Summary: Genetics testing revealed those with a greater susceptibility to stress have at least one copy of a variation in the serotonin transporter gene. Additionally, changes to connections in the middle temporal gyrus related to changes in cognitive performance during stress.
Source: University of Missouri-Columbia
Stress response is the body’s normal physiological reaction to a situation that it perceives as threatening. However, stress can also impact important aspects of thinking, including problem solving. Researchers from the University of Missouri School of Medicine and the MU Thompson Center for Autism and Neurodevelopmental Disorders have discovered a potential indicator of how stress affects the brain and alters its ability to problem solve. These findings could ultimately understand and optimize treatment for patients suffering from stress-related illnesses.
The results come from two companion studies involving 45 healthy college-age individuals who were genetically tested for the presence of at least one copy of a variation in the serotonin transporter gene (SERT), which is associated with greater susceptibility to stress. Participants were given a series of tests while being monitored by magnetic resonance imaging (MRI). The first test involved verbal processing tasks where participants were asked in two sessions (stress and no-stress control) how many items from a category they could name in a minute. Researchers found that stress did not impact overall performance for either gender or gene group, but effects of stress on performance did relate to changes in the brain’s overall functional connectivity in all participants, suggesting the brain could provide a biomarker for the effects of stress on cognition.
“This may begin to help us understand what is going on in the brain when stress is affecting cognition,” said supervising investigator David Beversdorf, MD, professor of radiology, neurology and psychology at the MU School of Medicine and the MU Thompson Center. “If we can develop an intervention that affects the brain’s networks, we may be able to mitigate the cognitively impairing effects of stress.”
In the other study, the same participants completed problem solving tasks in two sessions (stress and no-stress control) during MRI testing. Researchers discovered changes to the connections involving a section of the brain called the middle temporal gyrus related to changes in performance during stress in participants. This relationship depended on the presence or absence of the stress-related variant of the SERT gene, indicating a potential specific brain marker associated with susceptibility to stress during problem solving.
“When you look at the relationship of the imaging changes in the brain and the performance changes resulting from stress, the left middle temporal gyrus appears to be a critical hub, and this relationship depends on an individual’s genetic susceptibility to stress,” Beversdorf said. “The next step is to look at this in specific patient populations. Is this effect greater in PTSD populations or test anxiety patients? And if we can understand how to mitigate those effects, it could be very helpful to these patients.”
In addition to Beversdorf, the study authors include former University of Missouri Interdisciplinary Neuroscience Program graduate student and lead author Neetu Nair, PhD, now a postdoctoral fellow in the Department of Psychiatry at University of Missouri; Bradley Ferguson, PhD, assistant research professor of health psychology; and Shawn Christ, PhD, associate professor, Department of Psychology. Other collaborators include John Hegarty, PhD, a former graduate student in the Interdisciplinary Neuroscience Program and now a postdoctoral research fellow at the Stanford Autism Center; Patrick Hecht, PhD, also a former graduate student in the Interdisciplinary Neuroscience Program; and Michael Tilley, PhD, Assistant Professor of Biology at Central Methodist University.
The study, “Effects of stress on functional connectivity during verbal processing,” was recently published in the journal Brain Imaging and Behavior. The companion study, “Effects of stress on functional connectivity during problem solving,” published in the journal NeuroImage. Research reported in these publications was supported by a grant from the University of Missouri Research Board and the University of Missouri Mission Enhancement Fund. The authors of the study declare that they have no conflicts of interest related to this study. The content is solely the responsibility of the authors and does not necessarily represent the views of the funding agencies.
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Source: University of Missouri-Columbia Media Contacts: Eric Maze – University of Missouri-Columbia Image Source: The image is credited to David Beversdorf et al/NeuroImage.
Effects of stress on functional connectivity during problem solving
Aim Our purpose was to examine how stress affects functional connectivity (FC) in language processing regions of the brain during a verbal problem solving task associated with creativity. We additionally explored how gender and the presence of the stress-susceptible short allele of the serotonin transporter gene polymorphism influenced this effect.
Methods Forty-five healthy participants (Mean age: 19.6 ± 1.6 years; 28 females) were recruited to be a part of this study and genotyped to determine the presence or absence of at least one copy of the short (S) allele of the serotonin transporter gene, which is associated with greater susceptibility to stress. The participants underwent functional magnetic resonance imaging in two separate sessions (stress and no stress control). One session utilized a modified version of the Montreal Imaging Stress Test (MIST) to induce stress while the other session consisted of a no stress control task. The MIST and control tasks were interleaved with task blocks during which the participants performed the compound remote associates task, a convergent task that engages divergent thinking, which is a critical component of creativity. We examined the relationship between stress effects on performance and effects on connectivity of language processing regions activated during this task.
Results There was no main effect of stress on functional connectivity for individual ROI pairs. However, in the examination of whether stress effects on performance related to effects on connectivity, changes in middle temporal gyrus connectivity with stress correlated positively with changes in solution latency for individuals with the S allele, but anti-correlated for those with only the L allele. A trend towards a gene × stress interaction on solution latency was also observed.
Discussion Results from the study suggest that genetic susceptibility to stress, such as the presence of the S allele, affects neural correlates of performance on tasks related to verbal problem solving, as indicated by connectivity of the middle temporal gyrus. Future work will need to determine whether connectivity of the middle temporal gyrus serves as a marker for the effect of stress susceptibility on cognition, extending into stress susceptible patient populations.
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