A Breakthrough Global Study of Depression Finds 44 Genetic Variants Linked to the Disease

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iStock

Though depression affects an estimated 14 percent of the world’s population, scientists know very little about the underlying causes of the disorder, and that makes it incredibly difficult to treat. Even now, researchers are still debating whether common antidepressant medications even work at all, and if they do, why.

New research published in the journal Nature Genetics provides a big step in figuring out why some people suffer from depression while others don’t, identifying 44 genetic variants that are risk factors for major depression, 30 of which are new. They also found two regions of the brain that appear to be associated with the development of the disorder.

The study is the result of an international effort by more than 200 researchers involved with the Psychiatric Genomics Consortium. It looked at more than 135,000 cases of depression (both self-reported and clinically assessed) and almost 345,000 control cases. It’s the largest study on the genetic basis of depression ever done.

The researchers found that all humans carry some of the 44 risk factors identified. Some people carry more than others, putting them at greater risk for developing depression. They also identified the prefrontal and anterior cingulate cortices (both located at the front of the brain) as the regions of the brain probably linked with the development of depression.

Some of the risk factors the researchers identified are also involved in other psychiatric disorders, like schizophrenia, which isn't entirely surprising—a 2007 study from the Psychiatric Genomics Consortium found that people with depression, bipolar disorder, and schizophrenia as well as developmental disorders like ADHD and autism share the same variations in four locations in their genetic code.

By identifying genetic risk factors associated with major depressive disorder, the scientists hope to increase our understanding of why depression strikes some people and not others. "[M]ajor depression is a brain disorder," the researchers conclude. "Although this is not unexpected, some past models of [major depressive disorder] have had little or no place for heredity or biology." They firmly put to rest the idea that depression is entirely a matter of environment.

Environment certainly plays a role—the researchers found links between lower education levels and higher body mass index and depression risk as well—but genetics may impact whether someone whose circumstances put them at risk of depression actually develops the disorder. Depression is still highly stigmatized, which often prevents people from seeking treatment for it, according to several studies. Further understanding of the genetic underpinnings of the disorder may help counter negative perceptions of depression as a character flaw or a sign of laziness.

The study could eventually change how doctors treat depression. Many of the genetic variants identified by this study are linked to targets of current antidepressant medications, like serotonin. But the research may also lead to the development of new medications and therapies that could work for more people (current medications don't work for everyone) and potentially have fewer side effects than existing treatments.

The study partially relied on self-reported depression diagnoses, meaning there's some wiggle room in knowing whether those people are actually clinically depressed to the degree that a medical professional would diagnose. Further research will need to confirm that these genetic variants are indeed linked to depression. There are likely even more gene variants related to depression risk, as well, but they might have too small of an effect to be identified by this study. The researchers hope to continue their work to understand the links between environmental stressors, genetic variations, and depression risk in the future.

Mapping Technology Reveals 'Lost Cities' on National Geographic

Lin uses his iPad to visualize scanning data of a crusaders' fortress at the lagoon in Acre, Israel.
Lin uses his iPad to visualize scanning data of a crusaders' fortress at the lagoon in Acre, Israel.
Blakeway Productions/National Geographic

Imagine what Pompeii looked like before the lava hit, or Mayan pyramids before the jungle took over. In the past decade, scientists have been able to explore human settlements long since abandoned by using a new wave of accessible technology. Instead of needing an expensive plane and crew to fly aerial sensors, for example, explorers can mount them on cheaper drones and pilot them into previously unreachable areas. The resulting data can tell us more about the past, and the future, than ever before.

That’s the premise of Lost Cities with Albert Lin, a new TV series premiering on National Geographic on Sunday, October 20.

Lin, an engineer and National Geographic Explorer, uses cutting-edge tools to shed light on centuries-old cities in the most beautiful places on Earth. Ground-penetrating radar reveals buried structures without disturbing the landscape. A drone-mounted remote sensing method called LIDAR—short for "Light Detection and Ranging"—shoots lasers at objects to generate data, which Lin visualizes with 3D mapping software. The results suggest what the ruins probably looked like when they were new.

Albert Lin and crew in Peru
Thomas Hardy, Adan Choqque Arce, Joseph Steel, Duncan Lees, Albert Lin, and Alonso Arroyo launch the LIDAR drone at Wat'a in Peru.
National Geographic

“It’s like a window into a world that we’ve never had before,” Lin tells Mental Floss. “It’s shooting millions of laser pulses per second through a distance of air. By digitally removing the top layer of everything above the ground—trees, brush, cacti—you’re washing away the past. All of the sudden you’re left with these fingerprints—experiments in how we organized ourselves through time.”

For the six-episode series, Lin and the expert storytelling team were dispatched to the South Pacific, the Middle East, the Andes, the Arctic, and other destinations. Lin explains that while most of the sites are known to archaeologists, they’ve never been so precisely mapped in three-dimensional detail.

In the first episode, Lin travels to Nan Madol, an enigmatic complex of temples and other structures on the Micronesian island of Pohnpei. With the help of local researchers and indigenous leaders, Lin and the team scan the ruins and digitally erase trees, water, and forest undergrowth to unveil the complex's former grandeur.

“Technology and innovation have always been that gateway to go beyond the threshold, and see what’s around the corner,” Lin says. “Seeing these worlds for the first time since they were left, it’s almost like reversing the burning of the library of Alexandria. We can take the synthesis of knowledge of all these watershed moments of our human journey, and imagine a better future.”

Lost Cities With Albert Lin premieres Sunday, October 20 at 10/9c and resumes on Monday, October 21 at 10/9c on National Geographic.

