Associations between anxiety, depression, and risk of suicidal behaviors in Chinese medical college students.

Background: Previous studies have established a strong association between depression and suicidal behaviors, yet the relationship between anxiety and suicidal behaviors remains unclear. This study examines whether anxiety and depression are independent risk factors for suicidal behaviors in medical college students, and further, whether anxiety may increase the greater risk of suicidal behaviors (SB) in participants with depression. Methods: This cross-sectional study was conducted among 4,882 medical students. Demographic information, anxiety, and depression data were collected using online questionnaires or through a widely used social media app named WeChat. Results: Anxiety and depression were independent risk factors for suicidal behaviors, and levels of risk correlated positively with the severity of both anxiety and depressive symptoms. A dose-response relationship was identified between the severity of anxiety and the risk of SB, as well as the severity of depression and SB. Furthermore, anxiety increased the risk of suicidal behaviors in participants with depression, with a dose-response relationship between the severity of anxiety symptoms and the risk of SB. Conclusion: The findings highlight the importance of screening for anxiety and depressive symptoms in medical college students, as well as reducing anxiety in addition to depressive symptoms in treatment. This study provides valuable data as a reference for clinicians for suicide risk assessments.

Walking exercise alters pedunculopontine nucleus connectivity in Parkinson's disease in a dose-dependent manner.

Background: Gait disturbances are critical motor symptoms in Parkinson's disease (PD). The mechanisms of gait impairment in PD are not entirely understood but likely involve changes in the Pedunculopontine Nucleus (PPN), a critical locomotion center, and its associated connections. Exercise is universally accepted as helpful in PD, but the extent and intensity of exercise required for plastic changes are unclear. Methods: Twenty-seven PD subjects participated in a 3-month gait training intervention. Clinical assessments and resting-state functional magnetic resonance imaging were performed at baseline and 3 months after exercise. Functional connectivity of PPN was assessed by combining the methods of partial least squares, conditional dependence and partial correlation. In addition, paired t-tests were used to examine the effect of exercise on PPN functional connectivity and clinical measures, and Pearson's correlation was used to assess the association between altered PPN functional connectivity and clinical measures. Results: Exercise significantly improved Unified Parkinson's Disease Rating Scale-III (UPDRS-III). A significant increase in right PPN functional connectivity was observed after exercise, which did not correlate with motor improvement. However, the decrease in left PPN functional connectivity significantly correlated with the improvement in UPDRS-III and was linearly related to both number of walks and the duration of walks. In addition, exercise induced a significant increase in the laterality of PPN connectivity strength, which correlated with motor improvement. Conclusion: PPN functional connectivity is modifiable by walking exercise in both a dose-independent (right PPN and laterality of PPN connectivity strength) and dose-dependent (left PPN) manner. The PPN may contribute to pathological and compensatory processes in PD gait control. The observed gait improvement by walking exercise is most likely due to the reversal of the maladaptive compensatory mechanism. Altered PPN functional connectivity can be a marker for exercise-induced motor improvement in PD.

Excessive daytime sleepiness in medical students of Hunan province: Prevalence, correlates, and its relationship with suicidal behaviors.

BACKGROUND: Excessive daytime sleepiness (EDS) is common among medical students, but may have some serious consequences. This study aimed to investigate the prevalence and correlates of EDS among the medical students of Hunan Province, China. The correlation between EDS and suicidal ideation in our participants was also explored. METHODS: A cross-sectional study was employed among 4882 students from three medical schools in Hunan Province. Each student completed a survey on demographic variables, daytime sleepiness (Epworth sleepiness scale), anxiety (Self-Rating Anxiety Scale), depression (Self-Rating Depression Scale), and suicidal behaviors. Logistic regression analyses were conducted to investigate the risk factors for EDS among all participants and suicidal behaviors among those with EDS. RESULTS: Overall, the prevalence of EDS in this population was 24.6%. Multivariate logistic regression analysis revealed that being female, alcohol consumption, a history of physical disorder, body mass index, anxiety, depression, and suicidal ideation were independent correlates for EDS. Moreover, the prevalence of suicidal ideation among EDS participants was 38.6%, variables such as physical disorder history, age, anxiety, or depression were independently associated with suicidal ideation. LIMITATIONS: No causal relationships could be established as this was a cross-sectional study. Recall biases might exist due to the utilization of self-reported measurements. Moreover, participants were primarily female medical students (89%,4345/4882). CONCLUSION: EDS is very common among medical students. Special attention should be paid to students with EDS, especially when risks for suicidal ideation are particularly high among this population. These data are valuable for healthcare professionals in assessing the risks of suicide among participants with EDS.

