I used to suffer from twice weekly migraines and the neurologist once said that they are more prevalent amongst people of higher intelligence. I also used to suffer from SAD so does that mean that I'm super intelligent and if so, because I am much better on both counts does that mean that I'm now getting stupider....
but seriously, depression is a much misunderstood and debilitating illness with many possible root causes and its frustrating to read ill-informed opinions that belittle it.