Rep. Patrick Kennedy, son of late Sen. Ted Kennedy, says he won't seek reelection in Congress

I was upset to learn that Patrick Kennedy is leaving Congress. I mean he was elected with years of experience at 21 years old and will really be missed. I was curious if anyone from RI knew a back story as it appears that there was no possible way he could loose an election so I figure there was something more. I guess with the amount of money that family has, he needed to devote himself full time to manage the estate. From what I hear he had profound character in his personal life and was a champion in mental illness.
I know he comes form a highly esteemed family and just figured there was an untold reason for him leaving since a Kennedy has been in Washington for 60+ years.