Digit ratio, or the length ratio between the index and ring fingers, has been found to a correlate with a surprising diversity of traits. For example, men tend to have a longer ring finger than index finger, whereas in women, the trend is reversed. Digit ratio has also been correlated with aggression, academic performance, sexual preference, and myriad other characteristics.
As it turns out, digit ratio can be considered a crude estimate of prenatal androgen exposure, i.e. the concentration of testosterone in the womb. A shorter 2D:4D digit ratio is associated with higher testosterone exposure.
A recent study investigated the effects of digit ratio on athletic performance in professional fencers. The digit ratios of 58 men and 41 women were measured and correlation between professional ranking and digit ratio was calculated. Among female, but not male, fencers, low digit ratio (associated with higher prenatal androgen exposure) was associated with greater athletic performance after controlling for salient performance factors (age, height, weight, etc.) Digit ratio was shown to account for 12% of the variance in fencing success among the professionals. Moreover, athletes engaged in the most aggressive form of fencing (the sabre) had the lowest digit ratios on average.
Other studies have shown negative correlations between digit ratio and athletic performance, but few have shown a sexual dimorphism in the effects of digit ratio on performance. It seems greater prenatal androgen exposure may well predispose individuals for greater sporting success, at least at fencing.
Thursday, January 21, 2010
Ginkgo Biloba for Migraines
Ginkgo biloba extract is a fairly well-known dietary supplement traditionally used to enhance cognitive function. It is a potent antioxidant and has been shown to be neuroprotective in several studies. One of the ways in which Ginkgo works is by reducing platelet aggregation and thereby inhibiting clot formation. Ginkgo has also been shown to potentially improve memory, attenuate antidepressant-induced sexual dysfunction, and increase blood flow to extremities.
A recent study investigated the use of Ginkgolide B, a constituent of Ginkgo biloba, in preventing migraines with aura. A combination of Ginkgolide B, CoQ10, and riboflavin (vitamin B2) were given twice daily for six months. A significant decrease in both migraine frequency and migraine duration were found with treatment.
Ginkgo is traditionally used in doses of 50-400 mg per day. It would be difficult to estimate the amount needed to achieve a similar quantity of Ginkgolide B as used in the study, but anywhere between 200 - 400 mg would be a reasonable guess.
Ginkgo is available over the counter and is generally considered to be quite safe, though it should not be taken before surgery or in combination with other anticoagulants. For those suffering recurrent migraines, Ginkgo may well be worth a try.
A recent study investigated the use of Ginkgolide B, a constituent of Ginkgo biloba, in preventing migraines with aura. A combination of Ginkgolide B, CoQ10, and riboflavin (vitamin B2) were given twice daily for six months. A significant decrease in both migraine frequency and migraine duration were found with treatment.
Ginkgo is traditionally used in doses of 50-400 mg per day. It would be difficult to estimate the amount needed to achieve a similar quantity of Ginkgolide B as used in the study, but anywhere between 200 - 400 mg would be a reasonable guess.
Ginkgo is available over the counter and is generally considered to be quite safe, though it should not be taken before surgery or in combination with other anticoagulants. For those suffering recurrent migraines, Ginkgo may well be worth a try.
Sunday, January 10, 2010
Back to Basics: Adderall Part I
With articles in the New York Times, Scientific American, and a host of other respected publications, the study drug Adderall is becoming entrenched in the public mindset. Often, however, articles focus on users of the drug or potential consequences of its abuse rather than address the more mundane question of just what Adderall is. In this, the first article in "Back to Basics", I'll summarize some basic information about the drug.
Adderall is a mixture of amphetamine salts, consisting of 75% dextroamphetamine (or d-amphetamine) and 25% levoamphetamine (or l-amphetamine). Dextroamphetamine, which goes by the trade name Dexedrine or street name "speed", was synthesized first in 1887, was used extensively in World War II, and was available over-the-counter in the United States until 1970. It produces marked increases in mood, wakefulness, motivation, focus, and energy. Levoamphetamine, an isomer of dextroamphetamine, is neither as addictive nor as potent as its cousin, but may have a more pronounced effect on memory, according to a recent study.
It should be noted that the word amphetamine need not refer to either of the constituents of Adderall; indeed, MDMA (ecstasy), methampheatmine, and other chemicals are members of the amphetamine class, though they may produce dramatically different effects from Adderall. The media, an in particular anti-drug movements, have a tendency to make statements about the class of amphetamines as a whole, but the differences between them in effects and addictive potential are considerable.
