for Scientific Information on Coffee (ISIC) — an industry body — which is a notable conflict of interest the authors disclose but don't extensively discuss
After habitually consuming caffeine (not in coffee form) daily, usually multiple times a day, for more than a decade, a horrible mental health incident happened to me that forced me to stop it for a while. Afterwards I didn't resume the habit, and so I no longer have a tolerance.
This has let me evaluate what caffeine does with fresh eyes, so to say, because I can now consume it occasionally while having many non-caffeinated days to compare to. It's a profoundly psychoactive substance and does a lot of things to cognition. I guess I have decided I don't enjoy how it feels, having previously been dependent on it.
After habitually consuming coffee daily in large quantities for two decades, I had mental health incident, during which I drank twice the amount of coffee and it felt like water. After that incident I still drink previous amount of coffee, but feel much better, much more rested, on an upward trajectory and like I have finally managed to escape the swamp I dragged myself into over many years.
After reevaluating your comment and my experience I declare that coffee is not always a cause of mental health incidents, sometimes it might help people.
I've had the same experience. Caffeine is super addicting, the ritual & habits surrounding it is a potent pull. For myself, it makes me erratic, impulsive, more reactive and agitated. One cup a day puts me on edge, makes me sweat more, makes me more intolerant, makes everything feel too slow. It such a sneaky drug and it can really get under your skin without you realizing how much it changes you.
I don't have the same experience, and I drink one cup of coffee (270 ml) almost every day. No agitation, no impulsiveness. I can drink coffee in late evening (let's say 8 pm) and sleep well. I guess I'm trying to say that we should not project our own experience on others, everyone is different.
Quitting caffeine after decades of use was a bit of a mixed bag for me in the short term, but positive in the long term.
Going caffeine-free made it much easier to lose weight as I have far less cravings for high carbs and sugar now, presumably this is related to the impulsivity impact talked about in the paper.
Going caffeine-free also made me very depressed for a while with severe anhedonia, this lasted way longer (like 3-4 months) than one would generally expect for caffeine withdrawal symptoms.
I had seemingly become so used to the increased dopamine signaling while buzzed on caffeine that my brain was a mess for a rather extended period of time as it got used to not having it.
Overall I view quitting as a positive for me, but I'd warn anyone thinking about doing it to do it carefully and closely monitor their mental health. AFAIK the impacts of quitting can be quite different for different people, so my experience may differ than that of others, but I had no idea how much of a (temporary) mental health crash quitting caffeine could cause until I experienced it.
I'm almost exactly 1 year coffee-free (not caffeine free, but significantly less because tea is much less addictive for me).
Also positive in the long-term for me. Fewer digestive issues, less spiky dopamine sensitive or impulsiveness and performance during the day, better memory. I wish it weren't so.
But damn was the 3-6 months of anhedonia awful. I still feel pangs of it.
Agree, I drink it a lot and then stop drinking it at least once a year for a few weeks, and for sure it's a different mode of mind, but can't really qualify it besides that I remember my thinking being softer, calmer and perhaps even "more correct" without coffee.
(But I never had any mental-health incidents, and I drink a lot of it, more than all people that I personally know.)
I like this worldview. Prior to coffee, Europe was in the grip of the beer dwarves. Coffee demons took over and invented nationalism, capitalism and Keynesian economics.
The overwhelming majority of the enjoyable coffee experiences are caffeinated. While there is good decaf out there it's not the norm, specially in smaller markets.
I think they meant that coffee contains a lot of other compounds than just caffeine, which something like energy drinks or teas will not include. So you can't necessarily extend conclusions from a study on consumption of coffee to effects that other drinks that happen to include caffeine might have.
Edit: this is especially relevant here, as the study found similar effects in decaffeinated coffee drinkers. So the effects they observed, if real, are not related to caffeine.
I do believe a lot of it boils down to tolerance. I for example feel basically 0 effects, and drink it just because I like the taste (of a good one with milk, or exceptionally some good espresso / ristretto after big dinner).
I recently traveled and didn't have coffee for more than a week. No change I could feel, no craving, nothing. But one of my ex-gf was quite sensitive on many things, had frequent headaches, low blood pressure and coffee was helping with those visibly. So YMMV.
I agree. I'm deep into specialty coffee and I love making and drinking coffee a lot, but three cups is already higher than what I drink on a normal day. Also, most of the time when I go above this threshold, I drink decaf.
