Casey Anthony's Parents The Seizure Theory

9/8/2011 8:03 AM PDT

Casey Anthony's Parents -- The Seizure Explanation

Casey Anthony
's parents reportedly have a brand new theory in the death of their granddaughter -- suggesting Casey may have been incapacitated from a seizure while Caylee was drowning in "the swimming pool incident."

According to, Cindy and George Anthony revealed their theory to Dr. Phil during their recent sit-down interview. 

Cindy reportedly told Phil that Anthony suffered gran mal seizures in 2005 and 2008 -- and suggested that the seizures may be symptomatic of a condition that could make it difficult to "sort fact from fiction."

The interview is set to air on Sept. 12.