Electrical sources of P300 event-related brain potentials revealed by low resolution electromagnetic tomography. 1. Effects of normal aging

The P300 event-related potential (ERP) is considered to be closely related to cognitive processes. Previous reports regarding major generators contributing to the scalp-recorded P300 suggested widely distributed multiple sources. Based on ERPs recorded in 172 normal healthy subjects aged between 20 and 88 years in an auditory oddball paradigm, electrical activity in the brain corresponding to N1 and P300 components was localized by means of low resolution electromagnetic tomography (LORETA). The N1 LORETA generators, located in both auditory cortices, did not change over age. On the other hand, the P300 LORETA generators, located predominantly in the frontal neocortex and less pronounced in the posterior parietal cortex, decreased over age both in frontal and parietal source strength.

Sleep laboratory studies in restless legs syndrome patients as compared with normals and acute effects of ropinirole. 2. Findings on periodic leg movements, arousals and respiratory variables

The restless legs syndrome (RLS) is a common sensorimotor disorder which leads to severe sleep disturbances and showed a prevalence of 7.9% in our sleep laboratory. The aim of this study was to investigate periodic leg movements (PLM), arousal and respiratory variables in 12 untreated RLS patients and to measure the acute effects of 0.5 mg ropinirole, a nonergoline dopamine agonist, as compared with placebo. In the target variable PLM/h of total sleep time (PLM/h TST), RLS patients showed an increased value of 40/h (normal 0-5/h). Further, we found an increased number of PLM (368), PLM/h of time in bed (49/h), PLM/h of REM sleep (11), PLM/h of non-REM sleep (46) and PLM/h awake (61). The arousal index was also increased (32/h; normal 0-25/h), as were arousals due to PLM. In the confirmatory part of our descriptive data analysis, ropinirole 0.5 mg significantly improved, as compared with placebo, the index PLM/h TST by 75%. In the descriptive part, all the other PLM variables were improved as well. Arousals due to PLM decreased, while spontaneous arousals increased. Respiratory variables, which had a priori been in the normal range, showed a slight but significant improvement after the dopamine agonist. Thus, 0.5 mg ropinirole significantly improved the target variable PLM/h TST, along with objective and subjective sleep quality and morning noopsychic performance, as described in the preceding paper. Our data encourage further sleep studies including all above-mentioned variables in a larger group of RLS/PLM during sleep patients as well as long-term efficacy trials.

Efficiency of continuous positive airway pressure versus theophylline therapy in sleep apnea: comparative sleep laboratory studies on objective and subjective sleep and awakening quality

Sleep apnea is the most common sleep-related breathing disorder characterized by repetitive episodes of hypoxemia. Therapies include behavioral, surgical, orthodontic, pneumological, and pharmacological interventions. The aim of the present study was to compare the efficiency of pneumological therapy by nasal continuous positive airway pressure (CPAP) versus a pharmacological approach with theophylline (Respicur retard(R) 400 mg) on respiratory variables as well as objective and subjective sleep and awakening quality in patients with moderate sleep apnea measured by polysomnography and psychometry. Under CPAP therapy all respiratory variables improved and normalized, while under theophylline only the apnea-hypopnea index and the desaturation index improved but still did not return to normal values. Regarding sleep initiation and maintenance, CPAP therapy prolonged sleep latency and reduced movement time, while patients treated with theophylline showed reduced total sleep period, total sleep time and sleep efficiency. Sleep architecture demonstrated an increase in deep sleep and REM stages under CPAP therapy, and remained unchanged under theophylline. Concerning subjective sleep and awakening quality, both treatments improved well-being in the morning. Regarding objective awakening quality, reaction time performance was improved in both groups. In conclusion, CPAP treatment is more effective than theophylline regarding respiratory variables as well as the normalization of sleep maintenance and sleep architecture in sleep apnea patients.

Placebo-controlled sleep laboratory studies on the acute effects of zolpidem on objective and subjective sleep and awakening quality in nonorganic insomnia related to neurotic and stress-related disorder

