Dose-response analysis of the behavioral effects of diazepam: II. Psychomotor performance, cognition and mood

Mnestic disorders in long-term high-dose diazepam abuse: a pilot study

Cognitive impairment in long-term high-dose diazepam abusers (dose > 30 mg diazepam/day; duration of abuse > 12 months) was examined by administering four memory-related tests and comparing the outcomes with those of matched controls. Deficits were found in spatial and visual learning, spatial and visual short-term memory (STM) as well as for spatial and visual long-term memory (LTM). As for verbal aspects of memory, solely the acquisition of novel verbal material (verbal learning) was impaired, Furthermore, deficits in a concentration task were observed. In chronic abuse the established memory deficits are similar to cognitive impairment after single doses. Relaxing or anxiety-reducing effects of diazepam were no longer present. The results of this experimental study demonstrate the risks of diazepam use beyond therapeutic range.

Administration of the benzodiazepine midazolam increases tau phosphorylation in the mouse brain

Preclinical studies have shown that anesthesia might accelerate the clinical progression of Alzheimer's disease (AD) and can have an impact on tau pathology, a hallmark of AD. Although benzodiazepines have been suggested to increase the risk of incident dementia, their impact on tau pathology in vivo is unknown. We thus examined the impact of midazolam, a benzodiazepine that is often administered perioperatively as an anxiolytic, on tau hyperphosphorylation in nontransgenic and in hTau mice, the latter a model of AD-like tau pathology. The acute administration of midazolam in C57BL/6 mice was associated with downregulation of protein phosphatase-1 and a significant and persistent increase in brain tau phosphorylation. In hTau mice, tau hyperphosphorylation was also observed; however, midazolam was neither associated with proaggregant changes nor spatial reference memory impairment. In C57BL/6 mice, chronic midazolam administration immediately increased hippocampal tau phosphorylation, and this effect was more pronounced in older mice. Interestingly, in young C57BL/6 mice, chronic midazolam administration induced hippocampal tau hyperphosphorylation, which persisted for 1 week. In hTau mice, chronic midazolam administration increased hippocampal tau phosphorylation and, although this was not associated with proaggregant changes, this correlated with a decreased capacity of tau to bind to preassembled microtubules. These findings suggest that midazolam can induce significant tau hyperphosphorylation in vivo, which persists well beyond recovery from its sedative effects. Moreover, it can disrupt one of tau's critical functions. Hence, future studies should focus on the impact of more prolonged or repeated benzodiazepine exposure on tau pathology and cognitive decline.

Diazepam Tolerance Effects on Vestibular Function Testing, Part I: Saccadic Parameters during Electronystagmography

Objectives:

Benzodiazepines, particularly diazepam (DZ), are used in clinical practice to suppress acute vestibular symptoms. There have been limited studies looking at the effects of tolerance to DZ on parameters designed to measure the integrity of the vestibular system and its interaction with the oculomotor and balance systems.

Methods:

In a double-blinded, repeated-measures design, we randomized 30 young healthy men into one of two treatment groups (diazepam and placebo) and assessed with electro-oculography the effects of clinical divided doses of DZ on saccadic eye movements and sedation over 16 days.

Results:

Only sedation and saccadic latency were significant (p < .05) for treatment group, indicating selective effects on different central nervous system mechanisms. No significant effect for time was seen in any of the variables measured. Bonferroni t-test comparisons of the DZ group among 3 days were significant (p < .017) between baseline and day 3 for saccadic latency and accuracy and between day 3 and day 16 for self-ratings of sedation.

Conclusions:

Saccadic latency and accuracy and sedation ratings appear to be more sensitive to changes over time and less affected by subject variability than saccadic eye velocity. It remains questionable whether patients who have been on DZ for acute or extended periods of time need to discontinue the drug 48 hours before testing.

