It depends on what You want the dog to do for you.
A dog "alerting" is a natural ability. It's not taught. Only 10% of all dogs have that ability. Science is still wondering what they dog is picking on, because it's typically 10 to 15 minutes before a seizure.
A dog responding to a seizure might protect your head, tell others by barking. Roll you off your back, help you off the floor when conscious. Bring you to safety if you become delirious when walking. Maybe also be a for balance if your pills make you "drunklike"- but so would a metal walker, or service human.
These things are trainable.