Memory dysfunction and vigilance: neurophysiological and psychopharmacological aspects

Effects of Smart Drugs on Cholinergic System and Non-Neuronal Acetylcholine in the Mouse Hippocampus: Histopathological Approach

In recent years, people in the United States and other countries have been using smart drugs, called nootropic or cognitive enhancers, to improve concentration and memory learning skills. However, these drugs were originally prescribed for attention-deficit hyperactivity disorder and dementia, and their efficacy in healthy people has not yet been established. We focused on acetylcholine in the hippocampus, which is responsible for memory learning, and elucidate the long-term effects of smart drugs on the neural circuits. Smart drugs were administered orally in normal young mice for seven weeks. The hippocampus was sectioned and compared histologically by hematoxylin and eosin (HE) staining, immunohistochemistry for acetylcholine, and immunoelectron microscopy. There were no significant changes in acetylcholinesterase staining. However, in HE, we found perivascular edema, and choline acetyltransferase staining showed increased staining throughout the hippocampus and new signal induction in the perivascular area in the CA3, especially in the aniracetam and α-glyceryl phosphoryl choline group. Additionally, new muscarinic acetylcholine receptor signals were observed in the CA1 due to smart drug intake, suggesting that vasodilation might cause neuronal activation by increasing the influx of nutrients and oxygen. Moreover, these results suggest a possible new mechanism of acetylcholine-mediated neural circuit activation by smart drug intake.

Abnormal maturation of the resting-state peak alpha frequency in children with autism spectrum disorder

Age-related changes in resting-state (RS) neural rhythms in typically developing children (TDC) but not children with autism spectrum disorder (ASD) suggest that RS measures may be of clinical use in ASD only for certain ages. The study examined this issue via assessing RS peak alpha frequency (PAF), a measure previous studies, have indicated as abnormal in ASD. RS magnetoencephalographic (MEG) data were obtained from 141 TDC (6.13-17.70 years) and 204 ASD (6.07-17.93 years). A source model with 15 regional sources projected the raw MEG surface data into brain source space. PAF was identified in each participant from the source showing the largest amplitude alpha activity (7-13 Hz). Given sex differences in PAF in TDC (females > males) and relatively few females in both groups, group comparisons were conducted examining only male TDC (N = 121) and ASD (N = 183). Regressions showed significant group slope differences, with an age-related increase in PAF in TDC (R²  = 0.32) but not ASD (R²  = 0.01). Analyses examining male children below or above 10-years-old (median split) indicated group effects only in the younger TDC (8.90 Hz) and ASD (9.84 Hz; Cohen's d = 1.05). In the older ASD, a higher nonverbal IQ was associated with a higher PAF. In the younger TDC, a faster speed of processing was associated with a higher PAF. PAF as a marker for ASD depends on age, with a RS alpha marker of more interest in younger versus older children with ASD. Associations between PAF and cognitive ability were also found to be age and group specific.

The frequency of alpha oscillations: Task-dependent modulation and its functional significance

Power (amplitude) and frequency are two important characteristics of EEG alpha oscillations (8-12 Hz). There is an extensive literature showing that alpha power can be modulated in a goal-oriented manner to either enhance or suppress sensory information processing. Only a few studies to date have examined the task-dependent modulation of alpha frequency. Instead, alpha frequency is often viewed as a trait variable, and used to characterize individual differences in cognitive functioning. We performed two experiments to examine the task-dependent modulation of alpha frequency and its functional significance. In the first experiment, high-density EEG was recorded from 21 participants performing a Sternberg working memory task. The results showed that: (1) during memory encoding, alpha frequency decreased with increasing memory load, whereas during memory retention and retrieval, alpha frequency increased with increasing memory load, (2) higher alpha frequency prior to the onset of probe was associated with longer reaction time, and (3) higher alpha frequency prior to the onset of cue or probe was associated with weaker early cue-evoked or probe-evoked neural responses. In the second experiment, simultaneous EEG-fMRI was recorded from 59 participants during resting state. An EEG-informed fMRI analysis revealed that the spontaneous fluctuations of alpha frequency, but not alpha power, were inversely associated with BOLD activity in the visual cortex. Taken together, these findings suggest that alpha frequency is task-dependent, may serve as an indicator of cortical excitability, and along with alpha power, provides more comprehensive indexing of sensory gating.

Characterizing the roles of alpha and theta oscillations in multisensory attention

Cortical alpha oscillations (8-13Hz) appear to play a role in suppressing distractions when just one sensory modality is being attended, but do they also contribute when attention is distributed over multiple sensory modalities? For an answer, we examined cortical oscillations in human subjects who were dividing attention between auditory and visual sequences. In Experiment 1, subjects performed an oddball task with auditory, visual, or simultaneous audiovisual sequences in separate blocks, while the electroencephalogram was recorded using high-density scalp electrodes. Alpha oscillations were present continuously over posterior regions while subjects were attending to auditory sequences. This supports the idea that the brain suppresses processing of visual input in order to advantage auditory processing. During a divided-attention audiovisual condition, an oddball (a rare, unusual stimulus) occurred in either the auditory or the visual domain, requiring that attention be divided between the two modalities. Fronto-central theta band (4-7Hz) activity was strongest in this audiovisual condition, when subjects monitored auditory and visual sequences simultaneously. Theta oscillations have been associated with both attention and with short-term memory. Experiment 2 sought to distinguish these possible roles of fronto-central theta activity during multisensory divided attention. Using a modified version of the oddball task from Experiment 1, Experiment 2 showed that differences in theta power among conditions were independent of short-term memory load. Ruling out theta's association with short-term memory, we conclude that fronto-central theta activity is likely a marker of multisensory divided attention.

Cortical sources of EEG rhythms in congestive heart failure and Alzheimer's disease

INTRODUCTION

The brain needs continuous oxygen supply even in resting-state. Hypoxia enhances resting-state electroencephalographic (EEG) rhythms in the delta range, and reduces those in the alpha range, with a pattern similar to that observed in Alzheimer's disease (AD). Here we tested whether resting-state cortical EEG rhythms in patients with congestive heart failure (CHF), as a model of acute hypoxia, present frequency similarities with AD patients, comparable by cognitive status revealed by the mini mental state examination (MMSE).

METHODS

Eyes-closed EEG data were recorded in 10 CHF patients, 20 AD patients, and 20 healthy elderly subjects (Nold) as controls. LORETA software estimated cortical EEG generators.