Cognition-impairing effects of benzodiazepine-type drugs: role of GABAA receptor subtypes in an executive function task in rhesus monkeys

The present studies evaluated the role of α1 and α5 subunit-containing GABAA receptors (α1GABAA and α5GABAA receptors, respectively) in the ability of benzodiazepine (BZ)-type drugs to alter performance in the cognitive domain of executive function. Five adult female rhesus monkeys (ages of 9-17years old) were trained on the object retrieval with detours (ORD) task of executive function. For the ORD task, the monkeys were required to retrieve food items from a clear box with one open end that was rotated to different positions along with varying placements of food. When the non-selective BZ triazolam and the α1GABAA-preferring agonists zolpidem and zaleplon were evaluated in the ORD task, deficits in performance occurred at doses that did not increase the latency of monkeys to initiate responding and/or increase the percentage of reaches that were incorrect (i.e., reaches in which food was not obtained). Cognition-impairing effects of triazolam and zolpidem in ORD were blocked by the α1GABAA-preferring antagonist, βCCT, whereas the α5GABAA-preferring antagonist XLi-093 blocked the effects of triazolam but not zolpidem. While these findings suggest a role for both α1GABAA and α5GABAA receptor mechanisms, α1GABAA receptor mechanisms appear to be sufficient for impairments in executive function induced by BZ-type drugs.

Rupatadine does not potentiate the CNS depressant effects of lorazepam: randomized, double-blind, crossover, repeated dose, placebo-controlled study

AIM

The main objective was to assess whether benzodiazepine intake when rupatadine plasma concentrations were at steady-state would increase the CNS depressant effects. Rupatadine is a new H(1)-antihistamine which also inhibits platelet activating factor (PAF) release and has been shown to be clinically effective at doses of 10 mg.

METHODS

Sixteen healthy young volunteers took part in a crossover, randomized, double-blind, placebo controlled trial comprising two experimental periods (repeated administration for 7 days of rupatadine 10 mg or placebo as single oral daily doses, separated by a washout of 14 days). On days 5 and 7, according to a fully balanced design, a single oral dose of lorazepam 2 mg or placebo was added. CNS effects were evaluated on these days by seven objective tests of psychomotor performance and eight subjective visual analogue scales (VAS) at pre-dose and several times after drug intake. Four treatment conditions were evaluated: placebo, rupatadine 10 mg, lorazepam 2 mg and rupatadine 10 mg + lorazepam 2 mg.

RESULTS

Significant CNS effects, either impairment of psychomotor performance or subjective sedation, were observed when lorazepam was administered, either alone or in combination with steady state concentrations of rupatadine. No significant differences were found between these two conditions. In addition, rupatadine was not different from placebo. All treatments were well tolerated.

CONCLUSION

Repeated doses of rupatadine (10 mg orally) did not enhance the CNS depressant effects of lorazepam (2 mg orally, single dose) either in objective psychomotor tasks or in subjective evaluations.

Diazepam attenuates conditioned histamine release in guinea pigs

To clarify the possibility of pharmacological mediation on classical conditioning-associated asthmatic response, the effect of diazepam on an odor-induced conditioned histamine release was investigated in ovalbumin (OA)-sensitized guinea pigs, i.e. a model of bronchial asthma. The animals received conditioning sessions in which an antigen (OA) as the unconditioned stimulus and an odor (dimethylsulfide) as the conditioned stimulus (CS) were simultaneously inhaled. After the animals were intraperitoneally injected with saline or diazepam (2.5 or 5 mg/kg), they underwent exposure to the CS and blood collecting. This procedure was repeated three times in order that the animals would have each kind of injection. The animals injected with saline showed significantly higher levels of plasma histamine following the exposure to the CS as a conditioning effect compared with the baselines (P<0.05), whereas the group injected with diazepam (5 mg/kg) did not indicate such elevations. The suppressing effect of diazepam on the conditioned histamine release was also confirmed by a multiple regression analysis (5 mg/kg) and an analysis of covariance (2.5 and 5 mg/kg), even after adjustments for several factors regarding immunological sensitization and conditionability. The present study suggests that diazepam attenuates a conditioned histamine release.