It depends on how much caffeine is in your cup. Rather than measuring the size of a cup, I would go by the amount of coffee, as in the weight of the beans, used to brew it. The actual amount of caffeine is not as easy to measure, and even for the same kind of beans, there is natural variation.
For a traditional Italian espresso, about 7g of coffee beans are extracted. For a third-wave double espresso, it's usually 18g or more.
In my opinion, 10x7g is a lot. 2x12g is more than enough for me.
There is no realistic scenario where, no matter your extractions or bean selections, 6-10 shots of espresso a day is not an enormous amount of caffeine
caffeine extraction is largely a function of time in contact with water. Espresso is quite quick brew, so has less caffeine than other brewing methods (yes, there are plenty of other factors)
I’m super interested in this sort of study! However, it looks like n=62 here, which I think weakens the results —they’re probably just useful as suggestions of possible effects. Also, any food is expected to have similar effects on the microbiome. They didn’t test caffeine in isolation. In some ways that’s better (I don’t consume caffeine in isolation), but in some ways that’s less useful (it’s possible you get similar results from many random vegetables)
The LSD and sleeping pills were not in the original study I believe. That might be an artists representation of the image at the bottom of the original study, which I remember showed the results in a single row.
But they did test both caffeinated and uncaffeinated coffee, and found the same effects in both, indicating that the effect is caused by something in coffee other than the caffeine
Typical extraction yield is 18-20%. For a 20g dose that's 4g of material consumed, or about 30 individual beans.
I wonder if you could find similar effects with 4g or broccoli sprouts, or garlic, or ginger, or cumin seed, shiitake mushroom, seaweed, soursop leaf, or...
What's cool is this effect exists even in decaf coffee, as someone who primarily drinks decaf black, for flavor and for a good night's rest as I'm sensitive to caffeine.
What kind of decaf coffee do you drink? There are differences between the cheap chemical Methylene way to create decaf coffee and the expensive co2 way to get rid of the caffeine.
Is that methylene way even legal? It basically uses petroleum fuel in the process right? I assume it was outlawed a long time ago but that might be extreme naievete for US regulatory capability...
https://www.thedecafproject.com/ (Dec 2024) let you order matching swiss water, CO₂, and Ethyl Acetate (sugar cane byproduct) decaffeinated coffee from the same batches of beans. The EPA banned methylene chloride earlier in that year, but because of toxicity to workers, not because of risk from the resulting coffee itself (and it looks like the FDA didn't ban it.) So I guess you couldn't make decaf with it in the US but you could probably still import and sell it?
It would have been interesting to see if there was any difference relating to CYP1A2 (Cytochrome P450 1A2), the fast metabolizers and the slow metabolizers.
I have not much followed the science of gut microbiome and psychology. Is this really going where this article is pointing? That we can tease out causation in foods and habits via gut microbiome towards behavior and psychology? Pretty rad.
There's a decent amount of research going into the hormones that our GI biome produce and how it affects us. Our body has a few different biomes and they all seem to play somewhat important roles.
I must be weird, but coffee (or caffeine) doesn’t really “wake me up” in the mornings and I could drink it in the night and still sleep well. Because of that I don’t drink coffee; I prefer tea
I find that the effects can be pretty subtle, and if I'm already tired there's usually no coming back. What I think has worked best for me is to re-up on caffeine a few hours before I think I'll be tired, or around when a previous dose is wearing off. Also, if trying to stay awake, food and entertainment are also quite important. If I hit a point where I'm hungry, cold, and tired, and going to the kitchen to eat sounds like a chore, it's usually too late for me. When the bed's closer, it's hard to resist.
I've also noticed that I have a sort of natural energy in the morning. I think of it as being similar to how a seed has enough energy in itself to sprout and then get sunlight. It's probably so I can make myself eat and whatnot. I don't really need caffeine to "wake up" as much as I need it to stay awake later in the day, and even if I do have a coffee with breakfast, I'll often get tired before the normal day is over.
tea also has caffeine, although in smaller quantities. Maybe you mean that you don't care so you go by taste, just specifying because there's a common misconception about tea not having caffeine.
all tea has caffeine unless it's decaf. some things that aren't tea are called tea casually, but they aren't tea, for instance peppermint "tea" is not tea. by the same logic that one would call peppermint a tea, one would have to call coffee a tea. and beef broth.
