Recession's Silver Lining

Here's some economic news that might seem a little odd. Recessions (and depressions) may actually be good for your health. At least, that's the result of a study in the Proceedings of the National Academy of Sciences that's looking at the connection between the economy and certain health statistics.

In this particular study, the research team from the University of Michigan's Institute of Social Research looked at two health measures: life expectancy based on birth year, and death from non-natural causes (in this study specifically heart disease, kidney disease, tuberculosis and traffic accidents). These are fairly standard measures of health, and can give you a snapshot of how well a population is fairing. When they compared these health measures to the economic picture over time, a few interesting points fell out.

First, when you look at longevity through the 1920s it actually drops as the decade progresses. Then, in 1929, as the great depression begins, it jumps back up. In fact life expectancy increased an average of about 8 years over this period, which is a big change. Also the deaths from non-natural causes dropped right down during the great depression. Both flipped again once the depression was over, that is until 1936, when there was another economic downturn, and once again we see an improvement in overall health.

This seems counter-intuitive, if you look at the difference between developing and developed countries, it's easy to see how lower economic development generally maps onto lower quality of health. But the researchers point to China, where there are relatively high standards of health, as well as increasing economic development. On first blush, this would support the idea that money and health go hand in hand, except that health development in China happened decades before the economy improved. This suggests you can't trust cross-border comparisons when looking at the relationship between health and finance.

Secondly, another criticism could be that the effect on the poor is being washed out in the bigger picture, when you look at the rich and the poor together. After all, in a recession, the rich tend to get richer, and the poor, poorer. But in this study, the research team separate out the effects on whites and non-whites (which are, for the historical context, reasonable stand-ins for economic status) and found that overall non-whites had better health during the depression. So much for the poor suffering more.

What's behind all this? The answers are still speculative, but interesting. Here's one scenario. People have less free cash during a recession or depression, so they tend not to travel as much. In the 30s that would mean fewer car trips. Fewer cars on the road, fewer accidents. And without money, less alcohol gets consumed, which means less kidney disease. A lack of pollution (because the factories are shut down) could mean less lung disease in general, and from that less tuberculosis. And finally for heart disease, well, if you have a job, you're probably not being forced to work as hard as you once were, which means less stress, and fewer heart problems. Also, those without jobs usually had strong support at home, as well as in their local community, again lowering stress. With parents at home, that could contribute to raising small children, and given how the first few years are critical for long term survival, that may help explain why children were more likely to live until adulthood, skewing the statistics towards a longer life.

But while this is persuasive for looking at the depression, how well it maps onto the current recession is a difficult question. Causes of death are very different, cancer, for example, didn't make the list in the 1920s but is very important today. Researchers are not in agreement over how applicable this is to the current world. But what about looking to really figure out what was behind the improvements? If we can work out that, maybe that will help us come up with ways to improve everyone's life, recession or not.

Bearing False Witness

Time to combine segments from my two lives, that of a law student, and that of a journalist.

Key in any trial is the testimony of eye witnesses. In fact, in life in general we pay a lot attention when someone says, "I saw it with my own eyes." But how reliable is that testimony? Obviously the further away you get in time, the fuzzier the memory is going to be. But in some cases it isn't about memories becoming fuzzy, it's about them changing altogether.

The concept of a false memory is nothing new. A study by Elizabeth Loftus and colleagues using Bugs Bunny showed that it's possible to convince people that they saw Bugs wandering around Disneyland when they visited the park, even though he's the creation of Walt Disney's competition. The memories seem real though, people reported seeing the rabbit with Mickey Mouse, or shaking his hand, but that couldn't have happened.

You could argue that this isn't surprising. In most cases, it would have been a long time since the original visit that was now being remembered, but that's not the case for the latest work. The study by Dr. Kimberley Wade demonstrated that if you show someone video of an event, but video that's been altered, then that changed version will frequently replace their own memory. Suddenly they're remembering details of something that never actually happened.