Benzodiazépines : conséquences sur le fonctionnement mnésique des personnes âgées

Des études effectuées chez une population de volontaires sains en administration unique indiquent que les benzodiazépines (BZD) sont connues pour induire des déficits en mémoire. Cette population étudiée ne correspond toutefois pas avec celle qui consomme régulièrement ces substances soit les personnes âgées. Peu d’études ont été faites auprès de cette population cible afin de déterminer l’impact des BZD sur leur mémoire. Par contre, il existe des évidences suggérant aussi qu’il existe des conséquences importantes sur le fonctionnement de la mémoire des personnes âgées qui prennent des BZD. Les données actuelles vont même jusqu’à suggérer que les BZD exacerbent les déficits de mémoire chez les personnes âgées. Cela pourrait même constituer un facteur de risque précipitant le déclin cognitif et augmentant ainsi le risque de développer une démence.

Veränderte Aufmerksamkeit unter dem Benzodiazepin Lorazepam

Zusammenfassung: Aus der klinischen Praxis und einigen experimentellen Studien ergaben sich Hinweise, dass unter dem Einfluss von Benzodiazepinen Einschränkungen der Aufmerksamkeit auftreten können. In der vorliegenden Studie wurde der Frage nachgegangen, welche Komponenten der Aufmerksamkeit durch die Wirkung von Lorazepam beeinträchtigt werden. In einer placebo-kontrollierten Doppel-Blind-Studie mit 20 gesunden Probanden wurden folgende funktionelle Komponenten der Aufmerksamkeit 3 Stunden nach Einnahme von Lorazepam (p.o. 0.02mg/kgKörpergewicht) untersucht: Informationsverarbeitungsgeschwindigkeit, selektive Aufmerksamkeit, Daueraufmerksamkeit, geteilte Aufmerksamkeit und Aufmerksamkeitswechsel. Die Reaktions- bzw. Verarbeitungsgeschwindigkeit waren in allen verwendeten Verfahren mit Ausnahme der geteilten Aufmerksamkeit unter der Wirkung von Lorazepam signifikant erniedrigt. Hinsichtlich von Treffer- bzw. Fehlerraten war dagegen kein signifikanter Unterschied zwischen Lorazepam und Placebo zu beobachten. Die Wirkung von Benzodiazepinen scheint wenig selektiv bezüglich der verschiedenen Aufmerksamkeitskomponenten zu sein. Es kommt offenbar nach Benzodiazepin-Einnahme zu einer generalisierten Verlangsamung der Informationsverarbeitung.

Biomarkers for the effects of benzodiazepines in healthy volunteers

Studies of novel centrally acting drugs in healthy volunteers are traditionally concerned with kinetics and tolerability, but useful information may also be obtained from biomarkers of clinical endpoints. A useful biomarker should meet the following requirements: a consistent response across studies and drugs; a clear response of the biomarker to a therapeutic dose; a dose-response relationship; a plausible relationship between biomarker, pharmacology and pathogenesis. In the current review, all individual tests found in studies of benzodiazepine agonists registered for anxiety in healthy volunteers since 1966 were progressively evaluated for compliance with these requirements. A MedLine search yielded 56 different studies, investigating the effects of 16 different benzodiazepines on 73 different (variants of ) neuropsychological tests, which could be clustered into seven neuropsychological domains. Subjective and objective measures of alertness were most sensitive to benzodiazepines. The most consistent effects were observed on saccadic peak velocity (SPV) and visual analogue scores ( VAS) of alertness, where 100% and 79% of all studies respectively showed statistically significant effects. A dose-response relationship could be constructed for temazepam and SPV, which was used to determine dose equivalencies relative to temazepam, for seven different benzodiazepines. These dose equivalencies correlated with the lowest recommended daily maintenance dose (r2 = 0.737, P < 0.05). This relationship between SPV reduction and clinical efficacy could reflect the clinical practice of aiming for maximum tolerated levels, or it could represent a common basis behind SPV reduction and anxiolytic activity for benzodiazepines (probably sedation). The number of tests used in human psychopharmacology appears to be excessive and their sensitivity and reproducibility low.

