Effects of milnacipran on driving vigilance

BACKGROUND Many psychotropic drugs modify sensory and/or psychomotor functions involved in car driving and as such they can be a causative factor in road accidents. AIM To investigate the effects of the administration of milnacipran, a serotonin and noradrenaline dual-action antidepressant, on the sensory and psychomotor skills implicated in car driving and to determine any possible interactions with the effect of alcohol. METHODS Double-blind, placebo-controlled four-sequence cross-over design with 12 healthy volunteers. Laboratory tests designed to explore motor responses to auditory and visual stimuli and equilibrium on a sensory platform, as well as tests in a real on-road car driving situation, were carried out before the drug administration (control) and at the end of each sequence. RESULTS There was no significant difference in the results of laboratory tests between groups receiving milnacipran compared to placebo. In a real driving situation there were no significant effects of milnacipran. In addition, milnacipran did not accentuate the negative effects of alcohol. CONCLUSIONS Milnacipran, administered at 50 mg b.i.d. to healthy volunteers, does not modify the psychomotor skills required for driving.

Maze test performance and reported driving ability in early dementia

A battery of standard neuropsychological tests examining various features of executive function, attention, and visual perception was administered to 27 subjects with questionable to mild dementia and compared to a 4-point caregiver rating scale of driving ability. Based on the results of this study, a computerized maze task, employing 10 mazes, was administered to a second sample of 40 normal elders and questionable to moderately demented drivers. Comparison was made to the same caregiver rating scale as well as to crash frequency. In the first study of neuropsychological tests, errors on Porteus Mazes emerged as the only significant predictor of driving ability in a stepwise regression analysis. In the follow-up study employing the computerized mazes, all 10 mazes were significantly related to driving ability ratings. Computerized tests of maze performance offer promise as a screening tool to identify potential driving impairment among cognitively impaired elderly and demented drivers.

Carisoprodol - Effects on Human Performance and Behavior

Carisoprodol, a commonly prescribed muscle relaxant, has adverse effects on human performance and is gaining recognition as a factor in driver impairment and accident causation. Carisoprodol is a centrally acting skeletal muscle relaxant indicated for the relief of musculoskeletal pain. Carisoprodol and its major metabolite meprobamate have central nervous system (CNS) sedating effects similar to benzodiazepines or alcohol. Following the ingestion of carisoprodol or meprobamate symptoms such as drowsiness, confusion, poor balance, and coordination are well documented in drivers, all of which are detrimental to human performance and driving ability. Although identified as a drug capable of producing decreased human performance, the full extent of carisoprodol and meprobamate's involvement in motor vehicle accidents and effect on driving skills may not be fully appreciated. This is due in part to the common co-administration of other CNS depressants, hypnotics, or narcotic drugs and the lack of routine testing for carisoprodol and meprobamate in the human performance toxicology laboratory.

Why HID headlights bother older drivers

Driving requires effective coordination of visual, motor, and cognitive skills. Visual skills are pushed to their limit at night by decreased illumination and by disabling glare from oncoming headlights. High intensity discharge (HID) headlamps project light farther down roads, improving their owner's driving safety by increasing the time available for reaction to potential problems. Glare is proportional to headlamp brightness, however, so increasing headlamp brightness also increases potential glare for oncoming drivers, particularly on curving two lane roads. This problem is worse for older drivers because of their increased intraocular light scattering, glare sensitivity, and photostress recovery time. An analysis of automobile headlights, intraocular stray light, glare, and night driving shows that brightness rather than blueness is the primary reason for the visual problems that HID headlights can cause for older drivers who confront them. The increased light projected by HID headlights is potentially valuable, but serious questions remain regarding how and where it should be projected.

Relation between perceived driving disability and scores of vision screening tests

AIM

To determine the relation between perceived driving disability and vision screening tests.

METHODS

93 subjects, aged 50 years and over, with binocular visual acuity of at least 20/80. Perceived driving disability (PDD) was assessed by a questionnaire. Subtracting daytime from night-time driving question scores revealed PDD at night (PDDN), subtracting scores of questions for driving in familiar places from those in unfamiliar places revealed PDD at unfamiliar places (PDDU).

RESULTS

PDD was strongly related to visual acuity, contrast sensitivity and useful field of view (UFOV). Specific relations existed between PDDN and Nyktotests and Mesotests and between PDDU and UFOV. These associations were enhanced in a subset of subjects with better visual acuities.