Recent investigations in our sleep outpatient clinic demonstrated that 30% of patients exhibited organic and 70% nonorganic sleep disorders, with 41% showing as an additional diagnosis neurotic, stress-related, and somatoform disorders, 31% affective disorders and 15% mental and behavioral disorders due to psychoactive substance use. Thus, the aim of the study was to investigate the acute effects of the imidazopyridine zolpidem on objective and subjective sleep and awakening quality in the largest of the above-mentioned groups. In this single-blind, placebo-controlled cross-over study, 15 patients (9 females and 6 males aged 51.1 + 11. 3 years) diagnosed as having nonorganic insomnia (ICD-10: F 51.0) related to neurotic and stress-related disorders (F 1.1:12, F 41.2:2 and F 43.2:1) were included. Objective and subjective sleep and awakening quality measures were investigated in 3 subsequent nights in the sleep laboratory (adaptation, baseline/placebo and zolpidem 10 mg night), utilizing clinical, polysomnographic, psychometric and psychophysiological methods. The drug-free patients were matched according to age and sex with 15 normal healthy controls (age 51.2 + 11.8 years). Statistical analysis of polysomnographic variables demonstrated a significant lengthening of the total sleep period (TSP) and total sleep time (TST), an improvement in sleep efficiency and a shortening of sleep latencies after zolpidem as compared with placebo. These changes were opposite to the differences between patients and controls. Concerning sleep architecture, zolpidem increased the length of S4 and S3 + S4 as compared with placebo. Subjective sleep and awakening quality and the thymopsychic variables drive, mood, affectivity and wakefulness in the morning showed no significant changes, as a significant improvement had already occurred from the adaptation to the baseline/placebo night. Noopsychic variables (attention, concentration, attention variability, numerical memory, fine motor activity, reaction time measures) showed similar findings. Moreover, subjective sleep and awakening quality, thymopsychic and noopsychic measures during baseline/placebo recordings did not differ significantly from normative data (except for fine motor activity). Psychophysiological measures did not show any significant alterations either, except for a decrease in systolic blood pressure in the evening.

CONCLUSION

As compared with placebo, zolpidem induced a significant improvement in objective sleep quality, mainly by increasing TSP, TST and sleep efficiency and shortening sleep latencies, thereby normalizing the disorder of initiating and maintaining sleep. Deep sleep stages S3 + S4 increased (although at baseline/placebo these stages did not differ from controls), while S1, S2 and SREM did not change significantly. Subjective sleep and awakening quality as well as thymopsychic and noopsychic performance in the morning mainly showed a placebo and 'first- night effect' phenomenon in these patients. Thus, the changes induced by zolpidem were somewhat different from those after classical benzodiazepines.

Theophylline in snoring and sleep-related breathing disorders: sleep laboratory investigations on subjective and objective sleep and awakening quality

The aim of the present investigation was to comparatively examine the effect of theophylline on various sleep-related breathing disorders of different severity. In a single-blind, placebo-controlled crossover study, 30 patients were polysomnographically diagnosed as suffering from primary snoring (n = 7), obstructive snoring (n = 12) or moderate sleep apnea (n = 11). Subsequent polysomnographic investigations included one baseline, one placebo and one theophylline (Respicur retard 400 mg, Byk Gulden, Konstanz, Germany) night. Subjective sleep and awakening quality was evaluated by means of a test battery completed in the morning. Concerning respiratory variables, theophylline was most effective in patients with moderate sleep apnea. Obstructive snorers only showed a tendency towards improvement and primary snorers remained unchanged. Sleep architecture generally remained unchanged in all three patient groups. Objective awakening quality was partly improved in primary snorers, obstructive snorers, as well as in moderate sleep apnea patients as compared with baseline, but not as compared with placebo. Regarding subjective sleep and awakening quality, only primary snorers and obstructive snorers showed an improvement, as compared with baseline while moderate sleep apnea patients remained unchanged. Based on intergroup comparison, we conclude that patients with moderate sleep apnea showed the most pronounced improvement in regard to respiratory events. Concerning sleep initiation and maintenance, sleep architecture and subjective sleep and awakening quality, no significant intergroup differences were found. Regarding objective awakening quality, attention showed a significantly greater improvement in primary than in obstructive snorers and sleep apnea patients, while motor performance was most improved in obstructive snorers.

The gender gap in depression reconsidered: the influence of marital and employment status on the female/male ratio of treated incidence rates

BACKGROUND

The consistently observed predominance of female over male rates in depression - in treated as well as in untreated populations - has never been satisfactorily explained. Among the many possible biological and psychosocial explanations, marital and employment status have not been extensively studied and virtually nothing is known about the combined effect of these variables on sex differences in depression. A main reason for this lack of knowledge is the limited number of cases available in epidemiological studies.

METHODS

The present paper examines the combined effects of marital and employment status on sex differences in depression rates by analysing in-patient admission rates of all depressed patients aged 18-67 admitted for the first ever time to the Department of Psychiatry of the University of Vienna from a strictly defined catchment area over a period of 42 months. Stepwise Poisson regression analyses were carried out in order to identify the relative contribution of these variables to the variance of first ever in-patient admission rates for depression.