That depends on culture. All camelia s. teas have it (green etc) but almost none of common herbal teas in Europe have it (chamomile, menta, sage etc.) They are not called casually teas.
are you saying chamomile isn't called tea but it's one of the teas without caffeine? if so that's very confused.
camelia sinensis is tea. when i said that other things are casually called tea, i mean that what chamomile tea, for example, ought to be called is a tisane or an herbal infusion. casually, people might call it a tea; some people are so casual about it that they think it actually is tea. but it isn't.
Studies seem to indicate that coffee is at least as healthy, if not healthier than tea, and I have not heard this about caffeine specifically (aka the same effects coming from pills or energy drinks).
One fun fact: we still haven’t figured out why coffee makes us poop. We’ve studied every chemical in there and can’t seem to find a link, but the association is uh… well-known.
The only good thing that keeps me from collapsing into a state of limbo is coffee and now, even that's bad (seems more like a mixed bag, but still)? Sigh.
Maybe I have some neurological issue or something but whenever I quit coffee I find it extremely difficult to maintain any kind of motivation to sit in an open plan office and code. Coffee makes me a worker bee, I can understand why employers give it away for free.
Yeah, exactly. I can totally relate to this. I have actually monitored my productivity on an excel sheet and the days with coffee win by a large margin. I am not sure if it's withdrawal symptoms on the days without, though.
"These findings reveal previously unrecognised effects of coffee on the microbiota–gut–brain axis, suggesting that microbiome profiles could potentially predict coffee consumption patterns", or, perhaps, just ask the patient?
If you can predict someone's coffee intake based on testing of their microbiome then you've proven that coffee intake has predictable effects on the microbiome.
The important part isn't predicting coffee use, it's just the proof that there's you can predict and perhaps control in the opposite direction leading to more research.
Funded by the Institute for Scientific Information on Coffee (ISIC) — an industry body — which is a notable conflict of interest the authors disclose but don't extensively discuss
It does not sound like an outcome that big coffee paid for it to be so:
Behaviourally, coffee drinkers exhibited greater impulsivity and emotional reactivity, whereas non-coffee drinkers demonstrated better memory performance.
> It does not sound like an outcome that big coffee paid for it to be so:
Who said anything about big coffee? These guys might be a secret, anti-coffee organisation. /s
it's the barley cartel.
Do they though? Any data on that? Also, the highly caffeinated people might also be sleep deprived, which impacts memory and emotional regulation
The data is in the linked paper. It's a direct quote from the abstract.
Please delete this comment. It’s embarrassing
Maybe he forgot?
Every damn time, for chocolate, coffee, and red wine "studies."
After habitually consuming caffeine (not in coffee form) daily, usually multiple times a day, for more than a decade, a horrible mental health incident happened to me that forced me to stop it for a while. Afterwards I didn't resume the habit, and so I no longer have a tolerance.
This has let me evaluate what caffeine does with fresh eyes, so to say, because I can now consume it occasionally while having many non-caffeinated days to compare to. It's a profoundly psychoactive substance and does a lot of things to cognition. I guess I have decided I don't enjoy how it feels, having previously been dependent on it.
After habitually consuming coffee daily in large quantities for two decades, I had mental health incident, during which I drank twice the amount of coffee and it felt like water. After that incident I still drink previous amount of coffee, but feel much better, much more rested, on an upward trajectory and like I have finally managed to escape the swamp I dragged myself into over many years.
After reevaluating your comment and my experience I declare that coffee is not always a cause of mental health incidents, sometimes it might help people.
I've had the same experience. Caffeine is super addicting, the ritual & habits surrounding it is a potent pull. For myself, it makes me erratic, impulsive, more reactive and agitated. One cup a day puts me on edge, makes me sweat more, makes me more intolerant, makes everything feel too slow. It such a sneaky drug and it can really get under your skin without you realizing how much it changes you.
I don't have the same experience, and I drink one cup of coffee (270 ml) almost every day. No agitation, no impulsiveness. I can drink coffee in late evening (let's say 8 pm) and sleep well. I guess I'm trying to say that we should not project our own experience on others, everyone is different.
Quitting caffeine after decades of use was a bit of a mixed bag for me in the short term, but positive in the long term.