CONCLUSIONS

Vision screening tests correlate well with perceived driving disabilities, especially when a subtraction method is used in the questionnaire to reveal condition dependent disabilities. Additional tests for visual acuity are useful, especially in subjects with better visual acuity.

Vision impairment and older drivers: who's driving?

AIM

To establish the association between impaired vision and drivers' decisions to stop driving, voluntarily restrict driving, and motor vehicle accidents.

METHODS

Driving related questions were included in a population based study that determined the prevalence and incidence of eye disease. Stratified random cluster samples based on census collector districts were selected from the Melbourne Statistical Division. Eligible participants aged 44 years and over were interviewed and underwent a comprehensive ophthalmic examination. The outcomes of interest were the decision to stop driving, limiting driving in specified conditions, and driving accidents. The associations between these outcomes and the legally prescribed visual acuity (<6/12) for a driver's licence were investigated.

RESULTS

The mean age of the 2594/3040 (85%) eligible participants was 62.5 (range 44-101). People with visual acuity less than 6/12 were no more likely to have an accident than those with better vision (chi(2) = 0.175, p>0.9). Older drivers with impaired vision, more so than younger adults, restrict their driving in visually demanding situations (p<0.05). Of the current drivers, 2.6% have vision less than that required to obtain a driver's licence. The risk of having an accident increased with distance driven (OR 2.57, CL 1.63, 4.04 for distance >31 000 km) but not with age.

CONCLUSION

There was no greater likelihood of self reported driving accidents for drivers with impaired vision than those with good vision. While many older drivers with impaired vision limit their driving in adverse conditions and some drivers with impaired vision stop driving, there are a significant number of current drivers with impaired vision.

Different activation dynamics in multiple neural systems during simulated driving

Driving is a complex behavior that recruits multiple cognitive elements. We report on an imaging study of simulated driving that reveals multiple neural systems, each of which have different activation dynamics. The neural correlates of driving behavior are identified with fMRI and their modulation with speed is investigated. We decompose the activation into interpretable pieces using a novel, generally applicable approach, based upon independent component analysis. Some regions turn on or off, others exhibit a gradual decay, and yet others turn on transiently when starting or stopping driving. Signal in the anterior cingulate cortex, an area often associated with error monitoring and inhibition, decreases exponentially with a rate proportional to driving speed, whereas decreases in frontoparietal regions, implicated in vigilance, correlate with speed. Increases in cerebellar and occipital areas, presumably related to complex visuomotor integration, are activated during driving but not associated with driving speed.

Katamine - Effects on Human Performance and Behavior

Ketamine is a rapid-acting anesthetic commonly used during surgical procedures in both animals and humans, as an experimental drug in the treatment of chronic pain, and as a probe for the study of the cause of schizophrenia. When used medically as an anesthetic it is administered as an intravenous (IV) solution, but when diverted to the illicit market it can be injected, snorted, smoked, or consumed in drinks. Ketamine produces effects similar in some respects to phencyclidine (PCP) and lysergic acid (LSD), but of shorter duration. Psychedelic effects are produced quickly by low doses of the drug, although larger doses are frequently used in an attempt to produce "near-death" experiences. Convulsions and death can be caused by higher doses, although most deaths in which ketamine is detected are the result of poly-drug use or trauma. Reports of ketamine use at rave parties attended by young adults appear to be on the rise. The effects from ketamine last from 1-5 hours, and ketamine can be detected in the urine for a period of 1-2 days following use.

Cocaine - Effects on Human Performance and Behavior

A brief history of cocaine is provided followed by an overview of the pharmacology of cocaine. In addition to the mechanism of action, the effects of cocaine withdrawal and its effects in combination with ethanol are discussed. Special emphasis is placed on the metabolism of cocaine and the interpretation of the concentration of cocaine and metabolites detected in various matrices. Consideration is given to stability of the drug, pathology, postmortem observations, passive and unknowing ingestion, and dermal exposure. A brief overview of analytical methodology is also presented. Finally, the effects of cocaine on driving are examined.

