6 Things You Need To Know Today (December 9)

In reviewing the records of 70,000 women who participated in a long-running health study, researchers have found a surprising link between mental process and physical well-being. It turns out that the women who believed that good things were in store for them were 30 percent less likely to die of disease. A possible explanation? "It's easier to feel optimistic when you feel healthy and energetic," says cardiologist Dr. Sarah Samaan. (HealthDay)

For the first time in a decade, the death rate has increased—which means the overall life expectancy has declined for the first time since 1993. Yikes. (CDC)

The executive board for the Olympic Games just voted to provisionally recognize the combat sport Muay Thai as well as cheerleading. Provisional recognition lasts three years, during which time the IOC can vote to fully recognize the sports at any of their annual sessions. Only when they've been fully recognized can the sports apply to be included in the Games. (Quartz)

The latest update to the list of threatened species shows our planet's tallest animal is on the brink after suffering a devastating decline in numbers, with nearly 40 percent of giraffes lost in the last 30 years. The authoritative list, compiled by the International Union for the Conservation of Nature (IUCN), found the giraffe population had plummeted from about 157,000 to 97,500, and the species had jumped two IUCN categories from "least concern" to now "vulnerable." (BBC)

In America, younger adults (18 to 29 years old) are more likely than their older counterparts to think that organic produce is better for human health, and GMO foods are damaging to both human and environmental health. They are also twice as likely to follow a vegan or vegetarian diet than adults over 50. (Pew Research)

According to researchers, mice that were exposed to strobe lighting for an hour each day saw a 60 percent decrease in the harmful brain plaque thought to cause Alzheimer's disease. If findings transfer to humans, strobe lighting may be combined with other methods under evaluation, like the vibrating chair, for non-invasive treatment. (The Guardian)