Mikey Welsh, the former bassist for the band Weezer, has died "unexpectedly" at the age of 40. The cause of death has yet to be determined. Welsh last played on 2001's "Green Album," but suffered a mental breakdown the same year and later attempted suicide. He was diagnosed with psychological disorders and had a drug problem. He then dedicated himself to painting, working on large-scale canvases from his home in Burlington, Vt.