Demaryius ThomasHis parents have shared more information about their son’s death.

His parents found him unresponsive seven months later in Roswell, Ga. Bobby ThomasAnd Katina SmithHe revealed that his death was due to cardiac arrest caused by a seizure disorder.

Bobby stated that cardiac arrest is how they try to determine what happened to him in an interview with Bobby on July 5. Good Morning America, adding that Demaryius “suffocated—he died.”

Bobby and Katina stated that the details were discovered after Demaryius’ brain was donated to research. They discovered that Demaryius had Stage 2 Chronic Traumatic Encephalopathy. It is a common brain condition caused by repetitive head trauma, which can also be seen in athletes according to the Mayo Clinic. This rare condition can lead to memory loss, trouble thinking, altered behavior, mood swings, and other symptoms.

Demaryius’s parents stated that he had similar symptoms to his father before his death.

Bobby said that he was paranoid and had this tendency to act out all the time. But memory loss, that I witnessed, was also. He complained every day about his headaches.