I have no idea why your friend had a seizure or TIA.
I do know alcohol definitrly contributes to elevated triglycerides and cholesterol, both directly and indirectly. Triglycerides are a direct relationship. If you track those things, watch how they go down in sobreity. Sugar and carbs will also raise triglycerides in excess. Other cholesterol numbers can rise with inflmmation in the system. Alcohol can cause this. That would be more indirect, and related to other factors as well. This is no medical advice to anyone, just facts easily found in any search on the subject.