According to a link from Drudge, the older brother says that the shooter had a personality disorder and may have been autistic.

4:52 p.m: Ryan Lanza, 24, brother of gunman Adam Lanza, 20, tells authorities that his younger brother is autistic, or has Asperger syndrome and a “personality disorder.” Neighbors described the younger man to ABC as “odd” and displaying characteristics associated with obsessive-compulsive disorder.

abcnews.go.com