Category: Stress

Testosterone and cortisol explain market behaviour?

There’s a fascinating post on Testosterone, Cortisol and Market Behavior on the website Pure Pedantry. Normally, I’d have a whole lot of caveats and snarky comments to add, but Jake Young does a great job of handling an original research article by Coates and Herbert, ‘Endogenous steroids and financial risk taking on a London trading floor’ (abstract). You should definitely check out Jake’s post if you find this material interesting, as he deals with the article in greater depth. Unlike in my last piece on ‘neuroeconomics’, Bad brain science: Boobs caused subprime crisis, in which I thought the science writer involved was really responsible, in this case, it looks like the authors of the original study are partly to blame, and Young does a good job of highlighting this issue.

The original research paper examines the links between market risk-taking behaviour among traders with endogenous steroids: testosterone and cortisol. Since both are linked to aggression and stress, this would seem to be a good place to study the body’s response to risk taking. But things don’t go brilliantly, as Young suggests: ‘Let’s file this paper under “wildly over-interpreted” because there are some big caveats that you have to remember before you can make a claim anything like [hormone changes lead to market changes and higher market volatility].’

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Brain doping poll results in

According to Nature, 20% of scientists in an informal survey admitted to using ‘cognitive enhancing’ drugs: Poll results: look who’s doping. Ironically, the original survey was triggered by an April Fool’s prank played on the scientific community. My initial thought was, Do they count caffeine? Of course, they didn’t. If they did, numbers would obviously be different.

We asked specifically about three drugs: methylphenidate (Ritalin), a stimulant normally used to treat attention-deficit hyperactivity disorder but well-known on college campuses as a ‘study aid’; modafinil (Provigil), prescribed to treat sleep disorders but also used off-label to combat general fatigue or overcome jet lag; and beta blockers, drugs prescribed for cardiac arrhythmia that also have an anti-anxiety effect.

Check out the Nature site for a more complete discussion, but the conclusion is worth repeating:

The most popular of the drugs used by respondents to Nature’s poll seem to have fairly mild neuroenhancing effects, says Chatterjee, who calls the massive media interest in these drugs “neurogossip”. Nevertheless, the numbers suggest a significant amount of drug-taking among academics. As Eisen’s April Fool’s prank spread from blog to blog, it was hard to tell who was in on the joke and who was taking the announcement at face value. Although tricking people was a goal, Eisen had been aiming for something so ridiculous that most would chuckle. Instead, he worries that he might have hit a nerve: “I think it did make it less funny because it is actually too real.”

The initial discussion that led to the poll was referenced by Daniel a while back in a great piece, Brain Enhancement: Beyond Either/Or, that explored this topic in greater detail. If you haven’t checked it out, you should. Daniel talks about the ‘unintended consequences’ that almost always accompany drug use. I don’t have too much to add to that except that, with what we know about neuroplasticity, this should not surprise us at all. The brain and nervous system tend to adapt to any changes in the overall environment they inhabit: the tasks they do, the condition of the environment (which is both inside and outside of the body), any other chemicals introduced into the equation.
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Snakes and spiders on the brain

A little while ago, I wrote a piece, ‘Innate’ fear of snakes?, in which I took issue with a University of Virginia study that was described by a science writer (and perhaps by the researchers) as showing that humans have an ‘innate’ fear of snakes. At the time, I argued that what their research had shown was a propensity to pay attention to snake shapes, and not that this was an ‘innate’ fear, for reasons that I banged on about for a fair few words (go to the original if you’re a glutton for snake-related musings).

And now, vindication. Well, as much vindication as you can get considering that psychological research is liable to be undermined by another study in the next few months. According to a posting today on Science Daily, ‘Unlocking The Psychology Of Snake And Spider Phobias,’ researchers at the University of Queensland have tested both snake experts and those who are naive about the creatures to see if there is an innate fear.

In the study, researchers compared the responses to stimuli of participants with no particular experience with snakes and spiders, to that of snake and spider experts.
“Previous research has argued that snakes and spiders attract preferential attention (they capture attention very quickly) and that during this early processing a negative (fear) response is generated… as an implicit and indexed subconscious [action],” Dr [Helena] Purkis said.
“We showed that although everyone preferentially attends to snakes or spiders in the environment as they are potentially dangerous, only inexperienced participants display a negative response.”