That's concerning. Today it's very easy to doctor photographs or videotape with a home computer, and that can be used to influence a person's thinking. Even conversations or still images can change memory. If you look at how most journalism or police work is done, it's rare to get to a witness immediately, and any interference before you get a statement down on paper could lead to a false memory, that the witness sincerely believes. And in court cases, it can be months or even years until they get into court, so who knows how much memory can change.

Even for the rest of us, there are concerns. Marketers love drawing on nostalgia, it's a great way to make us buy products. What if they position products so that it looks like you have used it before. Suddenly you're in the grocery store buying stuff you remember, even if in reality, it's completely novel.

Can you trust your memory? Not completely, so if you want to really keep track, either write it down, or horde your video and still pictures carefully. You never know when your memory might be changed...

Showerhead Slime

Earlier this week, the news media picked up on a story in the Proceedings of the National Academy of Sciences. Basically, the story showed that Mycobacterium avium and related Mycobacteria (but, happily none associated with TB) were present in the showerheads of homes across the US. In and of itself, this shouldn't be a surprise, M. avium is present in the water supply, so there's no reason for it not to be in showers. The more interesting result was the level, relatively concentrated, and well above the background. Not only that, but when the researchers tried bleaching the shower heads, this only made the problem worse. M. avium is resistant to bleach, so there's a selection that goes on, killing other organisms and leaving a population of cells that's largely made up of this and related species.

So far, not a lot to concern anyone, unless they're licking their showerheads. The problem comes with aerosols. Aerosols are small droplets of water (or any material really) that float in the air. Thse can contain bacteria, and can be inhaled. Suck these droplets into your lungs (the idea goes) and maybe you'll take in some of the dangerous bacteria at the same time. If you're immune compromised (through being very young, very old, or having a damaged immune system) and there's a chance you'll develop lung disease.

That was the story in most of the media, and it generally ended with the advice to change your showerhead every 6 months or so, and to replace what you have now with a metal showerhead if yours is made of plastic.

But that's not the full story. In the paper itself, the researchers did look at aerosols, and found that the levels of bacteria were no higher than in the water that went into the shower in the first place. Their suggestion is that the bacteria are cleared in the first few moments after the shower is turned on, but as the paper suggests, this needs a lot more research before it can be confirmed. It's also possible, although not discussed in the paper, that bacteria in the showerhead aren't released as aerosols at all, but again, there's no real data to confirm or reject this.

The other technical consideration is that the detection in this study was indirect. Not that this is a problem with the study itself, detecting microbes from the water column is incredibly difficult. But it is a proxy measure (in this case looking at RNA), which doesn't tell you everything about the organism. For example, these bacteria are living as part of a biofilm (a complex community of bacteria living on a surface), and we know that biofilm living is very different than free living, which may affect how ready these organisms are to cause infection. Again, it doesn't prove that there's nothing going on, but does indicate we need more research to determine what the presence of these organisms really mean.

Overall, the paper is a good one, and it does remind us that we live in a world that's full of microbes. That's important to remember, and certainly for the immunocompromised it has to be taken very seriously, and we should respect the bugs around us. But at the same time, there's no real reason to live in fear. What our parents taught us as kids: wash your hands, sneeze into your sleeve, and don't spit on people, are the kinds of rules that will keep us clean. We've evolved for millions of years to live with bacteria, and we wouldn't survive without them. In fact, over cleaning can cause more problems than just carrying on with life.

So keep showering! If nothing else, it will prevent you from offending your friends.

Learning can be addictive

One of the toughest problems smokers face when trying to quit is the association of smoking with other activities. For some, it might be wanting a cigarette after a good meal. For others, getting into the car on the way home from work might stimulate the desire to light up. Whatever it is, the urge is often strong, and provides a real barrier to quitting.

If you think about it though, it's not a logical connection. There's no reason why getting into the car should lead you to smoke. Lots of people don't have this urge, even lots of smokers. So what's going on? The key here is learning. For whatever reason, the smoker has learned to associate the activity, the people or the place with the good feelings that come from lighting up a cigarette. And so they continue to smoke, or at least want to smoke.

