New brain research shows that the brains of problem gamblers have more difficulty than non-addicts in anticipating monetary rewards.

On Wednesday, JAMA Psychiatry published the findings of researchers at Radboud University in the Netherlands who analyzed 25 neuroimaging studies involving brain reward sensitivity of over 1,200 participants, about half of whom were addicted to either gambling or substances (coke, smack, weed, alcohol, nicotine, etc.) and the other half a control group of non-addicts.

The researchers set out to determine the nature and direction of “pathophysiologic reward-processing disruptions in the brain during anticipation and outcome notification of monetary rewards.”

The addicts’ brains showed decreased activation in the striatum – a core region of the brain’s reward circuit – during reward anticipation when compared to the non-addicts. Radboud researcher Arnt Schellekens said this suggested the addicts “did not expect much from the reward.”