Objective: We aimed to investigate the effects of Korean red ginseng (KRG) supplementation on gray matter volume of the human brain which could be related to cognitive enhancing effects of KRG. Methods: In this randomized, double-blind, placebo-controlled study, 51 healthy individuals were assigned to receive either KRG (1000 mg/day, n ¼ 26) or placebo (n ¼ 25) for 8 weeks. Gray matter volume of the whole brain was measured using voxel-based morphometry based on high-resolution T1-weighted magnetic resonance images acquired at baseline and week 8. The standardized composite cognitive scores of executive function, attention, and memory were also evaluated at baseline and week 8. Changes in gray matter volume as well as the composite cognitive scores were compared between the KRG and placebo groups. Results: Following 8 weeks of KRG supplementation, the gray matter volume of the left parahippocampal gyrus increased significantly in the KRG group, relative to the placebo group (p for interaction < 0.001). The KRG group also showed greater magnitude of enhancement in the composite cognitive scores relative to the placebo group (p for interaction ¼ 0.03). Conclusions: Gray matter volume increase in the parahippocampus may be a key neural change as induced by KRG supplementation, which could be associated with cognitive enhancement. K E Y W O R D S brain magnetic resonance imaging, cognition, gray matter, Korean red ginseng, voxel-based morphometry 1 | INTRODUCTION Korean red ginseng (KRG), also known as Panax ginseng, is a medicinal plant that has been used as a safe dietary supplement (Choi, 2008). Having ginsenosides as the major active ingredients, KRG has been reported to be potentially beneficial to a wide range of symptoms including physical, psychological, and cognitive dysfunctions
Objective This study aimed to investigate the relationship between insulin resistance and markers of neuronal viability and energy metabolism, as well as the additive effects of overweight or obesity, in individuals with type 2 diabetes mellitus (T2DM). Methods Using 1H‐magnetic resonance spectroscopy, prefrontal N‐acetyl aspartate (NAA) and creatine levels, markers for neuronal viability and energy metabolism, respectively, were measured in 50 adults with overweight or obesity and T2DM (T2DM‐O; aged 49.0 ± 7.4 years; 50% female), 50 adults with normal weight and T2DM (T2DM‐N), and 50 healthy adults with normal weight (healthy‐control [HC] group) matched for age and sex. The homeostatic model assessment for insulin resistance levels were calculated to assess insulin resistance. Results Prefrontal NAA levels were lower in the T2DM‐O group relative to the HC group (t = −2.51, P = 0.013). Higher insulin resistance was associated with lower prefrontal NAA levels in the T2DM‐O group (t = −2.21, P = 0.032) but not in the T2DM‐N group (t = −0.72, P = 0.48). Prefrontal creatine levels did not differ across the three groups. Conclusions Overweight and obesity might contribute to T2DM‐related neuronal viability deficits and could be the key links that connect insulin resistance to the decreased neuronal viability in the human diabetic brain.
Purpose To investigate the cerebral blood flow (CBF) alterations associated with poor sleep quality and memory performance in firefighters. Participants and Methods Thirty-seven firefighters (the FF group) and 37 non-firefighter controls (the control group) with sleep complaints were enrolled in this study. We performed brain arterial spin labeling perfusion magnetic resonance imaging (MRI) and compared the CBF between the two groups using whole-brain voxel-wise analyses. Self-reported sleep problems and actigraphy-measured sleep parameters, including the sleep efficiency, wake after sleep onset (WASO), total sleep time, and sleep latency, were assessed. Spatial working memory and learning performances were evaluated on the day of the MRI scan. Results The FF group, relative to the control group, had lower CBF in the right hemispheric regions: Middle temporal/lateral occipital, orbitofrontal, and insular cortices. Lower CBF in the right orbitofrontal cortex was linearly associated with poor sleep quality, as indicated by lower sleep efficiency and longer WASO. The CBF of the right insular cortex was also associated with longer WASO. Despite comparable degrees of self-reported sleep problems between the two groups, the FF group had lower sleep efficiency and longer WASO in the actigraphy, and lower spatial working memory and learning performance, relative to the control group. Poor sleep efficiency was linearly associated with lower spatial working memory performance. Conclusion These results demonstrated an association of poor sleep quality with decreased brain perfusion in the right orbitofrontal and insular cortices, as well as with reduced working memory performance.
Computerized relaxation training has been suggested as an effective and easily accessible intervention for individuals with psychological distress. To better elucidate the neural mechanism that underpins the effects of relaxation training, we investigated whether a 10-session computerized relaxation training program changed prefrontal gamma-aminobutyric acid (GABA) levels and cerebral blood flow (CBF) in women with psychological distress. We specifically focused on women since they were reported to be more vulnerable to develop stress-related disorders than men. Nineteen women with psychological distress but without a diagnosis of psychiatric disorders received the 10-day computerized relaxation training program that consisted of 30-min cognitive-relaxation training and 10-min breathing-relaxation training per day. At baseline and post-intervention, perceived stress levels, anxiety, fatigue, and sleep quality were assessed by self-report questionnaires. Brain magnetic resonance spectroscopy and arterial spin labeling scans were also performed before and after the intervention to evaluate GABA levels and relative CBF in the prefrontal region. Levels of perceived stress (t = 4.02, P < 0.001), anxiety (z = 2.33, P = 0.02), fatigue (t = 3.35, P = 0.004), and sleep quality (t = 4.14, P < 0.001) improved following 10 sessions of computerized relaxation training, resulting in a significant relief in composite scores of stress-related symptoms (t = −5.25, P < 0.001). The prefrontal GABA levels decreased (t = 2.53, P = 0.02), while relative CBF increased (t = −3.32, P = 0.004) after the intervention. In addition, a greater increase in relative prefrontal CBF was associated with better composite scores of stress-related symptoms following the intervention (t = 2.22, P = 0.04). The current findings suggest that computerized relaxation training may improve stress-related symptoms through modulating the prefrontal GABA levels and CBF in women with psychological distress.
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