LonelinessUniversity of Chicago social neuroscientist John T. Cacioppo pioneered research on the startling effects of loneliness: a sense of isolation or social rejection disrupts not only our ability to think and willpower but also our immune systems, and can be as damaging as obesity or smoking. On the flip side, social connection can be a powerful therapy. Cacioppo's sophisticated studies relying on brain imaging, analysis of blood pressure, immune response,