RESULTS

Compared to Nold, both AD and CHF groups presented higher delta (2-4Hz) and lower alpha (8-13Hz) temporal sources. The highest delta and lowest alpha sources were observed in CHF subjects. In these subjects, the global amplitude of delta sources correlated with brain natriuretic peptide (BNP) level in the blood, as a marker of disease severity.

CONCLUSIONS

Resting-state delta and alpha rhythms suggest analogies between the effects of acute hypoxia and AD neurodegeneration on the cortical neurons' synchronization.

SIGNIFICANCE

Acute ischemic hypoxia could affect the mechanisms of cortical neural synchronization generating resting state EEG rhythms, inducing the "slowing" of EEG rhythms typically observed in AD patients.

EEG delta oscillations as a correlate of basic homeostatic and motivational processes

Functional significance of delta oscillations is not fully understood. One way to approach this question would be from an evolutionary perspective. Delta oscillations dominate the EEG of waking reptiles. In humans, they are prominent only in early developmental stages and during slow-wave sleep. Increase of delta power has been documented in a wide array of developmental disorders and pathological conditions. Considerable evidence on the association between delta waves and autonomic and metabolic processes hints that they may be involved in integration of cerebral activity with homeostatic processes. Much evidence suggests the involvement of delta oscillations in motivation. They increase during hunger, sexual arousal, and in substance users. They also increase during panic attacks and sustained pain. In cognitive domain, they are implicated in attention, salience detection, and subliminal perception. This evidence shows that delta oscillations are associated with evolutionary old basic processes, which in waking adults are overshadowed by more advanced processes associated with higher frequency oscillations. The former processes rise in activity, however, when the latter are dysfunctional.

The effect of hypobaric hypoxia on multichannel EEG signal complexity

OBJECTIVE

The objective of this study was the development and evaluation of nonlinear electroencephalography parameters which assess hypoxia-induced EEG alterations, and describe the temporal characteristics of different hypoxic levels' residual effect upon the brain electrical activity.

METHODS

Multichannel EEG, pO2, pCO2, ECG, and respiration measurements were recorded from 10 subjects exposed to three experimental conditions (100% oxygen, hypoxia, recovery) at three-levels of reduced barometric pressure. The mean spectral power of EEG under each session and altitude were estimated for the standard bands. Approximate Entropy (ApEn) of EEG segments was calculated, and the ApEn's time-courses were smoothed by a moving average filter. On the smoothed diagrams, parameters were defined.

RESULTS

A significant increase in total power and power of theta and alpha bands was observed during hypoxia. Visual interpretation of ApEn time-courses revealed a characteristic pattern (decreasing during hypoxia and recovering after oxygen re-administration). The introduced qEEG parameters S1 and K1 distinguished successfully the three hypoxic conditions.

CONCLUSIONS

The introduced parameters based on ApEn time-courses are assessing reliably and effectively the different hypoxic levels. ApEn decrease may be explained by neurons' functional isolation due to hypoxia since decreased complexity corresponds to greater autonomy of components, although this interpretation should be further supported by electrocorticographic animal studies.

SIGNIFICANCE

The introduced qEEG parameters seem to be appropriate for assessing the hypoxia-related neurophysiological state of patients in the hyperbaric chambers in the treatment of decompression sickness, carbon dioxide poisoning, and mountaineering.

Levetiracetam: An improvement of attention and of oral fluency in patients with partial epilepsy

PURPOSE

The aim of the present study is to verify whether patients with partial epilepsy receiving levetiracetam (LEV) as an add-on treatment show an improvement in cognitive function.

METHODS

A neuropsychological battery of tests was administered to 35 patients with partial epilepsy before the assumption of LEV and after the achievement of the therapeutical dose of this drug, 7 weeks later. A control group of 35 patients with partial epilepsy was administered the same battery of tests twice, at the same time interval as the LEV group. The controls were administered the same pharmacological treatment, which did not include LEV in either of the two sessions.

RESULTS

We found a statistically significant improvement in cognitive functioning, i.e. in attention and oral fluency, in patients receiving LEV compared to the controls. The responders to LEV were 28.6%.

CONCLUSIONS

LEV as an add-on therapy improved attention level and verbal fluency in our sample of patients with partial epilepsy. It is reasonable to assume that LEV may influence the metabolism of attention and of language area, as already suggested for piracetam (PIR) from which LEV derives. Further studies are needed to confirm these findings.

Age-related cognitive decline in the menopause: effects of hormone replacement therapy on cognitive event-related potentials

OBJECTIVE

Although epidemiological and clinical studies suggest that hormone replacement therapy (HRT) may protect against cognitive disorders and neurodegenerative diseases, the relation between estrogen and cognition in postmenopausal women remains controversial.

METHODS

In a double-blind placebo-controlled, parallel group design study the effects of HRT with the estrogen-progestogen combination Presomen 1.25 compositum((R)) (1.25mg equine conjugated estrogens administered for 21 days plus the progestogen 5mg medrogeston given for 11 days) on event-related potentials (ERPs) in postmenopausal patients with age-related cognitive decline (DSM-IV code 780.9, ICD-10 code R 41.8) were investigated. After a pre-drug comparison with age-matched normal postmenopausal controls, 48 psychotropic drug-free patients aged 60 +/- 6 years were randomized to receive either placebo or verum for 4 months. ERPs were recorded before as well as on the 91-92 days of the study, which thus fell into the estrogen phase of the treatment during the fourth cycle.

RESULTS

At baseline, patients showed a lengthening of P300 latency and an attenuation of P300 amplitudes as compared with normal controls. After HRT with Presomen, a significant shortening of P300 latency as compared with placebo was observed.

CONCLUSIONS

The baseline P300 differences suggest that in the patient group the aging process was advanced, while after HRT with Presomen a significant improvement and normalization of information processing as indexed by P300 was observed.

