11 Facts You Should Know About Depression

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diego_cervo/iStock via Getty Images

You may say you feel depressed after getting passed up for a job or having a fight with a friend, but as people living with clinical depression and anxiety know too well, it's more than just a sad feeling. Depression disorders are characterized by feelings of emptiness and negativity, and symptoms range in severity from trouble getting out of bed to thoughts of suicide. While diagnoses are more common than ever before, that isn’t necessarily a bad thing: As more people seek out the many types of depression treatments now available, stigma around the condition lessens, and life with depression becomes more manageable for the millions who have it. Here are a few more facts about depression causes and treatments.

1. Depression symptoms can be physical as well as mental.

Depression is a mental illness, but its symptoms aren’t limited to the mind. In addition to insomnia, fatigue, and persistent sadness, patients may have physical pain in the form of headaches, muscle aches, and gastrointestinal discomfort. These symptoms may have something to do with serotonin and norepinephrine, which are neurotransmitters that govern pain as well as mood. Pain can make you feel worse emotionally and further dissuade you from leaving the house, which can reinforce feelings of isolation and loneliness—a vicious cycle many depression sufferers are familiar with.

2. Depression causes can vary from genes to alcohol abuse.

Depression is a complex condition that can be caused by a range of factors. Some people are genetically predisposed to depression. Others become depressed as the result of a long-term stressful life event—such as an abusive relationship, isolation, unemployment, chronic illness, or a traumatic childhood. If someone is predisposed to depression, sudden difficulties that arise in their lives can trigger a depressive episode. Drug and alcohol use have a chicken-and-egg relationship with the mental disorder: Substance abuse can lead to depression, and some people who are depressed turn to substances to cope. Whatever the underlying cause, the actual symptoms of depression occur when neurotransmitters in the brain responsible for regulating mood aren’t functioning properly.

3. One in seven new parents may have postpartum depression.

Postpartum depression is thought to be a side effect of the dramatic drop in estrogen and progesterone levels a new parent experiences following the birth of a baby. Other circumstances associated with being a new parent, such as stress, fatigue, and self-doubt, can lead to feelings of sadness and emptiness. Anyone who feels depressed for more than two weeks after delivering their child should reach out to a doctor for help.

4. Four depression types affect the brain in different ways.

A 2017 study in Nature Medicine suggested that neurological scans showed four different manifestations of depression, with some overlap between the subtypes. People with brain activity that corresponded to subtypes 1 and 2 felt more fatigue, while people with subtypes 3 and 4 were less likely to feel pleasure. Each subtype might respond differently to various treatments, researchers found. For example, transcranial magnetic stimulation (TMS), a method of administering magnetic impulses to change brain activity, is most effective for subtype 1.

5. Antidepressants target specific neurotransmitters to relieve depression symptoms.

Today, four categories of antidepressants are commonly prescribed for depression, and each works slightly differently. Selective serotonin reuptake inhibitors (SSRIs) like sertraline (Zoloft) and fluoxetine (Prozac) affect serotonin, the brain chemical associated with feelings of happiness and wellbeing. Serotonin and norepinephrine reuptake inhibitors (SNRIs) like duloxetine (Cymbalta) target norepinephrine—a neurotransmitter that promotes alertness—as well as serotonin. Norepinephrine-dopamine reuptake inhibitors (NDRIs), such as buproprion (Wellbutrin), increase norepinephrine and dopamine and purport to have fewer side effects than other drugs. Second-generation antipsychotics (SGAs) like aripiprazole (Abilify) are used to treat schizophrenia and bipolar disorder, and can also be used for depression when other medications haven't worked.

6. Dogs get depressed, too.

Animal researchers have observed depression-like symptoms in other species. Unsurprisingly, captive animals deprived of the social interactions they would have in the wild are particularly susceptible. Zoo animals, lab test subjects, and pet dogs can all exhibit what might be described as animal depression. Studies have even shown that fish can get depressed and respond positively to antidepressants. Depression in animals isn’t analogous to the condition in people, but studying how it affects animals might lead to better human treatments.