That's why psychologists who are helping people quit drugs of any kind try to dissociate behaviours from their cues. Whether it's introducing a substitute like gum, or having a person avoid the places where they like to indulge, it's all about changing the behaviour and learning new patterns.

So far, none of this is new. But Dr. John Dani, from Baylor College of Medicine, wanted to look under the hood and figure out what's going on inside the brain when someone takes an addictive drug. Why is it that we're so good at learning to associate addictive substances with cues, when we're not normally that successful?

What he found out is published here.(paper available September 10, 2009)

Find out more about Dr. Dani's Lab here.

In a series of experiments, Dr. Dani and his colleagues were able to show that nicotine (and by extension other addictive drugs) was able to enhance learning. That is, connections in the parts of the brain we associate with learning new things were stronger and more numerous when there was nicotine in they system, compared to controls. Although that needs to be qualified. This only worked when dopamine levels were also raised, showing the connection between the role of dopamine in learning, with the addictive substance.

This is an almost sinister finding. Our brains need to be able to learn, that's what keeps us alive. And dopamine is an important part of this learning process. After all, dopamine is associated with pleasurable experiences, and it makes good evolutionary sense to seek out food, sex and a safe place to sleep. Dopamine helps us find all of these, by making them pleasant. But these addictive drugs are taking over that system, and making drug seeking not just a pleasant experience, but one that we remember vividly. No wonder it's so hard to break an addiction.

This has some important implications. First of all, it reminds us that addiction is a physical thing, not just a weakness of will in the person who's trying to quit. But there's another angle to this, and that's understanding learning itself. By studying how these drugs interact with dopamine and the brain, maybe we can learn what's going wrong in various dementias, or Parkinson's disease (which is characterized by loss of dopamine), and in the long run, come up with treatments for them.

What this isn't, is a suggestion that smoking is good for you. The memories you form encourage you to remember smoking, and not much else, which can lead to all kinds of other health problems.

Musical Monkeys

OK, so it's not going to be hitting the top of the charts any time soon, but Dr. Charles Snowdon from the University of Wisconsin, Madison, thinks he knows what cotton-top tamarin monkeys like. Working with musician David Teie, he's created songs that both agitate and please these primates.

For the University press release, you can go here.

For the music itself, you can go here.

What I think is interesting about this story is how it fits into a curious evolutionary story. Music is present in most cultures around the world. When something is that widespread, then there's a good chance it exists for some kind of evolutionary reason. But music has created a problem. Many evolutionary traits can be seen in our closest relatives, the other primates. Music, both in terms of creation and appreciation, seemed to be missing. Yes, I know, people's pets will seem to recognize music, and even sing or dance along (remember the dancing parrot), but this is something deeper. Music seems to affect us at an emotional level, but play the same thing to a monkey and nothing.

That is until Dr. Snowdon's study. In this case, he's using music that's been created for the monkeys. It doesn't sound like music to our ears, but it contains tones that mimic sounds the monkeys naturally make. So, for them a rising tone and staccato notes mean danger, and long steady descending tones mean peace and calm. Create music with these patterns, and the monkeys respond in kind.

Now we have a possible evolutionary link. Like monkeys, we communicate emotion through our tone of voice, that's partly why email is a rotten way of communicating sarcasm. Could music be the natural extension of this? Not just to tell others how we're feeling, but to manipulate their emotions as well. It works in the monkeys, we know music does it to us too, were the first musical notes just a way of controlling the crowd?

If nothing else, this study opens the doors to studying music in other primates. All it takes is knowing what sounds are going to create themes they'll find interesting.

Oh, and one other thing. There was one type of human music these monkeys found soothing. The melodies of Motley Crue!

Image: Cotton-top tamarins grew calmer after they heard music compositions based on their own calm, friendly calls. But the monkeys became more agitated when University of Wisconsin-Madison psychology professor Charles Snowdon played music that contained elements of their own threatening or fearful calls. Courtesy Bryce Richter/University of Wisconsin, Madison