EEG-mapping differences between narcolepsy patients and controls and subsequent double-blind, placebo-controlled studies with modafinil

The aim of the present study was to investigate the role of EEG mapping as an objective and quantitative measure of vigilance in untreated and modafinil-treated narcoleptics, and compare it with the conventional neurophysiological method of the Multiple Sleep Latency Test (MSLT) and the subjective Epworth Sleepiness Scale (ESS). In 16 drug-free narcoleptics and 16 normal controls a baseline 3-min vigilance-controlled EEG (V-EEG) and a 4-min resting EEG (R-EEG) were recorded during midmorning hours. Thereafter, in a double-blind, placebo-controlled crossover design, patients were treated with a 3-week fixed titration of modafinil (200, 300, 400 mg) and placebo. EEG-mapping, MSLT and ESS measures were obtained before and at the end of the third week of therapy. Statistical overall analysis by means of the omnibus significance test demonstrated significant EEG differences between untreated patients and controls in the resting condition only (R-EEG). Subsequent univariate analysis revealed an increase in absolute and relative theta power, a decrease in alpha-2 and beta power as well as a slowing of the dominant frequency and the centroids of the alpha, beta and total power spectrum and thus objectified a vigilance decrement in narcolepsy. Modafinil 400 mg/d significantly improved vigilance as compared with placebo (p < or = 0.01), inducing changes opposite to the aforementioned baseline differences (key-lock principle). The MSLT and the ESS also improved under modafinil as compared with placebo, but changes were less consistent. Spearman rank correlations revealed the highest correlations between EEG mapping and the ESS, followed by those between EEG mapping and the MSLT, while the lowest correlation was found between the MSLT and the ESS. In conclusion, EEG mapping is a valuable instrument for measuring vigilance decrements in narcolepsy and their improvement under psychostimulant treatment.

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.

Hormone replacement therapy and vigilance: double-blind, placebo-controlled EEG-mapping studies with an estrogen-progestogen combination (Climodien, Lafamme) versus estrogen alone in menopausal syndrome patients

The aim of the double-blind, placebo-controlled study was to investigate the effects of a continuous combined estrogen-progestogen treatment (Climodien, Lafamme) as compared with estrogen alone on vigilance in insomniac postmenopausal syndrome patients, objectified by EEG mapping.

METHODS

In a 3-arm, 2-month parallel group design phase, patients received a combination of estradiol valerate 2 mg and the novel progestogen dienogest 3 mg (Climodien 2/3) or estradiol valerate 2 mg alone or placebo. In a subsequent open-label phase, all patients received estradiol valerate 2 mg+dienogest 2 mg (Climodien 2/2). EEG mapping was carried out before and after the 2-month double-blind phase as well as after the 2-month open-label treatment.

RESULTS

As compared with placebo, Climodien 2/3 induced a marked and highly significant increase in absolute power in all frequency bands, specifically in alpha-2 activity. Moreover, a significant increase in relative alpha-2 power, a decrease in relative delta and beta power as well as an acceleration of the dominant frequency and of the delta and alpha centroids suggested a marked improvement in vigilance. In contrast, under estradiol valerate 2 mg alone, only a slight augmentation of alpha and attenuation of relative delta and beta power occurred, suggesting only a slight vigilance improvement as compared with placebo. Thus, dienogest 2 mg increased the estrogen effect, which was also confirmed by a statistical evaluation of the differences between Climodien 2/3 and estradiol valerate alone (augmentation of alpha-2, attenuation of relative beta, acceleration of the dominant frequency). Moreover, Climodien 2/2 also markedly increased alpha-2 power, decreased relative beta-2 power and accelerated the alpha centroid. Finally, comparing Climodien 2/3 with Climodien 2/2, there was even a dose-efficacy relation.

CONCLUSIONS

Estradiol valerate 2 mg improves vigilance slightly, thereby confirming previous findings. The additional administration of dienogest does not minimize the effect of estrogen, but on the contrary increases it, which makes the combination superior to both placebo and estradiol valerate alone. Vigilance improvement may be of great therapeutic benefit to menopausal syndrome patients at a time when increased adaptability is needed to adjust to increasing sexual, marital, occupational and social difficulties known to occur specifically in this period of life.

Effect of rest on physicians' performance in an emergency department, objectified by electroencephalographic analyses and psychometric tests

OBJECTIVE

The aim of the field study was to objectify physicians' vigilance, well-being, and cognitive performance in the course of 24-hr shifts with and without afternoon rest. SUBJECTS, SETTING, AND DESIGN: Eleven residents (four women, seven men; age, 33.5 +/- 4.7 yrs) were observed when doing two regular 24-hr shifts at the emergency department (randomized crossover design): one without rest, the other with a period of rest in the early afternoon (duration, 2:31 +/- 1:04 hrs) and the opportunity of having a nap (duration, 1:07 +/- 0:26 hrs, n = 6). Electroencephalography and psychometric tests were carried out at 8 am and at midnight.

MEASUREMENTS

Measurements included subjective perception of workload, stress, and sleeping behavior; computer-analyzed electroencephalography; adjective checklist (Eigenschaftswörterliste 60 S, a self-rating scale); complex reaction time test; Pauli test (number of calculations during 3 mins); and numerical memory test.

RESULTS

Electroencephalographic analyses showed a significant decrease in alpha power and a significant increase in beta power in the evening as compared with the morning on both days. The nocturnal increase observed in delta activity was significantly less pronounced in duties with rest than in duties without rest. Physicians felt deactivated at night. The Eigenschaftswörterliste 60 S indicated deactivation at night and a rest-induced activation in the subgroup that had taken the opportunity to sleep in the afternoon. Psychometric tests did not show any significant differences, neither between performance in the morning and evening nor between results with and without rest.

CONCLUSION

As expected, electroencephalographic recordings showed nocturnal deactivation and a vigilance-promoting effect of the afternoon rest. These objective findings were in accordance with the results derived from self-rating scales. On the other hand, in short-lasting psychometric tests, performance was found unchanged after 16 hrs of routine work. In further studies, a discrimination between resting periods with and without sleep will be important.

EEG mapping in patients with restless legs syndrome as compared with normal controls

Restless legs syndrome (RLS) is a sensorimotor movement and sleep disorder with a high prevalence. While the sleep disturbance due to RLS has been studied quite well polysomnographically, little is known about the electrophysiological function during daytime. The aim of the present study was to investigate the diurnal quantitative EEG and clinical symptomatology in 33 drug-free RLS patients as compared with age- and sex-matched normal controls. Investigations comprised brain mapping of the vigilance-controlled EEG as well as completion of the Zung Self-Rating Depression Scale, the Zung Self-Rating Anxiety Scale, the Quality of Life Index, the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale for evaluation of clinical symptomatology. Statistical analysis demonstrated an increase in absolute delta and absolute and relative alpha-2 power, a decrease in absolute and relative alpha-1 power, an acceleration of the dominant frequency and the alpha centroid, and a slowing of the delta/theta centroid, as well as a non-significant attenuation in total power. These findings are characteristic of dissociated vigilance changes described in depression. Indeed, RLS patients demonstrated significantly higher depression and anxiety scores, lower quality of life and deteriorated sleep quality. The score of the Epworth Sleepiness Scale was not elevated, in contrast to the increased daytime sleepiness observed in other highly prevalent organic sleep disorders (e.g. sleep apnea). In conclusion, daytime EEG mapping revealed neurophysiological correlates of depression in RLS, which was confirmed by self-ratings at the symptomatological level.