Going caffeine-free made it much easier to lose weight as I have far less cravings for high carbs and sugar now, presumably this is related to the impulsivity impact talked about in the paper.
Going caffeine-free also made me very depressed for a while with severe anhedonia, this lasted way longer (like 3-4 months) than one would generally expect for caffeine withdrawal symptoms.
I had seemingly become so used to the increased dopamine signaling while buzzed on caffeine that my brain was a mess for a rather extended period of time as it got used to not having it.
Overall I view quitting as a positive for me, but I'd warn anyone thinking about doing it to do it carefully and closely monitor their mental health. AFAIK the impacts of quitting can be quite different for different people, so my experience may differ than that of others, but I had no idea how much of a (temporary) mental health crash quitting caffeine could cause until I experienced it.
I'm almost exactly 1 year coffee-free (not caffeine free, but significantly less because tea is much less addictive for me).
Also positive in the long-term for me. Fewer digestive issues, less spiky dopamine sensitive or impulsiveness and performance during the day, better memory. I wish it weren't so.
But damn was the 3-6 months of anhedonia awful. I still feel pangs of it.
Agree, I drink it a lot and then stop drinking it at least once a year for a few weeks, and for sure it's a different mode of mind, but can't really qualify it besides that I remember my thinking being softer, calmer and perhaps even "more correct" without coffee.
(But I never had any mental-health incidents, and I drink a lot of it, more than all people that I personally know.)
Coffee is a plant demon that created the western civilization as we know it today...
I like this worldview. Prior to coffee, Europe was in the grip of the beer dwarves. Coffee demons took over and invented nationalism, capitalism and Keynesian economics.
Notably, the article is looking at coffee, both caffeinated and decaffeinated. There is a lot more to coffee than just caffeine...
The overwhelming majority of the enjoyable coffee experiences are caffeinated. While there is good decaf out there it's not the norm, specially in smaller markets.
I think they meant that coffee contains a lot of other compounds than just caffeine, which something like energy drinks or teas will not include. So you can't necessarily extend conclusions from a study on consumption of coffee to effects that other drinks that happen to include caffeine might have.
Edit: this is especially relevant here, as the study found similar effects in decaffeinated coffee drinkers. So the effects they observed, if real, are not related to caffeine.
I do believe a lot of it boils down to tolerance. I for example feel basically 0 effects, and drink it just because I like the taste (of a good one with milk, or exceptionally some good espresso / ristretto after big dinner).
I recently traveled and didn't have coffee for more than a week. No change I could feel, no craving, nothing. But one of my ex-gf was quite sensitive on many things, had frequent headaches, low blood pressure and coffee was helping with those visibly. So YMMV.
How do you know that caffeine was the cause?
This of course cannot be generalized, but withdrawal is quite noticeable for personal well-being in a positive way.
thirty-one participants were moderate coffee-drinkers (CD, i.e., people that usually consume between 3 to 5 cups of coffee per day).
3-5 is moderate? To me, 3 is already high.
Also, sample size is pretty low and they're all Irish.
I agree. I'm deep into specialty coffee and I love making and drinking coffee a lot, but three cups is already higher than what I drink on a normal day. Also, most of the time when I go above this threshold, I drink decaf.
This study is Irish, so I think they likely use 170ml cups? That means a normal mug of ~500ml is 3 cups.
Perhaps they even use US coffee cup size, which is 118ml?
Honestly, using an unit of measurement that varies from 118ml to 250ml in a scientific paper brings the whole paper into question.
I’m Irish.
A NORMAL mug of 500ml??? this is insanity to me
Are the Irish unique when it comes to metabolizing coffee?
I do 6-10 espresso cups per day, so 3-5 does sound very moderate.
It depends on how much caffeine is in your cup. Rather than measuring the size of a cup, I would go by the amount of coffee, as in the weight of the beans, used to brew it. The actual amount of caffeine is not as easy to measure, and even for the same kind of beans, there is natural variation.
For a traditional Italian espresso, about 7g of coffee beans are extracted. For a third-wave double espresso, it's usually 18g or more.
In my opinion, 10x7g is a lot. 2x12g is more than enough for me.
