It's also part of a fad of how science works or is absorbed in culture.
Here's the Times in 1973, reviewing Kurt Vonnegut's Breakfast of Champions, in which the antagonist, Dwayne Hoover's actions are caused by the bad chemicals in his system.
Is Kurt Vonnegut Kidding Us?
http://www.nytimes.com/books/97/09/28/lifetimes/vonnegut-bre...
In 1973 it was chemistry. In 2013 it's neuroscience.