RESULTS

A total of 2599 depressed patients fulfilled the inclusion criteria. When analysed separately, sex, marital status and employment status were shown to have distinct influences, with the "not married" carrying a two-fold higher risk than the married (2:1), and female sex (1.7:1) as well as not being employed (1.7:1) showing similar but smaller effects. In the detailed combined analysis, marriage was significantly less advantageous for women than for men, while sex differences disappeared completely in the widowed group. Also, there was no sex difference in the employed divorced; in the employed widowed there was even a slight preponderance in men. The highest rates were found in not employed divorced women, the lowest in employed married men.

CONCLUSION

While in-patient admissions are certainly selective in relation to epidemiological data, the large sample made it possible to perform combined analyses of sex, marital status and employment status. It was shown that the statement of a female preponderance in depression, which was found for the total sample, is a gross oversimplification. If marital and employment status are considered simultaneously, the sex differences disappear in some subgroups and in some are even reversed. We suggest that the combined influence of marital and employment status should be studied in epidemiological studies as well before conclusions about the influence of sex on depression rates are drawn.

[Daytime tiredness correlated with nocturnal respiratory and arousal variables in patients with sleep apnea: polysomnographic and EEG mapping studies]

There is evidence that daytime tiredness is caused by apnea/hypopnea with oxygen desaturation and/or by sleep fragmentation due to arousals. The aim of this study was to investigate objective and subjective sleep and awakening quality and daytime vigilance--objectified by midmorning mapping of vigilance-controlled EEG (V-EEG)--in sleep apnea patients (N: 18), as compared with age- and sex-matched normal controls (N: 18) as well as to correlate nocturnal respiratory distress and arousals to daytime brain function. Statistical analyses demonstrated a deterioration in subjective and objective sleep and awakening quality in apnea patients. Midmorning V-EEG mapping in apnea patients exhibited less total power, more delta and theta, less alpha and beta activity, as well as a slower dominant frequency and centroid of the total activity compared to controls, which suggests a vigilance decrement. The Spearman rank correlation between 6 polysomnographically registered respiratory variables and 36 diurnal quantitative EEG measures demonstrated the following: the higher the apnea, apnea-hypopnea, snoring and desaturation indices and the lower the minimum and average low oxygen saturation, the more pronounced was diurnal tiredness. Eleven arousal measures based on ASDA criteria showed the following significant correlations: the higher the nocturnal arousal index and the more arousals due to hypopneas, the greater was daytime tiredness. On the other hand, the greater the average frequency change during arousals and the more spontaneous arousals, the better was daytime vigilance. Our findings show that, in contrast to the lengthy Multiple Sleep Latency (MSLT) and Maintenance of Wakefulness (MWT) tests which evaluate sleep pressure under resting conditions conducive to sleep, V-EEG mapping provides a brief objective measure of a sleep apnea patient's daytime tiredness under conditions of wakefulness more appropriate to reflect the patient's everyday life.

Decrease of vigilance assessed by EEG-mapping in type I diabetic patients with history of recurrent severe hypoglycaemia

In Type I diabetic patients with history of recurrent severe hypoglycaemia, a more rapid decrease in vigilance (slowing of brain function) during hypoglycaemia in comparison to patients without history of such events was found. Our aims were: (1) to study EEG parameters of vigilance in non-hypoglycaemic state in representative groups of Type I diabetic patients with and without previous recurrent severe hypoglycaemia; and (2) to compare them with non-diabetic controls. A vigilance-controlled EEG mapping (10-20 system, significance probability maps) was performed in a non-hypoglycaemic state (blood glucose 4.0-10.0 mmol/l) in a group of 13 Type I diabetic patients with a history of recurrent severe hypoglycaemia and compared to that of 14 Type I diabetic patients without history of severe hypoglycaemia, matched for HbA1c, age and gender, and to age- and gender-matched non-diabetic controls. When compared to non-diabetic controls, hypoglycaemia patients demonstrated a reduction in absolute power in beta band (13-35 Hz) and slowing of centroid frequencies of beta and total frequency bands (1.3-35 Hz) (up to P < 0.01), whereas patients without history of severe hypoglycaemia showed only a borderline reduction of absolute power in delta (1.3-3.5 Hz) band. Deceleration in hypoglycaemia patients versus those without recurrent hypoglycaemia was most remarkable (P < .01) in centroid frequency of total frequency band. Patients with history of recurrent severe hypoglycaemia demonstrated in non-hypoglycaemic state significantly reduced vigilance when compared to the group without hypoglycaemia history and to the controls, as well. Lower vigilance may be at least in part responsible for impaired hypoglycaemia perception in these patients, but, as it resembles EEG patterns seen in pathologic ageing, it might also represent a consequence of recurrent episodes of severe hypoglycaemia.

