According to a new survey, one three adults age 45 and over is lonely. The greatest predictors of loneliness are the size of a person’s social network and physical isolation. In the AARP survey, 46% aged 45 to 49 reported loneliness, compared to 37% of people in their 50s, 36% in their 60s, and 24% in their 70s. People who never speak to their neighbors are nearly twice as likely to be lonely. Surprisingly, loneliness can cause health risks equivalent to those of obesity or smoking up to 15 cigarettes per day.