Psychomotor performance and real driving performance of outpatients receiving diazepam

Medication Changes Among Older Drivers Involved in Motor Vehicle Crashes

Importance

Although older adults may use potentially driver-impairing (PDI) medications that can produce psychomotor impairment, little is known about changes to PDI medication use among older adults from the time before to the time after a motor vehicle crash (MVC).

Objective

To quantify use of and changes in PDI medications among older adults before and after an MVC.

Design, Setting, and Participants

This cohort study used linked Medicare claims and police-reported MVC data on 154 096 person-crashes among 121 846 older drivers. Eligible persons were drivers aged 66 years or older, involved in a police-reported MVC in New Jersey from May 1, 2007, through December 31, 2017, and with continuous enrollment in Medicare fee-for-service Parts A and B for at least 12 months and Part D for at least 120 days prior to the MVC. Data were analyzed from January 2022 to May 2024.

Main Outcomes and Measures

Use of benzodiazepines, nonbenzodiazepine hypnotics, opioid analgesics, and other PDI medications in the 120 days before and 120 days after the MVC. Because each person could contribute multiple MVCs during the study period if they met eligibility criteria, the unit of analysis was the number of person-crashes. The proportion of person-crashes after which PDI medications were started, discontinued, or continued was quantified as well.

Results

Among 154 096 eligible person-crashes, the mean (SD) age of the drivers was 75.2 (6.7) years at the time of the MVC. Of 121 846 unique persons, 51.6% were women. In 80.0% of the person-crashes, drivers used 1 or more PDI medications before the crash, and in 81.0% of the person-crashes, drivers used 1 or more PDI medications after the crash. Use of benzodiazepines (8.1% before the crash and 8.8% after the crash), nonbenzodiazepine hypnotics (5.9% before the crash and 6.0% after the crash), and opioid analgesics (15.4% before the crash and 17.5% after the crash) was slightly higher after the MVC. After the MVC, drivers in 2.1% of person-crashes started benzodiazepines and 1.4% stopped benzodiazepines, drivers in 1.2% of person-crashes started nonbenzodiazepine hypnotics and 1.2% stopped nonbenzodiazepine hypnotics, and drivers in 8.4% of person-crashes started opioid analgesics and 6.3% stopped opioid analgesics.

Conclusions and Relevance

This cohort study suggests that most older drivers involved in MVCs did not use fewer PDI medications after crashes than before crashes. Qualitative research of perceived risks vs benefits of PDI medications is necessary to understand the reasons why MVCs do not appear to motivate clinicians to deprescribe PDI medications as a strategy to avert potential harms, including additional MVCs.

Evaluation method regarding the effect of psychotropic drugs on driving performance: A literature review

Although automobile driving is necessary for many people, including patients with mental disorders, the influence of psychotropic drugs on driving performance remains unclear and requires scientific verification. Therefore, the objective of this study was to conduct a review of the literature in order to aid the development of a valid evaluation method regarding the influence of medication on driving performance. We conducted a literature search using two sets of terms on PubMed. One set was related to psychotropic drugs, and the other to driving tests. We excluded reviews and case studies and added literature found on other sites. A total of 121 relevant reports were found. The experiments were roughly divided into on-the-road tests (ORT) and driving simulators (DS). Although highway driving tests in ORT are most often used to evaluate driving performance, DS are becoming increasingly common because of their safety and low cost. The validity of evaluation methods for alcohol should be verified; however, we found that there were few validated tests, especially for DS. The scenarios and measurement indices of each DS were different, which makes it difficult to compare the results of DS studies directly. No evaluation indices, except for SD of lateral position, were sufficiently validated. Although highway ORT are the gold standard, DS were shown to have an increasing role in evaluating driving performance. The reliability of DS needs to be established, as does their validation with alcohol in order to accumulate more high-quality evidence.

Medication use and the risk of motor vehicle collisions among licensed drivers: A systematic review

OBJECTIVES

Driving under the influence of prescription and over-the-counter medication is a growing public health concern. A systematic review of the literature was performed to investigate which specific medications were associated with increased risk of motor vehicle collision (MVC).