Artifact processing in computerized analysis of sleep EEG - a review

Quantitative analysis of sleep EEG data can provide valuable additional information in sleep research. However, analysis of data contaminated by artifacts can lead to spurious results. Thus, the first step in realizing an automatic sleep analysis system is the implementation of a reliable and valid artifact processing strategy. This strategy should include: (1) high-quality recording techniques in order to minimize the occurrence of avoidable artifacts (e.g. technical artifacts); (2) artifact minimization procedures in order to minimize the loss of data by estimating the contribution of different artifacts in the EEG recordings, thus allowing the calculation of the 'corrected' EEG (e.g. ocular and ECG interference), and finally (3) artifact identification procedures in order to define epochs contaminated by remaining artifacts (e.g. movement and muscle artifacts). Therefore, after a short description of the types of artifacts in the sleep EEG and some typical examples obtained in different sleep stages, artifact minimization and identification procedures will be reviewed.

Differential effects of normal aging on sources of standard N1, target N1 and target P300 auditory event-related brain potentials revealed by low resolution electromagnetic tomography (LORETA)

The P300 event-related potential (ERP) is considered to be closely related to cognitive processes. In normal aging, P300 scalp latencies increase, parietal P300 scalp amplitudes decrease and the scalp potential field shifts to a relatively more frontal distribution. Based on ERPs recorded in 172 normal healthy subjects aged between 20 and 88 years in an auditory oddball paradigm, the effects of age on the electrical activity in the brain corresponding to N1 and P300 components were estimated by means of low resolution electromagnetic tomography (LORETA). This distributed approach directly computes a unique 3-dimensional electrical source distribution by assuming that neighbouring neurons are simultaneously and synchronously active. N1 LORETA generators, located predominantly in both auditory cortices and also symmetrically in prefrontal areas, increased with advancing age for standards but remained stable for targets. P300 LORETA generators, located symmetrically in the prefrontal cortex, in the parieto-occipital junction and in the inferior parietal cortex (supramarginal gyrus) and medially in the superior parietal cortex, were differentially affected by age. While age did not affect parieto-occipital sources, superior parietal and right prefrontal sources decreased pronouncedly. Thus, in normal aging, P300 current density decreased in regions were a fronto-parietal network for sustained attention was localized.

Nonorganic insomnia in generalized anxiety disorder. 2. Comparative studies on sleep, awakening, daytime vigilance and anxiety under lorazepam plus diphenhydramine (Somnium) versus lorazepam alone, utilizing clinical, polysomnographic and EEG mapping methods

Previous human pharmacological and toxicological studies demonstrated advantages of the combination drug Somnium [SOM, lorazepam (LOR) 1 mg plus diphenhydramine 25 mg] over 1 mg LOR alone, as it showed synergistic effects in hypnotic properties and antagonistic effects in regard to toxicity. In the present double-blind, parallel-group study, hypnotic and anxiolytic effects of SOM were studied in 44 patients with non-organic insomnia related to mild generalized anxiety disorder (GAD), as compared with LOR alone. After a placebo run-in phase of 1 week, they received active treatment (1 tablet SOM or LOR 1 mg) for 4 weeks and thereafter placebo again for 1 week. Clinical evaluations included the physician's general assessment of efficacy, tolerance and adverse effects, the Hamilton anxiety rating scale (HAMA), the Zung self-rating anxiety scale (SAS) and depression scale, the withdrawal symptom scale (WSS), hematology and blood chemistry. Sleep laboratory evaluations included objective and subjective sleep and awakening quality, measured by polysomnography, self-rating of sleep and awakening quality (SSA) and a psychometric test battery in the morning, as well as measurement of daytime brain function, objectivated by EEG mapping. Physicians' global evaluation of insomnia demonstrated no changes in the pre-drug placebo period, moderate improvement under both drugs, with a marginal advantage of SOM over LOR in the first 2 weeks, and a return to pre-drug values in the post-drug placebo period. Anxiety improved in observer ratings (HAMA) under both drugs, in self-rating (SAS) under the combination drug only, with the scores returning to pre-drug placebo values after post-drug placebo substitution. There were no significant findings in the self-rating depression scale and the WSS, with the exception of an improvement in the WSS score 4 weeks after SOM, as compared with pre-drug placebo. There were no rebound phenomena. Both drugs were well tolerated-in regard to both adverse effects and laboratory findings. Confirmatory statistics on the polysomnographically recorded target variable latency to sleep onset stage 2 demonstrated a significant shortening of sleep latency after SOM and a significant superiority of the combination drug SOM over LOR after acute dosing, as compared with pre-drug placebo. Descriptive statistics demonstrated further a significant improvement of sleep efficiency and total sleep time after SOM and of wakefulness time and number of awakenings during the total sleep period after both drugs, but no interdrug differences. Sleep architecture remained unchanged. Subjective sleep quality improved with both drugs, morning drowsiness and the total SSA score only with SOM, while LOR was superior to SOM regarding morning somatic complaints. There were neither changes nor interdrug differences in the morning noopsyche. In psychophysiology, critical flicker frequency decreased more under SOM than LOR. After 4 weeks therapy, no significant findings in polysomnography and subjective sleep and awakening were seen, except for an increase in movement time under LOR (tolerance development). In objective awakening quality, psychometry revealed an improvement of reaction time under SOM and a decrease of attention variability and an increase in fine-motor activity under LOR, with an interdrug comparison showing a significant superiority of SOM over LOR in regard to reaction time, reaction time variability and reaction time performance. After placebo substitution, rebound phenomena were seen in polysomnography and subjective sleep and awakening in the 1st night of the SOM group only, which were gone in the 7th placebo night, however. Noopsychic performance remained improved in both groups, with a superiority of SOM to LOR in regard to reaction time and reaction time variability. (ABSTRACT TRUNCATED)

