Seizures can be caused by a large number of things. Old head injuries, medical conditions including epilepsy, diabetes, CVA (stroke), heat stroke, drug overdose, tumour...ect. One of our first checks after a seizure is blood sugar. In our scales normal ranges are between 4 and 7 as diagnosed by a glucometer. Next we go into personal history to accertain whether the patient has high blood pressure or the obvious, epilepsy, diabetes.... generally trying to rule out causes. The real diagnostics are done at the hospital. The fact that your friend is in intensive care has me wondering what they found as rarely are they sent to intensive care.
I hope that your friend fully recovers and has no long lasting effects.