METHODS

The a priori inclusion criteria were: (1) studies published from English-language sources on or after January 1, 1960, (2) licensed drivers 15 years of age and older, (3) peer-reviewed publications, master's theses, doctoral dissertations, and conference papers, (4) studies limited to randomized control trials, cohort studies, case-control studies, or case-control type studies (5) outcome measure reported for at least one specific medication, (6) outcome measure reported as the odds or risk of a motor vehicle collision. Fourteen databases were examined along with hand-searching. Independent, dual selection of studies and data abstraction was performed.

RESULTS

Fifty-three medications were investigated by 27 studies included in the review. Fifteen (28.3%) were associated with an increased risk of MVC. These included Buprenorphine, Codeine, Dihydrocodeine, Methadone, Tramadol, Levocitirizine, Diazepam, Flunitrazepam, Flurazepam, Lorazepam, Temazepam, Triazolam, Carisoprodol, Zolpidem, and Zopiclone.

CONCLUSIONS

Several medications were associated with an increased risk of MVC and decreased driving ability. The associations between specific medication use and the increased risk of MVC and/or affected driving ability are complex. Future research opportunities are plentiful and worthy of such investigation.

Tolerance, sensitization and dependence to diazepam in Balb/c mice exposed to a novel open space anxiety test

Balb/c mice were exposed to an elevated platform that is extended on two opposite sides with lowered steep slopes. They were tested for 12min per session in 6 successive days. They received i.p. administration of either saline or one dose of diazepam (DZP 0.5, 1, 3mg/kg) in sessions 1-3, and saline in sessions 4 and 5. All groups of mice received a single dose of DZP (1mg/kg) in session 6. DZP produced inverted U-shaped dose-responses on the number of entries into different areas of the apparatus, with a peak in mean response at 1mg/kg whereas its effect on the duration of entries was mostly comparable between the 3 doses. It increased the number of crossings on the surface of the platform and facilitated entries onto the slopes. DZP-treated mice crossed frequently onto and spent longer time on the slopes in sessions 1-3 whereas saline-treated mice remained on the platform in sessions 1-6. Withdrawal of DZP in sessions 4-5 increased the latency of first entry and decreased the number and duration of entries onto the slopes which was reversed with the administration of 1mg/kg of DZP in the next session. This ON-OFF the drug may be due to the half-life of DZP which is very short in mice and rats ( approximately 0.88h). It also indicates that DZP-treated mice did not benefit from previous experience of entries onto the slopes which suggests a possible "state-dependent" effect. Administration of DZP after repeated exposures to the test did not facilitate entries onto the slopes but instead increased significantly the number of crossings on the surface of the platform; this increase was much higher than that observed in mice initially treated with DZP and exposed to the test. There is no evidence of habituation in saline-treated mice: the number of crossings on the platform was comparable between the first 5 sessions of the test. These results demonstrate that repeated exposures to the same anxiogenic environment resulted in avoidance responses developing tolerance and approach responses developing sensitization. They suggest that tolerance and sensitization are two opposite sides of the habituation process to the same stimulus and may account for the maintained state of anxiety.

Current technologies and considerations for drug bioanalysis in oral fluid

Drug oral fluid analysis was first used almost 30 years ago for the purpose of therapeutic drug monitoring. Since then, oral fluid bioanalysis has become more popular, mainly in the fields of pharmacokinetics, workplace drug testing, criminal justice, driving under the influence testing and therapeutic drug monitoring. In fact, oral fluid can provide a readily available and noninvasive medium, without any privacy loss by the examinee, which occurs, for instance, during the collection of urine samples. It is believed that drug concentrations in oral fluid may parallel those measured in blood. This feature makes oral fluid an alternative analytical specimen to blood, which assumes particular importance in roadside testing, the most published application of this sample. Great improvements in the development of accurate and reliable methods for sample collection, in situ detection devices (on-site drug detection kits), and highly sensitive and specific analytical methods for oral fluid testing of drugs have been observed in the last few years. However, without mass spectrometry-based analytical methods, such as liquid chromatography coupled to mass spectrometry (LC–MS) or tandem mass spectrometry (LC–MS/MS), the desired sensitivity would not be met, due to the low amounts of sample usually available for analysis. This review will discuss a series of published papers on the applicability of oral fluid in the field of analytical, clinical and forensic toxicology, with a special focus on its advantages and drawbacks over the normally used biological specimens and the main technological advances over the last decade, which have made oral fluid analysis of drugs possible.