Differentiating cognitive or motor dimensions associated with the perception of fall-related self-efficacy in Parkinson's disease.

In Parkinson's disease (PD), concurrent declines in cognitive and motor domain function can severely limit an individual's ability to conduct daily tasks. Current diagnostic methods, however, lack precision in differentiating domain-specific contributions of cognitive or motor impairments based on a patients' clinical manifestation. Fear of falling (FOF) is a common clinical manifestation among the elderly, in which both cognitive and motor impairments can lead to significant barriers to a patients' physical and social activities. The present study evaluated whether a set of analytical and machine-learning approaches could be used to help delineate boundary conditions and separate cognitive and motor contributions to a patient's own perception of self-efficacy and FOF. Cognitive and motor clinical scores, in conjunction with FOF, were collected from 57 Parkinson's patients during a multi-center rehabilitation intervention trial. Statistical methodology was used to extract a subset of uncorrelated cognitive and motor components associated with cognitive and motor predictors, which were then used to independently identify and visualize cognitive and motor dimensions associated with FOF. We found that a central cognitive process, extracted from tests of executive, attentional, and visuoperceptive function, was a unique and significant independent cognitive predictor of FOF in PD. In addition, we provide evidence that the approaches described here may be used to computationally discern specific types of FOF based on separable cognitive or motor models. Our results are consistent with a contemporary model that the deterioration of a central cognitive mechanism that modulates self-efficacy also plays a critical role in FOF in PD.

Peripheral GABAA receptor activation modulates rat tongue afferent mechanical sensitivity.

OBJECTIVES: The expression of GABA(A) receptors and the effects of GABAA receptor agonists on the response properties of tongue afferent fibres were investigated in female rats to determine if peripheral GABA receptors might be a target of topical benzodiazepines when used for pain relief in burning mouth syndrome patients. DESIGN: Nerve fibres in tongue sections from six female rats were identified using protein gene product 9.5, and the co-expression of the γ subunit of GABAA receptor and substance P assessed in the nerve fibres. In vivo extracellular recordings of trigeminal ganglion neurons that innervate the tongue were undertaken in 27 anesthetised female rats and their responses to mechanical and thermal stimulation characterised before and after topical application of GABA, the GABA(A) receptor selective agonist muscimol or vehicle control. RESULTS: The vast majority of tongue nerve fibres examined (95%) expressed the γ subunit of GABA(A) receptor. Bath application of muscimol, but not GABA, significantly increased the mechanical thresholds of tongue afferent fibres compared to vehicle, but only after the tongue had been heated with 60°C water. CONCLUSIONS: GABA(A) receptors are present on tongue nerve fibres and their activation alters the mechanical sensitivity these fibres. These findings suggest that topical application of benzodiazepines to the oral mucosa may decrease pain in burning mouth syndrome through a local action on peripheral GABAA receptors.

Parkinson's disease rigidity: relation to brain connectivity and motor performance.

OBJECTIVE: (1) To determine the brain connectivity pattern associated with clinical rigidity scores in Parkinson's disease (PD) and (2) to determine the relation between clinically assessed rigidity and quantitative metrics of motor performance. BACKGROUND: Rigidity, the resistance to passive movement, is exacerbated in PD by asking the subject to move the contralateral limb, implying that rigidity involves a distributed brain network. Rigidity mainly affects subjects when they attempt to move; yet the relation between clinical rigidity scores and quantitative aspects of motor performance are unknown. METHODS: Ten clinically diagnosed PD patients (off-medication) and 10 controls were recruited to perform an fMRI squeeze-bulb tracking task that included both visually guided and internally guided features. The direct functional connectivity between anatomically defined regions of interest was assessed with Dynamic Bayesian Networks (DBNs). Tracking performance was assessed by fitting Linear Dynamical System (LDS) models to the motor performance, and was compared to the clinical rigidity scores. A cross-validated Least Absolute Shrinkage and Selection Operator (LASSO) regression method was used to determine the brain connectivity network that best predicted clinical rigidity scores. RESULTS: The damping ratio of the LDS models significantly correlated with clinical rigidity scores (p = 0.014). An fMRI connectivity network in subcortical and primary and premotor cortical regions accurately predicted clinical rigidity scores (p < 10(-5)). CONCLUSION: A widely distributed cortical/subcortical network is associated with rigidity observed in PD patients, which reinforces the importance of altered functional connectivity in the pathophysiology of PD. PD subjects with higher rigidity scores tend to have less overshoot in their tracking performance, and damping ratio may represent a robust, quantitative marker of the motoric effects of increasing rigidity.