There is no realistic scenario where, no matter your extractions or bean selections, 6-10 shots of espresso a day is not an enormous amount of caffeine
caffeine extraction is largely a function of time in contact with water. Espresso is quite quick brew, so has less caffeine than other brewing methods (yes, there are plenty of other factors)
That’s not normal. It’s like saying “I drink 6-10 beers a day so 3-5 is very moderate”
I’m super interested in this sort of study! However, it looks like n=62 here, which I think weakens the results —they’re probably just useful as suggestions of possible effects. Also, any food is expected to have similar effects on the microbiome. They didn’t test caffeine in isolation. In some ways that’s better (I don’t consume caffeine in isolation), but in some ways that’s less useful (it’s possible you get similar results from many random vegetables)
In 1995, NASA did spiders experiment. Caffeine is a siginificant impulsivity trigger. :)
https://rarehistoricalphotos.com/nasa-spiders-drugs-experime...
LSD has unconnected strands in the air. I guess this is expected.
The LSD and sleeping pills were not in the original study I believe. That might be an artists representation of the image at the bottom of the original study, which I remember showed the results in a single row.
Nice web, Mr. Crack spider.
> They didn’t test caffeine in isolation
But they did test both caffeinated and uncaffeinated coffee, and found the same effects in both, indicating that the effect is caused by something in coffee other than the caffeine
Doesn't decaf also contain caffeine, just a lot less of it?
Typical extraction yield is 18-20%. For a 20g dose that's 4g of material consumed, or about 30 individual beans.
I wonder if you could find similar effects with 4g or broccoli sprouts, or garlic, or ginger, or cumin seed, shiitake mushroom, seaweed, soursop leaf, or...
What's cool is this effect exists even in decaf coffee, as someone who primarily drinks decaf black, for flavor and for a good night's rest as I'm sensitive to caffeine.
What kind of decaf coffee do you drink? There are differences between the cheap chemical Methylene way to create decaf coffee and the expensive co2 way to get rid of the caffeine.
https://cleanlabelproject.org/wp-content/uploads/CLP-Decaf-C...
Is that methylene way even legal? It basically uses petroleum fuel in the process right? I assume it was outlawed a long time ago but that might be extreme naievete for US regulatory capability...
https://www.thedecafproject.com/ (Dec 2024) let you order matching swiss water, CO₂, and Ethyl Acetate (sugar cane byproduct) decaffeinated coffee from the same batches of beans. The EPA banned methylene chloride earlier in that year, but because of toxicity to workers, not because of risk from the resulting coffee itself (and it looks like the FDA didn't ban it.) So I guess you couldn't make decaf with it in the US but you could probably still import and sell it?
I don't buy the methylene processed ones, generally it's Swiss water processed or like you said the CO2 processed ones.
It would have been interesting to see if there was any difference relating to CYP1A2 (Cytochrome P450 1A2), the fast metabolizers and the slow metabolizers.
At least subjectively, coffee seems to help my memory. But maybe that's why I started drinking coffee?
I would probably drop coffee it was proven to have negative effects on memory.
> But maybe that's why I started drinking coffee?
you don't remember why, do you?
I have not much followed the science of gut microbiome and psychology. Is this really going where this article is pointing? That we can tease out causation in foods and habits via gut microbiome towards behavior and psychology? Pretty rad.
There's a decent amount of research going into the hormones that our GI biome produce and how it affects us. Our body has a few different biomes and they all seem to play somewhat important roles.
Yeah there's nontrivial evidence that among other things, the complex community living inside you manipulates your brain.
My psychiatrists agree that “hallucination” (in lay terms: “hearing voices” or “seeing things”) only refers to things that aren’t real.
Coffee modifies physiology and cognition? You're telling me this for the first time.
The paper is about previously unknown ways coffee affects the body.
I was so surprised at this headline that I nearly leapt out of my chair!
But it says it’s the same for decaf. That is more interesting
Been treating coffee as caffeine with aroma. Any important points about coffee itself?
Humans known since 45 minutes after first drink
Would be real interesting to see a similar study on tea.
Whatever the case, a cup of coffee is basically what kickstarts my day.
I must be weird, but coffee (or caffeine) doesn’t really “wake me up” in the mornings and I could drink it in the night and still sleep well. Because of that I don’t drink coffee; I prefer tea
I find that the effects can be pretty subtle, and if I'm already tired there's usually no coming back. What I think has worked best for me is to re-up on caffeine a few hours before I think I'll be tired, or around when a previous dose is wearing off. Also, if trying to stay awake, food and entertainment are also quite important. If I hit a point where I'm hungry, cold, and tired, and going to the kitchen to eat sounds like a chore, it's usually too late for me. When the bed's closer, it's hard to resist.
