Brominated vegetable oil, an ingredient in Mountain Dew, is responsible for:
depression, memory loss, hallucinations, violent tendencies, seizures, cerebral atrophy, acute irritability, tremors, ataxia, confusion, loss of peripheral vision, slurred speech, stupor, tendon reflex changes, photophobia due to enlarged pupils, and extensor plantar responses.
http://www.gulflink.osd.mil/library/randrep/pb_paper/mr1018.2.chap10.html