Nonorganic insomnia in generalized anxiety disorder. 1. Controlled studies on sleep, awakening and daytime vigilance utilizing polysomnography and EEG mapping

Objective and subjective sleep and awakening quality as well as daytime vigilance of insomniac patients with generalized anxiety disorder (GAD) were investigated, as compared with normal controls. Forty-four outpatients (25 females, 19 males), aged 24-65 (mean 43) years, diagnosed with non-organic insomnia (ICD-10: F 51.0), related to mild GAD (F 41.1), with a Hamilton anxiety (HAMA) score of 22 +/- 6 and a Zung self-rating anxiety (SAS) score of 37 +/- 6 were included. After 1 adaptation night, sleep induction, maintainance and architecture were measured objectively by polysomnography, subjective sleep and awakening quality were assessed by self-rating scales and visual analog scales, objective awakening quality was measured by a psychometric test battery, and diurnal tiredness was measured by a 3-min vigilance-controlled EEG (V-EEG) and a 4-min resting EEG mapping. In polysomnography patients demonstrated-as compared with normals-significantly increased wake time during the total sleep period and more early-morning awakening, decreased total sleep and sleep efficiency. Subjective sleep quality was deteriorated as well, as were well-being, drive, mood, and wakefulness in the morning. In noopsychic performance, GAD patients did rather well in attention, concentration, attention variability, and numerical memory, while fine-motor activity and reaction time were deteriorated. In psychophysiology, critical flicker frequency was decreased in the morning, while muscle strength, blood pressure and pulse rate showed no differences. EEG mapping during the late morning hours (10.00-12.00 h) demonstrated hypervigilance in the V-EEG, while in the resting recording an increased sleep pressure was detected. The latter was correlated significantly to the SAS score, but less so to the observer-rated Hamilton anxiety score. Our findings suggest that CNS hypervigilance and hyperarousal, as actual symptoms of GAD, lead to nocturnal insomnia, which in turn may cause-as a consequence of sleep pressure not slept off-diurnal tiredness.

Topographic distribution of sleep spindles in young healthy subjects

The application of an automatic sleep spindle detection procedure allowed the documentation of the topographic distribution of spindle characteristics, such as number, amplitude, frequency and duration, as a function of sleep depth and of recording time. Multichannel all-night EEG recordings were performed in 10 normal healthy subjects aged 20-35 years. Although the interindividual variability in the number of sleep spindles was very high (2.7 +/- 2.1 spindles per minute stage 2 sleep), all but two subjects showed maximal spindle activity in centro-parietal midline leads. Moreover, this topography was seen in all sleep stages and changed only slightly--to a more central distribution--towards the end of the night. On the other hand, slow (11.5-14 Hz) and fast (14-16 Hz) spindles showed a completely different topography, with slow spindles distributed anteriorly and fast spindles centro-parietally. The number of sleep spindles per min was significant depending on sleep stages, with the expected highest occurrence in stage 2, and on recording time, with a decrease in spindle density from the beginning towards the end of the night. However, spindle amplitude, frequency and individual duration was not influenced by sleep depth or time of the night.

