Good question. There appears to be no single cause, although there are several factors that put Boston-area Puerto Ricans at higher risk for depression, including high rates of obesity and diabetes. But some causes of the depressive epidemic might prove harder to treat:
Their depression, the surveyed Puerto Ricans said, was often fueled by the sight of relatives departing Boston for warmer climes.
"They constantly referred to their social networks being undermined by people picking up and leaving," said Northeastern researcher Luis Falcón .
Barely, barely relevant question: What causes some people to get seasonal affective disorder and not others?
Slightly different questions:
* What causes some people to be affected more than others by low light levels and cold? No one likes the winter, but some people can barely function in it.
* What causes some people to be affected more than others by being poor and discriminated against? Poverty and racism are good reasons so be depressed, but some people get it much worse.