I've also noticed that I have a sort of natural energy in the morning. I think of it as being similar to how a seed has enough energy in itself to sprout and then get sunlight. It's probably so I can make myself eat and whatnot. I don't really need caffeine to "wake up" as much as I need it to stay awake later in the day, and even if I do have a coffee with breakfast, I'll often get tired before the normal day is over.
I think this description is often associated with ADHD memes.
Falling asleep after a can of energy drink.
tea also has caffeine, although in smaller quantities. Maybe you mean that you don't care so you go by taste, just specifying because there's a common misconception about tea not having caffeine.
Some tea has caffeine, most has don't.
all tea has caffeine unless it's decaf. some things that aren't tea are called tea casually, but they aren't tea, for instance peppermint "tea" is not tea. by the same logic that one would call peppermint a tea, one would have to call coffee a tea. and beef broth.
That depends on culture. All camelia s. teas have it (green etc) but almost none of common herbal teas in Europe have it (chamomile, menta, sage etc.) They are not called casually teas.
> They are not called casually teas.
are you saying chamomile isn't called tea but it's one of the teas without caffeine? if so that's very confused.
camelia sinensis is tea. when i said that other things are casually called tea, i mean that what chamomile tea, for example, ought to be called is a tisane or an herbal infusion. casually, people might call it a tea; some people are so casual about it that they think it actually is tea. but it isn't.
good thing I have claude to summarize this and quickly realized that sample size was small and nothing much new unless you are a microbiome researcher
If the effect size is big small sample sizes does not matter as much as otherwise.
You really have to look at the power analysis and the sample size together.
Saying this as a general truth. I am not sure about the power of the method in this papper, i only read the abstract.
> ... reintroduction triggered acute microbiome changes independent of caffeine.
This sounds interesting. I've never really considered the constituents of coffee other than caffeine and what unique effects they may bring.
I wonder if I would experience behavioral effects if I replaced my coffee intake with caffeinated non-coffee drinks or pills?
Studies seem to indicate that coffee is at least as healthy, if not healthier than tea, and I have not heard this about caffeine specifically (aka the same effects coming from pills or energy drinks).
One fun fact: we still haven’t figured out why coffee makes us poop. We’ve studied every chemical in there and can’t seem to find a link, but the association is uh… well-known.
>why coffee makes us poop.
That seems to vary wildly between individuals. It doesn't have that effect on me.
The only good thing that keeps me from collapsing into a state of limbo is coffee and now, even that's bad (seems more like a mixed bag, but still)? Sigh.
Don't fret. You're allowed to enjoy things that aren't part of the scientific reductionist longevity influencer lifestyle fad :)
Nitpick: What you’re referring to is not scientific.
There have been positive and negative reports for a long long time. If coffee was going to kill us, I’d certainly have died in school!
Maybe I have some neurological issue or something but whenever I quit coffee I find it extremely difficult to maintain any kind of motivation to sit in an open plan office and code. Coffee makes me a worker bee, I can understand why employers give it away for free.
So, the coffee stays for now.
Yeah, exactly. I can totally relate to this. I have actually monitored my productivity on an excel sheet and the days with coffee win by a large margin. I am not sure if it's withdrawal symptoms on the days without, though.
Coffee in general is unreasonably healthy as a beverage. The overwhelming majority of science agrees it’s a quality health drink.
Non-industry funded science?
Relax. Tomorrow there will be a paper/article saying coffee is great for you.
Did you know:
Keep the coffee buddy."These findings reveal previously unrecognised effects of coffee on the microbiota–gut–brain axis, suggesting that microbiome profiles could potentially predict coffee consumption patterns", or, perhaps, just ask the patient?
Could you elaborate on how to interpret your comment without it leading to anti-intellectualism?
It was a joke
You are missing the point.
If you can predict someone's coffee intake based on testing of their microbiome then you've proven that coffee intake has predictable effects on the microbiome.
The important part isn't predicting coffee use, it's just the proof that there's you can predict and perhaps control in the opposite direction leading to more research.