My friend starts to feel dizzy and then loses the ability to talk and see and then passes out, when waking, her head hurts badly i have been after her as a girlfriend and everytime i ask her out she passes out out like mentioned above. she is very skinny

Your : Your friend is being very foolish. She needs to have a check up for this. The problem is unlikely to be neurological and more likely to be medical. You mention that she is skinny. She may not be getting enough to eat and drink to maintain her blood pressure so that her brain isn't getting enough blood flow and she passes out. She may have bulemia and isn't able to maintain the potassium her body needs. In any case she could injure herself if this happened while she was walking across the street or up a flight of stairs. If she won't listen to you, try to talk to her mom. She needs help.

Abnormal: Your friend absolutely needs medical assessment. If she doesn't take in adequate calories or nutrients that may be a culprit. The fact that she passes out when you discuss the issue suggests a behavior component.