Your Fingers Show Your Athletic Potential and Anxiety

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The Norwegian University of Science and Technology (NTNU)
By comparing your index and ring fingers, a neuroscientist can tell if you are likely to be anxious, or if you are likely to be a good athlete.

By comparing your index and ring fingers, a neuroscientist can tell if you are likely to be anxious, or if you are likely to be a good athlete.

It is well-known that adults whose index finger is shorter than their ring finger were exposed to greater amounts of testosterone when they were in the womb.

Both women and men with this characteristic are — on average — better equipped to solve mentally demanding 3D rotation tasks as adults. As a group, they also have better physical and athletic abilities, but are more prone to having ADHD and Tourette’s syndrome.

Why on earth is this the case? Both boys and girls are exposed to testosterone in the womb. Everyone has different levels of male and female sex hormones. Some men have a lot of testosterone, some have less, and the same applies to women. Women who have received a lot of prenatal testosterone don’t need much testosterone as adults.

The level of testosterone in utero affects one’s finger length as an adult.

24 women and a drop of testosterone

“The relationship between the index finger and ring finger in particular indicates how much testosterone you have been exposed to in utero,” says Carl Pintzka, a medical doctor and researcher at the National Competence Service for Functional MRI.

In his doctoral dissertation at NTNU, Pintzka investigated how the brain functions differently in women and men. As part of this study, he tested an established theory about the significance of finger length and how the brain works.

He measured the finger length of 42 women and gave half of them a drop of testosterone. The other half were given a placebo. Afterwards, the women had to solve various mental tasks.

Short index finger, more testosterone

“We could then look at how testosterone levels affect different abilities in healthy women both in the womb and in adulthood,” says Pintzka.

An index finger that is relatively short compared to the ring finger indicates that one has been exposed to a lot of testosterone in utero, whereas a relatively long index finger suggests a lower exposure to testosterone in the womb.

“One mechanism behind this relationship is the difference in the receptor density for oestrogen and testosterone in the various fingers in utero. This relationship has also been shown to remain relatively stable after birth, which implies that it’s strictly the fetal hormone balance that determines this ratio,” says Pintzka.

More testosterone, better sense of place

The relationship between the index finger and ring finger in humans is associated with a variety of abilities in adulthood.

“The greatest effect has been found for various physical and athletic measures, where high levels of prenatal testosterone are consistently linked with better capabilities,” Pintzka says. “Beyond this we find a number of uncertain results, but a general feature is that high levels of testosterone generally correlate with superior abilities on tasks that men usually perform better, such as various spatial tasks like directional sense,” he adds.

Conversely, low levels of testosterone are associated with better abilities in verbal memory tasks, such as remembering lists of words. Fetal hormonal balance also likely affects the risk of developing various brain-related diseases.

… but also more ADHD and autism

Pintzka says studies show that high levels of testosterone in utero correlate with an increased risk of developing diseases that are more common in men, such as ADHD, Tourette’s and autism. Low levels of testosterone are associated with an increased risk of developing diseases that are more common in women, like anxiety and depression.

His study primarily involved researching how testosterone affects different spatial abilities in women. The women were asked to navigate a virtual maze, and to mentally rotate different three-dimensional objects.

More study needed According to Pintzka, the study results indicate a trend towards a positive effect of high testosterone levels on spatial abilities in utero. He believes that a larger study would be able to show a significant correlation. Furthermore, the results suggest that these hormone levels are important both in utero and in adulthood.

In other words, no definite conclusions can be drawn quite yet. Pintzka found no prenatal hormonal effects on study participants’ ability to navigate a virtual maze.

“The women who scored best on the mental rotation tasks had high levels of testosterone both prenatally and in their adult lives, while those who scored worst had low levels in both,” says Pintzka.

Journal Reference:

Carl W.S. Pintzka, Hallvard R. Evensmoen, Hanne Lehn, Asta K. Håberg. Changes in spatial cognition and brain activity after a single dose of testosterone in healthy women. Behavioural Brain Research, 2016; 298: 78 DOI: 10.1016/j.bbr.2015.10.056

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How Your Gut Controls Your Brain

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Whether you’re suffering from anxiety or are just in a crabby mood, before you start poking around your head as if looking for answers, you might do well to aim a little lower: your gut.

“Do you have gut instincts? Do you get butterflies in your stomach when you’re nervous? Can a job interview cause you to have stomach cramps?” asks Elizabeth Lipski, PhD, CCN, CHN, author of Digestion Connection. “These things happen because your nervous system and digestive system are intertwined.”

The connection between the brain and the gut is called the gut-brain axis, and it’s a two-way street. “The gut and the brain and the brain and the gut are intimately connected in a bi-directional way,” says David Perlmutter, MD, author of Brain Maker. “We’re just beginning to understand that this incredible relationship exists between our digestive system and the brain.”

While science is just catching up to the idea that the brain and the gut are more intertwined than we ever imagined, this idea has been appreciated by natural practitioners for a long time.

“Many years ago, naturopaths and holistically oriented doctors understood that bacterial imbalances were problematic,” says Gerard Mullin, MD, author of The Gut Balance Revolution. “They knew that to get healthy you had to rebalance the gut bacteria. But modern science, which is very pill oriented, has been proactively dismissive of these things and felt it was predicated on quackery. Now the evidence is so overwhelming, and more and more people appreciate it.”

Here’s some of the evidence that experts are pointing to when it comes to the complicated relationship between your brain and belly.