Eptastigmine restores the aged rat's normal cortical spectral power pattern

We studied the ability of eptastigmine, a second-generation acetylcholinesterase inhibitor (AChEI), to reverse the age-related increase of electroencephalogram (EEG) mean cortical spectral power in slow-wave delta activity and decrease in fast-wave alpha and beta activity. The relative basal spectral power profile evaluated for 50 min of the old (27-30 months) in comparison to young (4-6 months) awake rats was consistently different, showing a significant increase in delta(0.2-4.0 Hz) frequency and a significant decrease of alpha(8.2-13.0 Hz) and beta(13.2-25.0) bands. When 0.5, 1, 2, 4 mg kg(-1)of eptastigmine were administered orally as single increasing doses for old and young rats 2 h prior to the EEG recordings, lasting 2 h, the relative mean spectral power difference (Delta%) showed a linear log dose-related decrease in delta activity and a progressive increase in alpha and beta activity in old rats. Compared to vehicle, in young rats, the eptastigmine dose of 0.5 mg kg(-1)produced a significant decrease in delta activity and an increase in beta activity. The spontaneous motor activity, evaluated through cumulative horizontal and vertical counts for 30 min in old rats was significantly decreased when compared to young rats. Single oral treatment with eptastigmine (0.5 mg kg(-1)for young and 2 mg kg(-1)for old rats) given 2 h before the test did not significantly change motor activity in comparison to vehicle group of the same age. These results suggest a possible strategy to alleviate the severe slowing of neocortical EEG accompanying the cognitive decline.

Effects of nitroglycerine on cerebral blood flow velocity, quantitative electroencephalogram and cognitive performance

BACKGROUND

Despite the widespread use of nitroglycerine, little is known of its cerebral haemodynamic effects. The present study was undertaken to evaluate the effects of nitroglycerine on cerebral circulation and cognitive function in normal volunteers.

DESIGN

Twelve healthy male volunteers (age 25 +/- 3 years; mean +/- SD) received continuous intravenous infusions of nitroglycerine at 1 mg h-1 and 2 mg h-1 rates as well as placebo (0.9% saline) under randomized, double-blind cross-over conditions on three different occasions. A 10-min quantitative EEG (qEEG) was recorded before, during and repeatedly after infusion. Blood flow velocity in the left arteria cerebri media (MCA) was measured simultaneously by means of transcranial Doppler sonography. Cognitive performance was assessed with a computerized test battery.

RESULTS

Administration of nitroglycerine caused a significant reduction of mean blood flow velocity in the left MCA. In parallel a significant increase of absolute power density < 4 Hz was noted. The latter effect was dose dependent. Cognitive functions, such as attention and memory, were not altered.

CONCLUSIONS

The decrease in cerebral blood flow velocity in the left MCA may be due to vasodilatation and/or reduction in perfusion. The concomitant increase of slow wave power in the qEEG may indicate an impairment of brain function.

Effects of nicergoline on age-related decrements in radial maze performance and acetylcholine levels

The effects of chronic oral administration of nicergoline (5.0 mg/kg; bid) on locomotor activity, eight-arm radial maze performance plus striatal, cortical, and hippocampal acetylcholine (ACh) levels were examined in young and aged Wistar rats. Chronic nicergoline administration did not modify either the locomotor activity or radial maze learning in young rats. Young rats learned the radial maze procedure rapidly and improved their performance throughout the successive training sessions. Radial maze performance in young rats was characterised by very few arm reentries. Aged rats were hypoactive and did not explore or enter the radial maze arms, and consequently performed poorly in the radial maze throughout the training sessions. Nicergoline treatment did not significantly modify locomotor activity in aged rats. Aged rats treated with nicergoline also performed poorly initially but improved with repeated training in the radial maze. This improvement was associated with an increasing number of arms being entered and very few arm reentries. Reduced acetylcholine (ACh) levels were also associated with age. Aged rats had significantly reduced levels of ACh in the straitum and cortex, but not the hippocampus as compared to young rats. Nicergoline treatment did not change ACh levels in young rats, but substantially restored the reduced ACh levels in aged rats. These results indicate that nicergoline is an effective cognitive enhancer in a learning model of age-related deficits and that these results may be related to changes in the cholinergic system.

Memory processes, brain oscillations and EEG synchronization

This article tries to integrate results in memory research from divergent disciplines such as cognitive psychology, neuroanatomy, and neurophysiology. The integrating link is seen in more recent findings that provide strong arguments for the assumption that oscillations are a basic form of communication between cortical cell assemblies. It is assumed that synchronous oscillations of large cell assemblies--termed type 1 synchronization--reflect a resting state or possibly even a state of functional inhibition. On the other hand, during mental activity, when different neuronal networks may start to oscillate with different frequencies, each network may still oscillate synchronously (this is termed type 2 synchronization), but as a consequence, the large scale type 1 oscillation disappears. It is argued that these different types of synchronization can be observed in the scalp EEG by calculating event-related power changes within comparatively narrow but individually adjusted frequency bands. Experimental findings are discussed which support the hypothesis that short-term (episodic) memory demands lead to a synchronization (increase in band power) in the theta band, whereas long-term (semantic) memory demands lead to a task-specific desynchronization (decrease or suppression of power) in the upper alpha band. Based on these and other findings, a new memory model is proposed that is described on three levels: cognitive, anatomical and neurophysiological. It is suggested that short-term (episodic) memory processes are reflected by oscillations in an anterior limbic system, whereas long-term (semantic) memory processes are reflected by oscillations in a posterior-thalamic system. Oscillations in these frequency bands possibly provide the basis for encoding, accessing, and retrieving cortical codes that are stored in the form of widely distributed but intensely interconnected cell assemblies.