The use of oral fluid for therapeutic drug management: clinical and forensic toxicology

One of the underlying tenets of clinical pharmacology is that only free drugs are pharmacologically active. It is thought that only free drugs can cross biological membranes to interact with a given receptor to alter its function, and that drug responses, both efficacious and toxic, are a function of unbound concentrations. The rationale for measuring drugs in oral fluid is that the free fraction of a drug in plasma reaches equilibrium with the drug in saliva. Although reports concerning the appearance of organic solutes in saliva have been in the literature for over 70 years, it has only been in the past 30 years that there has been emphasis on the appearance of drugs. Although many assumptions for drug level monitoring in saliva are made, the primary requisite for salivary monitoring to be useful is a constant or predictable relationship between the drug concentration in saliva and the drug concentration in plasma. Measurement of oral fluid drug levels for the purpose of managing patients and making dosage adjustments may be useful for select drugs or drug classes. However, it does not appear to be useful for the majority of drugs therapeutically monitored. Some work with antipsychotic medications has indicated that although the measurement of drug concentrations themselves may not be useful for dosage adjustment, the ratio of parent drug to metabolite may reflect altered metabolic status due to either pharmacogenetic variation or other clinical conditions. Furthermore, analysis of saliva may provide a cost-effective approach for the screening of large populations.

Effects of alcohol and other drugs on driver performance

In the past century we have learned that driving performance is impaired by alcohol even in low dosage, and that many other drugs are also linked to impairment. This paper is a summary of some of the more relevant studies in the past fifty years--an overview of our knowledge and unanswered questions. There is no evidence of a threshold blood alcohol (BAC) below which impairment does not occur, and there is no defined category of drivers who will not be impaired by alcohol. Alcohol increases not only the probability of collision, but also the probability of poor clinical outcome for injuries sustained when impaired by alcohol. This review samples the results of the myriad studies that have been performed during the last half century as experiments have moved from examination of simple sensory, perceptual and motor behaviours to more complex measures of cognitive functioning such as divided attention and mental workload. These more sophisticated studies show that significant impairment occurs at very low BACs (< 0.02 gm/100 ml). However, much remains to be determined regarding the more emotional aspects of behaviour, such as judgment, aggression and risk taking. Considering that the majority of alcohol related accidents occur at night, there is a need for increased examination on the role of fatigue, circadian cycles and sleep loss. The study of the effects of drugs other than alcohol is more complex because of the number of substances of potential interest, the difficulties estimating drug levels and the complexity of the drug/subject interactions. The drugs of current concern are marijuana, the benzodiazepines, other psychoactive medications, the stimulants and the narcotics. No one test or group of tests currently meets the need for detecting and documenting impairment, either in the laboratory or at the roadside.

Speed-of-processing and driving simulator training result in improved driving performance

Useful field of view, a measure of processing speed and spatial attention, can be improved with training. We evaluated the effects of this improvement on older adults' driving performance. Elderly adults participated in a speed-of-processing training program (N = 48), a traditional driver training program performed in a driving simulator (N = 22), or a low-risk reference group (N = 25). Before training, immediately after training or an equivalent time delay, and after an 18-month delay each participant was evaluated in a driving simulator and completed a 14-mile (22.5-km) open-road driving evaluation. Speed-of-processing training, but not simulator training, improved a specific measure of useful field of view (UFOV), transferred to some simulator measures, and resulted in fewer dangerous maneuvers during the driving evaluation. The simulator-trained group improved on two driving performance measures: turning into the correct lane and proper signal use. Similar effects were not observed in the speed-of-processing training or low-risk reference groups. The persistence of these effects over an 18-month test interval was also evaluated. Actual or potential applications of this research include driver assessment and/or training programs and cognitive intervention programs for older adults.

