Developing neurophysiological metrics for the assessment of mental workload and the functional state of the brain

Modern working environments are often information intensive and work performance requires acting on multiple tasks simultaneously, i.e., multitasking. Also, irregular and prolonged work schedules, shift work and night work are typical in many work sectors. This causes both acute and chronic sleep loss, which results in performance impairment, such as increased reaction times, memory difficulties, cognitive slowing, and lapses of attention. Long lasting sleep loss and sustained overloading increase the risk of human errors and may cause work related stress and even occupational burn-out. According to the Finnish Occupational Safety and Health Act (738/2002, Työturvallisuuslaki), Section 25 Avoiding and reducing workloads, an employer should assess the workload the employee is exposed to. Despite the fact that this important issue is enacted in the law, the objective measures to assess the workload are lacking. This Thesis reviews neurophysiologic methods for assessment of cognitive workload and sleep loss. Then it describes experimental studies where the feasibility of conventional event related potential (ERP) and electroencephalography (EEG) methods were tested both in assessment of internal state of participants during challenging task performance after sleep debt and in diagnostic of work-related central nervous system disorder. After that, methodological improvements both on ERPs and EEG metrics are shown: ERPs were analysed with a single-trial method, and EEG methodology was developed for estimation of both internal (caused by sleep loss) and external (caused by task demands) load. The methods were tested in healthy controls. The most promising metric to study overall brain load, including both cognitive workload as well as sleep loss, is suggested to be theta Fz / alpha Pz -ratio. It increases both with growing cognitive workload level and time spent awake, being sensitive also to sleep loss. This metric is possible to measure both in laboratory and in the field conditions. Measurements may be carried out even during real work tasks, at least in professions where most work is done in office-like environments. As the ratio increases with cognitive brain load similar to the heartbeat with increasing physical load, the ratio was named "brainbeat"

Wake-up strokes are linked to obstructive sleep apnea and worse early functional outcome

Background and Aims Presence of sleep-disordered breathing (SDB) and especially obstructive sleep apnea (OSA) is a known risk factor for ischemic stroke. Additionally, SDB effects negatively on recovery after stroke. Up to one fourth of strokes are present on awakening. The link between OSA and wake-up stroke (WUS) has been suggested. We aim to determine the association between OSA and WUS in a Finnish stroke unit cohort. Material and Methods An observational prospective longitudinal study consisted of 95 TIA (transient ischemic attack) and mild to moderate stroke patients referred to a Stroke Unit in Finland. Respiratory polygraphy was performed within 72 h of hospital admission. Patients were classified into WUS and non-WUS, and functional outcome measures (mRS, rehabilitation, hospitalization time) were collected. Functional outcomes and prevalence of OSA were compared between non-WUS and WUS. Results OSA (AHI > 15/h) was more frequent among WUS than non-WUS (71% and 36%, respectively, p = 0.009). Functional outcome measured with mRS was worse in patients with WUS than non-WUS on registration day and at hospital discharge (p = 0.001). Need for rehabilitation in WUS was 43% of cases compared to 23% of non-WUS (p = 0.067). Hospitalization time was longer (5-15days) in 55% of WUS and 41% of non-WUS patients (p = 0.261). Conclusion Moderate-to-severe OSA is related to WUS compared to non-WUS. In addition, WUS have worse short-term outcomes measured in mRS. Further studies are needed to determine if OSA is causally linked to WUS.Peer reviewe

Relationship between SDB and short-term outcome in Finnish ischemic stroke patients

Objectives Presence of sleep-disordered breathing (SDB) affects negatively recovery from stroke. The aim of this study is to evaluate the relationships between sleep-disordered breathing (SDB) and outcome measures in Finnish stroke unit cohort: mRS, need of rehabilitation and hospitalization time. Material and Methods An observational longitudinal study consisted of 95 patients referred to the Stroke Unit of Satakunta Hospital District over a period of November 2013 to March 2016. Patients were tested for SDB within 72 hr from the hospital admission because of ischemic stroke or TIA. The patients underwent polysomnography with NOX T3 wireless recorder. Results There are 37% (n = 35) non-OSA patients, 20% (n = 19) of patients have mild obstructive sleep apnea (OSA) and 39% (n = 37) have moderate/severe OSA and 4% (n = 4) have CSA. Patients with OSA have higher proportion of disability scores of mRS 3-5 (38%) compared to non-OSA (11%) and mild OSA (5%) patients on registration day (mRS0), and the same trend is seen at hospital discharge 35% versus 9% and 5%. (p = .009). Proportion of patients with OSA who needed rehabilitation is 65% (n = 19) versus non-OSA patients 17.5% (n = 4) and mild OSA patients 17.5% (n = 4;p = .039). We observed longer duration of hospitalization (5-15 days) in 29% of OSA patients compared to mild OSA patients 47% and OSA patients 54%. (p = .045). Conclusion Ischemic stroke patients with OSA have higher disability, higher need of rehabilitation, and longer hospitalization length. Prescreening tools for recognizing these stroke patients in acute phase could be valuable. That could result in earlier initiation of treatment and might prevent worse recovery from stroke.Peer reviewe