7. Depressed people may use certain phrases in speech.

Depression is often an invisible illness, but one analysis of depression-focused internet forums found that users tended to use a lot of first-person pronouns like I and me and fewer third-person pronouns like they, he, or she. The finding suggested that people with depression are focused on themselves and feel disconnected from others. Another linguistic indicator of depression is the use of absolutist words such as always, constantly, and completely, which may be associated with a black-and-white view of reality.

8. A hot bath might ease some depression symptoms.

For a study, researchers from Freiburg University in Germany pitted exercise—often touted as a depression-fighter—against hot baths to see which was more effective at alleviating symptoms. Subjects with depression who took 30-minute hot baths and relaxed with hot water bottles and warm blankets for 20 minutes twice a week saw their condition improve more than the subjects who exercised for 45 minutes twice a week. The study [PDF] wasn't peer-reviewed and it came with a few caveats. The sample size started small with just 45 subjects, and of the 23 people assigned to the exercise group, 13 failed to complete the study because they were unable or unwilling to be physically active. But the results support the theory that hot baths can stabilize one’s mood by normalizing body temperature and circadian rhythms.

9. Some of history's famous figures have (possibly) had depression.

It’s impossible to truly diagnose someone when they’re dead, but using historical documents and other clues, scholars have speculated that some of history’s greatest thinkers had depression. They include Abraham Lincoln (friends called him the most depressed person they'd ever seen), Charles Dickens (he was described as falling into a depression at the start of each book), and Leo Tolstoy (he wrote of contemplating suicide in one letter). The list of living celebrities with depression is more reliable. Buzz Aldrin, Dolly Parton, and J.K. Rowling have all spoken about dealing with the disorder.

10. Daylight Saving Time might trigger depression.

Depression that’s connected to a certain time of year is known as seasonal affective disorder, or SAD, and 6 percent of the U.S. population suffers from it. Medical experts aren’t entirely sure what causes it, but it may have something to do with changing daylight hours disrupting patients' circadian rhythms, the system that governs sleep cycles. This may also be why hospital admissions for depression spike the month immediately following Daylight Saving Time.

11. Depression rates are rising—but maybe not for the reasons you think.

According to the World Health Organization, more than 300 million people suffer from depression globally. That number is much larger than it was a few years ago. Between 2005 and 2015, rates of depressive illness rose by nearly 20 percent. Depression is also 10 times more common among people born after 1945. This doesn’t necessarily mean that people feel worse than they did a century ago—awareness of the condition has grown tremendously in recent years and people today may be more likely to seek help for their depression and receive a diagnosis. It's also possible that older generations kept their struggles to themselves.

7 Facts About Blood

Moussa81/iStock via Getty Images
Moussa81/iStock via Getty Images

Everyone knows that when you get cut, you bleed—a result of the constant movement of blood through our bodies. But do you know all of the functions the circulatory system actually performs? Here are some surprising facts about human blood—and a few cringe-worthy theories that preceded the modern scientific understanding of this vital fluid.

1. Doctors still use bloodletting and leeches to treat diseases.

Ancient peoples knew the circulatory system was important to overall health. That may be one reason for bloodletting, the practice of cutting people to “cure” everything from cancer to infections to mental illness. For the better part of two millennia, it persisted as one of the most common medical procedures.

Hippocrates believed that illness was caused by an imbalance of four “humors”—blood, phlegm, black bile, and yellow bile. For centuries, doctors believed balance could be restored by removing excess blood, often by bloodletting or leeches. It didn’t always go so well. George Washington, for example, died soon after his physician treated a sore throat with bloodletting and a series of other agonizing procedures.

By the mid-19th century, bloodletting was on its way out, but it hasn’t completely disappeared. Bloodletting is an effective treatment for some rare conditions like hemochromatosis, a hereditary condition causing your body to absorb too much iron.

Leeches have also made a comeback in medicine. We now know that leech saliva contains substances with anti-inflammatory, antibiotic, and anesthetic properties. It also contains hirudin, an enzyme that prevents clotting. It lets more oxygenated blood into the wound, reducing swelling and helping to rebuild tiny blood vessels so that it can heal faster. That’s why leeches are still sometimes used in treating certain circulatory diseases, arthritis, and skin grafting, and helps reattach fingers and toes. (Contrary to popular belief, even the blood-sucking variety of leech is not all that interested in human blood.)

