Skin temperature as a predictor of on-the-road driving performance in people with central disorders of hypersomnolence.

Excessive daytime sleepiness is the core symptom of central disorders of hypersomnolence (CDH) and can directly impair driving performance. Sleepiness is reflected in relative alterations in distal and proximal skin temperature. Therefore, we examined the predictive value of skin temperature on driving performance. Distal and proximal skin temperature and their gradient (DPG) were continuously measured in 44 participants with narcolepsy type 1, narcolepsy type 2 or idiopathic hypersomnia during a standardised 1-h driving test. Driving performance was defined as the standard deviation of lateral position (SDLP) per 5 km segment (equivalent to 3 min of driving). Distal and proximal skin temperature and DPG measurements were averaged over each segment and changes over segments were calculated. Mixed-effect model analyses showed a strong, quadratic association between proximal skin temperature and SDLP (p < 0.001) and a linear association between DPG and SDLP (p < 0.021). Proximal skin temperature changes over 3 to 15 min were predictive for SDLP. Moreover, SDLP increased over time (0.34 cm/segment, p < 0.001) and was higher in men than in women (3.50 cm, p = 0.012). We conclude that proximal skin temperature is a promising predictor for real-time assessment of driving performance in people with CDH.

Comparing objective wakefulness and vigilance tests to on-the-road driving performance in narcolepsy and idiopathic hypersomnia.

Patients with narcolepsy or idiopathic hypersomnia (IH) are at increased risk of driving accidents. Both excessive daytime sleepiness, i.e. unwanted sleep episodes during the day, and disturbed vigilance are core features of these disorders. We tested on-the-road driving performance of patients with narcolepsy or IH coming in for a routine driving fitness evaluation and examined: (1) correlations between driving performance and the Maintenance of Wakefulness Test (MWT), Sustained Attention to Response Task (SART) and Psychomotor Vigilance Test (PVT) as objective tests; (2) the predictive power of the MWT and SART for increased risk of impaired driving; (3) the best set of objective predictors for increased risk of impaired driving. Participants were 44 patients (aged 18-75 years) with narcolepsy type 1 (NT1), type 2 (NT2) or IH. They completed the MWT, SART, PVT, a subjective sleepiness questionnaire, and a standardised on-the-road driving test. The standard deviation of the lateral position (SDLP) was used as outcome measure of driving performance. The MWT had low correlation with the SDLP (ρ = -0.41 to -0.49, p < 0.01). The SART and PVT had low correlations with SDLP (ρ = 0.30 and ρ = 0.39, respectively, both p < 0.05). The predictive power of MWT for an increased risk of impaired driving was significant, but low (area under the curve = 0.273, p = 0.012), and non-significant for SART. We conclude that in our present group, none of the tests had adequate ability to predict impaired driving, questioning their use for clinical driving fitness evaluation in narcolepsy and IH. Real-time monitoring of sleepiness while driving seems more promising in these patients.

An explorative approach to understanding individual differences in driving performance and neurocognition in long-term benzodiazepine users.

OBJECTIVE: Previous research reported cognitive and psychomotor impairments in long-term users of benzodiazepine receptor agonists (BZRAs). This article explores the role of acute intoxication and clinical complaints. METHODS: Neurocognitive and on-road driving performance of 19 long-term (≥6 months) regular (≥twice weekly) BZRA users with estimated plasma concentrations, based on self-reported use, exceeding the therapeutic threshold (CBZRA +), and 31 long-term regular BZRA users below (CBZRA -), was compared to that of 76 controls. RESULTS: BZRA users performed worse on tasks of response speed, processing speed, and sustained attention. Age, but not CBZRA or self-reported clinical complaints, was a significant covariate. Road-tracking performance was explained by CBZRA only. The CBZRA  + group exhibited increased mean standard deviation of lateral position comparable to that at blood-alcohol concentrations of 0.5 g/L. CONCLUSIONS: Functional impairments in long-term BZRA users are not attributable to self-reported clinical complaints or estimated BZRA concentrations, except for road-tracking, which was impaired in CBZRA + users. Limitations to address are the lack of assessment of objective clinical complaints, acute task related stress, and actual BZRA plasma concentrations. In conclusion, the results confirm previous findings that demonstrate inferior performance across several psychomotor and neurocognitive domains in long-term BZRA users.