8 Ways Science Can Boost Your Halloween Fun

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iStock

Halloween is all about embracing the supernatural, but science shouldn't entirely fall by the wayside during the spookiest of holidays. Here are a few ways it can actually improve your holiday, from making trick-or-treating easier to fooling your brain into thinking you're eating tasty treats even though you're nibbling on candy cast-offs.

1. Slow the decomposition of your Halloween jack-o'-lantern.

A Halloween display of five jack-o-lanterns
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You don't have to be an expert gardener to keep your jack-o'-lantern looking fresh all Halloween season long. While scouting out pumpkins, pick hard, unblemished ones and steer clear of those with watery dark spots. These splotches indicate frost damage.

Hold off on carving until right before Halloween so your gourds won't rot—but if you can't resist, try squirting their exteriors with lemon juice after you're done slicing and dicing. The acid inhibits pumpkin enzymes, which react with oxygen and cause browning. A light misting of bleach solution will help keep fungus at bay. Some apply vegetable oil or Vaseline to prevent shriveling and drying. We experimented with various techniques in this video.

For extra TLC, you might even want to bring your jack-o'-lanterns in at night if temperatures dip; if you live in a hot and humid area, extend its life by placing it in the fridge overnight. Try using glow sticks or LED lights instead of flesh-singeing candles.

2. Use apps to plan a treat-or-treating route.

Three children in Halloween costumes trick-or-treating
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Thanks to technology, trick-or-treaters (and their hungry adult companions) can now scout out which neighbors are doling out the best candy and which are sticking with Tootsie Rolls, apples, and toothbrushes. Simply download the app for Nextdoor, the neighborhood-based social network, to check out an interactive "treat map" that lets users tag whether their home is handing out treats, and what that treat is.

Since safety is far more important than sugar, guardians should also consider adding a tracking app to their arsenal come Halloween, especially if their kid's venturing out alone. The Find My Family, Friends, Phone app gives the real-time locations of trick-or-treaters, provides alerts for when they turn home, and also comes with a "panic" button that provides emergency contact details when pressed.

3. Optimize your candy's flavor (even if it's SweeTarts).

Hard candies and gummies strewn across a table
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Not crazy about this year's Halloween loot? Fool yourself into thinking those black licorice pieces and peanut chews taste better than they actually do by eating them after you scarf down the chocolate and Sour Patch Kids. According to a 2012 study published in Psychological Science, being aware that these items of candy are your very last candies actually tricks the brain into appreciating them more (and thus thinking they're tastier than they really are).

Meanwhile, a 2013 study from the same journal found that creating a candy-eating ritual enhances flavor and overall satisfaction. Nibble the ridged edges off a Reese's peanut butter cup before tackling the creamy center, sort the M&Ms by color, and take your time unwrapping a chocolate bar.

4. Create a DIY fog machine with carbon.

Dry ice in a glass bowl
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Save money at Party City by creating your own fog machine at home. When dropped in water, dry ice—or frozen carbon dioxide—creates a gas that's a combination of carbon dioxide and water vapor, but looks like the fog you'd see rolling through a haunted graveyard [PDF].

5. Eat sort-of-heart-healthy Halloween candy.

A stack of dark chocolate chunks on a dark stone background
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Halloween candy isn't always bad for you. While shopping for this year's trick-or-treat bounty, steer clear of sugary confections and milk chocolate mini-bars. Opt for dark chocolate treats instead. Research suggests that our gut microbes ferment the antioxidants and fiber in cocoa, creating heart-healthy anti-inflammatory compounds. Plus, dark chocolate or cocoa also appears to help lower blood pressure for people with hypertension, decrease bad cholesterol, and stave off cardiovascular disease and diabetes, among other benefits.

6. Analyze data on Halloween candy trends and give the people what they want.

Lollipops
5second/iStock via Getty Images

Thanks to data science, you can make sure you're giving out the best treats on the block. Bulk candy retailer CandyStore.com combed through 10 years of data (2007 to 2016, with a particular focus on the months leading up to Halloween) to gauge America's top-selling sweets. They created an interactive map to display their results, which includes the top three most popular Halloween handouts in each state and Washington, D.C. Be prepared for plenty of stoop-side visitors and adorable photo ops.

7. Bake better Halloween treats with chemistry.

Frosted Halloween cookies shaped like ghosts and pumpkins
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Cooking is essentially chemistry—and depending on your technique, you can whip up chewy, fluffy, or decadent Halloween treats according to taste.

Folding chunks of chilled butter into your dough will give you thick, cake-like cookies, as will swapping baking soda for baking powder. When butter melts, its water converts into gas, which leaves lots of tiny holes. If the butter flecks in question are colder and larger, they'll leave bigger air pockets. As for the baking powder, it produces carbon dioxide gas both when it's mixed into the dough and when it's heated. For an extra boost in texture, you can also try adding more flour.

Prefer chewier cookies? Start out with melted butter in the dough, and stick with plain old baking soda.

And for extra-fragrant and flavorful baked goods, opt to use dark sugars—like molasses, honey, and brown sugar—because they're filled with glucose and fructose instead of plain old sucrose. As cookies bake, they undergo two processes: caramelization, in which the sugar crystals liquefy into a brown soup; and the Maillard reaction, a chemical reaction between the dough's proteins and amino acids (flour, egg, etc.) and the reducing sugars that causes tasty browning.

8. Take deep breaths to stay calm in haunted houses.

A brown-haired woman in a red polka dot blouse standing with a frightened expression next to a spider web.
iStock

Halloween can be tough for people with anxiety or low thresholds for fear. While visiting a haunted house or watching a scary movie, remember to take deep breaths, which fends off the body's flight-or-fight response, and reframe your anxiety in your mind as "excitement." It's also a good idea to schedule spine-chilling activities after an activity that triggers feel-good endorphins—say, after a walk to check out your neighbors' awesome Halloween displays.

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