Automated sleep staging in people with intellectual disabilities using heart rate and respiration variability

BACKGROUND

People with intellectual disabilities (ID) have a higher risk of sleep disorders. Polysomnography (PSG) remains the diagnostic gold standard in sleep medicine. However, PSG in people with ID can be challenging, as sensors can be burdensome and have a negative influence on sleep. Alternative methods of assessing sleep have been proposed that could potentially transfer to less obtrusive monitoring devices. The goal of this study was to investigate whether analysis of heart rate variability and respiration variability is suitable for the automatic scoring of sleep stages in sleep-disordered people with ID.

METHODS

Manually scored sleep stages in PSGs of 73 people with ID (borderline to profound) were compared with the scoring of sleep stages by the CardioRespiratory Sleep Staging (CReSS) algorithm. CReSS uses cardiac and/or respiratory input to score the different sleep stages. Performance of the algorithm was analysed using input from electrocardiogram (ECG), respiratory effort and a combination of both. Agreement was determined by means of epoch-per-epoch Cohen's kappa coefficient. The influence of demographics, comorbidities and potential manual scoring difficulties (based on comments in the PSG report) was explored.

RESULTS

The use of CReSS with combination of both ECG and respiratory effort provided the best agreement in scoring sleep and wake when compared with manually scored PSG (PSG versus ECG = kappa 0.56, PSG versus respiratory effort = kappa 0.53 and PSG versus both = kappa 0.62). Presence of epilepsy or difficulties in manually scoring sleep stages negatively influenced agreement significantly, but nevertheless, performance remained acceptable. In people with ID without epilepsy, the average kappa approximated that of the general population with sleep disorders.

CONCLUSIONS

Using analysis of heart rate and respiration variability, sleep stages can be estimated in people with ID. This could in the future lead to less obtrusive measurements of sleep using, for example, wearables, more suitable to this population.

Safety, Tolerability, Pharmacokinetics and Quantitative Electroencephalography Assessment of ACD856, a Novel Positive Allosteric Modulator of Trk-Receptors Following Multiple Doses in Healthy Subjects

BACKGROUND

ACD856 is a positive allosteric modulator of tropomyosin receptor kinase (Trk) receptors which has shown to have pro-cognitive and anti-depressant-like effects in various animal models. It is currently in clinical development for the treatment of Alzheimer's disease and other disorders where cognition is impaired and is also considered for indications such as depression or other neuropsychiatric diseases. ACD856 has a novel mechanism of action modulating the activity of the Trk-receptors, resulting in increased stimulation of the neurotrophin signaling pathways. Previous studies applying single intravenous and oral doses of ACD856 indicate that ACD856 is safe and well-tolerated by healthy volunteer subjects, and that it has suitable safety and pharmacokinetic properties for further clinical development.

OBJECTIVES

To investigate the safety and tolerability of 7 days of treatment with multiple ascending oral doses of ACD856 in healthy subjects, and to characterize its pharmacokinetic (PK) properties. In addition, pharmacodynamic effects of ACD856 using quantitative electroencephalography (qEEG) as an indicator for central target engagement were assessed.

DESIGN

This was a prospective, phase I, double-blind, parallel-group, placebo-controlled, randomized study of the safety, tolerability, PK and pharmacodynamics of multiple ascending oral doses of ACD856 in healthy subjects. ACD856 or placebo were administered in 3 ascending dose cohorts of 8 subjects. Within each cohort, subjects were randomized to receive either ACD856 (n=6) or placebo (n=2).

SETTING

The study was conducted at a First-in-Human unit in Sweden.

PARTICIPANTS

Twenty-four healthy male and female subjects.

INTERVENTION

The study medication was administered as an oral solution, with ACD856 or the same contents without the active ingredient (placebo). The dose levels ranged from 10 mg to 90 mg. ACD856 was administered once daily for 7 days, targeting steady state.