γ-Hydroxybutyrate (GHB) - Effects on Human Performance and Behavior

γ-Hydroxybutyrate (GHB) is a powerful central nervous system (CNS) depressant which has had a history of limited therapeutic use and, more recently, potential for abuse. GHB is a naturally occurring compound present in mammalian CNS and peripheral tissues, and a minor metabolite and precursor of γ-amino butyric acid. GHB is also an emerging recreational drug and has limited therapeutic potential. It is now a federally controlled substance. Since the substances γ-butyrolactone and 1,4-butanediol rapidly convert to GHB in vivo, they are abused as metabolic precursor drugs for GHB and are available in a wide variety of forms. GHB alters dopaminergic activity in the CNS, and its effects are primarily those of a CNS depressant. Following low doses, euphoria, relaxation, reduced inhibitions and sedation can be observed, while vomiting, sweating, severe respiratory depression, and unconsciousness are common with GHB intoxication. Tolerance to the effects of GHB develops with chronic use, and physical and psychological addiction can follow. This monograph reviews the chemistry of GHB and its precursor drugs, their reported medicinal and recreational uses, pharmacology, pharmacokinetics, metabolism, analytical methodology, and interpretation issues such as postmortem endogenous concentrations and specimen storage conditions. The manuscript concludes with a discussion of the effects GHB may have on human performance. Given the ability of GHB to induce sleep and unconsciousness, recreational use of GHB and its precursor drugs GBL and 1,4-butanediol has the potential of causing impairment in psychomotor and cognitive skills.

Cannabis (Marijuana) - Effects on Human Performance and Behavior

Cannabis is one of the oldest and most commonly abused drugs in the world. Recently, tremendous advances have been made in our understanding of the endogenous cannabinoid system with the identification of cannabinoid receptors, cannabinoid receptor antagonists, endogenous neurotransmitters, metabolic enzymes, and reuptake mechanisms. These advances have helped us to elucidate the mechanisms of action of cannabis and the side effects and toxicities associated with its use. In addition, potential therapeutic applications are being investigated for the use of smoked cannabis and synthetic THC (dronabinol). Most workplace, military, and criminal justice positive urine drug tests are due to the use of cannabis. In addition, alternative matrices, including saliva, sweat, and hair, are being utilized for monitoring cannabis use in treatment, employment, and criminal justice settings. Experimental laboratory studies have identified cognitive, physiological, and psychomotor effects following cannabis. Epidemiological studies reveal that cannabis is the most common illicit drug world-wide in impaired drivers, and in motor vehicle injuries and fatalities. Driving simulator studies also indicate performance impairment following cannabis use; however, the results of open- and closed-road driving studies and of culpability studies do not consistently document increased driving risk. Clearly a combination of ethanol and cannabis use significantly increases risks. This article reviews the pharmacokinetics and pharmacodynamics of cannabis and places special emphasis on the effects of cannabis on complex tasks such as driving and flying.

Benzodiazepines - Effects on Human Performance and Behavior

There exist a large number of drugs belonging to the benzodiazepine family. These include the 1,4-benzodiazepines such as diazepam, temazepam and oxazepam, the often more potent diazolo- and triazolo-groups represented by alprazolam, midazolam, triazolam etc. These drugs represent a large range of potencies from submilligram doses to over 100 mg and a range of polarities. Consequently, blood or plasma concentrations associated with prescribed use range from sub-nanogram per mL to near-microgram per mL. Their medical use varies, but they are predominantly used as hypnotics and sedatives. Some members are also used in the treatment of post-traumatic stress and obsessive-compulsive disorders, alcohol withdrawal, muscle spasm, and seizures. Recreationally, drug users favor these drugs to reduce the symptoms of withdrawal and unpleasant effects of heroin and cocaine. They are also commonly used as "date-rape" drugs to render a victim incapable of resisting an attack. Benzodiazepines elicit a large number of physiological and psychological responses in humans that often can lead to significant behavioral changes and adverse effects on skills required for safe driving. These include reduced lane control, increased reaction times, reduced hand-eye coordination and cognitive impairment. Impairment can exceed that seen with 0.05 g% ethanol. In high doses benzodiazepines can cause persons to exhibit classical features of CNS-depressant drugs such as nystagmus, ataxia, slurred speech, and impaired divided attention skills. As one would expect with hypnotics and sedatives, any sleep deprivation, or situations involving monotonous driving can lead to a reduced ability to concentrate and maintain vigilance. Adverse effects on REM and NREM sleep patterns will exacerbate fatigue-related components to driving. Persons with sleep abnormalities, e.g., sleep apnea, may be more likely to be affected by benzodiazepines than those with normal sleep patterns. Ethanol and narcotic analgesics also affect sleep patterns and may compound any CNS-depressant effects associated with the use of benzodiazepines.