Optimal digital filters for analyzing the mid-latency auditory P50 event-related potential in patients with Alzheimer's disease

Background: Filtering is an effective pre-processing technique for improving the signal-to-noise ratio of ERP waveforms. Filters can, however, introduce substantial distortions into the time-domain representations of ERP waveforms. Inappropriate filter parameters may lead to the presence of statistically significant but artificial effects, whereas true effects may appear as insignificant. New method: The present study aimed to determine the optimal digital filters for analyzing the auditory P50 component in patients with Alzheimer's disease. To provide evidence of the optimal filter settings, different high-pass and low-pass filters were applied to ERP waveforms obtained from a conditioning testing paradigm. The results facilitate practical recommendations for selection of filters that maximize the signal-to-noise ratio of the P50 components without introducing significant distortions. Results: The present study confirms that filter parameters have a significant effect on the amplitude and gating measures of the P50 component. Setting the high-pass cut-off at 0.1 Hz and the low-pass cut-off at 90Hz (or above) is recommended for P50 component analyses. Comparison with existing methods: The majority of ERP studies on sensory gating report using high-pass filters with 10-Hz cut-offs to measure P50 suppression. Such a high cut-off appeared to induce significant distortions into the ERP waveforms; thus, the authors advise against using these excessive high-pass cut-offs. Conclusions: Filtering broadband signals, such as ERP signals, necessary results in time-domain distortions. However, by adjusting the filter parameters carefully according to the components of interest, it is possible to minimize filter artifacts and obtain more easily interpretable ERP waveforms. (C) 2016 Elsevier B.V. All rights reserved.Peer reviewe

Breakfast high in whey protein or carbohydrates improves coping with workload in healthy subjects

Peer reviewe

Achievement emotions among adolescents receiving special education support in mathematics

This study investigated mathematics-related achievement emotions among Finnish adolescents (N = 1379) receiving special education support (SEdS) in self-contained and general mathematics classrooms and receiving no mathematics SEdS through multilevel modeling. Mathematics performance, gender, and classroom size were controlled for. Adolescents receiving SEdS in general classrooms reported less enjoyment and pride and more anger, anxiety, shame, hopelessness, and boredom than those receiving SEdS in self-contained classrooms and those receiving no SEdS. In contrast, adolescents receiving SEdS in self-contained classrooms reported more enjoyment and pride and less anger, anxiety, and hopelessness than those receiving no SEdS. Furthermore, adolescents receiving no SEdS reported more anxiety, hopelessness, and boredom in general classrooms when the proportion of classmates receiving SEdS was higher. We discuss the practical implications for developing SEdS in relation to achievement emotions.Peer reviewe

Identification of Motor Symptoms Related to Parkinson Disease Using Motion-Tracking Sensors at Home (KAVELI) : Protocol for an Observational Case-Control Study

