Discovered: The NIH connects artificial sweeteners with depression; why fingers get all pruney underwater; insulin findings could lead to needle-free diabetes medication; deaf mice made to hear again.

Calorie-free beverages aren't worry-free. Diet soda drinkers have previously been told that their habit could lead to cancer (even though researchers doubt aspartame is toxic). Now they have to worry about whether or not their zero-calorie beverages are making them depressed. A new National Institutes of Health study found that those who drink four or more cans of diet soda per day are 30 percent more likely to develop depression than non-soda drinkers. But the correlation here isn't limited to Diet Coke — fruit punch drinkers actually had a higher rate of depression, according to the NIH. Study author Honglei Chen explains the takeaway: 

Our research suggests that cutting out or down on sweetened diet drinks or replacing them with unsweetened coffee may naturally help lower your depression risk. ... More research is needed to confirm these findings, and people with depression should continue to take depression medications prescribed by their doctors.

[New York Daily News]

The usefulness of pruney hands. Some might call them an ugly nuisance, those wrinkles that form all over your hands after soaking in the tub too long. But scientists call them an evolutionary advantage. A team of researchers led by Newcastle University's Tom Smulders studied people's ability to move objects from one box to another. Some had left their fingers in water for awhile — others left them dry. The pruney-handed subjects were 12 times faster at transferring wet objects from box to box, suggesting that prunes help humans grip things better underwater. [New Scientist]

​Diabetics may soon be able to ditch injections. Australian researchers think they've discovered how exactly insulin hormones bind to receptors, a mystery that has perplexed scientists for decades. "What we have done is to come up with that first 3D picture of how insulin interacts with its receptor," says Walter and Eliza Hall Institute professor Mike Lawrence. "You might call it a 'molecular handshake.'" This finding might help lead to diabetes medications that don't involved injections, a development that should please needle-phobic diabetics. [The Australian]

Deaf mice hear again, thanks to the miracle of science. Mice that have become deaf after prolonged exposure to noise are hearing again, thanks to drugs developed by Massachusetts Eye and Ear Infirmary stem cell biologist Albert Edge and his colleagues. Their tests on gamma-secretase inhibitors have shown unprecedented hair cell regeneration in the ears of these deaf mice.  This doesn't mean humans will be seeing the drug to cure deafness on the market anytime soon, but  Edge says, "it's a foot in the door." [ScienceNow]