I keep hearing about these and finally found one. This is a 2011 decision and shows the misogynist reasoning need to arrive at this. I have heard of this with PTSD but not  the Bipolar route. Check out the “at least as likely as not” train of conjecture. Don’t get me wrong. I’m not dissing the Vet, just commenting on creative reasoning.  It takes me back to Michael Keaton in Mr. Mom when he opined about his remodel-“220-221 (volts). Whatever it takes”.

http://www.va.gov/vetapp11/Files2/1111288.txt

This is rich:

In light of the above, the Board finds that the Veteran's hepatitis 
C is at least as likely as not due to his IV drug use, but that his
 IV drug use is at least as likely as not due to his 
service-connected bipolar disorder.  Accordingly, the Board 
concludes that that Veteran's hepatitis C is at least as likely as 
not causally or etiologically related to his service-connected 
bipolar disorder.  Service connection for hepatitis C is granted.