The C is very right here in my opinion. Cannabis only has an effect on you if you let it. But if you're really looking to see if weed is the cause, I think 3 months is a more realistic time period for proper evaluation. May seen like alot, but if you live to be 80 it's only 1/320 of your life. Pretty measly amount of time really... And you never know, you could find something out that will change the rest of your life. For example - Weed does/doesn't cause that effect.