Driving performance and neurocognitive skills of long-term users of sedating antidepressants.

OBJECTIVE: To assess driving performance and neurocognitive skills of long-term users of sedating antidepressants, in comparison to healthy controls. METHODS: Thirty-eight long-term (>6 months) users of amitriptyline (n = 13) and mirtazapine (n = 25) were compared to 65 healthy controls. Driving performance was assessed using a 1-h standardised highway driving test in actual traffic, with road-tracking error (standard deviation of lateral position [SDLP]) being the primary measure. Secondary measures included neurocognitive tasks related to driving. Performance differences between groups were compared to those of blood alcohol concentrations of 0.5 mg/ml to determine clinical relevance. RESULTS: Compared to controls, mean increase in SDLP of all antidepressant users was not significant, nor clinically relevant (+0.75 cm, 95% CI: -0.83 cm; +2.33 cm). However, users treated less than 3 years (n = 20) did show a significant and clinically relevant increase in SDLP (+2.05 cm). No significant effects were observed on neurocognitive tasks for any user group, although large individual differences were present. Most results from neurocognitive tests were inconclusive, while a few parameters confirmed non-inferiority for users treated longer than 3 years. CONCLUSION: The impairing effects of antidepressant treatment on driving performance and neurocognition mitigate over time following long-term use of 3 years.

Driving performance and neurocognitive skills of long-term users of benzodiazepine anxiolytics and hypnotics.

OBJECTIVE: The aim of this study is to compare actual driving performance and skills related to driving of patients using benzodiazepine anxiolytics or hypnotics for at least 6 months to that of healthy controls. METHODS: Participants were 44 long-term users of benzodiazepine and benzodiazepine-related anxiolytics (n = 12) and hypnotics (n = 32) and 65 matched healthy controls. Performance was assessed using an on-the-road driving test measuring standard deviation of lateral position (SDLP, in cm) and a battery of neurocognitive tasks. Performance differences between groups were compared with a blood alcohol concentration of 0.5 mg/ml to determine clinical relevance. RESULTS: Compared with controls, SDLP was significantly increased in hypnotic users (+1.70 cm) but not in anxiolytic users (+1.48 cm). Anxiolytic and hypnotic users showed significant and clinically relevant impairment on neurocognitive task measuring executive functioning, vigilance, and reaction time. For patients using hypnotics for at least 3 years, no significant driving impairment was observed. CONCLUSION: Impairing effects of benzodiazepine hypnotics on driving performance may mitigate over time following longer term use (i.e. 3 years or more) although neurocognitive impairments may remain.

Single- and dual-task performance during on-the-road driving at a low and moderate dose of alcohol: A comparison between young novice and more experienced drivers.

Driving experience and alcohol are two factors associated with a higher risk of crash involvement in young novice drivers. Driving a car is a complex task involving multiple tasks leading to dividing attention. The aim of this study was to compare the single and combined effects of a low and moderate dose of alcohol on single- and dual-task performance between young novice and more experienced young drivers during actual driving. Nine healthy novice drivers were compared with 9 more experienced drivers in a three-way, placebo-controlled, cross-over study design. Driving performance was measured in actual traffic, with standard deviation of lateral position as the primary outcome variable. Secondary task performance was measured with an auditory word learning test during driving. Results showed that standard deviation of lateral position increased dose-dependently at a blood alcohol concentration (BAC) of 0.2 and 0.5 g/L in both novice and experienced drivers. Secondary task performance was impaired in both groups at a BAC of 0.5 g/L. Furthermore, it was found that driving performance in novice drivers was already impaired at a BAC of 0.2 g/L during dual-task performance. The findings suggest that young inexperienced drivers are especially vulnerable to increased mental load while under the influence of alcohol.