MEASUREMENTS

Safety and tolerability assessments included adverse events, laboratory, vital signs, 12-lead electrocardiogram (ECG), physical examination, assessment of stool frequency and questionnaires to assess symptoms of anxiety, depression, as well as suicidal ideation and behavior. In addition, cardiodynamic ECGs were extracted to evaluate cardiac safety. PK parameters were calculated based on measured concentrations of ACD856 in plasma, urine, and cerebrospinal fluid (CSF) samples. Metabolite profiling, characterization and analysis was performed based on and urine samples. qEEG was recorded for patients in the two highest dose cohorts (30 and 90 mg/day) as a pharmacodynamic assessment to explore central target engagement.

RESULTS

Treatment with ACD856 was well tolerated with no serious adverse events. No treatment emergent or dose related trends were observed for any of the safety assessments. ACD856 was rapidly absorbed and reached maximum plasma exposure at 30 to 45 minutes after administration. Steady state was reached before Day 6, with an elimination half-life at steady state of approximately 20 hours. At steady state, ACD856 exhibited accumulation ratios for Cmax and AUC of approximately 1.6 and 1.9 respectively. The exposure, Cmax and AUC0-24, increased proportionally with the dose. There was no unchanged ACD856 detected in urine. The metabolic pattern in urine and plasma was similar, and in alignment with the metabolites observed in preclinical toxicology studies. The level of ACD856 measured in CSF at steady state increased with dose, indicating Central Nervous System (CNS) exposure at relevant levels for pharmacodynamic effects. ACD856 demonstrated significant dose-dependent treatment-associated changes on qEEG parameters. Specifically, increase of the relative theta power and decrease of the fast alpha and beta power was observed, leading to an acceleration of the delta+theta centroid and an increase in the theta/beta ratio.

CONCLUSIONS

ACD856 was well tolerated at the tested dose levels (10-90 mg/daily for 7 days) in healthy subjects. The compound has a robust pharmacokinetic profile, with rapid absorption and dose-dependent exposure. ACD856 was shown to pass the blood-brain-barrier, reach relevant exposure in the CNS and to induce dose-dependent treatment-related changes on qEEG parameters, indicating central target engagement.

Direct application of an ECG-based sleep staging algorithm on reflective photoplethysmography data decreases performance

OBJECTIVE

The maturation of neural network-based techniques in combination with the availability of large sleep datasets has increased the interest in alternative methods of sleep monitoring. For unobtrusive sleep staging, the most promising algorithms are based on heart rate variability computed from inter-beat intervals (IBIs) derived from ECG-data. The practical application of these algorithms is even more promising when alternative ways of obtaining IBIs, such as wrist-worn photoplethysmography (PPG) can be used. However, studies validating sleep staging algorithms directly on PPG-based data are limited.

RESULTS

We applied an automatic sleep staging algorithm trained and validated on ECG-data directly on inter-beat intervals derived from a wrist-worn PPG sensor, in 389 polysomnographic recordings of patients with a variety of sleep disorders. While the algorithm reached moderate agreement with gold standard polysomnography, the performance was significantly lower when applied on PPG- versus ECG-derived heart rate variability data (kappa 0.56 versus 0.60, p < 0.001; accuracy 73.0% versus 75.9% p < 0.001). These results show that direct application of an algorithm on a different source of data may negatively affect performance. Algorithms need to be validated using each data source and re-training should be considered whenever possible.

0436 Deep Learning for Scoring Sleep Based on Signals Available in Home Sleep Apnea Test Studies: Cardiorespiratory Sleep Staging

Introduction

Typically, neurological signals are not recorded in home sleep apnea testing (HSAT) and thus standard sleep scoring is not applicable. The respiratory event index is calculated using total recording time rather than total sleep time (TST) resulting in a risk of underestimating sleep apnea severity. The objective of the study was to evaluate if artificial intelligence approaches can provide sleep scoring based on cardiorespiratory signals (CReSS) with reasonable accuracy.

Methods

Supervised deep learning for scoring sleep was trained with 472 and tested in 116 polysomnographies (PSG), scored independently by two experts and by a consensus scorer. The resulting bidirectional long short-term memory recurrent neural network (RNN) was integrated in the Somnolyzer system and validated in 97 PSGs of patients with obstructive sleep apnea (OSA) which had been scored independently by four human experts. Cohen’s kappa agreement for four stages (W, L: N1+N2, D: N3, R) was determined as compared to a consensus scoring.

