There's a great book that explains the loss of community. It's called "Bowling Alone: The Collapse and Revival of American Community" by Robert D. Putnam
I used this book a ton as a reference for many of my university essays pertaining to why voter turnout is down, but it does explain how the American community has utterly vanished among younger and middle-aged people.
Yea, a book that overs this is:
"Bowling Alone: The Collapse and Revival of American Community"
> Dozens of painstaking studies... have established beyond reasonable doubt that ... [t]he more integrated we are with our community, the less likely we are to experience colds, heart attacks, strokes, cancer, depression and premature death of all sorts...
> ... the positive contributions to health made by social integration and social support rival in strength the detrimental contributions of ... risk factors like ... smoking, obesity, elevated blood pressure, and physical inactivity.
> ...as a rough rule of thumb, if you belong to no groups but decide to join one, you cut your risk of dying over the next year in half.
Putnam was surveying a large number of studies, not just the Harvard one.
 Putnam, Robert D, Bowling Alone: The Collapse and Revival of American Community; https://www.amazon.com/Bowling-Alone-Collapse-American-Commu...