Men addicted to internet gaming have different levels of activity in areas of the brain associated with impulsiveness than women with the same addiction, a new study shows.

"Altered brain functions may be one of the factors causing the sex variances in the severity of internet dependency," said lead researcher Yawen Sun, MD, from Renji Hospital at the Shanghai Jiao Tong University School of Medicine.

Men with internet gaming disorder — specifically those who spend a lot of time playing massive multiplayer online role-playing games, such as World of Warcraft — have less activity in the superior frontal gyrus, an area of the prefrontal lobe associated with impulse control. But women with the same disorder do not have these differences, she explained.

Previous neuroimaging studies have "revealed sex differences in impulsivity characteristics in people with positive family histories for alcoholism," Sun reported at the Radiological Society of North America 2018 Annual Meeting in Chicago. And in people with such family histories, activation of the inferior frontal gyrus during inhibitory responses is greater.

This effect is more pronounced in men with a family history of alcoholism than women (Neuropsychopharmacology. 2013;38:1854-1863). In addition, a larger right superior frontal gyrus, along with greater impulsivity, has been shown in male methamphetamine users (Brain Struct Funct. 2017;222:215-227).

"I speculate that men are more susceptible to the effects of long-term online game playing than women. The changes in the brain may be one of the risk factors, not the result," Sun explained, saying she hopes to do more research to explore this hypothesis.

The changes in the brain may be one of the risk factors, not the result.

It has been shown that the brains of men and women are different (Science. Posted online April 11, 2017) and that men might be more predisposed to excessive gaming. And although sex differences in internet gaming disorder have been studied using task functional MRI (fMRI) (Prog Neuropsychopharmacol Biol Psychiatry. 2019;88:1-10), no resting-state fMRI studies have compared the brains of men and women who engage in excessive amounts of multiplayer gaming.

Sun and her colleagues assessed 32 men and 23 women with gaming disorders (average age, about 22 years) and 52 age-matched control subjects. The men in the group played an average of 35.40 hours per week and the women played an average of 33.09 hours.

Internet gaming disorder, defined as the excessive and recurrent use of online internet games, was evaluated with the Internet Addiction Diagnostic Questionnaire (IADQ) modified by Beard (Cyberpsychol Behav. 2001;4:377-383).

"Gaming is different from substance abuse or drug addiction in that no substance or chemical intake is involved," Sun pointed out. "However, excessive internet use may lead to physical dependence similar to that observed in other addictions."

All 105 study participants — right-handed native Chinese speakers — underwent resting-state fMRI. During the procedure, they were instructed to relax with their eyes closed and not engage in any directed, systematic thought.

Amplitude of low frequency fluctuation (ALFF) and seed-based functional connectivity were used to identify group differences in brain disease and obtain diagnostic and prognostic information. The Barratt Impulsiveness Scale 11 (BIS-11) was used to assess behavioral inhibition function.

ALFF values in the orbital part of the left superior frontal gyrus were lower in men than in women with gaming disorder, and BIS-11 scores were higher. In addition, the correlation coefficient between ALFF values and BIS-11 scores was stronger in men than in women with gaming disorder (–0.439 vs 0.165; P = .0307).

In men, there was less functional connectivity between the superior frontal gyrus and the posterior cingulate cortex, the right angular gyrus, and the right dorsolateral prefrontal cortex in the gaming group than in the control group.

In those with gaming disorder, there was less functional connectivity between the superior frontal gyrus and the posterior cingulate cortex in men than in women.

These findings suggest that gaming might be related to sex-specific patterns of functional connectivity in men and women. Men had alterations in regional and network-level brain function, such as lower levels of brain activity in the superior frontal gyrus, Sun explained.

Men have higher levels of sensation-seeking behavior and more motivation to succeed in computer games, she told Medscape Medical News, which might predispose them to a higher tendency for gaming disorder.

However, there could be other factors involved in the scores. "High levels of testosterone in male adolescents may contribute to characteristics related to gaming, such as taking greater risks, being less responsive to punishment, and exhibiting more aggressive behaviors," she explained.

The overall prevalence of gaming disorder in adolescents in Europe was shown to be 4.4%, although it was higher in males than females (5.2% vs 3.8%), in one epidemiologic study (Addiction. 2012;107:2210-2222).

In a study of Hong Kong adolescents, the prevalence rate of gaming disorder ranged from 17.0% to 26.8% (J Pediatr Adolesc Gynecol. 2016;29[1 suppl]:S22-S30).

"The fMRI technology provides an opportunity to further explore the neural mechanisms underlying gaming disorder," although not many neuroimaging studies have tackled this issue, Sun said.

We don't know if this is a manifestation of a pre-existing neurobiology that can be for gaming or drug abuse or another type of maladaptive behavior.

The World Health Organization recently recognized gaming disorder as a diagnosable condition, but "the American Psychiatric Association is not ready to fully classify it," said Vincent Mathews, MD, Medical College of Wisconsin in Milwaukee.

"We don't know if this is a manifestation of a pre-existing neurobiology that can be for gaming or drug abuse or another type of maladaptive behavior," he told Medscape Medical News. "Is it a separate condition or is it an internet condition? Is the gaming part the unique part?"

This study doesn't answer those questions, he noted, adding that it is important to determine whether gaming disorder "is manifestation of something else."

In addition, "the study had relatively small numbers, and it's hard to know how well other comorbidities were screened out," Mathews said.

This study was funded by the National Natural Science Foundation of China (No. 81571650 and 81571757); Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support (No. 20172013); Shanghai Science and Technology Committee Medical Guide Project (No. 17411964300); Medical Engineering Cross Research Foundation of Shanghai Jiao Tong University (No. YG2017QN47); Research Seed Fund of Renji Hospital, School of Medicine, Shanghai Jiao Tong University (RJZZ17-016); and Incubating Program for Clinical Research and Innovation of Renji Hospital, School of Medicine, Shanghai Jiao Tong University (PYIII-17-027). Sun and Mathews have disclosed no relevant financial relationships.

Radiological Society of North America (RSNA) 2018 Annual Meeting: Abstract SSK16-08. Presented November 28, 2018.

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