Humans

Greg O'Brien talks about how his life has changed in the five years since he was diagnosed with early-onset Alzheimer's disease. "More and more I don't recognize people," he says.

The British Parliament has voted to allow scientists to attempt to do "DNA transplants" on women's eggs to try to help them have healthy babies. Doctors want to do this to help families carrying devastating "mitochondrial diseases." But opponents question whether transferring DNA from healthy eggs into the eggs of women carrying these diseases is safe, and whether it would open the door to "designer babies."

Human relationships are entanglements, and those connections often aren't clear to us at all. When Maria Bamford impersonated her mom, she realized what she loved about her — and about herself.

A play based on interviews with former NFL players, their families and fans digs deep: What's so fun about a sport that devastates bodies and brains? And what if it can't be made safer?

Scientists studying HIV and Ebola have noticed another virus hitching along for the ride in some blood samples. Now they're trying to figure out whether the lurker helps the body fend off disease.

As vessels become more porous, researchers say, they allow toxins in the bloodstream to reach, and damage, delicate brain cells and raise the risk for dementia.