Gamers beware: when you’re blasting through the newest shooter, you might not just be killing virtual bad guys, but some of your brain power as well.  

A new study, conducted by Université de Montreal researchers and published in the latest issue of the Molecular Psychiatry journal, found that avid players of action video games have less grey matter in their hippocampus, a section of the brain that is important for memory and spatial awareness.

According to the study, reduced grey matter in that area of the brain is associated with higher risks of disorders like alzheimer’s, schizophrenia, PTSD and depression.

“If action video games lead to decreases in grey matter in the hippocampus [of young adults], caution should be exerted when encouraging their use... [by] children, young adults and older adults to promote cognitive skills such as visual short-term memory and visual attention," the authors wrote.

While prior research had shown a relationship between playing video games and increased hand-eye coordination and other cognitive functions, study lead author Greg West said it appears that when it comes to action games, there’s a tradeoff.

"Video games have been shown to benefit certain cognitive systems in the brain, mainly related to visual attention and short-term memory," said West. "But there is also behavioral evidence that there might be a cost to that, in terms of the impact on the hippocampus.”