People approach life from a large range of anxiety levels. You’ve probably even noticed this among your own friends. One person seems to take everything life throws at her in stride, while another sees the smallest of obstacles as huge stumbling blocks.

So are less anxious people born with their ability to roll with the punches or have they just had the good fortune to not experience high stress environments? In other words, do our genes predispose us to being anxious? Or do our environments and life experiences dictate how mellow we are?

See also: How Can You Tell If You Have Anxiety?

Our Brain Chemistry

Our body’s nervous system transmits information (from the brain to our muscles, for example) through electrically excitable cells called neurons. To communicate with each other, those neurons have to transmit signals over the gaps between themselves, junctions called synapses. Each neuron has around 7,000 junctions between other cells and so the human brain is expected to have 100-500 trillion synapses. We actually start out with more, a 3-year-old may have almost a quadrillion synapses, but that number declines as we age.

Cells use chemicals called neurotransmitters to pass signals from the transmitters on one neuron to the receptors on a neighboring neuron. We are not sure how many different neurotransmitters our brains use, but researchers have so far identified over 100 of these messenger molecules.

One such neurotransmitter is anandamide, a name that comes from the Sanskrit word ananda for joy or bliss, which (you guessed it) helps our brain communicate happiness, ease, and comfort. The levels of anandamide, otherwise known as the bliss molecule, in our brain are regulated by the fatty acid FAAH (fatty acid amide hydrolase) which works to deactivate the anandamide by converting it into other acids.

A Hard-Wired Chill Pill?

What if some people have a gene that makes them less anxious? Drs. Francis Lee and Iva Dincheva of Weill Cornell Medical College have been investigating a gene variation that, for the roughly 20% of adults lucky enough to have it, causes them to have less FAAH. Without as much FAAH to break down their anandamide, the anandamide can persist longer in the synapses to send its blissful chemical messages. The new research shows those with the gene variation are not only more mellow, but also more easily able to forget prior negative experiences.

To test the link between this gene and anxiety levels, the doctors at Cornell put the human FAAH variant gene into mice. When allowed to roam a maze, the mice given the gene spent more time in the open parts of a maze, a sign that they are more comfortable in their surroundings, compared to a control group of mice that were not given the gene and preferred the enclosures.

The now variant mice also had greater connectivity between the prefrontal cortex, basically the main switchboard in our brains, and the amygdala, an area of the brain important for processing fear. Such connectivity suggests lower stress levels and greater emotional control.

The researchers did a further test to determine if having the gene variation also meant being able to recover from anxiety faster, on top of being less anxious overall. They started with a neutral stimulus (something like a plain image) which they presented to both the mice and a group of a humans, some with the FAAH variant gene and some without it. They trained the mice and humans to associate fear and discomfort with the stimulus, for example, by poking someone or playing a high-pitched, loud sound whenever a person was shown the image.

So what happened?

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