Background: Clinical characterization of motion in patients with Parkinson disease (PD) is challenging: symptom progression, suitability of medication, and level of independence in the home environment can vary across time and patients. Appointments at the neurological outpatient clinic provide a limited understanding of the overall situation. In order to follow up these variations, longer-term measurements performed outside of the clinic setting could help optimize and personalize therapies. Several wearable sensors have been used to estimate the severity of symptoms in PD; however, longitudinal recordings, even for a short duration of a few days, are rare. Home recordings have the potential benefit of providing a more thorough and objective follow-up of the disease while providing more information about the possible need to change medications or consider invasive treatments. Objective: The primary objective of this study is to collect a dataset for developing methods to detect PD-related symptoms that are visible in walking patterns at home. The movement data are collected continuously and remotely at home during the normal lives of patients with PD as well as controls. The secondary objective is to use the dataset to study whether the registered medication intakes can be identified from the collected movement data by looking for and analyzing short-term changes in walking patterns. Methods: This paper described the protocol for an observational case-control study that measures activity using three different devices: (1) a smartphone with a built-in accelerometer, gyroscope, and phone orientation sensor, (2) a Movesense smart sensor to measure movement data from the wrist, and (3) a Forciot smart insole to measure the forces applied on the feet. The measurements are first collected during the appointment at the clinic conducted by a trained clinical physiotherapist. Subsequently, the subjects wear the smartphone at home for 3 consecutive days. Wrist and insole sensors are not used in the home recordings. Results: Data collection began in March 2018. Subject recruitment and data collection will continue in spring 2019. The intended sample size was 150 subjects. In 2018, we collected a sample of 103 subjects, 66 of whom were diagnosed with PD. Conclusions: This study aims to produce an extensive movement-sensor dataset recorded from patients with PD in various phases of the disease as well as from a group of control subjects for effective and impactful comparison studies. The study also aims to develop data analysis methods to monitor PD symptoms and the effects of medication intake during normal life and outside of the clinic setting. Further applications of these methods may include using them as tools for health care professionals to monitor PD remotely and applying them to other movement disorders.Peer reviewe

Preliminary Normative Study of ImPACT® in Finnish Professional Male Ice Hockey Players

Assessment of cognition is an important part of concussion management. The common paradigm of baseline and postinjury evaluations is recommended but due to the often lacking baseline data, reliable normative values are needed. The Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT®) battery is a widely used method of cognitive assessment offering several language options. There are few comparative studies between language groups on this test battery. ImPACT was administered at baseline to 184 Finnish male Professional Ice Hockey league players. The performance of the Finnish sample differed from previously published English and Czech language samples on the Visual Motor Speed and Reaction Time composites with medium effect-sizes (d = 0.38–0.52). Age, but not education or prior concussions, was associated with ImPACT performance. ImPACT performance is not uniform across language and culture groups and the findings highlight the need for language-specific norms. Finnish reference values for ImPACT for ages 26 are presented. A similar approach is encouraged for other languages.Peer reviewe

Wake-up strokes are linked to obstructive sleep apnea and worse early functional outcome

Background and Aims: Presence of sleep-disordered breathing (SDB) and especially obstructive sleep apnea (OSA) is a known risk factor for ischemic stroke. Additionally, SDB effects negatively on recovery after stroke. Up to one fourth of strokes are present on awakening. The link between OSA and wake-up stroke (WUS) has been suggested. We aim to determine the association between OSA and WUS in a Finnish stroke unit cohort. Material and Methods: An observational prospective longitudinal study consisted of 95 TIA (transient ischemic attack) and mild to moderate stroke patients referred to a Stroke Unit in Finland. Respiratory polygraphy was performed within 72 h of hospital admission. Patients were classified into WUS and non-WUS, and functional outcome measures (mRS, rehabilitation, hospitalization time) were collected. Functional outcomes and prevalence of OSA were compared between non-WUS and WUS. Results: OSA (AHI > 15/h) was more frequent among WUS than non-WUS (71% and 36%, respectively, p = 0.009). Functional outcome measured with mRS was worse in patients with WUS than non-WUS on registration day and at hospital discharge (p = 0.001). Need for rehabilitation in WUS was 43% of cases compared to 23% of non-WUS (p = 0.067). Hospitalization time was longer (5-15days) in 55% of WUS and 41% of non-WUS patients (p = 0.261). Conclusion: Moderate-to-severe OSA is related to WUS compared to non-WUS. In addition, WUS have worse short-term outcomes measured in mRS. Further studies are needed to determine if OSA is causally linked to WUS.</p

Achievement emotions among adolescents receiving special education support in mathematics

This study investigated mathematics-related achievement emotions among Finnish adolescents (N = 1379) receiving special education support (SEdS) in self-contained and general mathematics classrooms and receiving no mathematics SEdS through multilevel modeling. Mathematics performance, gender, and classroom size were controlled for. Adolescents receiving SEdS in general classrooms reported less enjoyment and pride and more anger, anxiety, shame, hopelessness, and boredom than those receiving SEdS in self-contained classrooms and those receiving no SEdS. In contrast, adolescents receiving SEdS in self-contained classrooms reported more enjoyment and pride and less anger, anxiety, and hopelessness than those receiving no SEdS. Furthermore, adolescents receiving no SEdS reported more anxiety, hopelessness, and boredom in general classrooms when the proportion of classmates receiving SEdS was higher. We discuss the practical implications for developing SEdS in relation to achievement emotions.</p