A single-photon emission computed tomography imaging study of driving impairment in patients with Alzheimer's disease

Single-photon emission computed tomography (SPECT) was used in this study to examine the neurophysiologic basis of driving impairment in 79 subjects with dementia. Driving impairment, as measured by caregiver ratings, was significantly related to regional reduction of right hemisphere cortical perfusion on SPECT, particularly in the temporo-occipital area. With increased severity of driving impairment, frontal cortical perfusion was also reduced. Clock drawing was more significantly related to driving impairment than the Mini-Mental State Examination (MMSE). Driving impairment in Alzheimer's disease is related to changes in cortical function which vary according to the severity of the disease. Cognitive tests of visuoperceptual and executive functions may be more useful screening tools for identifying those at greatest risk for driving problems than examinations like the MMSE that are weighted toward left-hemisphere-based verbal tasks.

Driving under the Influence of Non-Alcohol Drugs

In this article the methodological basis for our knowledge within the field of driving under the influence of non-alcohol drugs is reviewed. The experimental and epidemiological studies on drugs in relation to driving do not constitute a complete basis for conclusions to be drawn, but give at the present state nevertheless a platform to indicate increased hazard connected with the use of several drugs. It appears that the main problem with respect to therapeutic use of medicinal drugs is experienced with benzodiazepines (BZDs) and related drugs, and to a lesser extent with opioids and antidepressants. Antihistamine use does not appear to be a serious problem. The major problem within the field of drugged driving as it emerges today in the US and Europe is the high dose use (abuse) of BZDs and related drugs, opioids and illicit drugs such as cannabis, amphetamines, cocaine and related drugs with accompanying danger to traffic safety. Methods determining clinical drug effects in people combined with measurements of drug blood concentrations seem to constitute the best basis for evaluation of "influence". New methods to detect drugged drivers are under development, with saliva tests presently being the most promising. Legislation in the field can be of the "zero tolerance" type or the "impairment" type; combinations of these principles might well turn out to be the most efficient. Detection of drugged driving is presently, in relation to population size, most frequent in Norway, a country with not too pronounced drug problems, indicating a large potential for future detection of drugged driving in other countries. The prevention of drugged driving, especially in the drug-abusing group which has a high recidivism rate, is a challenge for future policy in this field.

Measuring Alcohol in Blood and Breath for Forensic Purposes - A Historical Review

This review concerns important events and trends in the evolution of chemical tests for alcohol intoxication on two continents; Europe and North America. In particular, the pioneer workers in this field and their major contributions to forensic alcohol analysis are emphasized. Quantitative methods for the determination of alcohol in blood, breath, and urine appeared early in the twentieth century and experimental alcohol research had already started in several European countries. The first statutory limits of blood-alcohol concentration (BAC) were introduced in Norway and Sweden during the 1930-1940s where Widmark's micro-diffusion method was approved for forensic purposes. Between 1931-1935 in the U.S., the first instrument (the Drunkometer) was developed for measuring the concentration of alcohol in a person's breath to supplement various clinical signs and symptoms of drunkenness. The breath-alcohol concentration (BrAC) was always translated into the presumed coexisting BAC to furnish corroborative or presumptive evidence of impairment at the wheel. After the Breathalyzer device was developed by Borkenstein around 1953-54, breath-alcohol testing became firmly established for law enforcement purposes in the U.S. and Canada. The classic wet-chemistry methods of blood-alcohol analysis were displaced by enzymatic procedures in the early 1950s and in the 1960s gas chromatographic (GC) methods dominated. Today, headspace GC is the mainstay in forensic science laboratories for the determination of alcohol and other volatile substances in body fluids. The first breath-alcohol devices used in Europe were relatively simple screening tests for alcohol at the roadside and positive results were always followed-up by quantitative analysis of alcohol in blood or urine. The technology of breath-alcohol testing has changed dramatically over the years from chemical oxidation and colorimetric procedures towards physicochemical techniques such as gas chromatography, electrochemical oxidation, and multiple wavelength infrared spectrophotometry. In the early 1980s evidential breath-alcohol instruments were approved for law enforcement purposes in many European countries and threshold limits of BrAC were introduced alongside the existing statutory BAC limits.