“It’s a bit humbling, this information, but the fact is, more than 90 percent of the neurotransmitters—chemicals like dopamine and serotonin, that actually serve to regulate our mood—are made in the gut,” says Dr. Perlmutter.

He explains that it’s the bacteria themselves that play an important role in the very manufacture of these neurotransmitters. If your gut is populated with the wrong bugs, they won’t be able to make the same feel-good chemicals, which can have a major impact on your mood.

In fact, these gut bacteria play such an important role in creating these neurotransmitters that an imbalanced gut is even linked to depression. “The reason people take antidepressants is to elevate levels of serotonin in the brain; and yet, the target here is the gut, not the brain, because the gut is where these chemicals come from in the first place,” says Dr. Perlmutter

Depression is also an inflammatory condition. And the first place to start looking for inflammation is in the gut.

“When there’s an imbalance in your gut bacteria, that is going to create shifts in your expression of gut hormones,” says Dr. Mullin. “It’ll cause the gut lining to become more permeable. That will allow the bacterial toxins to disseminate and cause an inflammatory reaction, which can affect brain function adversely.”

Similarly to depression, an imbalanced gut may also be at the root of anxiety. Research published in Psychiatry Research found that those who ate more probiotic-rich fermented foods were less likely to experience social anxiety.

Cognitive Function
That foggy feeling you get after eating too much junk food isn’t in your head—it’s in your gut. “If I had to choose one word that I hear from my patients, it’s ‘clarity,'” says Dr. Perlmutter, describing what happens when people rebalance their gut. “A lot of what we hear from patients is, ‘The fog was lifted.’ People didn’t realize there was fog until it has lifted and they become clear.”

Research from Oregon State University supports this anecdotal reaction. They found that mice fed a high-fat, high-sugar diet saw a shift in gut bacteria that was linked to a loss of cognitive flexibility (the ability to adapt to changing situations) and short- and long-term memory.

Dr. Perlmutter explains that the wrong gut bacteria can lead to “static on the line,” as he puts it. “The brain has got to receive plenty of energy to function. In the presence of inflammatory chemicals, the brain is less efficient at creating energy and it doesn’t work as well,” he says. “What happens in that situation is you develop static on the line. Your bandwidth goes down. It’s taking longer and longer to load those mental websites, if you will. And understand that gut bacteria are the mediators of inflammation throughout the body, including in the brain.”

Cravings and Recognizing Fullness
There’s a small part of your head that says, “I don’t need that french fry,” but the much louder message is, “More!” Turns out that the foods you put into your stomach affect how your brain looks at the rest of your meal.

Research from the Society for the Study of Ingestive Behavior found that feeding rats a high-fat diet led to gut bacteria shifts and caused the brain to fail to receive the “I’m full” message from the belly.

“The brain is changed by eating unbalanced foods,” explains Krzysztof Czaja, DVM, PhD, a principal investigator on the study and associate professor of neuroanatomy at the University of Georgia College of Veterinary Medicine. “It induces inflammation in the brain regions responsible for feeding behavior. Those reorganized circuits and inflammation may alter satiety signaling.”

Plus, bacteria may also be at the helm when it comes to steering you toward healthy—or unhealthy—choices. Research published in BioEssaysfound that microbes are able to manipulate us into eating things that they want to eat—and bad bacteria crave junk food. These germs are able to manipulate taste receptors, make us feel bad, or send out rewards to control the foods we send into our stomachs.

Skeptical that a tiny little germ could control your behavior? Dr. Perlmutter explains that gut microbes are so powerful that they can make a rat fall in love with a cat (and then promptly get eaten). The toxoplasmosis organism lives inside the digestive tract of a cat, and it would like to stay there. However, the cat will ultimately excrete the germ in its feces. To get back into the cat, the microbe manipulates whatever host picks it up—in this instance, a rat.

“When a rodent is infected with toxoplasmosis organism, the bacteria changes the brain of the rodent so that it begins to see the cat as a sexual partner,” says Dr. Perlmutter. Presenting itself as a mate to a cat is a surefire way to get that rodent eaten. “The cat then gobbles it up,” he says.

“How powerful an example is that that the germ is manipulating its host (the rodent) in order to continue its life cycle?!”


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Testosterone seems to help people with social anxiety

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Testosterone makes people with social anxiety disorder less likely to avoid the gaze of other people. This is one of the conclusions of a study by behavioural scientists at Radboud University. The study is the first to demonstrate that testosterone can help people with social anxiety. The scientific journalPsychoneuroendocrinology published the results online on 16 September.

 Previous studies on healthy people have indicated that testosterone facilitates contact with other people. It has also been shown that people with social anxiety have less testosterone than healthy people do, and that they are highly likely to suffer from social avoidance. “Testosterone has an anxiety-suppressing effect, and it facilitates contact in social situations. We wanted to see what it would do in people with social anxiety,” explains Dorien Enter, behavioural scientist at Radboud University and first author of the article.

Seeking eye contact

Enter conducted a placebo-controlled study involving 19 women with a social anxiety disorder (SAD) and a control group of equal size without SAD. On one day of the study, they received testosterone, and on the other day, a placebo. Neither the researcher nor the test subject knew which condition applied. Enter examined whether the test subjects avoided eye contact – a typical behaviour for people with social anxiety – with angry, happy and neutral faces on a computer screen. Eye-tracking was used to follow their gaze. What did the research reveal? The test subjects with social anxiety who had received testosterone avoided eye contact less often than was the case for those in the placebo condition.

Previous studies have indicated that testosterone facilitates social contact.

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