Caffeine-induced increases in the brain and plasma concentrations of neuroactive steroids in the rat

The effects of caffeine, a naturally occurring stimulant, on the brain and plasma concentrations of neuroactive steroids were examined in the rat. A single intraperitoneal injection of caffeine induced dose- and time-dependent increases in the concentrations of pregnenolone, progesterone, and 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone) in the cerebral cortex. The increases were significant at a caffeine dose of 25 mg/kg and greatest (+188, +388, and +71%, respectively) at a dose of 100 mg/kg in rats killed 30 min after caffeine administration. Caffeine also increased the plasma concentrations of pregnenolone and progesterone with a dose-response relation similar to that observed in the brain, whereas the caffeine-induced increase in the plasma concentration of allopregnanolone was maximal at a dose of 50 mg/kg. Caffeine increased the plasma concentration of corticosterone, but it had no effect on the brain or plasma concentrations of 3alpha, 21-dihydroxy-5alpha-pregnan-20-one and dehydroepiandrosterone. Moreover, the brain and plasma concentrations of pregnenolone, progesterone, and allopregnanolone were not affected by caffeine in adrenalectomized-orchiectomized rats. These results suggest that neuroactive steroids may modulate the stimulant and anxiogenic effects of caffeine.

Conditions under which lorazepam can facilitate retrieval

Memory is composed of three stages: acquisition, consolidation, and retrieval. By impairing acquisition processes, benzodiazepines cause anterograde amnesia while leaving intact information learned before the drug was taken. In some circumstances, retrieval of this information is even improved by benzodiazepines. It has been hypothesized that this phenomenon is not a true facilitation of retrieval processes, but is the result of reduced interference from items presented after drug administration and is thus a secondary consequence of drug-induced amnesia. Experiment 1 investigated the effect of 0.5, 1, and 2.5 mg of lorazepam on explicit episodic memory in healthy young volunteers. The 1-mg dose was found to significantly improve recall of items presented before drug administration without causing amnesia for items presented after drug administration, thus excluding an interference explanation. Experiment 2 investigated the conditions necessary to obtain facilitated retrieval with 1 mg of lorazepam. The results showed that facilitation was found only when two lists of semantically related material were presented, but that both of the lists could be presented before drug administration, thus excluding an effect of lorazepam on consolidation. Facilitation could be demonstrated in both direct (free recall) and indirect (backwards reading) retrieval tasks and when all of the material was presented after lorazepam administration. This improved retrieval could therefore be of clinical relevance, but any benefits would be reduced at higher doses that at the same time impair acquisition of new information. However, because 1 mg of lorazepam is an effective anxiolytic dose, these results suggest that it is possible to combine effective anxiety reduction with some benefits to memory.

Comparison of acute alprazolam (0.25, 0.50 and 1.0 mg) effects versus those of lorazepam 2 mg and placebo on memory in healthy volunteers using laboratory and telephone tests

This study was designed to confirm the hypothetical dose-dependent effect of alprazolam on memory and to compare its effects on tests measuring different aspects of cognitive and psychomotor functioning. A secondary purpose was to compare the sensitivity of newly developed telephone tests with a standard laboratory test of memory. Twenty healthy male volunteers (aged 18-35 years) participated in a five-way double-blind crossover design. Treatments were single oral doses of alprazolam (0.25, 0.5 and 1.0 mg), placebo and lorazepam 2.0 mg. The latter was included as an internal control for demonstrating sensitivity of the method. Lorazepam significantly impaired all performance measures except two: verbal fluency and accuracy of music recognition were insensitive to drug effects. Alprazolam had clear dose-dependent effects on different aspects of memory: 0.25 mg did not affect any parameter; 0.5 mg impaired performance in a Word Learning Test and a Spatial Memory Test and also psychomotor performance; 1.0 mg additionally impaired Syntactic Reasoning, Semantic Verification, and Critical Flicker Fusion performance. Alprazolam's effects were not selective for any of the cognitive functions as measured in this study. The telephone tests were clearly less sensitive than the standard test, though sufficient for showing significant effects of alprazolam 1 mg and lorazepam 2 mg.