Influence of Long-Term Benzodiazepine use on Neurocognitive Skills Related to Driving Performance in Patient Populations: A Review.

Acute benzodiazepine intoxication produces severe impairment of neurocognitive skills related to driving. It is less clear whether such impairments also occur in patients who use benzodiazepines chronically. The current review evaluated neurocognitive skills of long-term benzodiazepine users and addressed 2 major questions: do long-term users develop tolerance for the impairing effects of benzodiazepines on neurocognitive performance, and if so, does tolerance warrant a change in driver fitness classification systems that currently deem users of benzodiazepines unfit to drive? Neurocognitive impairments were reported in patients who on average used benzodiazepines for 5-15 years. In addition, sensitivity to acute benzodiazepine impairment decreased in long-term users, suggesting (partial) tolerance. Definitions of clinical relevance of neurocognitive impairments in long-term users and how these were affected by duration of benzodiazepine use were generally lacking. Also, sensitivity of neurocognitive tasks to drug effects and their validity to predict fitness to drive were generally unknown. Because of these limitations, no firm conclusion can be drawn regarding a re-classification of long-term benzodiazepine effects on driver fitness.

Driving Performance of Depressed Patients who are Untreated or Receive Long-Term Antidepressant (SSRI/SNRI) Treatment.

Introduction Depression is a mental disorder likely to affect everyday functions. The present study aimed to assess actual driving performance of depressed patients who were without specific antidepressant treatment or received long-term antidepressant treatment. Methods A standardized on-the-road driving test was used to assess standard deviation of lateral position (SDLP) in 3 patient groups receiving either no antidepressant treatment (with or without benzodiazepine medication) or treatment with selective serotonin/noradrenalin reuptake inhibitors for a period of 6-52 weeks. Severity of depression was assessed using Beck's Depression Inventory and the Hamilton Depression Rating Scale. The performance of patient groups was compared to healthy controls. Results The mean SDLP of untreated and treated patients was significantly higher than that of healthy controls. Driving impairment in the long-term treated group was significantly less than in the untreated groups. SDLP was positively correlated to severity of depression across all groups. Discussion It is concluded that symptoms of depression are a major cause of driving impairment. Reductions in severity of depression through antidepressant treatment reduce severity of driving impairment.

Measuring fatigue following acquired brain injury: A validation study of the Psychomotor Vigilance Test.

OBJECTIVE: To evaluate the construct validity of Psychomotor Vigilance Test performance for measuring fatigue in people with acquired brain injury. DESIGN: Observational cross-sectional study. PARTICIPANTS: Fifty-four people with acquired brain injury and 61 healthy controls. METHODS: Participants performed the Psychomotor Vigilance Test and reported momentary fatigue before and after this test and general fatigue. Associations between performance and fatigue in patients were tested by correlational and hierarchical multiple linear regression analyses, controlling for sleep quality, daytime sleepiness, and mood. RESULTS: Patients performed worse on the test compared with controls. Within the patient group, worse test performance was associated with increases in momentary post-test fatigue and general fatigue, indicating convergent validity, but also with daytime sleepiness, and mood complaints, indicating a lack of divergent validity. When controlling for sleepiness and mood, the association between performance and general fatigue was no longer significant, whereas the association between performance and post-test fatigue remained. CONCLUSION: Performance on the Psychomotor Vigilance Test cannot be used as a specific measure for fatigue, but it appears to be a more general measure of severity of symptoms including fatigue, mood, and sleepiness. Therefore, the Psychomotor Vigilance Test may be a useful measure to examine the effects of interventions aimed at reducing these symptoms.