>"But if you are close to someone who is a user, over the long run you will notice differences. Sometimes its just that they don't have the same spark."

The loss of a spark can happen regardless of drug use. Work in an unsupportive environment over a long period of time, a breakup, or the failure to achieve a long-sought goal can cause a person to change over time. In addition, the underlying condition that the medication is treating may cause the effect, which could have been worse had the medication not been prescribed.

It's plausible that medications may have understudied long-term effects, but there are too many confounding causes to attribute a behavioral change to long-term medication use.