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13-05-2019 17:34:28

How Brain Response to Emotional Experiences Varies in Multiple Sclerosis

Emotional experiences had abnormal variability in brain response for women with multiple sclerosis (MS), according to a study published in Cortex.

Researchers analyzed the relationship between modification in emotional experience and changes in the fronto-limbic recruitment organization in MS. Women who were right-hand dominant, had an Expanded Disability Status Scale score ≤5, diagnosed as having relapsing-remitting MS, and receiving beta-interferon treatment were included in the study. A control group of women matched on age, education level, and right-handedness was also evaluated.

Functional magnetic resonance imaging (fMRI) was used to detect hemodynamic response to positive, negative, and neutral emotional pictures observed while being scanned. Whole-brain analysis included evaluating images between positive vs neutral and negative vs neutral. Brain regions-of-interest analysis 14 regions specific to emotional scene processing. Participants rated their feelings of valence and arousal to the same pictures both during and after fMRI analysis. Data were collected for executive functions of inhibition, flexibility, and working memory. Processing speed, anxiety, alexithymia, and fatigue data were also obtained.

Significant differences between MS (n=25) and control (n=27) cohorts in neuropsychological assessment and self-reported questionnaires included lower scores on the Symbol Digit Modalities Test (P =.017), increased depression (P <.0001), increased anxiety (P =.001), increased alexithymia (P <.0001), and increased fatigue (P <.0001).

Post scan analysis of raw values showed no difference between the 2 cohorts. Analysis of disparity, however, revealed lower score for valence (positive valence P =.001; negative valence P =.0036; neutral valence P =.016) and arousal (positive valence P =.024; negative valence P =.003) in the MS cohort when compared against controls.

Analysis of the brain regions-of-interest showed abnormal variability, before correction, in left inferior orbitofrontal gyrus (positive valence P =.002), left amygdala (negative valence P =.004), right fusiform gyrus (negative valence P =.008), right caudate nucleus (negative valence P =.009), and right pallidum (negative valence P =.01) in the MS cohort. Regression analysis of the left inferior orbitofrontal region in the MS cohort revealed a total score of clinical and neurological data which negatively correlated with the functional brain variability signal in the positive emotional condition.

A limitation of this study, as pointed out by study authors, included the inability to discriminate hypo- or hypersignal. They also point out that lower statistical power due to sample size and the inclusion of only women could limit the impact of these findings. Further, indications from previous studies suggesting the impact of beta-interferon treatment on emotional disorders should be taken into account.

The researchers go on to conclude that this study is “the first evidence of a modification in the pleasant emotional experience in women suffering from MS and highlights the underlying brain mechanisms.”

This study was funded by Merck Serono and FORNASEP

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