Researchers in Montreal found that habitual players of action video games have less gray matter in their hippocampus (a part of the brain that regulates emotions and is associated with long-term memory and spatial navigation).
The greater the hippocampal atrophy the greater the risk of Alzheimer's disease as well as depression, schizophrenia and post-traumatic stress disorder.
Interestingly, researchers found that 90 hours of playing action video games (Call of Duty, Killzone, and Borderlands 2) led to hippocampal atrophy (shrinkage) while 90 hours of playing 3D-platform video games led to an INCREASE in gray matter within the hippocampus.
Mol Psychiatry. 2017 Aug 8