Lack of interaction between a new antihistamine, mizolastine, and lorazepam on psychomotor performance and memory in healthy volunteers

1. The possible interaction between a new H1 antihistamine, mizolastine, and lorazepam was assessed in a randomised, double-blind, cross-over, placebo-controlled study involving 16 healthy young male volunteers who received mizolastine 10 mg or placebo once daily for 8 days with a 1 week wash-out interval. The interaction of mizolastine, at steady-state, with a single oral dose of lorazepam or placebo was assessed on days 6 or 8 of each treatment period. 2. Psychomotor performance and cognitive function were evaluated using objective tests (critical flicker fusion threshold, choice reaction time, tapping, arithmetic calculation, body sway) and self-ratings (visual analogue scale, ARCI) before and at 2, 4, 6 and 8 h after dosing. Short-term memory (Sternberg memory scanning immediate free recall of a word list) and long-term memory (delayed free recall and recognition of words and pictures) were assessed before and at 3 h after dosing. Pharmacodynamic interactions were evaluated by repeated measures ANOVA in a 2 x 2 factorial interaction model. 3. Mizolastine, 10 mg once daily, at steady-state, was devoid of sedation and detrimental effect on skilled performance and memory. 4. In contrast, a single 2 mg dose of lorazepam produced marked impairment of psychomotor performance, cognitive functions (significant reduction in flicker fusion threshold, tapping and arithmetic calculation and increase in reaction times and body sway) and subjective sedation from 2 to 8 h after dosing. In addition, lorazepam induced an anterograde amnesia, characterised by a decrease in delayed free recall and recognition, and a deficit in short term memory.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of neuroleptics on cognitive and psychomotor function. A preliminary study in healthy volunteers

The effects of haloperidol (1 mg), benzhexol (5 mg), diazepam (10 mg) and caffeine (400 mg) on subjective and objective measures of cognitive and psychomotor function were compared with placebo in 20 healthy volunteers. While both diazepam and benzhexol were associated with highly significant impairments in subjective altertness, critical flicker fusion threshold and choice reaction time (CRT), haloperidol could not be distinguished from placebo in most tests but was actually associated with an apparent improvement in CRT (in males) and simple visual reaction time. The perceptual maze test detected impairment by benzhexol on processing speed but was not sensitive to any other drug effects. Multiple-dose studies are required to establish if there is a true activating effect of haloperidol using a test of sustained attention. No effect of Eysenck personality subtype or life events on baseline or drug response data was detected.

Relationship between drug plasma concentrations and psychomotor performance after single doses of ethanol and benzodiazepines

In a placebo controlled, crossover study psychomotor effects of single doses of diazepam, 10 and 20 mg, flunitrazepam, 1 and 2 mg, as well as 0.9 g ethanol/kg body weight were investigated over a time period of 6 h in 12 healthy men. Blood samples were collected simultaneously with the test sessions to determine drug concentrations in plasma or blood. The ethanol dose caused the least performance impairment, followed by 10 mg diazepam. The most pronounced impairment was caused by 2 mg flunitrazepam, whereas 20 mg diazepam and 1 mg flunitrazepam caused intermediate impairment and were approximately equipotent on group level. Considerable interindividual differences with respect to maximal impairment following a particular drug treatment were observed, with poor correlation between individual maximal impairments and individual peak plasma concentrations of the drug. The maximal impairment in simple reaction time following the flunitrazepam treatments occurred earlier relative to the peak plasma concentration of the drug as compared to the diazepam treatments. This may indicate that acute tolerance develops differently for the two drugs.

Diazepam (Valium): its dependency liability

Reports of the withdrawal syndrome following discontinuation of diazepam and drug dependence fears have contributed to diazepam's displacement as the most popular anxiolytic agent. Reports of the withdrawal syndrome, the factors involved in withdrawal, and the remedies proposed for diazepam withdrawal symptoms are reviewed.

Simultaneous modeling of the pharmacokinetic and pharmacodynamic properties of benzodiazepines. I: Lorazepam