Sleep quality during alcohol withdrawal with bright light therapy

1. Alcohol withdrawal is a complex syndrome that ranges from anxiety, insomnia to delirium tremens. Common treatment is the application of sedative medication. Exposure to bright light in the daytime should advance the normal sleep/wake cycle and moreover it should improve the availability of man's adaptive behavior during alcohol withdrawal. 2. This pilot study describes bright light therapy (BL) during alcohol withdrawal in ten alcohol dependent patients (DSM-III-R: 291.80) without any sedative medication. BL (3000 Lux) was administered on day 3 of abstinence between 7.00-9.00 a.m. and 5.00-9.00 p.m. Total-sleep-polysomnography (recordings between 10.30 p.m.-6.00 a.m.) and self-rating scale were performed to compare intraindividual changes during three nights. After one adaptation night (immediately after alcohol withdrawal), one baseline night and one "BL-night" and one "post-BL night" were analysed. 3. At baseline, total sleep time and sleep efficiency were severely deteriorated, but tended to improve in the following nights after BL. Sleep onset latency showed a significant decline after BL. Stages 3 and 4 were reduced at baseline. Latencies to slow wave sleep were significantly shortened after BL. REM increased in the nights after BL. Subjective sleep quality improved after BL. Although the present results, bright light having a possible stabilizing effect on sleep maintenance and sleep architecture during acute alcohol withdrawal, the authors could only derive hypotheses for further ongoing controlled investigations using placebo light, to receive final verification.

First-night-effects on generalized anxiety disorder (GAD)-based insomnia: laboratory versus home sleep recordings

First-night effects (FNE) were comparatively investigated in patients with disorders in initiating and maintaining sleep (DIMS) associated with generalized anxiety disorder (GAD) in laboratory (n = 22) and home sleep polysomnography (n = 21). Patients had to be drug-free for at least 2 weeks prior to the first recording. Evaluation measures included 1) objective data on sleep initiation and maintenance; 2) sleep architecture based on polysomnographic recordings, analyzed visually according to the criteria of Rechtschaffen and Kales; 3) subjectively estimated sleep and awakening quality, assessed by a self-rating scale and visual analogue scales; 4) objective awakening quality as measured by a psychometric test battery; and 5) psychophysiological data, including critical flicker frequency, muscle strength, pulse, and blood pressure. Statistical analysis using multivariate analysis of variance (MANOVA) demonstrated multiple FNE in both groups regarding sleep efficiency, total sleep time, percentage of time in stage 2 sleep, percentage of time in stage 3/4 sleep, minutes of rapid eye movement (REM) sleep, and REM sleep latency. There was a group-by-night effect in the number of awakenings. There were no significant FNE regarding subjective sleep and awakening quality in either group. Differential adaptation effects were observed in attention and fine motor activity, with improvement in laboratory-recorded patients and deterioration in home-recorded patients. Differential findings also occurred in regard to evening blood pressure, with laboratory-recorded patients showing more adaptation.

Multichannel auditory event-related brain potentials: effects of normal aging on the scalp distribution of N1, P2, N2 and P300 latencies and amplitudes

Event-related potentials (ERPs) were recorded at 17 leads in an auditory oddball paradigm in 172 normal healthy subjects aged between 20 and 88 years. With advancing age, N1 latency increased parietally (0.12 ms/year), P2 latency increased frontally (0.34 ms/ year) and N2 and P300 latencies increased all over the scalp (0.37 ms/year for N2; 0.92 ms/year for P300). P300 latency/age relationship was curvilinear with accelerated latency increase in elderlies (0.35 ms/year for subjects below 60 years; versus 2.03 ms/year for subjects above 60 years). With advancing age, standard tone ERP amplitudes were enhanced frontally (0.03 microV/year for N1; 0.07 microV/year for P2), N2 amplitudes were attenuated frontally (0.11 microV/year) and P300 amplitudes were attenuated parietally (0.15 microV/year). Multichannel analysis demonstrated that ERP latencies and amplitudes depended on electrode location. Standard tone ERP latencies changed their topographic distribution with age, whereas target tone ERP latencies did not. While N1 amplitude distribution was unaffected by age, P2, N2 and P300 topography changed significantly with age: P2 topography to a more frontal distribution and increased 'global field power'; N2 topography to a more parietal distribution: P300 topography to a more frontal and more equipotential distribution Thus, specific age effects on different ERP components were confirmed.

Severe hypoglycaemia unawareness is associated with an early decrease in vigilance during hypoglycaemia