2. Scientists didn't understand how blood circulation worked until the 17th century.

William Harvey, an English physician, is generally credited with discovering and demonstrating the mechanics of circulation, though his work developed out of the cumulative body of research on the subject over centuries.

The prevailing theory in Harvey’s time was that the lungs, not the heart, moved blood through the body. In part by dissecting living animals and studying their still-beating hearts, Harvey was able to describe how the heart pumped blood through the body and how blood returned to the heart. He also showed how valves in veins helped control the flow of blood through the body. Harvey was ridiculed by many of his contemporaries, but his theories were ultimately vindicated.

3. Blood types were discovered in the early 20th century.

Austrian physician Karl Landsteiner discovered different blood groups in 1901, after he noticed that blood mixed from people with different types would clot. His subsequent research classified types A, B and O. (Later research identified an additional type, AB). Blood types are differentiated by the kinds of antigens—molecules that provoke an immune system reaction—that attach to red blood cells.

People with Type A blood have only A antigens attached to their red cells but have B antigens in their plasma. In those with Type B blood, the location of the antigens is reversed. Type O blood has neither A nor B antigens on red cells, but both are present in the plasma. And finally, Type AB has both A and B antigens on red cells but neither in plasma. But wait, there’s more! When a third antigen, called the Rh factor, is present, the blood type is classified as positive. When Rh factor is absent, the blood type is negative.

Scientists still don’t understand why humans have different blood types, but knowing yours is important: Some people have life-threatening reactions if they receive a blood type during a transfusion that doesn’t “mix” with their own. Before researchers developed reliable ways to detect blood types, that tended to turn out badly for people receiving an incompatible human (or animal!) blood transfusion.

4. Blood makes up about 8 percent of our total body weight.

Adult bodies contain about 5 liters (5.3 quarts) of blood. An exception is pregnant women, whose bodies can produce about 50 percent more blood to nourish a fetus.)

Plasma, the liquid portion of blood, accounts for about 3 liters. It carries red and white blood cells and platelets, which deliver oxygen to our cells, fight disease, and repair damaged vessels. These cells are joined by electrolytes, antibodies, vitamins, proteins, and other nutrients required to maintain all the other cells in the body.

5. A healthy red blood cell lasts for roughly 120 days.

Red blood cells contain an important protein called hemoglobin that delivers oxygen to all the other cells in our bodies. It also carries carbon dioxide from those cells back to the lungs.

Red blood cells are produced in bone marrow, but not everyone produces healthy ones. People with sickle cell anemia, a hereditary condition, develop malformed red blood cells that get stuck in blood vessels. These blood cells last about 10 to 20 days, which leads to a chronic shortage of red blood cells, often causing to pain, infection, and organ damage.

6. Blood might play a role in treating Alzheimer's disease.

In 2014, research led by Stanford University scientists found that injecting the plasma of young mice into older mice improved memory and learning. Their findings follow years of experiments in which scientists surgically joined the circulatory systems of old and young mice to test whether young blood could reverse signs of aging. Those results showed rejuvenating effects of a particular blood protein on the organs of older mice.

The Stanford team’s findings that young blood had positive effects on mouse memory and learning sparked intense interest in whether it could eventually lead to new treatments for Alzheimer’s disease and other age-related conditions.

7. The sight of blood can make people faint.

For 3 to 4 percent of people, squeamishness associated with blood, injury, or invasive medical procedures like injections rises to the level of a true phobia called blood injury injection phobia (BII). And most sufferers share a common reaction: fainting.

Most phobias cause an increase in heart rate and blood pressure, and often muscle tension, shakes, and sweating: part of the body’s sympathetic nervous system’s “fight or flight” response. But sufferers of BII experience an added symptom. After initially increasing, their blood pressure and heart rate will abruptly drop.

This reaction is caused by the vagus nerve, which works to keep a steady heart rate, among other things. But the vagus nerve sometimes overdoes it, pushing blood pressure and heart rate too low. (You may have experienced this phenomenon if you’ve ever felt faint while hungry, dehydrated, startled, or standing up too fast.) For people with BII, the vasovagal response can happen at the mere sight or suggestion of blood, needles, or bodily injury, making even a routine medical or dental checkup cause for dread and embarrassment.