Double-blind, placebo-controlled, hormonal, syndromal and EEG mapping studies with transdermal oestradiol therapy in menopausal depression

In a double-blind, placebo-controlled study, the antidepressant and vigilance-promoting properties of transdermal oestrogen in post-menopausal depression were investigated utilizing hormonal, syndromal and EEG mapping evaluations. Sixty-nine menopausal women, aged 45-60 years without previous hormonal replacement therapy, diagnosed as major depression without psychotic or suicidal symptoms (DSM-III-R criteria), were randomly assigned to a 3-month treatment with transdermal oestradiol [Estraderm TTS (ETTS) 50 micrograms, applied twice weekly] or placebo. No other psychoactive medication was allowed. After removal of protocol violators, 32 patients were evaluable in each group, which did not differ in age, height or weight. As five patients discontinued prematurely in both groups and in one placebo patient a post-drug EEG could not be obtained, 27 patients remained in the ETTS and 26 in the placebo group for efficacy analysis. While in the placebo group, oestradiol (E2) and follicle stimulating hormone (FSH) remained unchanged, E2 increased and FSH decreased significantly in the ETTS group. Syndromal evaluation showed a significant improvement in the Kupperman Index (KI) as well as Hamilton Depression Rating Scale (HAMD) in both groups, with no inter-group difference. However, EEG mapping demonstrated significant inter-drug differences in brain function, mostly over the left temporal region. While ETTS patients showed an increase of alpha and alpha-adjacent theta activity and a decrease of beta activity, as well as an acceleration of the delta/theta centroid and a slowing of the alpha, beta and total power centroid, no changes occurred in the placebo-treated patients. These neurophysiological findings suggest improvement of vigilance by oestrogen, previously referred to as "mental tonic" effect. There were no changes, however, in the frontal alpha asymmetry index, reflecting left frontal hypo- and right frontal hyperactivation. Thus, this neurophysiological variable represents a state-independent marker for depression. The tolerability of ETTS was very good.

Cognitive effects of a new pyrrolidine derivative (levetiracetam) in patients with epilepsy

1. A new pyrrolidine derivative (levetiracetam), resembling piracetam, was given as antiepileptic concomitant drug to patients with chronic epilepsy. 2. In a single-blind add-on rising-dose study the cognitive side-effects were investigated twice after one week of administration. 3. The results did not show any significant changes in cognitive performances.

Topographic EEG changes due to hypobaric hypoxia at simulated high altitude

Multichannel human EEG signals were studied topographically in subjects exposed to an atmosphere of reduced air pressure in a chamber in which high-altitude conditions were simulated. EEG signals from 16 electrodes placed on the scalp were recorded simultaneously with electrocardiography and vertical eye movement. Baseline records were first obtained at sea level (PRE 0 m), and then at reduced air pressures corresponding to the altitudes of 3000 m, 4000 m, and 6000 m, respectively, and after returning to sea level (POST 0 m). A complete set of EEG records under all 6 conditions was obtained in 5 of the 15 subjects, and under 5 conditions (all except the 6000 m condition) in 3 other subjects. The spectral powers of 1 min epochs of the multichannel EEG signal under each altitude condition were compared to that at PRE 0 m using analysis of variance. Under the 3000 m condition, the spectral power of the 10-11 Hz components was significantly decreased and, with increasing altitude, significant decrease of spectral power was observed in a wider range of the alpha frequency band. Under the 6000 m condition, the decrease of spectral power of the alpha band in the posterior brain areas was -7 dB compared to the baseline. In contrast, the spectral power of the theta frequency band in anterior brain areas increased significantly in the 5000 m and 6000 m conditions. At the POST 0 m condition after return from the 5000 m condition (without exposure to the 6000 m condition), the EEG showed recovery to the level of the baseline PRE 0 m condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Ergoloids and ischaemic strokes; efficacy and mechanism of action

In this double-blind, randomized study the efficacy of the ergoloid compounds, co-dergocrine mesylate and nicergoline, in the rehabilitation of patients with ischaemic stroke was investigated. A group of 30 patients was treated daily with 60 mg nicergoline, orally, and a second group of 27 patients was given 1.8-6 mg co-dergocrine mesylate, orally or intramuscularly, daily (depending on the time since the initial ischaemic insult) for 6 months. Outcome measures included: motoricity index (limb function); Sandoz Clinical Assessment Geriatric (SCAG) scale; psychometric tests to assess functions such as attention, psychomotor performance, perception and sensory and short-term memory; conventional and computerized electroencephalography; and P300 and reaction time measures. The results showed improvements in some aspects such as limb function (P < 0.05), SCAG score (P < 0.01) and some electrophysiological parameters (P < 0.01) after treatment with both drugs. Though statistically significant most of the changes were not large. The efficacy of both drugs was qualitatively similar. The quantitative difference in some aspects in favour of nicergoline could be attributed to differences in the mechanisms of action of the two drugs, although it is also possible that the difference may reflect the dosages used. Nootropic drugs may induce a condition that facilitates the effects of cognitive training.

Nicergoline in senile dementia of Alzheimer type and multi-infarct dementia: a double-blind, placebo-controlled, clinical and EEG/ERP mapping study

In a double-blind, placebo-controlled study on the therapeutic efficacy and central effects of nicergoline, an ergot alkaloid with metabolic, antithrombotic and vasoactive action, 112 patients with mild to moderate dementia, diagnosed according to DSM III-R criteria (MMS 13-25), living in pensioners' homes, were included. Fifty-six were subdiagnosed as senile dementia of the Alzheimer type (SDAT), 56 as multiinfarct dementia (MID), based on computed tomography and Hachinski scores (< or = 49 SDAT, > or = 7 MID). They received, after 2 weeks' run-in period (placebo), randomized for 8 weeks either 2 x 30 mg nicergoline (NIC) or 2 x 1 placebo (PLAC) orally. The four subgroups (SDAT/NIC. SDAT/PLAC, MID/NIC, MID/PLAC; 4 x 28 patients) were comparable in regard to age and sex. Only four, four, four and two patients of the respective groups did not finish the study for minor reasons. Confirmatory statistical analysis demonstrated in the target variable-the Clinical Global Impression (CGI)-a significant superiority of Global Impression (CGI)-a significant superiority of NIC over PLAC in both the SDAT and MID groups. Global improvement (CGI item 2) was seen in both nicergoline subgroups (3 and 3), while no changes occurred under placebo (4 and 4, respectively). The responder versus non-responder ratio was in the SDAT/NIC group 16/8, versus 8/16 in the SDAT/PLAC group (chi 2 = 4.1, P = 0.04); in the MID/NIC group 17/7, versus 7/19 in the MID/PLAC group (chi 2 = 7.96, P < 0.005). Furthermore, there was a significant improvement of the Mini-Mental State and the SCAG score in both the MID and SDAT group after 8 weeks of nicergoline, which was significantly superior to the minimal improvement or no change in placebo-treated SDAT and MID patients. EEG mapping demonstrated in NIC-treated SDAT and MID patients a significant decrease in delta and theta, increase in alpha 2 and beta activity and an acceleration of the centroid of the total power spectrum as compared with pretreatment, while opposite changes occurred in PLAC-treated SDAT and MID patients. The differences between PLAC and NIC reached the level of statistical significance. Event-related potential (ERP) recordings demonstrated a significantly shortened P300 latency under NIC treatment in both SDAT and MID patients, while there was a trend towards lengthening under PLAC. Thus, nicergoline improved vigilance and information processing at the neurophysiological level, which leads at the behavioural level to clinical improvement both in degenerative and vascular dementia.