Visual search and urban driving under the influence of marijuana and alcohol

The purpose of the present study was to assess the effects of low doses of marijuana and alcohol, and their combination, on visual search at intersections and on general driving proficiency in the City Driving Test. Sixteen recreational users of alcohol and marijuana (eight males and eight females) were treated with these substances or placebo according to a balanced, 4-way, cross-over, observer- and subject-blind design. On separate evenings, subjects received weight-calibrated doses of THC, alcohol or placebo in each of the following treatment conditions: alcohol placebo + THC placebo, alcohol + THC placebo, THC 100 &mgr;g/kg + alcohol placebo, THC 100 &mgr;g/kg + alcohol. Alcohol doses administered were sufficient for achieving a blood alcohol concentration (BAC) of about 0.05 g/dl. Initial drinking preceded smoking by one hour. The City Driving Test commenced 15 minutes after smoking and lasted 45 minutes. The test was conducted over a fixed route within the city limits of Maastricht. An eye movement recording system was mounted on each subject's head for providing relative frequency measures of appropriate visual search at intersections. General driving quality was rated by a licensed driving instructor on a shortened version of the Royal Dutch Tourist Association's Driving Proficiency Test. After placebo treatment subjects searched for traffic approaching from side streets on the right in 84% of all cases. Visual search frequency in these subjects did not change when they were treated with alcohol or marijuana alone. However, when treated with the combination of alcohol and marijuana, the frequency of visual search dropped by 3%. Performance as rated on the Driving Proficiency Scale did not differ between treatments. It was concluded that the effects of low doses of THC (100 &mgr;g/kg) and alcohol (BAC < 0.05 g/dl) on higher-level driving skills as measured in the present study are minimal. Copyright 2001 John Wiley & Sons, Ltd.

Performance tests

This paper discusses the use of psychological performance tests to assess the effects of environmental stressors. The large number and the variety of performance tests are illustrated, and the differences between performance tests and other psychological tests are described in terms of their design, construction, use, and purpose. The stressor emphasis is on the effects of drugs since that is where most performance tests have found their main application, although other stressors, e.g., fatigue, toxic chemicals, are mentioned where appropriate. Diazepam is used as an example. There is no particular performance emphasis since the tests are intended to have wide applicability. However, vehicle-driving performance is discussed because it has been the subject of a great deal of research and is probably one of the most important areas of application. Performance tests are discussed in terms of the four main underlying models--factor analysis, general information processing, multiple resource and strategy models, and processing-stage models--and in terms of their psychometric properties--sensitivity, reliability, and content, criterion, construct, and face validity. Some test taxonomies are presented. Standardization is also discussed with reference to the reaction time, mathematical processing, memory search, spatial processing, unstable tracking, verbal processing, and dual task tests used in the AGARD STRES battery. Some comments on measurement strengths and appropriate study designs and methods are included.

Urine toxicology screens in drivers suspected of driving while impaired from drugs

OBJECTIVE

Police departments, in conjunction with the National Highway Traffic Safety Administration, have developed a standardized evaluation aimed at identifying drivers impaired by drugs other than ethanol. These evaluations are performed by specially trained police officers known as Drug Recognition Experts.

METHODS

We retrospectively reviewed the evaluations of 242 drivers detained for driving while impaired in the City and County of Denver from January 1, 1988 to June 30, 1990.

RESULTS

All drivers had urine toxicology screens performed, which were positive for a mean 1.2 +/- 0.9 SD (range zero to four) for drugs having the potential for causing driving impairment. The 193/242 urine screens (79.8%) testing positive showed the following drugs: cannabis 162 (66.9%), stimulants (including cocaine metabolites) 80 (33.1%), depressants (benzodiazepines and barbiturates) 24 (9.9%), narcotics 12 (5.0%), inhalants (toluene) 1 (0.4%), hallucinogens (LSD) 1 (0.4%), and other 3 (1.2%). Drug Recognition Experts, based on their initial evaluation, were able to predict correctly some or all of the drugs found on the urine screens in 178/242 (73.6%) of cases. Overall agreement between the Drug Recognition Experts opinions and urine screen results had a kappa value (p < 0.05) of 0.41.

