Two new U.S. studies shed light on opioid epidemic
The findings are important because joint replacement is increasingly common and there are sharply rising rates of opioid overdoses in the United States.
Each drink worsens decision-making, possibly upping HIV risk
'Keep working at it' could be key to success, studies suggest
Targeting certain regions affects smokers' satisfaction, which plays role in addiction
The part of the brain affected by the event seems to make a difference, researchers find