From the Times on exercise and depression:
Exercise may help to safeguard the mind against depression through previously unknown effects on working muscles, according to a new study involving mice. The findings may have broad implications for anyone whose stress levels threaten to become emotionally overwhelming.
Has there ever been a better time to be a mouse?
ARE YOU A MAN OR A MOUSE?
Mouse emotions are, of course, opaque to us. We can’t ask mice if they are feeling cheerful or full of woe. Instead, researchers have delineated certain behaviors that indicate depression in mice. If animals lose weight, stop seeking out a sugar solution when it’s available — because, presumably, they no longer experience normal pleasures — or give up trying to escape from a cold-water maze and just freeze in place, they are categorized as depressed.
Comparable behavior in humans would be gaining weight, seeking out sugary "solutions", and dropping the remote control and freezing in place while keeping up with the Kardashians.