CONCLUSIONS

There was a high rate (79.8%) of positive urine toxicology screens in drivers suspected of nonethanol drug impairment. In most cases, Drug Recognition Experts were able to reliably predict the results of these screens.

Impairment of performance associated with long-term use of benzodiazepines

The long-term effects of benzodiazepines (BDZ) on psychomotor and cognitive functions were assessed in 28 out patients, users of low therapeutic doses of diazepam (13.6 ± 4.9 mg/day, range: 5-20 mg/day) for 5-20 years (10.1 ± 5.0 years). These patients' performance was compared with two control groups: 53 BDZ-free anxious out patients and 56 healthy volunteers. The three groups were similar in sex, age and education. BDZ chronic users were tested before and after short-term (3 weeks) and long-term discontinuation (at an average of 10 months). Performance of chronic users of BDZ was consistently worse than those of the control groups, suggesting an impairment in these patients on both psychomotor and cognitive functions. These were not related to either dose or cumulative exposure to BDZ, and were also independent of diagnosis and levels of anxiety and depression. Moreover, these deficits were persistent as their performance failed to improve after drug discontinuation.

Low blood alcohol concentrations and driving impairment. A review of experimental studies and international legislation

While noting that there is no international scientific or legislative uniformity in blood alcohol concentration (BAC) levels admissible for driving motor vehicles, the authors analyse problems concerning the effects of low levels of ethyl alcohol on driving ability. A summary of the international literature on this subject reveals: the existence of contrasting assumptions, with scientific evidence clearly demonstrating altered psychomotor functions; the need to adopt sufficiently complex psychometric tests to reveal the effects of low BACs; the need to improve standardization of experimental studies on man-machine interaction; the need to investigate the following areas: tolerance to alcohol; low BACs with inexperienced, infrequent drinkers and chronic, heavy drinkers; hangover effects; alcohol-gender-age interactions, and specific effects on young drivers; alcohol-drug combinations. The analysis of legislation and enforcement policies also reveals the need for: re-evaluation of the international legal BAC threshold and standardization of procedures for ascertaining the degree of driving disability; further scientific research to compare and evaluate selected legislative initiatives currently in place in most states; to identify the best strategies and procedures to detect and arrest impaired drivers; to determine the optimum random testing rate to maximize deterrent effects in the workplace at minimal cost; to design innovative and comprehensive approaches to rehabilitation programs needed for subgroups of offenders and of workers; to study the effectiveness of new legislations and policies.

Saliva testing for drugs of abuse

Saliva testing for drugs of abuse can provide both qualitative and quantitative information on the drug status of an individual undergoing testing. Self-administration by the oral, intranasal, and smoking routes often produces "shallow depots" of drug that contaminate the oral cavity. This depot produces elevated drug concentrations that can be detected for several hours. Thereafter, saliva drug concentrations generally reflect the free fraction of drug in blood. Also, many drugs are weak bases and saliva concentrations may be highly dependent upon pH conditions. These factors lead to highly variable S/P ratios for many of the drugs of abuse. Table 3 provides a compilation of experimental and theoretical S/P (total) ratios determined for drugs of abuse. Estimations of the theoretical S/P (total) ratios for acidic and basic drugs were based on the Henderson-Hasselbalch equation. Saliva pH was assumed to be 6.8 unless reported otherwise by the investigators. Generally, there was a high correlation of saliva drug concentrations with plasma, especially when oral contamination was eliminated. Assay methodology varied considerably, indicating that saliva assays could be readily developed from existing methodology. There are many potential applications for saliva testing for drugs of abuse. Table 4 lists several general areas in which information from saliva testing would be useful. Clearly, saliva drug tests can reveal the presence of a pharmacologically active drug in an individual at the time of testing. Significant correlations have been found between saliva concentrations of drugs of abuse and behavioral and physiological effects. Results indicate that saliva testing can provide valuable information in diagnostics, treatment, and forensic investigations of individuals suspected of drug abuse. It is expected that saliva testing for drugs of abuse will develop over the next decade into a mature science with substantial new applications.

