…researchers used positron emission tomography (PET) scans to measure opioid receptor levels in the brains of 14 pathological gamblers and 15 healthy volunteers. There was no difference between the two groups. However, when they scanned their brains after giving each participant an amphetamine tablet, which causes a high known as an endorphin rush, they found that gamblers weren’t able to release as many endorphins. After the participants answered a questionnaire, they also found that gamblers experienced a lower feeling of euphoria. {read more here}