Results

Epoch-by-epoch comparison between CReSS autoscoring and manual consensus scoring resulted in Cohen’s kappa of 0.68 (W: 0.74, L: 0.63, D: 0.54, R: 0.79). The intra-class correlation coefficient (ICC) between TST derived from CReSS and from neurological scoring was 0.86 (95%-CI: 0.79-0.90), while the ICC between subjective TST from sleep questionnaire and the objective TST was only 0.65 (95%-CI: 0.45-0.77). REM-related OSA had a prevalence of 16% and was detected with an accuracy of 95%.

Conclusion

With a kappa of 0.68, the cardiorespiratory-based RNN classifier is far above previously published values and reflects a substantial agreement with the manual consensus scoring in patients with sleep-disordered breathing. Thus, applying CReSS allows a more accurate determination of the OSA-severity and even a detection of REM related OSA in HSAT studies.

Support

All authors are employees of Philips

0435 Autoscoring of Sleep and Associated Events Versus a Reference Scorer Competing with Three Additional Manual Scorings: A Clinical Validation Study

Introduction

Manual scoring of polysomnographic (PSG) data is a time-consuming and tedious process with noticeable inter-rater variability. Autoscoring may overcome these limitations if it delivers valid results. The goal of this study was to validate a comprehensive autoscoring system in a clinically representative population.

Methods

The validation data consisted of 97 PSGs in patients with sleep-related breathing disorder, scored manually by a reference scorer and three further experts. The Somnolyzer autoscoring system combined pattern recognition for events such as spindles, k-complexes, slow-waves, eye-movements, apneas, hypopneas, desaturations and leg movements with an artificial intelligence classifier consisting of a bidirectional long short-term memory recurrent neural network (RNN) architecture. Intra-class correlation coefficients (ICC) for absolute agreement were determined for the commonly used metrics in sleep medicine to compare both, the three human expert scorings and the autoscoring versus the reference scoring.

Results

ICC coefficients for autoscoring and the three manual scorings versus the reference scoring were for sleep efficiency: .95, .83, .91, .93; N1(%): .71, .44, .39, .56; N2(%): .87, .63, .55, .45; N3(%): .80, .62, .44, .32; R(%): .92, .89, .91, .88; arousal index: .88, .81, .22, .78; PLMI: .97, .88, .86, .91; AHI: .91, .89, .87, .78; OA: .94, .89, .91, .90; CA: .96, .96, .96, .82; MA: .93, .77, .43, .41. Thus, the ICCs between autoscoring and the reference scoring were equal or higher than the ICCs between any of the three manual scorings and the reference scoring for all endpoints.

Conclusion

Autoscoring of PSGs based on artificial intelligence outperformed even the best of three human expert scorers. Since the autoscoring performs pattern recognition in real-time, the final autoscoring results are available immediately after the end of the recording.

Support

All authors are employees of Philips

CS03-03 - Sleep and sleep disorders in somatoform pain disorder

Introduction

Somatoform pain disorder (SPD) is frequently associated with sleep disorders, specifically restless legs syndrome and insomnia, which in turn lowers the pain threshold and worsens pain.

Objectives

The aim of the present study was to investigate differences in wake-EEG by low-resolution electromagnetic tomography (LORETA) and objective and subjective sleep and awakening quality in SPD patients as compared with controls and study acute and chronic effects of trazodone CR on these variables and pain measures.

Methods

Fifteen patients with SPD (F45.4) and co-morbid insomnia (F51.0) were compared with 15 controls and participated in a single-blind, placebo-controlled, cross-over study on the acute effect of 100 mg trazodone CR, followed by a six-week open titration period. Statistics involved clinical, EEG-LORETA, PSG and psychometry.

Results

LORETA showed reduced power, mainly in the beta band in almost all pain matrix areas (SI, SII, ACC, SMA, PFC, PPC, insula, amygdala, hippocampus). PSG demonstrated a lack of deep sleep and increased arousals and stage shifts, with opposite changes induced by trazodone after acute and chronic therapy. Improvement of sleep was associated with improvement of pain, evaluated by visual-analog scales.