Traffic accidents and drivers suspected for drug influence

All records from the Danish Medicolegal Council concerning drivers suspected for drug influences were examined for the 5 year period 1981-1985. 461 records were included, 62 women and 399 men. In 250 cases drugs from more than one of ten groups had been taken thus making 786 combinations of drug/driving. The major drug group was benzodiazepines, accounting for 65% of all drug intake. Opioids also contributed substantially, found in 38% of the cases. A traffic accident had occurred in 180 (39%) of the records. Drivers who had been taking antidepressives were involved in an accident in 67%, significantly above the mean. For benzodiazepines, the corresponding percentage was 43%, while for opioids it was only 23%, significantly below the mean. This striking difference has been demonstrated in most of the studies concerning drugs in traffic. It may support the hypothesis that opioids do not necessarily make driving dangerous, as do antidepressives, barbiturates and especially benzodiazepines.

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 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.

Benzodiazepines and vigilance performance: a review

The literature on the effects of anxiolytic and hypnotic drugs on performance in tasks requiring sustained attention is confusing. This review is an attempt to evaluate the usefulness of vigilance tasks in the assessment of adverse effects of benzodiazepines. The long, monotonous, character of these tasks may be more relevant to many tasks performed in everyday life than the short, and often stimulating, tasks commonly employed in test batteries. From 37 available studies, 26 were examined in detail. In young, normal volunteers, vigilance tasks were found to be sensitive, often dose dependently, to the impairing effects of drugs, even in low doses (2.5 mg diazepam). With these subjects the tasks may be successfully used to compare different benzodiazepines with respect to residual activity. Both accuracy and speed of performance appear to be affected. However, in people actually using the drugs ("patients"), adverse effects on performance are usually not found. There is no evidence that benzodiazepines aggravate the vigilance decrement occurring under normal conditions. They do affect overall level of perceptual sensitivity, but show less effects on response criterion. The drugs do not seem to interact with anxiety or sleep quality in their effect on performance, but there are few studies with patients, and the assessment of anxiety is not without problems. It is unlikely that impairments in vigilance are simply a byproduct of global, sedative effects, but there is uncertainty regarding measures of general sedation. Developing tolerance with repeated doses has been noted only occasionally, but the opposite of tolerance, aggravated impairment, has also been reported.

Detection of blood benzodiazepines in injured people. Relationship with alcoholism

In 2021 accident victims (household, work and road accidents) the qualitative test for benzodiazepines in the serum by the EMIT method was positive in 9.6% of cases, including 3.2% of subjects who also had a blood alcohol level greater than 0.10 milligram. Benzodiazepines were detected with a particularly high frequency in household accidents and road accidents and rarely in work accidents. These results raise the problem of the role of benzodiazepines as a possible risk factor for accidents, particularly road accidents.

Clinical relevance of effects of benzodiazepines on learning and memory

The effects of benzodiazepines on learning and memory are examined in the various clinical situations in which these drugs are used. Alterations in performance arising from the conditions for which benzodiazepines are prescribed are also considered. Current evidence indicates that, in anxious patients, as in normal volunteers, benzodiazepines impair the acquisition of new information (episodic memory). Although some tolerance may develop to these impairments, deficits are observed even after patients have been taking their medication chronically. Like amnesic patients, benzodiazepine-treated subjects may be unaware of their impaired ability to learn. The effects of the impairments on behavioral psychotherapies are considered.