This investigation compares the time course changes in the central nervous system (CNS) impairment effects on psychomotor and cognitive skills and relates these changes to the plasma lorazepam concentrations in a pharmacokinetic-pharmacodynamic (PK-PD) model. Six male subjects received a single oral dose of lorazepam or placebo. The CNS effects were measured by using computerized continuous tracking (TRKN), body sway with eyes open (SWAY OPEN), and digit symbol substitution (DSS) tests. Plasma lorazepam concentrations were best characterized by a two-compartment model with first-order absorption. Plotting the plasma lorazepam concentration and measured effect across time revealed a counterclockwise hysteresis loop. Fitting the time course of the effects in an integrated PK-PD model required an effect compartment with the equilibrium rate constant between it and the plasma compartment. The magnitude of the temporal lag was quantified by the half-time of equilibration between concentration in the hypothetical effect compartment and the plasma lorazepam level (t1/2keo). The CNS effect measured by TRKN was characterized by a mean estimate of maximum predicted effect (Emax) of 418 with a t1/2keo of 0.43 hr, an estimate of effect site drug level to produce 50% of Emax (EC50) of 35.8 ng/ml and a power parameter (gamma) of 6.29. Corresponding parameter mean estimates for SWAY OPEN and DSS as measures of drug CNS effect were quite similar.

Diazepam and discriminative motor control: acute, chronic and withdrawal effects

Rats were trained to hold a force transducer operated with a paw so that it remained between upper and lower limits of a force band for a continuous 1.5-sec period to deliver each food pellet. Acute doses of diazepam impaired measures of this performance. Separate groups received chronic diazepam injections (6 mg/kg, IP) either presession (Before Group) or postsession (After Group), or presession vehicle (Vehicle Group). The After and Vehicle Groups demonstrated that neither chronic postsession diazepam, nor time alone, altered motor performance. The performance of the Before Group was affected by the daily diazepam, and although tolerance to the impairment developed, it was incomplete. Late in the chronic-administration phase (after 75 days) a toxic effect of the suspending agent became evident in all groups as a decrease in work rate, although the other performance indices were not affected. The withdrawal of diazepam from the Before Group led to improved performance which returned to the original baseline level.

Effects of diazepam on a belief-updating task

This study examined the effects of a minor tranquilizer, diazepam, on a cognitive task that involved the updating of beliefs. On this task, subjects are first asked to express their strength of belief in a hypothesis and then to update this on the basis of new evidence. Past research has shown that revision of beliefs can be affected by many variables including the strength with which the initial belief is held, whether new information is perceived as positive or negative vis-à-vis the hypothesis, and the order in which evidence is processed. The purpose of this study was to assess whether a tranquilizer, diazepam, would affect the updating of beliefs, and specifically whether it would dampen the extent to which people revise their opinions. 12 healthy subjects participated in four experimental sessions, in which they received diazepam (0.14 mg/kg) or placebo and completed an updating task in which they received information in either of two orders, positive-negative or negative-positive. In each session, subjects saw a different experimental stimulus determined by a Latin-square design, and also completed pre- and postdrug mood questionnaires. Analysis showed order of presentation induced a recency effect similar to that obtained in previous studies, and the diazepam produced significant tranquilizer-like effects on self-report questionnaires. However, the diazepam had no effect on the updating task. These findings indicate that previously reported order effects in the belief updating task are robust and unaffected by a drug that has known sedative and memory-impairing properties.

Effects of butoctamide hydrogen succinate and nitrazepam on psychomotor function and EEG in healthy volunteers

We studied the effects of butoctamide hydrogen succinate and nitrazepam on psychomotor function and EEG in eight male volunteers aged 19-32. The hypnotic effects, effects on psychomotor performance, EEG activity and standing steadiness between BAHS 1000 mg and nitrazepam 5 mg were compared at regular intervals for 10 h. The serum levels of both drugs were also assayed. The hypnotic effects of BAHS were very weak compared to those of nitrazepam. BAHS did not exert any effects on psychomotor performance and standing steadiness during the test period. In contrast, nitrazepam impaired psychomotor performance and standing steadiness as the serum drug levels increased. Nitrazepam decreased the alpha activity and increased the beta activity in a concentration-dependent manner. BAHS did not change the alpha activity but increased beta-2 activity at Fz and Cz at 10 h of the post-drug period. BAHS was eliminated more rapidly than nitrazepam. These results indicated that BAHS, at the dose used, was less potent than nitrazepam and the effects on psychomotor performance and standing steadiness were minimal.