Typical doses of Adderall range from 10-40 mg per day, and the drug may come as an instant release tablet with a half-life of 12 hours or a sustained release capsule with a half-life approaching 18 hours. Due to short-term neurological adaptations, however, the perceived effects of Adderall tend to last for a shorter period of time.
Adderall is indicated (i.e. approved by the FDA) for attention deficit hyperactive disorder (ADHD) and narcolepsy, though it is often prescribed for depression, chronic fatigue syndrome, and traumatic brain injury.
With the basics covered, the next post in this series will look at how Adderall works in the brain.
Adderall is a mixture of amphetamine salts, consisting of 75% dextroamphetamine (or d-amphetamine) and 25% levoamphetamine (or l-amphetamine). Dextroamphetamine, which goes by the trade name Dexedrine or street name "speed", was synthesized first in 1887, was used extensively in World War II, and was available over-the-counter in the United States until 1970. It produces marked increases in mood, wakefulness, motivation, focus, and energy. Levoamphetamine, an isomer of dextroamphetamine, is neither as addictive nor as potent as its cousin, but may have a more pronounced effect on memory, according to a recent study.
It should be noted that the word amphetamine need not refer to either of the constituents of Adderall; indeed, MDMA (ecstasy), methampheatmine, and other chemicals are members of the amphetamine class, though they may produce dramatically different effects from Adderall. The media, an in particular anti-drug movements, have a tendency to make statements about the class of amphetamines as a whole, but the differences between them in effects and addictive potential are considerable.
Typical doses of Adderall range from 10-40 mg per day, and the drug may come as an instant release tablet with a half-life of 12 hours or a sustained release capsule with a half-life approaching 18 hours. Due to short-term neurological adaptations, however, the perceived effects of Adderall tend to last for a shorter period of time.
Adderall is indicated (i.e. approved by the FDA) for attention deficit hyperactive disorder (ADHD) and narcolepsy, though it is often prescribed for depression, chronic fatigue syndrome, and traumatic brain injury.
With the basics covered, the next post in this series will look at how Adderall works in the brain.
Staying Awake
With the increasing prevalence of stimulant medications (e.g. Adderall) on college campuses and the rise of ADHD diagnoses fueling stimulant supply, dextroampheatmine, the main active ingredient in Adderall, has never been easier to come by. But if you need to stay up late, for studying or just for fun, what drug is the best choice? Thankfully, some curious scientists have given us the answer.
A study in the journal Sleep last year compared the efficacy of caffeine, dextroamphetamine, and modafinil on maintaining executive function in sleep deprivation. Here executive function refers to an individual's ability to make decisions, gather information, and mentally manipulate that information. The results were somewhat surprising: none of the drugs tested was superior in all tests of executive functioning. Different drugs were better suited to different tests.
In one test, called the Tower of London, participants had to arrange beads on a computer screen to fit a specified pattern while following a few simple rules; here, dextroamphetamine and modafinil showed superiority to both placebo and caffeine. Yet in solving the famous Tower of Hanoi problem, caffeine was superior to both placebo and the other two drugs tested.
The researchers summarized these findings by suggesting that modafinil and dextroamphetamine excel at maintaining spatial memory and problem solving skills during sleep deprivation and that caffeine is superior in tasks requiring inhibition and "the ability to focus on achieving multistep subgoals to achieve a larger goal."
The results are subject to interpretation, certainly, but it is not a great leap to suggest that caffeine may be more effective at imporoving performance on longer, more extensive endeavours, such as writing a paper, assembling a presentation, or pounding out code. In contrast, dextroamphetamine (or Adderall) and modafinil may be more effective for solving complex individual problems, as in a mathematical, scientific, or computer-oriented task. The differences between the drugs are not extreme, but if already augmenting one's intellectual prowess with psychoactive drugs, you might as well do it optimally.
A study in the journal Sleep last year compared the efficacy of caffeine, dextroamphetamine, and modafinil on maintaining executive function in sleep deprivation. Here executive function refers to an individual's ability to make decisions, gather information, and mentally manipulate that information. The results were somewhat surprising: none of the drugs tested was superior in all tests of executive functioning. Different drugs were better suited to different tests.
In one test, called the Tower of London, participants had to arrange beads on a computer screen to fit a specified pattern while following a few simple rules; here, dextroamphetamine and modafinil showed superiority to both placebo and caffeine. Yet in solving the famous Tower of Hanoi problem, caffeine was superior to both placebo and the other two drugs tested.
