Here’s some news that could put an interesting twist in the gambling addiction/genetics debate (not to mention supply new reasons to sue drug companies): ABC News reports that several of the drugs prescribed for Parkinson’s disease and restless legs syndrome can cause a range of dangerous behavioral side effects including increased drinking, drug use, risky sex, and gambling.

The drugs, which include Mirapex and Requip, are dopamine agonists, which mimic dopamine in the brain to boost the movement and coordination centers—and also stimulate the pleasure response by reinforcing certain behaviors. Unwitting patients who’ve taken the drugs have wound up with costly gambling habits, DUI arrests, and compulsive eating disorders, as well as even stranger effects—one man reportedly plays basketball for up to 36 hours at a time, while another compulsively fishes.

Given that more than 10 million prescriptions have been written for Mirapex alone, it’s not unlikely that we’ll see some serious fallout, be it motorists killed by a drunk driver on the drug, or an STD spike as a result of risky sexual practices (which are already on the rise among seniors, the demographic most likely to be taking meds for Parkinson’s and RLS).

As such, it’s worth it to start asking to what degree patients should be held legally responsible for their actions while taking the drug—and, perhaps even more importantly for lawyers, whether the drug companies can be held at all responsible for all that irresponsible boozing and sex.