Discrimination between demented patients and normals based on topographic EEG slow wave activity: comparison between z statistics, discriminant analysis and artificial neural network classifiers

The topographic distributions of absolute delta and theta powers were used to classify demented patients and normals by means of z statistics, discriminant analysis and artificial neural networks (NN). The data were taken from two psychopharmacological studies in mildly to moderately demented patients (111 and 96 patients for studies I and II, respectively) and from 56 normal healthy controls. All patients were diagnosed according to DSM-III criteria and were free of medication for at least 2 weeks. The NN used was a strictly layered feed-forward network with complete connections. The z-transformed absolute power values in the combined delta and theta frequency range at 17 electrodes, recorded in a 3 min vigilance-controlled EEG with eyes closed, were used as input. After having trained the NN successfully by backpropagating of errors, the generalization test with independent data results in a classification performance of 90% determined by "relative operating characteristic" analysis. The NN out-performed z statistics and discriminant analysis. This high percentage of correct classifications may justify the development of further application of NNs based on topographic EEG data.

Piracetam and other structurally related nootropics

Nearly three decades have now passed since the discovery of the piracetam-like nootropics, compounds which exhibit cognition-enhancing properties, but for which no commonly accepted mechanism of action has been established. This review covers clinical, pharmacokinetic, biochemical and behavioural results presented in the literature from 1965 through 1992 (407 references) of piracetam, oxiracetam, pramiracetam, etiracetam, nefiracetam, aniracetam and rolziracetam and their structural analogues. The piracetam-like nootropics are capable of achieving reversal of amnesia induced by, e.g., scopolamine, electroconvulsive shock and hypoxia. Protection against barbiturate intoxication is observed and some benefit in clinical studies with patients suffering from mild to moderate degrees of dementia has been demonstrated. No affinity for the alpha 1-, alpha 2-, beta-, muscarinic, 5-hydroxytryptamine-, dopamine, adenosine-A1-, mu-opiate, gamma-aminobutyric acid (GABA) (except for nefiracetam (GABAA)), benzodiazepine and glutamate receptors has been found. The racetams possess a very low toxicity and lack serious side effects. Increased turnover of different neurotransmitters has been observed as well as other biochemical findings, e.g., inhibition of enzymes such as prolylendopeptidase. So far, no generally accepted mechanism of action has, however, emerged. We believe that the effect of the racetams is due to a potentiation of already present neurotransmission and that much evidence points in the direction of a modulated ion flux by, e.g., potentiated calcium influx through non-L-type voltage-dependent calcium channels, potentiated sodium influx through alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor gated channels or voltage-dependent channels or decreases in potassium efflux. Effects on carrier mediated ion transport are also possible.

Effect-kinetics on brain protection of two codergocrine-mesylate preparations (Aramexe retard® and Hydergine®) by EEG mapping and psychometry under hypoxia

In a double-blind, placebo-controlled study the effect-kinetics on brain protection of a new retard formulation of codergocrine-mesylate (CDM) (Aramexe retard, 5 mg) were investigated and compared with a standard CDM drug (5 mg Hydergine) utilizing blood gas analysis, EEG mapping and psychometry. A transient, reversible hypoxic hypoxidosis (i.e. impairment of cerebral metabolism due to hypoxia) was experimentally induced by a fixed gas combination of 9.8% oxygen (O(2)) and 90.2% nitrogen (N(2)) (found at an altitude of 6000 m), which was inhaled for 23 min under normobaric conditions by 18 healthy volunteers. After an adaptation session they received randomized 5 mg Aramexe retard, 5 mg Hydergine and placebo. Evaluation of blood gases, EEG mapping and psychometry was carried out at 0,2, 4,6, and 8 h after oral drug administration - each time under normoxic and hypoxic conditions. Blood gas analysis demonstrated a drop in SaO(2) from 99% under normoxia to 70% under hypoxia, in Po(2) from 100 to 33 mmHg, and in Pco(2) from 36 to 31 mmHg, while pH increased from 7.43 to 7.48. Base excess and standard bicarbonate remained stable. Under hypoxia EEG mapping exhibited an increase in delta/theta, a decrease of alpha and increase of beta activity, as well as a slowing of the centroid of the total power spectrum, which reflects deterioration of vigilance. Both CDM preparations significantly attenuated this vigilance decrement, with 5 mg Hydergine showing its encephalotropic peak effect in the second hour, 5 mg Aramexe retard in the sixth and eighth hours. At the behavioral level, hypoxic hypoxidosis induced a deterioration of the noo- and thymopsyche (by 53% under placebo), which was significantly mitigated by both 5 mg Aramexe retard (19%) and Hydergine (32%).

Quantitative EEG before and after open heart surgery in children. A significant decrease in the beta and alpha 2 bands postoperatively

Quantitative EEGs of 30 patients undergoing open heart surgery were investigated before, 6 days, 11 days and 44 days after operation. The study was conducted in order to investigate whether quantitative EEGs can show postoperative changes in children after open heart surgery. In 28 children, no new neurological signs of cerebral involvement were seen postoperatively. The most striking feature in these children was a significant decrease in the beta and the alpha 2 bands 6 and 11 days postoperatively. The pattern in the delta band was dominated by an increase 6 days postoperatively. Except for a slight decrease in alpha 2 waves, all variables were restored to preoperative values at 44 days after the operation. We found a significant decrease in plasma sodium and chloride after surgery but children with no or slight declines (1-3 mmol/l) also showed increased slow activity postoperatively. Therefore we conclude that an organic brain syndrome, although usually mild and transient, is a general phenomenon after open heart surgery.

Alpha frequency, cognitive load and memory performance

EEG-signals were recorded from subjects as they performed a modified version of Schneider's and Shiffrin's memory search paradigm. The hypothesis was tested whether individual (centre of gravity) alpha frequency, termed IAF, is related to memory performance and/or attentional demands. The results show that memory performance exerts the strongest effect on IAF. As compared to a resting period, the difference in IAF between age-matched good and bad memory performers reached a maximum when subjects were actually retrieving information from their memory. During retrieval, the IAF of good performers is 1.25 Hz higher than for bad performers. Attentional and task demands also tend to reduce IAF, but as compared to memory performance-to a much lesser degree. The results of amplitude analyses demonstrate further that during retrieval, alpha desynchronization is more pronounced for bad performers than for good performers. Taken together, the results indicate that a decrease in IAF is always related to a drop in performance.

