Action Video Games Linked to Gray Matter Reduction

Deborah Brauser

August 09, 2017

In three neuroimaging studies, investigators are cautioning against blanket encouragement of children and young and older adults to play video games in order to improve cognitive skills.

New research suggests that certain types of games – and an individual's own navigation style – may lead to decreased brain plasticity.

There were almost 100 total participants in the three studies. In the first, there were significantly greater reductions in gray matter in the left hippocampus in a group of habitual action video-game players (VGPs) than in a group of nonplayers.

Also, 83% of the VGPs were considered to be response learners rather than spatial learners, vs 43% of the non-VPGs. Spatial learners favor their hippocampus and rely on various landmarks to orient and navigate themselves through a game. Response learners favor the reward system/caudate nucleus and memorize a sequence's left and right turns.

The second study randomly assigned 43 non-VGPs to play 90 hours of either first-person shooting (action) games or 3-D platform games. Among the response-learners in the shooting-game group, hippocampal gray matter was reduced, whereas in the spatial learners, it was increased.

Among those playing 3-D games, both the response and spatial learners showed increases in gray matter, although in different brain areas.

In the third study, all 21 non-VGPs were assigned to play role-playing (action) video games. Echoing the second study's action-game group, gray matter was decreased in the response learners, whereas it was increased in the spatial learners.

"We studied the impact of different genres of video games on the hippocampus structure important for healthy cognition and memory," lead author Greg L. West, PhD, associate professor of psychology at the University of Montreal, Quebec, Canada, told Medscape Medical News.

Dr Greg West

The most surprising finding "was that people's navigation strategy had such a big impact on the effect of the game on the hippocampus," said Dr West. "That tells me that there is something quite different about these two types of learners."

The findings were published online August 7 in Molecular Psychiatry.

Cognitive Trade-off?

"The hippocampus and caudate nucleus memory systems each contributes to an individual's optimal function," write the investigators. They add that episodic memory and stress regulation are associated with the former, whereas the latter is part of the reward pathway and is associated with procedural memory.

Based on past research, "while engaging in behaviors that promote the caudate nucleus is important for developing habits as well as certain cognitive skills, such as implicit learning, the over reliance on this system may result in the underuse of the hippocampal memory system, leading to atrophy in this structure."

The researchers note that action games such as Call of Duty have been promoted as improving skills such as visual attention in all age groups. They wanted to see whether there was a trade-off in terms of reducing hippocampal gray matter.

The first study included 33 right-handed participants (88% men; mean age, 24 years). A questionnaire asked about use of first-person and third-person shooter games. Those who reported playing one of these types of games at least 6 hours per week in the past 6 months were considered to be action VGPs (n = 17; mean game time, 19.1 hours per week).

To determine the participants' memory strategies, all underwent a multipart virtual reality task, called the 4 on 8 virtual maze (4/8VM). For a spatial strategy, the gamers relied on the positions of landmarks such as trees and mountains to move around a target. For a response-learning strategy, counting from the starting point or another patterning system was used.

All participants also underwent MRI.

When comparing between-group differences in gray matter in the hippocampus, habitual action VGPs were found to have significant reductions in left hippocampal gray matter compared with the non-VGPs (P < .0005).

Game Type, Strategies Assessed

The second study, which had a longitudinal design, included 43 total participants. All were non-VGPs and were in their early 20s (33% men).

After undergoing the 4/8 VM, 21 of the participants underwent laboratory training in playing single-player shooting-action games, such as Call of Duty and Medal of Honor; 22 participants underwent training in playing 3-D platform games from the Super Mario series. For both groups, the training lasted a total of 90 hours over an average of 59 days.

The investigators "hypothesized that because the demands...require the speeded deployment of attention to make quick decisions and efficient motor responses, response learning would be promoted" in the action games.

Although response learning "might also be promoted in 3D-platform games, their design necessitate the player to rely on spatial learning to produce a cognitive map of the game's environment."

Posttraining MRI scans were compared with pretraining scans for both groups. Findings from the action-game group showed the following:

  • Response learners (n = 11) were found to have significant reductions in levels of gray matter in the right hippocampus (P < .001);

  • Spatial learners (n = 10) were found to have significant increases in gray matter in the left hippocampus (P < .001); and

  • The difference in hippocampal changes was significant between the two strategy groups (P < .0001).

For the platform-game group:

  • Response learners (n = 11) were found to have a significant increase in gray matter within the right hippocampus (P < .005); and

  • Spatial learners (n=11) were found to have a significant increase in gray matter in the right entorhinal cortex (P < .005).

Dr West noted that the platform-game players as a whole were found to have increases in gray matter in the hippocampal memory system. "So, that type of game benefited everyone in some fashion." He added that the hippocampus and entorhinal cortex "work in unison and are important biomarkers for cognitive health."

Positive and Negative Effects

In the third study, which also had a longitudinal design, a different group of 21 non-VGPs (38% men, all in their early 20s) were trained in the laboratory to play action role-playing games, such as Dead Island and Borderlands 2.

These games have the same shooting components as those used in the second study, "but with the additional element of forcing players to navigate in a large open world environment that is heavily dependent on an in-game Global Positioning System," write the researchers.

"In other words, players are encouraged to follow a rigid path...rather than use the external landmarks to navigate," they add.

In the full group, posttraining scans showed significant gray matter reductions in both the left and right hippocampus (P < .001 for both locations).

When split into two subgroups on the basis of navigation strategy, the response learners were found to have a "bilateral decrease" in gray matter in the left (P < .001) and right hippocampus (P < .0001), whereas the spatial learners were found to have significantly increased gray matter in both areas (both, P < .001).

"We believe this is the first study to demonstrate the positive and negative impact of action video games on the brain, thereby offering reconciliation of opposing views in the literature," write the investigators.


They note that further research, in conjunction with action-game designers, is needed to examine how to promote in-game spatial learning, rather than just response strategies.

"Further, because aging is associated with increased use of response learning strategies, our results underscore the need to carefully consider the parameters of the cognitive training tools that we employ to increase attention and short-term memory performance in this population."

Dr West noted that "some caution" should be paid to children because of the possibility of neurodevelopment problems and to patients with such neurologic conditions as Parkinson's disease, depression, or posttraumatic stress disorder.

"The take-home message is that we need to pay attention to the types of games we're recommending for children and for people with or at risk for certain cognitive disorders related to lower gray matter in the hippocampus," he said.

"At this point, the evidence suggests that 3D platform and logic and puzzle games are beneficial to the hippocampal memory system. So I would feel comfortable recommending that people play those types of games."

The research was funded by grants from Fonds de Recherche du Québec – Nature et Technologies and the Natural Science and Engineering Council of Canada. The study authors have reported no relevant financial relationships.

Mol Psychiatry. Published online August 7, 2017. Full article

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