Conclusion

Our LORETA findings demonstrate a dysfunctional pain modulation in SPD. Trazodone induced changes in subjective and objective sleep and awakening quality that were opposite to the differences between SPD patients and controls (key-lock principle) and associated with pain improvement.

Quantitative electrophysiology during night- and daytime including electroencephalography and event-related potential EEG/ERP topography and tomography (LORETA) in hyperthyroidism

Introduction

In contrast to the abundance of visual qualitative EEG reports in patho-endocrinology, there is a paucity of quantitative EEG findings.

Objectives

Electrophysiology may be utilized for differential diagnosis of hypersomnolence.

Aims

To investigate long-term daytime sleepiness in a young female neurologist with the tentative diagnosis of narcolepsy in addition to moderate depression/anxiety and congenital thyroid hypoplasia treated with thyroxin.

Methods

Three-night polysomnography, multiple sleep latency test (MSLT), visual EEG/ERP-mapping, LORETA, psychometrics and blood analyses were performed.

Results

Polysomnography revealed normal sleep efficiency and sleep architecture, but a high arousal index of up to 63/h TST. The MSLT showed a shortened mean sleep latency of 3.7 min. without REM-sleep onsets, objectifying the high Epworth Sleepiness score of 18. Visual EEG evaluation exhibited a fast alpha rhythm with intermittent theta and delta intrusions and paroxysmal activities. EEG-mapping showed an accelerated dominant frequency and ubiquitous increase in absolute (especially delta and beta) power, ERP revealed shortened N1 latency and very high amplitudes in all components (P300 > 5 SD). LORETA demonstrated significant regional increases in delta, alpha-2 and beta-1 power in the anterior cingulate, orbital, ventromedial, dorsolateral prefrontal cortex and temporal cortex, predominantly right hemispherically. Psychometry showed increased anxiety (SAS) and depression (SDS) and reduced quality of life. Finally, hormonal analysis pointed to thyrotoxicosis factitia (ICD-10 E05.4).

Conclusion

Diagnostic investigations clearly elucidated the pathogenesis of the presenting diagnosis of organic hypersomnia triggered by increased sleep-microarousals due to thyrotoxicosis factitia. Discontinuation of hormone substitution led to a normalization process that will be discussed.

FC12-06 - On the relevance of comorbidity in psychiatry: EEG loreta in generalized anxiety disorder with and without nonorganic Insomnia

Introduction

Comorbidity is increasingly regarded as important for both diagnosis and treatment of psychiatric disorders.

Objectives

Electrophysiological neuroimaging such as low-resolution brain electromagnetic tomography (LORETA) may be utilized to obtain insight into the pathogenesis of mental diseases.

Aims

The aim of the present study was to compare EEG tomographic data obtained in generalized anxiety disorder (GAD) with and without nonorganic insomnia.

Methods

In the first study, LORETA was performed in 44 untreated patients (25 females) with the primary diagnosis of nonorganic insomnia (F51.0) associated with GAD (F41.1) and 44 age- and sex-matched normal controls. In the second study, 18 patients (9 females) with the primary diagnosis of GAD without mandatory insomnia were compared with 18 controls.

Results

While patients with F51.0 and concomitant F41.1 showed an increase in LORETA power in the delta, theta, alpha-1 and alpha-2 frequencies, GAD patients without mandatory insomnia demonstrated a decrease in LORETA power - specifically in delta (more left than right hemisphere, involving occipital cortex, insula, cingulate and frontal cortex) and beta (occipital cortex), mirroring neuroimaging findings on the neural circuitry of anxiety.

Conclusions

Different EEG LORETA findings were obtained in GAD patients, depending on the comorbidity: While in daytime recordings patients with nonorganic insomnia demonstrated increased slow activities reflecting daytime tiredness and sleepiness, GAD patients without insomnia exhibited a decrease in slow activity and thus hypervigilance. According to the key-lock principle different pharmacological strategies have to be applied, which will be demonstrated on the basis our own data sets.

Sleep habits and sleep complaints in Austria: current self-reported data on sleep behaviour, sleep disturbances and their treatment

OBJECTIVES

To acquire current information on sleep habits, disturbances and treatment options in the adult population of Austria and compare results with previously collected data.