To elucidate neurophysiological characteristics in hypoglycaemia unawareness, we investigated the relationship between electroencephalography (EEG) parameters of vigilance and awareness of various symptom categories early in response to hypoglycaemia in intensively treated diabetic patients with different degrees of hypoglycaemia unawareness. Hypoglycaemia (venous plasma glucose below 2.2 mmol/1) was induced with an intravenous insulin bolus in seven patients with insulin-dependent diabetes mellitus (IDDM) with a history of hypoglycaemia unawareness and repeated severe hypoglycaemia, as well as in a group of seven IDDM patients with good awareness of hypoglycaemia. Both groups were comparable in age, treatment strategy, glycaemic control and level of late complications. Basic cognitive performance and other symptom categories were estimated serially during a period of 2 h following the insulin bolus. A vigilance-controlled EEG was recorded continuously; its automatic analysis included the evaluation of vigilance indices. In the baseline prehypoglycaemic state, hypoglycaemia unaware patients showed higher initial vigilance (p = .05) than the aware group. Unaware patients reported fewer neurogenic (p = .002, mainly cholinergic, p = .009) hypoglycaemia symptoms during hypoglycaemia, and developed an impairment in cognitive performance over time (p = .002). EEG analysis indicated a more rapid decrease in vigilance after the hypoglycaemic stimulus for unaware patients than for aware patients. The lowering of plasma glucose to 3.06-3.89 mmol/l already induced a significant increase in delta and theta, as well as a decrease in alpha relative power only in the unaware group. Differences between groups with regards to the degree of deceleration were most pronounced early, during only slight hypoglycaemia, and topographically spread over central and parietal brain regions. Further lowering of plasma glucose induced an even more pronounced, abrupt increase in slow waves in unaware patients at higher plasma glucose levels than in hypoglycaemia aware subjects (for delta waves at 2.41 +/- 0.16 vs. 1.96 +/- 0.1 mmol/l, p = .04). This preceded the worsening of cognitive performance during hypoglycaemia in unaware patients by 19 +/- 3 min. Hypoglycaemia unawareness associated with previous unconsciousness is associated with- and may be the result of-an early hypoglycaemia-induced reduction in vigilance and an early EEG deceleration, which seems to be a teleologically effective measure for delaying eventual cerebral energy failure in hypoglycaemia.

Hormonal, syndromal and EEG mapping studies in menopausal syndrome patients with and without depression as compared with controls

The aim of the study was to investigate brain function in menopausal depression by EEG mapping, as compared with menopausal syndrome patients without depression and normal controls, and to correlate neurophysiological with clinical and hormonal findings in order to elucidate the pathogenesis of depression in the menopause.

METHODS

One hundred and twenty-nine menopausal women, aged 45-60 years, with no previous hormonal replacement therapy were investigated in regard to hormones (estradiol [E2], follicle stimulating hormone [FSH]), clinical symptomatology (Kupperman Index [KI], Hamilton depression score [HAMD]) and brain function (EEG mapping). Based on KI and DSM-III-R research criteria for major depression, 3 groups were available for statistics (after removal of protocol violators): group A had a KI of <15 and no depression (n = 29); group B had a KI of > or = 15 and no depression (n = 29) and group C had a KI of > or = 15 and fulfilled the criteria for major depression (n = 60).

RESULTS

EEG maps of depressed patients demonstrated less total power and absolute power in the delta, theta and beta band, more relative delta and less alpha power as well as a slower delta/theta and faster alpha and beta centroid than controls, suggesting a vigilance decrement. Group B did not differ from group A. Correlation maps showed significant relationships between estradiol levels and EEG measures (the lower the E2, the worse the vigilance) and between the EEG measures and the Hamilton depression (HAMD) score (the worse the vigilance, the higher the depression score). There were no correlations between the hormones E2 and FSH and the syndromes KI and HAMD. In the target variable, the asymmetry index, depressed patients showed less alpha power over the right than left frontal lobe, whereas normal controls exhibited the opposite. Group B did not differ from group A. The frontal asymmetry index was significantly correlated with the Hamilton depression score and suggests right frontal hyper- and left frontal hypoactivation in depression.

CONCLUSIONS

Although hormonal findings are not directly linked to psychic changes, low estradiol levels do contribute to a decreased vigilance at the neurophysiological level , which is in turn correlated with higher depressive and menopausal symptomatology at the behavioural level. Depression is further correlated to a right frontal hyper- and left frontal hypoactivation.

On the cerebro-protective effects of caroverine, a calcium-channel blocker and antiglutamatergic drug: double-blind, placebo-controlled, EEG mapping and psychometric studies under hypoxia