9 Surprising Facts About the Scientific Study of Sex

vadimguzhva/iStock via Getty Images
vadimguzhva/iStock via Getty Images

The scientific study of sex is much more exciting than an awkward sex ed class. While writing my book Sex Weird-o-Pedia, these were some of the most interesting facts about science and sex that I came across.

1. Some sex researchers didn't want their findings to get into the wrong hands.

The pioneering sex researcher Richard von Krafft-Ebing didn’t want his knowledge in the hands of ordinary folk. So he wrote Psychopathia Sexualis, the founding document of modern sexology—which was published in Germany in 1886 then translated and published in English in 1939—in Latin to discourage regular Joes (and/or Janes) from reading it.

2. You burn more calories mowing the lawn than you do having sex.

Young woman poses for selfie while mowing the lawn
Alina Rosanova/iStock via Getty Images

Sex might seem strenuous when things get hot and heavy, but it's usually not that great of a workout. You'd have to go at it for nearly 200 minutes to burn as much energy having sex as you do during a 30-minute run. Even mowing the lawn burns about three times more calories than sex. According to the British Heart Foundation, sex burns about the same amount of energy per minute as ironing clothes.

3. A surprising number of mothers claim to be virgins.

In a 2013 study of several thousand pregnant women in the U.S. published by BMJ, about 1 percent of the participants claimed they were virgins when they gave birth. This, of course, calls into question the veracity of studies that rely on self-reported sexual behaviors.

4. Penicillin may have ignited the sexual revolution.

One economist says that penicillin, and not the birth control pill, was the real enabler of the sexual revolution. A study published in the Archives of Sexual Behavior in 2013 shows that penicillin contributed to a 75 percent decline in the number of deaths caused by syphilis from 1947 to 1957. Since the new treatment made sex safer, people started having riskier sex, which resulted in increases in the numbers of children born out of wedlock and teenage pregnancies.

5. Twins can have different dads.

A photo of fraternal twins
Aleksandr Zhurilo/iStock via Getty Images

While it is very rare, it is possible for fraternal twins to have two different fathers. What’s more common is for a rom-com to be based on this scenario.

6. Gender may influence how people handle sexual jealousy.

Research from evolutionary psychologists indicates that people’s gender influences how they react to sexual jealousy. For men, they react more strongly to sexual unfaithfulness than emotional infidelity. For women, it is the reverse. The theory behind these behaviors comes back to evolution: Males who were intolerant toward their wives becoming sexually active with other men were less likely to become an object of derision and more likely to see their own genes pass onto future generations. Women who prevented their husbands from emotionally bonding with other women reduced the chances of the men spending their resources on other women.

7. One of Ivan Pavlov's colleagues created his own (slightly x-rated) conditioning experiment with dogs.

You’re probably aware of Russian researcher Ivan Pavlov and his famous conditioning experiment in which he trained a dog to salivate at the sound of a bell. What you might not know is that one of Pavlov’s American students, W. Horsley Gantt, conditioned dogs to become sexually aroused when they heard specific tones. The experiment, according to Mandy Merck's In Your Face: 9 Sexual Studies, was intended "to study conflicts of the drives between ... experimentally induced anxiety states and sexual excitement."

8. Couples whose first child is a girl are more likely to get divorced.

Parents pay attention to their phones instead of their daughter
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Married couples whose first child is a girl are more likely to get divorced than those whose first child is a boy. Scientists are split as to why this is. One theory is that female embryos are better able to endure maternal stress than male embryos, so pregnant women in unhappy marriages are less likely to have a miscarriage if the child they are bearing is a girl. But once they have a daughter, these couples are more likely to split up since there were already fissures in their relationship prior to the child’s birth.

9. There's a link between pubic hair and STIs.

A downside of pubic grooming is that it might raise STI risk. In a study conducted by a University of Texas scholar, people who regularly shaved their pubic areas contracted STIs about 80 percent more often than those who never shaved down there. One suggestion is that those who regularly shave are more likely to tear their skin, making it easier for viruses to enter the body.

Ross Benes is the author of Sex Weird-o-Pedia: The Ultimate Book of Shocking, Scandalous, and Incredibly Bizarre Sex Facts.

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