MATERIALS AND METHODS

A representative sample of the Austrian population (women: n = 522, men: n = 478).

RESULTS

Seventy-five percent reported daily sleep-duration between 6 and 8 h. In 76%, sleep latency was <30 min, 15% described difficulties in sleep maintenance. Longer sleep on weekends was prevalent in 54%, 23% took a nap. Concerning sleep environment, 31% reported sleeping alone; the rest had a constant or occasional bed partner. Sleep disturbances such as sleep disruption or prolonged sleep latency were reported by 18%. Predominant symptoms included snoring/apneas (22%), nightmares (22%) and restless legs (21%). Daytime tiredness was reported by 17% and sleepiness by 20%. Twenty-four percent did not take treatment. Only 7% asked for medical help: 96% consulted their physician; 47% tried to change their way of living. Sleep promoting drugs were taken by 7%. Sleep improving measures were: sleep promoters (45%), general measures (20%), consultation of general practitioner (20%), psychotherapy (6%), and technical tools (3%). Comparison with a dataset of 1993 revealed only a slight increase in short sleepers and a slight decrease in long sleepers.

CONCLUSIONS

Subjectively reported sleep disorders proved to be relatively stable between 1993 and 2007.

EEG topography and tomography (LORETA) in diagnosis and pharmacotherapy of depression

Earlier investigations suggested an involvement of the right hemisphere and the left prefrontal cortex (PFC) in the pathogenesis of depression. This paper presents our own electroencephalographic (EEG) topography and low-resolution brain electromagnetic tomography (LORETA) data obtained in unmedicated depressed patients, and the effects of two representative drugs of non-sedative and sedative antidepressants, i.e., citalopram (CIT) and imipramine (IMI), as compared with placebo in normal subjects. Sixty female menopausal syndrome patients with the diagnosis of a depressive episode without psychotic symptoms as well as 30 healthy controls were investigated. Concerning the effects of antidepressants, normal healthy subjects received single oral doses of 20 mg CIT, 75 mg IMI and placebo p.o. A 3-min vigilance-controlled EEG and a 4-min resting EEG was recorded pre- and post-drug administration and analyzed by means of EEG mapping and LORETA. In the EEG mapping, depressed patients demonstrated a decrease in absolute power in all frequency bands, an augmentation of relative delta/theta and beta and a decrease in alpha activity as well as a slowing of the delta/theta centroid and an acceleration of the alpha and beta centroid, which suggests vigilance decrements. In the alpha asymmetry index, they showed right frontal hyper- and left frontal hypoactivation correlated with the Hamilton Depression Score (HAMD). LORETA predominantly revealed decreased power in the theta and alpha-1 frequency band. Negative correlations between theta power and the HAMD were observed in the ventro-medial PFC, the bilateral rostral anterior cingulate cortex (ACC) and the left insular cortex; between alpha-1 power and the HAMD in the right PFC. In the EEG mapping of antidepressants, 20 mg CIT showed mainly activating, 75 mg IMI partly sedative properties. LORETA revealed that CIT increased alpha-2, beta-1, beta-2 and beta-3 power more over the right than over the left hemisphere. However, also a left temporal and frontal delta increase was observed. In conclusion, EEG topography and tomography of depressed menopausal patients demonstrated a right frontal hyper- and left frontal hypoactivation in the alpha asymmetry index as well as a vigilance decrease, with a right-hemispheric preponderance. Within antidepressants at least 2 subtypes may be distinguished from the electrophysiological point of view, a non-sedative and a sedative. LORETA identifies cerebral generators responsible for the pathogenesis of depression as well as for the mode of action of antidepressants.

Effects of a mandibular repositioning appliance on sleep structure, morning behavior and clinical symptomatology in patients with snoring and sleep-disordered breathing

BACKGROUND

Mandibular repositioning appliances (MRAs) have become an established treatment for snoring and sleep-disordered breathing - though most studies only focused on the evaluation of respiratory variables.

METHODS

This single-blind, placebo-controlled case-series study investigated the effects of an individually adjustable MRA on psychopathology, macro-/microstructure of sleep, periodic leg movements, morning performance, mood/affect and psychophysiology. Fifty patients (37 males) aged 59.7 +/- 10.3 years, suffering from primary snoring (7), mild (22), moderate (15) and severe apnea (6), spent 4 nights in the sleep laboratory (adaptation, placebo, drug and MRA night). The drug night is not subject of the present paper.