EEG mapping and psychopharmacological studies with denbufylline in SDAT and MID

Computed tomography (CT), electroencephalograms (EEG), clinical and psychometric data were obtained in 96 mildly to moderately demented patients (72 women, 24 men), aged 61-96 years (mean 82), diagnosed according to DSM-III criteria. Patients were off drugs for at least 2 weeks and subdiagnosed according to the modified Marshall-Hachinski ischemic score and CT in 45 senile dementia of the Alzheimer type (SDAT) and 51 multiinfarct dementia (MID) patients. Evaluations were carried out before and 12 weeks after treatment with either 100 mg denbufylline BID or placebo and included EEG mapping, the Sandoz Clinical Assessment Geriatric (SCAG) score/factors, the Clinical Global Impression (CGI), the Digit Symbol Substitution Test (DSST), the Trail-Making Test (TMT) and the Digit Span Test (DS). Descriptive data analysis including confirmatory statements found delta/theta activity enhanced, alpha and beta activity reduced, total power augmented, and the centroid slowed down over various brain regions in patients as compared with controls. The two subtypes of dementia could be differentiated in some conventional EEG variables but mostly by means of power asymmetry indices. Denbufylline induced a statistically significant and clinically relevant improvement in both SDAT and MID patients, whereas after placebo this was not the case in CGI, the TMT, and the DS, with interdrug differences being significant in all primary target variables such as the CGI, MMS, SCAG, and DSST. Thus, both the degenerative and vascular type of dementia exhibited a therapeutic benefit that could be objectified at the neurophysiological level by EEG mapping in an improvement of vigilance.

Dose-response studies with co-dergocrine mesylate under hypoxia utilizing EEG mapping and psychometry

In a double-blind, placebo-controlled trial, human brain function and mental performance were studied under two different degrees of hypoxia after administration of two different doses (6 mg and 9 mg) of co-dergocrine mesylate (CDM) utilizing blood gas analysis, EEG mapping and psychometry. Hypoxic hypoxidosis (i.e. impairment of cerebral metabolism due to hypoxia) was experimentally induced by a fixed gas combination of 9.8% oxygen (O2) and 90.2% nitrogen (N2) (found in 6000 m altitude), and of 8.6% O2, 91.4% N2 (found in 7000 m altitude), which was inhaled for 23 min under normobaric conditions by 18 healthy volunteers. They received randomized after an adaptation session placebo, 6 mg and 9 mg co-dergocrine mesylate (CDM). Evaluation of blood gases, brain mapping and psychometry was carried out at 0, 2, 4, 6, 8 h after oral drug administration. Blood gas analysis demonstrated a drop in PO2 to 42 and 32 mm Hg 23 min after inhalation of the 9.8% and 8.6% gas mixture, respectively, PCO2 decreased to 32 and 31 mm Hg, pH increased to 7.46 and 7.47 and base excess increased to 0.50 and 0.90 nmol/l, respectively. EEG mapping demonstrated an increase in delta and decrease of alpha power and a slowing of the centroid over almost the whole brain. 6 mg and slightly less so 9 mg CDM attenuated this deterioration of vigilance (i.e. dynamic state of the neuronal network determining adaptive behavior). At the behavioral level, moderate hypoxia induced a deterioration of noopsychic performance, which was mitigated by 6 mg, but not by 9 mg CDM. A deepening of the hypoxia resulted in a loss of these brain protective effects of both doses. Decrement of the thymopsyche increased after both doses in the moderate hypoxic condition, while under marked hypoxia 6 mg CDM attenuated and 9 mg aggravated this deterioration. Time-wise, brain protective effects reached the level of statistical difference between the 2nd and the 6th hour. Somatic complaints like feeling dazed, giddiness and headache were mitigated dose dependently by CDM in the moderate, but not in the marked hypoxic hypoxidosis.

Brain protection of nicergoline against hypoxia: EEG brain mapping and psychometry

In a double-blind, placebo-controlled trial human brain function and mental performance as well as the antihypoxidotic properties of nicergoline were studied utilizing blood gas analysis, EEG brain mapping and psychometry. Hypoxic hypoxidosis was experimentally induced by a fixed gas combination of 9.8% oxygen (O2) and 90.2% nitrogen (N2) equivalent to 6,000 m altitude, which was inhaled for 23 min under normobaric conditions by 16 healthy volunteers. They received randomized after an adaptation session placebo, 10 mg, 30 mg and 60 mg nicergoline (NIC). Evaluation of blood gases, brain mapping and psychometry was carried out at 0, 2, 4, 6, 8 hrs oral drug administration. Blood gas analysis demonstrated a drop in PO2 from 95 to 35 and 34 mm Hg in the 14 and 23 min of inhalation, respectively. PCO2 decreased too (38 to 34 and 34 mm Hg), while pH increased (7.39 to 7.44 and 7.44). Base excess increased (-0.6 to 0.6 and 0.4) while standard bicarbonate decreased (24.4 to 24.1 and 23.8 mmol/l). Thus, blood gases remained stable between the 14 and 23 min of hypoxia during which time the neurophysiological and behavioral evaluations were carried out. EEG brain mapping exhibited an increase in delta/theta activity mostly over the parietal, temporal and central regions (left more than right), while alpha activity decreased (mostly over the parietal, central, frontal, fronto-temporal and temporo-occipital regions). 30 and 60 mg NIC attenuated this deterioration of vigilance. At the behavioral level, hypoxic hypoxidosis induced a deterioration of the noo- and thymospsyche which was mitigated by NIC. Based on 13 psychometric variables, the hypoxia-induced performance decrement was on the overall (2nd-8th hr) 43% after placebo as compared with pretreatment normoxic values, while only 29, 24 and 31% after 10, 30 and 60 mg nicergoline, respectively. The difference between placebo and the optimal dosage of nicergoline 30 mg reached the level of statistical significance (p less than 0.01, multiple Wilcoxon).