Assessment of the effects of drugs on memory

This survey is based on 70 controlled investigations of the effects of drugs on memory in healthy volunteers. Although detracting effects were predominant, enhancements were reported as well. The effects of 29 well-known drugs on 15 familiar tests are summarized in a way that permits comparisons of the effects of different drugs and of test sensitivities. There is a discussion of factors that could bias or obscure investigations of the effects of drugs on learning and remembering.

The effect of anxiolytic drugs on memory in anxious subjects

The benzodiazepines (BZs), represented by diazepam, are the class of drugs used most frequently to treat clinical anxiety disorders. Since it is known that acute BZ intake impairs memory function, the effects of BZs on memory were evaluated in chronic users of BZ medications. In addition, the acute effects of diazepam were compared with those of the non-BZ anxiolytic buspirone on memory function in anxious subjects. Memory function was evaluated by a free verbal recall procedure where subjects recalled a list of 16 noncategorized nouns immediately after the word list was read (immediate recall) and again 20 min later (delayed recall). When the chronic BZ users were tested for free verbal recall during their first visit, 4-14 h after their last dose, they did not differ in immediate or delayed recall from an age- and sex-matched group of unmedicated anxious subjects. At a subsequent visit, the acute effects of BZ medications were studied 60-90 min after the subjects took their usual dose. Although acute BZ administration did not alter immediate recall, delayed recall was significantly impaired in the chronic BZ users. Thus, complete tolerance does not develop to the acute memory-impairing effects of BZs after long-term use. Acute administration of the anxiolytic drugs diazepam (5 mg) or buspirone (5 or 10 mg) did not alter immediate recall in another group of unmedicated anxious subjects. Diazepam selectively impaired delayed recall of the word list when compared with placebo. In contrast, neither dose of buspirone altered delayed recall. To the extent that such effects on verbal recall tests are reflected in a patient's daily activities, the failure of buspirone to adversely affect memory function could contribute to its usefulness as an alternative antianxiety therapy.

Differential CNS effects of diazepam in elderly adults

The present study examines the effects of 0.07, 0.14 and 0.21 mg/kg of diazepam on the performance of several cognitive and neuromotor tasks, including wheel tracking, digit symbol substitution and standing steadiness. The drug or placebo was administered at 3-week intervals to healthy elderly men (N = 8) and women (N = 8). Both medium and high doses significantly impaired performance on the cognitive tasks, whereas only the latter dose induced similar impairment effects on the neuromotor tasks. Wheel tracking and standing steadiness displayed rapid onset and offset of the drug effect, while acute tolerance developed at a considerably slower rate on the digit symbol substitution tasks. Specifically, the subjects continued to show poorer cognitive performance for over 3 hours after dosing, but were no longer impaired on the basically neuromotor skills at 3 hours.

Tranquillising memories: a review of the effects of benzodiazepines on human memory

Studies from 1973 to 1985 of the effects of benzodiazepines on memory are summarised and reviewed. Anterograde amnesia appears a common effect of all benzodiazepines although its onset and duration vary with the particular benzodiazepine, its dose and route of administration. Memory impairments increase with task difficulty. There is some evidence that partial tolerance to amnesic effects develops with repeated doses of diazepam, but research with other benzodiazepines is inconclusive. Amnesia is in part a by-product of the sedative action of benzodiazepines, although these drugs may also have a specific effect of disrupting the consolidation of information in long-term memory. State-dependent effects are partial and relatively small. Methodological problems are discussed and attention is drawn to the lack of repeated dose studies, of studies with patient populations and with anxious volunteers.

Effects of benzodiazepines on acquisition and performance: a critical assessment

Evidence related to the effects of benzodiazepines on learning and memory is reviewed in the contexts of human verbal learning studies and animal studies using both aversive and non-aversive paradigms. While the impairment of acquisition by benzodiazepines appears to be a robust phenomenon generalizing across species and experimental conditions, the impairment in the performance of an already-learned task by such drugs appears to be more restrictive and highly dependent upon experimental contingencies. Thus far, performance impairment appears to be found mainly in animal studies using non-aversive, food-motivated tasks, with such tasks being particularly well suited for investigating such a phenomenon. At present, there is a noticeable lack of knowledge regarding the neurochemical substrates underlying BDZ-induced impairment. Finally, some issues that may contribute to the presence or absence of a BDZ-induced performance impairment in published studies are briefly considered.

