A study published recently in Molecular Psychiatry has found a possible link between playing first-person action games and the loss of grey matter from your brain's memory center. The four-year study, which tracked groups of 18-to-30-year-olds, found that those who played first-person games for more than six hours per week showed a reduction of grey matter in the hippocampus, the part of the brain that plays a role in the consolidation of information from short-term to long term memories, as well as spatial memory, which is used for navigation and spacial orientation.

"The hippocampus is critical to healthy cognition, yet results in the current study show that action video game players have reduced grey matter within the hippocampus," reads the introduction to the report. "A subsequent randomised longitudinal training experiment demonstrated that ﬁrst-person shooting games reduce grey matter within the hippocampus in participants using non-spatial memory strategies."

I can't read the full study myself—not due to my potentially damaged brain but because it appears to be behind a $700 paywall—but CBC News has a nice summary. The study was undertaken by Dr. Gregory West, associate professor of psychology at the Université de Montréal, and Véronique Bohbot, associate professor at McGill University. Among the subjects of the study—chosen because they had not been gamers previously—85% of those who played FPS games for more than 90 hours demonstrated a "statistically significant" drop in hippocampal matter.

So, that doesn't sound like great news, especially if, like me, you've been playing FPS games since they were invented. People with reduced grey matter in the hippocampus have a higher risk for conditions such as depression and Alzheimer's disease. If you play other types of games, the same study has some nicer news: a control group comprised of subjects playing "3D platform games" displayed "growth in either the hippocampus or the functionally connected entorhinal cortex."

Don't freak out, though, FPS players. Dr. West said this will require much more study in the future before there is a definitive link, and even if you are losing grey matter from playing CS:GO or Overwatch, it doesn't necessarily mean you're in danger.

Prof. Andrew Przybylski of Oxford University, for example, is skeptical of the study. "Just because hippocampal size can be correlated with some things that we are worried about in other populations," he says, "does not mean there is actually some consistent, unlawful connection between hippocampus size and dementia."