Topographic brain mapping of EEG after acute application of ergotalkaloids in the elderly

In a double-blind, placebo-controlled, crossover study the encephalotropic and nootropic effects of single doses of two ergotalkaloids (30 and 60 mg nicergoline and 5 mg co-dergocrine mesylate (CDM)) were investigated in 12 elderly subjects (mean age 67 years), utilizing topographic brain mapping of the EEG. Evaluation of EEG, memory, pulse and blood pressure were carried out at 0, 2, 4, 6 and 8 h. Topographic brain maps demonstrated an augmentation of total power, an acceleration of the centroid of the total activity, a decrease of delta/theta and an increase of beta activity (mostly in the alpha-adjacent frequency bands), as well as an acceleration of the centroid of the delta/theta and a slowing of the beta centroid. These changes are indicative of improvement in vigilance of elderly subjects after ergotalkaloids, which was also reflected in the significant improvement of memory after nicergoline. Topographically, the main effect was found over the frontal, central and temporal regions. Timewise, the pharmacodynamic peak fell into the 4th h, although with 60 mg significant encephalotropic effects could be observed in the 2nd and in the 6th h. The drugs were well tolerated.

On the treatment of the alcoholic organic brain syndrome with an alpha-adrenergic agonist modafinil: double-blind, placebo-controlled clinical, psychometric and neurophysiological studies

1. In a double-blind study forty abstinent hospitalized male patients with an alcoholic organic brain syndrome (OBS) were treated for 6 weeks with either 200 mg modafinil or placebo. 2. Modafinil (CRL 40476) is a putative central alpha-1 adrenergic agonist. It's pharmacological profile is quite different from that of amphetamine, which can be seen by the lack of peripheral sympathomimetic effects. The vigilance promoting effect of modafinil has been shown previously in pharmaco-EEG and psychometric studies as well as in clinical studies involving treatment of daytime sleepiness in idiopathic hypersomniacs and narcoleptics. 3. The present clinical investigations demonstrated that the spontaneous restitution of the alcoholic OBS was significantly augmented and accelerated by modafinil. 4. Psychometric tests did not show significant intergroup differences. Modafinil- and placebo-treated patients improved continously over the 6-week period. 5. Psychophysiological and autonomous nervous system parameters were affected neither by placebo nor by modafinil. 6. Neurophysiological investigations by means of quantitative pharmaco-EEG showed partly inconsistent findings. However, superimposed dosages of modafinil (on the top of 6 weeks chronic administration) induced a decrease of slow activity and an increase of alpha activity suggesting an improvement of vigilance after the daily drug intake. 7. Considering the beneficial effects of modafinil in abstinent chronic alcoholic patients, it may be said that activation and improvement of adaptive behaviour by an alpha-adrenergic agonist could be regarded as a therapeutic principle in the treatment of the OBS, eventually due to noradrenergic deficits.

The hyperventilation-induced ischaemia model in human neuropharmacology: neurophysiological and psychometric studies of aniracetam and 3-OH aniracetam

Standardized hyperventilation in young subjects induces changes in the EEG, a decrease in the velocity of the cerebral blood flow and a decline in cognitive performance, which are comparable to those occurring in patients with cerebral ischaemia. The anti-ischaemic properties of aniracetam and 3-OH aniracetam were tested in this model. A single oral dose of 3-OH aniracetam 1500 mg appeared to have the most pronounced effect on hyperventilation-induced EEG changes and cognitive deterioration. The test drugs had no effect on the heart rate or blood flow velocity. The effects agree with those of other drugs classified as noötropics.

EEG brain mapping in evaluating the time-course of the central action of DUP 996--a new acetylcholine releasing drug

1. In a double-blind, placebo-controlled study the encephalotropic effects of DUP 996, a novel phenylindolinone derivative for Alzheimer's disease enhancing the release of acetylcholine in cholinergic nerve terminals in the brain only when its release is triggered, were studied with special consideration of the pharmacodynamic time-course. 2. Thirteen healthy male volunteers aged 18-40 years received randomized and at weekly intervals, single oral doses of placebo and 30 mg DUP 996. Blood sampling for plasma concentration analysis, EEG recordings and evaluation of pulse, blood pressure and side effects were carried out at 0, 1, 2, 4, 8, 12 and 24 h. 3. Computer-assisted spectral analysis of the EEG and subsequent topographic brain mapping of the drug-induced EEG changes demonstrated significant central effects of DUP 996 suggesting vigilance-improving properties. The findings were characterized mostly by an augmentation of total power as well as by an increase of absolute power in the alpha and alpha-adjacent beta activity. 4. Time-course investigations demonstrated two pharmacodynamic peaks: a first one in the 2nd h and a second one in the 12th h. In detail CNS effects increased up to the 2nd h, showed a drop in the 4th h, increased again thereafter to peak in the 12th h. Even in the 24th h there were significant differences between DUP 996 and placebo. The latter suggests an indirect effect and/or an active metabolite, as the parent drug is rapidly absorbed and has a rather short plasma half-life between 1-3 h. 5. DUP 996-induced EEG-changes over time were most pronounced over temporo-occipital, temporo-frontal, parietal and frontal regions, e.g. over brain areas afflicted most by Alzheimer's disease. 6. Evaluation of vital signs, laboratory findings and ECG as well as adverse effects showed a very good tolerability of DUP 996.

Double-blind, placebo-controlled quantitative EEG and psychometric studies in elderlies on vigilance-promoting effects of an almitrine/raubasine combination (Duxil)

In a double-blind, placebo-controlled study the encephalotropic and psychotropic properties of an acutely and 3-weeks subacutely administered novel drug Duxil (consisting of 30 mg of the antihypoxic almitrine which increases the oxygenation of the arterial blood by specific action on the pulmonary exchange system and of 10 mg raubasine, which potentiates this effect via increase in peripheral circulation), were investigated in 12 elderly subjects in their 70s. Each subject had a treatment of 3 weeks with Duxil and placebo (1 tablet b.i.d.) with an interval of 1 week in between (the order of drug sequence was randomized). EEG recordings, psychometric and psychophysiological tests as well as evaluation of pulse, blood pressure and side effects were carried out at 0, 2, 4, 6 and 8 h after the administration of one single dose on day 1 (acute effect), at the 0 h on day 21 (subacute effect) as well as at the 2, 4, 6, and 8 h after one additional superimposed dosage on day 21 (superimposed effect). Computer-assisted spectral analysis of the EEG demonstrated after single doses of two tablets of Duxil only subtle changes in the resting EEG, while after subacute administration and even more so after one superimposed dosage highly significant changes were observed, which were characterized by an increase of total power, alpha and alpha-adjacent beta activity, decrease in fast beta activity, and by an augmentation of absolute and relative power of the dominant frequency. These findings are indicative of an improvement in vigilance. The latter was seen also at the behavioral level, as psychometric tests showed specifically in noopsychic variables a significant improvement in intellectual, mnestic and psychomotor performance after the novel antihypoxic compound, as compared with placebo. There were practically no changes in thymopsychic variables. Evaluation of psychophysiological variables and side effects showed extremely good tolerability of the drug.