Mazurek, Kevin A.

Abstract Workplace stress is one of the main sources of stress for adults, although physiological and cognitive factors may impact each person's stress response. Numerous studies have shown heart rate, heart rate variability, neural activity, and cognitive performance are affected by stress. Additionally, visual and auditory stimuli in one's environment have been shown to affect individuals' reaction to stressful events. To our knowledge, few studies have examined how each of these physiological and cognitive measures relate to one's perception of stress, the ability to recover from stress, and what environmental factors may help with stress recovery. Here, 80 healthy adults performed a laboratory-controlled stress induction task where they experienced and recovered from an acute psychological stressor (Trier Social Stress Test, TSST, using verbal math skills and a public presentation that was videotaped). Throughout the assessment, heart rate, heart rate variability, and neural activity were measured using wearable devices to assess changes before, during, and after the stressor. Additionally, participants were assessed their perceived stress levels at specific times throughout the assessment. After the psychological stressor, participants were randomly assigned to one of four recovery conditions within a multisensory relaxation room: Control (C), Auditory Only (A), Visual Only (V), or Combined Auditory and Visual (AV). During the stressor, anxiety, heart rate, and beta EEG power increased and high-frequency power and heart rate variability decreased, confirming participants reactivity to the stressor ( P < 0.01 for all vs. baseline). Only the V and AV conditions led to notable reductions in anxiety (15 and 17%, respectively) vs. the C condition, but these did not reach statistical significance. There was no difference between V and AV, suggesting a stronger impact of V. We observed no differences between conditions during recovery for HR and HRV. Overall, these findings suggest the visual features of the relaxation room impacted self-reported anxiety, however physiological and neurological effects did not demonstrate a statistically meaningful response.

Abstract Nerve conduction F-wave studies contain crucial information about subclinical motor dysfunction that can be used to diagnose patients with amyotrophic lateral sclerosis (ALS). However, F-wave responses are highly variable in morphology, making waveform interpretation challenging. Artificial intelligence techniques can extract time–frequency features to provide new insights into ALS diagnosis and prognosis. A retrospective analysis was performed on F-wave responses from 46 802 patients. Discrete wavelet transforms were applied to time-series waveform responses after stimulating ulnar, median, fibular and tibial nerves. Wavelet coefficient statistics, onset age, sex and body mass index were features for training a Gradient Boosting Machine model on 40 095 patients (5329 diagnosed with motor neuron disease). Model performance was tested on responses from 689 ALS patients meeting Gold Coast criteria and 689 age- and sex-matched controls. An exploratory analysis examined model performance on cohorts of patients with inclusion body myositis, cervical radiculopathy, lumbar radiculopathy or peripheral neuropathy, which can mimic ALS symptoms. Factors affecting survival were estimated through Cox proportional hazards regression. The model trained using wavelet features on the full waveform had 90% recall, 87% precision and 88% accuracy. Similar model performance was measured using features from only the M-wave or F-wave. Classification probabilities for ALS patients were statistically different from the diagnoses mimicking ALS symptoms (P &lt; 0.001, ANOVA, Tukey’s post hoc test). Higher model classification probabilities of ALS, older age at onset, and family history of ALS alone or with frontotemporal dementia were factors decreasing survival. Longer diagnostic delay and upper limb onset site were factors increasing survival. Model scores two standard deviations below the mean had 4 months increased survival (two standard deviations below had 3 months decreased survival). Artificial intelligence techniques extracted important information from F-wave responses to estimate a patient’s likelihood of ALS and their survival risks. Although the model can make predictions at a specific decision threshold as presented here, the true strength of such a model lies in its ability to provide probabilities about whether a patient is likely to have ALS in comparison to other mimicking diagnoses, such as inclusion body myositis, cervical or lumbar radiculopathy or peripheral neuropathy. These probabilities provide clinicians with additional information that they can use to make the final diagnosis with greater confidence and precision. Integrating such a model into the clinical workflow could help clinicians to diagnose ALS sooner and manage treatment based on estimated survival, which might improve outcomes and the quality of life of patients.

Abstract Introduction In young adults, pairing a cognitive task with walking can have different effects on gait and cognitive task performance. In some cases, performance clearly declines whereas in others compensatory mechanisms maintain performance. This study investigates the preliminary finding of behavioral improvement in Go/NoGo response inhibition task performance during walking compared with sitting, which was observed at the piloting stage. Materials and Methods Mobile brain/body imaging (MoBI) was used to record electroencephalographic (EEG) activity, 3-dimensional (3D) gait kinematics and behavioral responses in the cognitive task, during sitting or walking on a treadmill. Results In a cohort of 26 young adults, 14 participants improved in measures of cognitive task performance while walking compared with sitting. These participants exhibited walking-related EEG amplitude reductions over frontal scalp regions during key stages of inhibitory control (conflict monitoring, control implementation, and pre-motor stages), accompanied by reduced stride-to-stride variability and faster responses to stimuli compared with those who did not improve. In contrast, 12 participants who did not improve exhibited no EEG amplitude differences across physical condition. Discussion The neural activity changes associated with performance improvement during dual tasking hold promise as cognitive flexibility markers that can potentially help assess cognitive decline in aging and neurodegeneration.