RESULTS

Confirmatory statistics showed an improvement of the snoring index by 72%. Descriptively, the apnea index and the apnea-hypopnea index normalized. A clinical improvement was seen in the Pittsburgh Sleep Quality Index, the Zung Anxiety/Depression Scales and the Epworth Sleepiness Scale. The restless legs syndrome also improved. Polysomnographically, sleep stages REM and 4 as well as REM latency increased, stage 3, movement time, stage shifts and periodic leg movements decreased, as did all arousal measures. Subjectively, morning well-being, drive, affectivity and wakefulness improved. Objectively, attention, motor and reaction time performance, critical flicker frequency as well as muscular strength increased, diastolic blood pressure and the pulse rate decreased.

CONCLUSION

Apart from its good therapeutic effects on snoring and respiratory variables (snoring showed complete or partial response in 68%, the apnea-hypopnea index in 67% of the apnea patients), the MRA also improved psychopathology, objective and subjective sleep and awakening quality.

Sleep spindle-related activity in the human EEG and its relation to general cognitive and learning abilities

Stage 2 sleep spindles have been previously viewed as useful markers for the development and integrity of the CNS and were more currently linked to 'offline re-processing' of implicit as well as explicit memory traces. Additionally, it had been discussed if spindles might be related to a more general learning or cognitive ability. In the present multicentre study we examined the relationship of automatically detected slow (< 13 Hz) and fast (> 13 Hz) stage 2 sleep spindles with: (i) the Raven's Advanced Progressive Matrices (testing 'general cognitive ability'); as well as (ii) the Wechsler Memory scale-revised (evaluating memory in various subdomains). Forty-eight healthy subjects slept three times (separated by 1 week) for a whole night in a sleep laboratory with complete polysomnographic montage. Whereas the first night only served adaptation and screening purposes, the two remaining nights were preceded either by an implicit mirror-tracing or an explicit word-pair association learning or (corresponding) control task. Robust relationships of slow and fast sleep spindles with both cognitive as well as memory abilities were found irrespectively of whether learning occurred before sleep. Based on the present findings we suggest that besides being involved in shaping neuronal networks after learning, sleep spindles do reflect important aspects of efficient cortical-subcortical connectivity, and are thereby linked to cognitive- and memory-related abilities alike.

Double-blind, placebo-controlled pharmacodynamic studies with a nutraceutical and a pharmaceutical dose of ademetionine (SAMe) in elderly subjects, utilizing EEG mapping and psychometry

In a double-blind, placebo-controlled crossover study, the effects of S-adenosyl-l-methionine (SAMe) on brain function measures of 12 normal elderly volunteers (6 m/6 f, aged 57-73 years, mean: 61 years) were investigated by means of EEG mapping and psychometry. In random order, the subjects were orally administered a pharmaceutical dose of 1600 mg SAMe, a nutraceutical dose of 400 mg SAMe and placebo, each over a period of 15 days, with wash-out periods of 2 weeks in between. EEG recordings, psychometric tests and evaluations of tolerability and side effects were carried out 0, 1, 3 and 6 h after drug administration on days 1 and 15. Multivariate analysis based on MANOVA/Hotelling T2 tests of quantitative EEG data demonstrated significant central effects of SAMe as compared with placebo after acute, subacute and superimposed drug administration of both the nutraceutical and the pharmaceutical dose. EEG changes induced by SAMe were characterized by an increase in total power, a decrease in absolute and relative power in the delta/theta and slow alpha frequencies, an increase in absolute and relative power in the alpha-2 and beta frequencies as well as an acceleration of the alpha centroid and the centroid of the total power spectrum. The delta/theta and the beta centroid showed variable changes over time. The dominant alpha frequency was accelerated, the absolute and relative power in the dominant alpha frequency attenuated after SAMe as compared with placebo. These acute and subacute pharmaco-EEG findings in elderly subjects are typical of activating antidepressants. Time-efficacy calculations showed that acute oral administration of SAMe in both the nutraceutical and the pharmaceutical dose induced the pharmacodynamic peak effect in the first hour with a subsequent decline. The 3rd and 6th hours still showed a significant encephalotropic effect after the 1600 mg dose. The maximum EEG effect was noted after 2 weeks of oral administration of both 1600 mg/die and 400 mg/die. The superimposed dose induced significant encephalotropic effects in the 3rd hour after 400 mg and in the 3rd and 6th hours after 1600 mg as compared with pre-treatment. Dose-efficacy calculations showed that the pharmaceutical dose of 1600 mg had a more pronounced effect on the CNS than the nutraceutical dose of 400 mg, with both doses being superior to placebo. Psychometric tests concerning noopsychic and thymopsychic measures as well as critical flicker fusion frequency generally demonstrated a lack of differences between SAMe and placebo, which reflects a good tolerability of the drug in elderly subjects. This was corroborated by the findings on side effects, pulse and blood pressure.

