anxiety symptoms vs. vaso-vagal response

July 29, 2007 6:51 PM

psychology-fites: Why is it that typically, people who have anxiety attacks do NOT trigger the vaso-vagal response instead (and potentially pass out?)

I've had both happen, myself - the vaso-vagal response triggered by a long-standing, stupid phobia of having blood drawn - and additionally, crazy panic attacks as a result of stopping medication. Sure enough, I've never passed out from an anxiety attack. It makes sense why you don't faint during an an anxiety attack, heart pounding away....but what is it that causes these differing end results? Obviously there's some kind of fear involved with the triggers, rational or no, it's just bizarre to me that the end results of these are so different. Personally i'd prefer the anxiety attack - fainting sucks.

posted by bitterkitten to Health & Fitness (3 answers total)

er, sorry can't answer your question directly, but I've fainted, in the past, from blood draws and I have no phobia to blood draws. I think the short answer will be along the lines that syncope and anxiety are not necessarily related, they operate on different aspects of the physiology, even if there is overlap.

This may not really be a psychology question but a physiology question, so hopefully one of the helpful mefi Dr's will pop in and clear things up.

The wiki has some interesting background into on fainting
posted by edgeways at 10:41 PM on July 29, 2007

I think, actually, that the fainting reflex doesn't have anything to do with anxiety. I have the same blood drawing phobia and the last time I had it done I took an anti-anxiety pill. I was clearheaded enough to not freak out during the act but I still almost passed out after a few minutes.
posted by sugarfish at 6:30 AM on July 30, 2007

Best answer: Vasovagal syncope happens when your blood pressure drops. The explanation I heard is that if you're injured (as your body fears you will be when someone comes at you with pointy objects), you want your blood pressure low so that you're less likely to bleed to death.

Anxiety increases your blood pressure, in the typical "fight, flee, or freeze" response. Your heart rate increases and adrenaline surges to prepare your body to act.

Basically, if you're already injured, fainting lets your body turn off unnecessary functions (like conscious brain functioning) and to keep blood in your body in order to preserve energy and blood to keep you physically alive. If you're about to be attacked, your body instead wants to move as quickly as possible to defend yourself or avoid the attack. Blood-injection-injury phobias trigger the first response; panic symptoms are related to the second.
posted by occhiblu at 9:22 AM on July 30, 2007