The researchers summarized these findings by suggesting that modafinil and dextroamphetamine excel at maintaining spatial memory and problem solving skills during sleep deprivation and that caffeine is superior in tasks requiring inhibition and "the ability to focus on achieving multistep subgoals to achieve a larger goal."
The results are subject to interpretation, certainly, but it is not a great leap to suggest that caffeine may be more effective at imporoving performance on longer, more extensive endeavours, such as writing a paper, assembling a presentation, or pounding out code. In contrast, dextroamphetamine (or Adderall) and modafinil may be more effective for solving complex individual problems, as in a mathematical, scientific, or computer-oriented task. The differences between the drugs are not extreme, but if already augmenting one's intellectual prowess with psychoactive drugs, you might as well do it optimally.
Height Matters
Intuitively, the notion that adult height substantially impacts the lives of both men and women is not surprising. Height is a major determinant of sexual attractiveness, physical prowess, and a host of psychological factors. Taller people tend to be more attractive, better at sports, and more respected as leaders than those of shorter stature. In childhood especially, height can alter perceptions of self-confidence that will last a lifetime.
It is then perhaps not surprising than researchers have found several substantial correlations with adult height. In a study published in the Journal of Applied Psychology, significant positive correlations between adult height and social esteem, leader emergence, and performance were found. Height was slightly more related to success in men, but the sex difference did not reach statistical significance. Even more concretely, researchers found a significant positive correlation between height and income, even after controlling for sex, age, and weight.
The study comprises a meta-analysis of the literature as opposed to a single data point, further validating its claims. As evidence mounts for the considerable role of stature in income and social image, it seems that the market for drugs and surgeries to augment adult height may enlarge considerably. Studies have already pointed to pharmacological means by which parents might increase the maximal height of their children. The only question, it seems, is one of ethics and side effects, but there has never been a better justification.
It is then perhaps not surprising than researchers have found several substantial correlations with adult height. In a study published in the Journal of Applied Psychology, significant positive correlations between adult height and social esteem, leader emergence, and performance were found. Height was slightly more related to success in men, but the sex difference did not reach statistical significance. Even more concretely, researchers found a significant positive correlation between height and income, even after controlling for sex, age, and weight.
The study comprises a meta-analysis of the literature as opposed to a single data point, further validating its claims. As evidence mounts for the considerable role of stature in income and social image, it seems that the market for drugs and surgeries to augment adult height may enlarge considerably. Studies have already pointed to pharmacological means by which parents might increase the maximal height of their children. The only question, it seems, is one of ethics and side effects, but there has never been a better justification.
Newsflash: Exercise Is Good For You
A recent study in the journal Steroids has offered yet another reason to head outside and leave the couch behind. Researchers subjected mice to thirty minutes of treadmill running and then took samples of muscle tissue for analysis. They found that concentrations of the steroid hormones testosterone, DHT (dihydrotestosterone), and DHEA (dehydroepiandrosterone) were increased (compared to baseline) after exercise as well as expression of the enzyme 5alpha-reductase. In women, expression of the androgen receptor also increased.
Testosterone is usually thought of as the chemical basis of virility and the hormonal source of "male-ness". Though there's some truth to that claim, the reality is that masculinity is much more complex than a single chemical running through the blood. In fact, women have appreciable levels of testosterone, and those levels are responsible for regulating processes as disparate as libido, bone density, and muscle growth. Importantly, increased testosterone in muscle tissue is associated with strength and muscle increases.
The most important result of the study, though, may be the sex difference in expression of the androgen receptor. Testosterone, being a hormone, must bind to the androgen receptor to exert biological effects. Increased expression of the androgen receptor consequently results in more of the testosterone signal being propagated, which means stronger muscles and, likely, strong bones.
In short, yet more validation of a well-known fact -- that exercise makes you strong and healthy -- with a twist: the benefits for women may be even more substantial than those for men.
Testosterone is usually thought of as the chemical basis of virility and the hormonal source of "male-ness". Though there's some truth to that claim, the reality is that masculinity is much more complex than a single chemical running through the blood. In fact, women have appreciable levels of testosterone, and those levels are responsible for regulating processes as disparate as libido, bone density, and muscle growth. Importantly, increased testosterone in muscle tissue is associated with strength and muscle increases.
The most important result of the study, though, may be the sex difference in expression of the androgen receptor. Testosterone, being a hormone, must bind to the androgen receptor to exert biological effects. Increased expression of the androgen receptor consequently results in more of the testosterone signal being propagated, which means stronger muscles and, likely, strong bones.
In short, yet more validation of a well-known fact -- that exercise makes you strong and healthy -- with a twist: the benefits for women may be even more substantial than those for men.
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