The behavioral actions of diazepam and oxazepam are similar

In a double-blind and randomized study, we assessed the comparative pharmacodynamic profiles and behavioral effects of diazepam and oxazepam administered to young healthy volunteers. Diazepam 0.3 mg/kg or oxazepam 1.2 mg/kg or placebo were each administered orally to 13 subjects who were tested with tasks which measured learning and memory, cognition, psychomotor performance and mood before and for 9 h after treatment. The two drugs had similar actions, although subjective effects were milder after oxazepam, which also had a slower onset of action. There was no evidence of rebound behavioral impairment.

The amnesic action of benzodiazepines in man

A qualitative description of the amnesia produced by the benzodiazepines in man is presented. The benzodiazepines exert their greatest effects in tests of long-term episodic memory in which they cause a dose-related impairment in the acquisition of new information, do not appear to affect retention and may facilitate retrieval. Benzodiazepines do not appear to impair semantic memory or the acquisition of skills. Although state-dependent learning may be observed with benzodiazepine treatment it is a small effect and cannot account for most of the observed impairments. The amnesia appears to be characteristic of all benzodiazepines and may be related to the sedative action of these compounds but evidence on the latter point is inconclusive. The importance of the amnesic action in a population of clinically anxious outpatients taking benzodiazepines over an extended period remains to be investigated. The benzodiazepines may provide the cognitive psychologist with a useful tool to investigate the mechanisms of normal memory.

Caffeine and diazepam: separate and combined effects on mood, memory, and psychomotor performance

The effects of caffeine and diazepam on several mood, cognitive, learning, memory, and psychomotor tasks were investigated in a double-blind study of 108 young healthy adults who were randomly assigned to nine treatments; oral administration of caffeine (0, 3 and 6 mg/kg), diazepam (0, 0.15, and 0.30 mg/kg) and their combinations. Subjects completed a battery of tasks once before and twice after administration of the drugs. Caffeine alone showed no effects on cognitive, learning, and memory performance, but impaired fine motor coordination and increased anxiety and tenseness. Diazepam alone produced sedation, lowered other ratings of subjective moods, and impaired cognitive, learning, and memory performance. The two drugs did not antagonize the effects of each other, except in the symbol cancellation task.

Behavioral effects of oral versus intravenous administration of diazepam

The behavioral effects of oral versus intravenous administration of diazepam were studied in 50 volunteers using a battery of memory, cognitive, mood and psychomotor tests repeated over a 4.5 hr period. Subjects received diazepam 0.2 mg/kg or placebo as capsules, commercial tablets or intravenous solution in a randomized double blind manner. While a quick onset of effects occurred with intravenous administration followed by the capsule and tablet oral administrations in that order, the recovery rate was similar for the 3 methods of administration. Contrary to many claims in the literature the effects of oral administration were substantial. Behavioral impairment was directly related to the magnitude of the memory component of the task. On many of the tasks the pattern of diazepam impairment was one of delayed improvement of performance, a pattern which would only be apparent with repeated testing. Subjects who received diazepam showed a paradoxical enhancement of recall for material learned before the drug.

Dose-response analysis of the behavioral effects of diazepam: I. Learning and memory

A total of 120 healthy volunteers were randomly assigned to four treatments (placebo, 0.1, 0.2, and 0.3 mg/kg) and three testing times (7 AM, 1 PM and 7 PM). Immediate and delayed free recall of word lists revealed consistent decreases in performance as oral diazepam dose increased from 0.1, 0.2, to 0.3 mg/kg. Paradoxically, as the dose increased, the number of predrug list words recalled also increased. A serial number-learning task displayed a pattern of delayed improvement of acquisition as the dose increased. Response times in a semantic-categories task were prolonged as the dose increased. Parallel recovery functions were observed for all doses and tasks. Full recovery after a single administration of 0.1, 0.2, and 0.3 mg/kg doses was estimated to occur after 3.5, 4.5, and 5.5 h, respectively. Several analyses were consistent with the view that acquisition and not retrieval was impaired by diazepam. There were no circadian interactions with the effects of the drug.