1. In a double-blind, placebo-controlled study, the acute antihypoxidotic properties of the calcium-channel blocking and antiglutamatergic caroverine were investigated utilizing blood gas analysis, EEG mapping and psychometry under a transient, reversible, hypoxic hypoxidosis. 2. The latter was induced by a fixed gas combination of 9.8% oxygen (O2) and 90.2% nitrogen (N2) (found in 6000 m altitude), which was inhaled for 23 min under normobaric conditions by 16 healthy, young volunteers. They received randomized after an adaptation session, single oral doses of placebo, 40, 80 and 120 mg caroverine. Evaluation of blood gases, EEG mapping and psychometry were carried out 0, 2, 4, 6 and 8 h post-drug, during hypoxia. 3. Blood gas analysis demonstrated a drop in PO2 from 95 to 33 and 30 mmHg, in PCO2 from 38 to 30 and 30 mmHg in the 14th and 23rd minute of inhalation, respectively, while pH increased from 7.41 to 7.50 and 7.51. Base excess and standard bicarbonate remained stable. 4. EEG mapping under hypoxia exhibited a marked increase of delta/theta, decrease of alpha and an increase of superimposed beta activity, which reflects deterioration of vigilance. 5. Caroverine attenuated this hypoxia-induced vigilance decrement in a dose- and time-dependent manner 6-8 h after 80 mg and 2-8 h after 120 mg. 6. Hypoxic hypoxidosis induced a deterioration of memory and attention variability, which was mitigated by 80 and 120 mg caroverine. However, there was an augmentation of the hypoxia-induced decrement in psychomotor performance after 120 mg. 7. The drug was well tolerated, and there were no significant differences compared with placebo with regard to pulse and blood pressure.

Comparative pharmacodynamic studies with the novel serotonin uptake-enhancing tianeptine and -inhibiting fluvoxamine utilizing EEG mapping and psychometry

In a double-blind, placebo-controlled study, the encephalotropic and psychotropic effects of tianeptine (TIA)--a new tricyclic antidepressant, enhancing serotonin reuptake--were investigated as compared with the serotonin reuptake inhibiting antidepressant, fluvoxamine (FLU), utilizing EEG mapping, psychometric and psychophysiological measures. 16 healthy volunteers (8 males, 8 females) aged 21-35 (man 27) years received randomized and at weekly intervals single oral doses of placebo, 12.5 and 25 mg TIA and 50 mg FLU. EEG recordings, psychometric and psychophysiological tests and evaluation of pulse, blood pressure and side effects were carried out at 0, 2, 4, 6 and 8 hours; blood sampling, in addition, at hour 1. TIA plasma levels rose fast to peaks at 1-2 hours and declined rapidly as well, while the MC5 metabolite peaked in the 4th hour and declined more slowly. EEG mapping demonstrated that both TIA and FLU induced significant changes in brain function between the 1st and 8th hour, which, however, differed in their time course. 12.5 mg TIA exhibited, as compared with placebo, slight activating properties in the EEG (decrease of delta and theta, increase of alpha and beta, acceleration of the centroid), parallelled by thymopsychic improvement (mood elevation). 25 mg TIA showed EEG activation up to the 4th hour, later EEG sedation, accompanied by an initial thymopsychic improvement and differential changes thereafter (improved mood, decreased vigility), with the noopsyche improving at all times (attention, Pauli test). 50 mg FLU induced initially sedation and thereafter activation, accompanied by thymopsychic deterioration and subsequent improvement, the latter also being observed in the noopsyche (attention, memory). In pupillary and skin conductance measures, generally a slight activation occurred after placebo, which was attenuated by 25 mg TIA. Correlation maps between plasma levels and EEG changes demonstrated: the higher the TIA plasma levels, the more absolute and relative beta power, the less alpha power and the faster the centroid of the total power spectrum, reflecting CNS-activation. Topographically, the correlations were mostly seen over both fronto-temporal regions. In the latter, dominant frequency signalled desactivation in the right and activation in the left hemiphere after both antidepressants which, thereby induced changes in brain function opposite to those observed in depression. Both drugs were well tolerated.

EEG topography during insulin-induced hypoglycemia in patients with insulin-dependent diabetes mellitus

A group of young patients with insulin-dependent diabetes mellitus (n = 14; 8 men, 6 women; 33.1 +/- 8.9 years) were examined by topographic EEG mapping under normoglycemic and hypoglycemic conditions (glucose levels after intravenous insulin injection down to 32.6 +/- 7.6 mg/dl). From the clinical aspect, 7 of them had a good and 7 had a poor awareness of hypoglycemia. During hypoglycemia, a decrease in alpha activity (p < 0.05), an increase in delta (p < 0.05), and especially in theta activity (p < 0.05) were found. The most sensitive parameter was the alpha/theta ratio. In the range of slight hypoglycemia (50-60 mg/dl) the increase in delta and theta activity showed a topographic maximum in lateral frontal regions. During deep hypoglycemia there was a topographic maximum of slow frequencies in posterior parts of the brain (centrotemporal to parieto-occipital regions). The differences between the group with good and with poor awareness of hypoglycemia were most pronounced during slight hypoglycemia in C3, C4, and Pz (p < 0.05). At lower glucose levels group distinction was no longer possible. These EEG changes correspond to a temporary organic brain syndrome.