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Contagious stress and children redux

Sandy G at The Mouse Trap reviews my earlier post on how parents’ stress can affect their children in a posting entitled Stress contagion: from parents to the child? It’s a thoughtful response — thanks, Sandy G. And there’s lots more interesting stuff at The Mouse Trap to check out for our readers. I especially enjoyed a rambling, but incredibly engaging piece, Catch 22: Psychosis, Culture and the Mind Wars; it’s a great read with so many fruitful tangential thoughts that I may have to come back and post on it again.

Sandy G. does a nice job of summarizing the four channels I suggest might be operative in transmitting stress effects to children from their parents. I think he unfairly dismisses the ‘other communication channels’ (#3); there’s some evidence, including even cross-species effects, that there are ways we affect each other’s emotional states that are not imitation and ‘chameleon’ effects. I give the example of pheromones, but that’s not the only way that this could happen. But, fair enough, Sandy doesn’t think it’s plausible, I do. The evidence is hardly conclusive so this kind of disagreement is exactly the sort of thing we need to inspire new research (‘SandyG laughed at my theories… wahahahaha, this will show him!’).

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Parents’ stress, children’s health

Blogging on Peer-Reviewed ResearchTo all the stressed-out parents out there, here, let me just hand you a bit more to worry about. A research team led by Dr. Mary T. Caserta at the University of Rochester (more on her research here) have an article in press at Brain, Behavior, and Immunity entitled, ‘The associations between psychosocial stress and the frequency of illness, and innate and adaptive immune function in children’ (abstract here, unfortunately, I couldn’t find a downloadable version of the whole article). 169 school-aged children and their parents were studied through health diaries and over seven sequential visits, each separated by six months (three years total, by my quick calculation). At these visits, children were tested for human herpesvirus 6 reactivation and general measures of immune function were examined, such as ‘natural killer (NK) cell function and the percentage of CD4 and CD8 cells associated with immune control of cytomegalovirus (CMV).’

The study was to test the relation between parental stress and children’s immune systems:

Family processes have a substantial impact on children’s social and emotional well-being, but little is known about the effects of family stress on children’s physical health. To begin to identify potential links between family stress and health in children, we examined associations between specific aspects of family psychosocial stress and the frequency of illnesses in children, measures of innate and adaptive immune function, and human herpesvirus 6 (HHV-6) reactivation.

The researchers found that parental stress was associated with the illness rates in their children. Although HHV6 activation rates did not increase, the rate of illness in the children (according to the diaries, presumably) and the activation of the children’s immune systems were both elevated. It’s not entirely clear to me from the abstract, so I’ll have to wait for the full write-up to get a sense for the mechanisms involved. The researchers concluded, ‘There is an association between specific psychosocial stress exposure and rates of illness and immune function in normally developing children.’

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More on sleep and time: the Letterman effect

Steve Higgins of Of Two Minds has a short post discussing recent research on, as the title says, Is TV changing our circadian rhythms? I think it’s another interesting factor to go into our subject-level dynamic systems model of time and sleep, after discussions by Daniel on Time Globalized and my earlier post on ‘Giant Sleep Machines’ and the Brain (which, now that I read it, sounds like a bit like a cheesy horror movie title).

Higgins discusses the article, ‘Cues for Timing and Coordination: Latitude, Letterman, and Longitude,’ by Daniel S. Hamermesh, Caitlin Knowles Myers, and Mark L. Pocock from the Journal of Labor Economics. I’ve searched for the original paper, and I can’t find it, even through the website of JLE; I’m not going to post this with the little ‘blogging about peer-reviewed research’ logo because I can’t really find the original. I suspect that it might be forthcoming; however, what I think is a working version of the JLE paper can be found through ANU here, and another working paper on a related topic by members of the team can be found here).

To get information about circadian rhythms, the research team used the Bureau of Labor Statistics’ American Time Use Survey (ATUS), focusing on how Americans divided time among their three most time-consuming activities: work, sleep, and television watching. Comparing the times people spent on these activities and their schedule with the time of sunrise and sunset, Hamermesh and his colleagues were ‘amazed how little daylight matters nowadays, and how much artificial time zones matter.’ (This quote and several others from a short article on the research at PsyOrg.)

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