Identifying target regions for vigilance improvement under hormone replacement therapy in postmenopausal syndrome patients by means of electroencephalographic tomography (LORETA)

RATIONALE

Daytime fatigue, which at the neurophysiological level is due to vigilance decrements, is a frequent complaint in postmenopausal women.

OBJECTIVES

In a three-arm, 2-month, parallel group-design study, vigilance-promoting effects of a novel continuous combination (=Climodien 2/3) of estradiol valerate (EV; 2 mg) and dienogest (DNG; 3 mg) were compared with the effects of both EV alone and placebo in 55 insomniac, postmenopausal syndrome patients.

METHODS

Low-resolution brain electromagnetic tomography (LORETA) was undertaken to identify the cerebral target regions of hormone replacement therapy.

RESULTS

An omnibus significance test revealed Climodien to increase activity in 882 of 2,394 voxels in the alpha-2 band, followed by 733, 706, and 664 voxels in the beta-2, beta-1, and beta-3 bands, and 509 voxels in the delta band, whereas 2 mg EV alone did not produce a significant suprathreshold activity. Current density increased predominantly in the right hemisphere, which had already been described in the literature as the center of the vigilance system. In the fast alpha range, which plays a major role in the context of vigilance, increased activity was found in the right prefrontal, temporal, and superior parietal cortices, i.e., those brain areas of the right-sided fronto-parietal neuronal network that are responsible for sustained attention. A further activity increase was seen in the anterior cingulate gyrus associated with attentional control and conflict monitoring. The right temporal lobe showed increased current density in all frequency bands.

CONCLUSIONS

Electroencephalographic tomography (LORETA) identified the right-hemispheric vigilance system as the target region of Climodien.

EEG-tomographic studies with LORETA on vigilance differences between narcolepsy patients and controls and subsequent double-blind, placebo-controlled studies with modafinil

The aim of the present study was to identify brain regions associated with vigilance in untreated and modafinil-treated narcoleptic patients by means of low-resolution brain electromagnetic tomography (LORETA). 16 drug-free narcoleptics and 16 normal controls were included in the baseline investigation. Subsequently patients participated in a double-blind, placebo-controlled crossover study receiving a three-week fixed titration of modafinil (200, 300, 400 mg) and placebo. Measurements comprised LORETA, the Multiple Sleep Latency Test (MSLT) and the Epworth Sleepiness Scale (ESS) obtained before and after three weeks' therapy. Statistical overall analysis by means of the omnibus significance test demonstrated significant inter-group differences in the resting (R-EEG), but not in the vigilance-controlled recordings (V-EEG). Subsequent univariate analysis revealed a decrease in alpha-2 and beta 1-3 power in prefrontal, temporal and parietal cortices, with the right hemisphere slightly more involved in this vigilance decrement. Modafinil 400 mg/d as compared with placebo induced changes opposite to the aforementioned baseline differences (key-lock principle) with a preponderance in the left hemisphere. This increase in vigilance resulted in an improvement in the MSLT and the ESS. LORETA provided evidence of a functional deterioration of the fronto-temporo-parietal network of the right-hemispheric vigilance system in narcolepsy and a therapeutic effect of modafinil on the left hemisphere, which is less affected by the disease.