Benzodiazepines, but not antidepressants or neuroleptics, induce dose-dependent development of tolerance to lorazepam in psychiatric patients

Psychomotor effects of oral lorazepam 3 mg were studied in psychiatric patients stratified into four groups: 1) a group of six patients with no previous use of psychotrophic drugs (NoD), 2) a group of 12 patients treated with antidepressants and/or neuroleptics (PsyD), 3) a group of 10 patients treated with low doses of benzodiazepines (BZs) (lowBZ), and 4) a group of nine patients treated with high doses of BZs (high BZ). Similar objective psychomotor tests and subjective assessments were administered under single-blind conditions to all treatment groups at baseline, after intake of placebo, and after intake of 3 mg lorazepam. Both lorazepam (CGC) and total BZs (bioassay) in serum were assayed. The results demonstrate that treatment with BZs induce dose-dependent development of tolerance to psychomotor effects of lorazepam. Antidepressants and neuroleptics failed to induce cross-tolerance to lorazepam. The rise in serum lorazepam concentrations after lorazepam intake was similar (about 28 micrograms/l) in all treatment groups, suggesting a functional, not dispositional, tolerance. However, the initial learning effect in psychomotor performance was poorer among BZ users than among others.

A conveyor belt task for assessing visuo-motor coordination in the marmoset (Callithrix jacchus): effects of diazepam, chlorpromazine, pentobarbital and d-amphetamine

A conveyor belt task for assessing visuo-motor coordination in the marmoset is described. Animals are motivated by apple, a preferred food, under a state of minimal food deprivation. The apparatus used was designed to test animals within their home cages and not restrained in any way, thus avoiding possible confounding factors associated with restraint stress. Stable baseline levels of performance were reached by all animals in a median of 24 sessions. Performance was shown to be differentially sensitive to the effects of four psychoactive drugs. Moderate doses of diazepam, chlorpromazine and pentobarbital disrupted visuo-motor coordination in a dose-related manner. The possibility that disruption of performance observed at higher doses may have resulted from non-specific actions of these drugs such as decreases in feeding motivation were not supported by results from ancillary experiments. Changes in performance characteristic of high dose effects were similar in nature to changes observed when the degree of task difficulty was increased. Doses of d-amphetamine up to and including those reported to produce signs of stereotypy failed to influence performance. The potential of the conveyor belt task for measuring visuo-motor coordination in both primate and rodent species is discussed.

Investigating drug--ethanol interactions

Methodology developed in our laboratories for testing the interactive effects of ethanol and drugs on human psychomotor performance is discussed. An attempt has been made to relate the findings of our studies to the results of real-life impairment, particularly in traffic crashes. Proposals for more comprehensive testing of drug--ethanol interactions have been put forward which may increase the predictive value of such tests.

Visual motor co-ordination and dynamic visual acuity

Data on the effect of an antihistamine (triprolidine 10 mg) on visuo-motor coordination and dynamic visual acuity were used to establish interactions between these skills. Analysis of covariance and principal component analysis were used. The analyses suggested two main effects--an effect on the activity of the neuromuscular system and one which impaired ability to anticipate target movement. Detection of impaired performance by any task may have wider implications to the effectiveness of the individual than that obviously suggested by the skill itself.

Driving tests with patients

Mental illness and the use of psychotropic drugs are considered to influence driving skills of patients. However, studies which indicate the relative contributions of these factors are rare. It is emphasized that for measuring the effects of psychotropic drugs on driving performance of patients, real driving tests are needed. Actual driving and psychomotor performance of patients receiving diazepam, and patients and healthy volunteers receiving mebhydrolin were measured to illustrate the use of real driving tests. The results of both studies are discussed in terms of problems associated with the application of these tests. Patient recruitment is considered to be a major problem. To draw conclusions under these circumstances is extremely difficult, but still acceptable in comparison with the limitations and methodological difficulties of the more commonly used laboratory tests. Some guidelines for driving tests with patients are given.

Diazepam impairs lateral position control in highway driving

Nine expert drivers operated an instrumented vehicle in tests over a highway at night after being treated with diazepam (5 and 10 milligrams), a placebo, and nothing. They reacted to 10 milligrams of diazepam with increased lateral position variability. Potentially dangerous impairment was inferred from the reactions of some subjects.