Gerard A. Kennedy

Cognitive components of simulated driving performance: Sleep loss effects and predictors

Driving is a complex task, which can be broken down into specific cognitive processes. In order to determine which components contribute to drowsy driving impairments, the current study examined simulated driving and neurocognitive performance after one night of sleep deprivation. Nineteen professional drivers (age 45.3±9.1) underwent two experimental sessions in randomised order: one after normal sleep and one after 27h total sleep deprivation. A simulated driving task (AusEd), the psychomotor vigilance test (PVT), and neurocognitive tasks selected from the Cognitive Drug Research computerised neurocognitive assessment battery (simple and choice RT, Stroop Task, Digit Symbol Substitution Task, and Digit Vigilance Task) were administered at 10:00h in both sessions. Mixed-effects ANOVAs were performed to examine the effect of sleep deprivation versus normal sleep on performance measures. To determine if any neurocognitive tests predicted driving performance (lane position variability, speed variability, braking RT), neurocognitive measures that were significantly affected by sleep deprivation were then added as a covariate to the ANOVAs for driving performance. Simulated driving performance and neurocognitive measures of vigilance and reaction time were impaired after sleep deprivation (p<0.05), whereas tasks examining processing speed and executive functioning were not significantly affected by sleep loss. PVT performance significantly predicted specific aspects of simulated driving performance. Thus, psychomotor vigilance impairment may be a key cognitive component of driving impairment when sleep deprived. The generalisability of this finding to real-world driving remains to be investigated.

Self-Reported Sources of Stress in Senior High School Students

The main sources of stress reported by 423 Australian final-year high school students using the Academic Stress Questionnaire were school-related as expected. The highest sources of this stress were examinations and outcomes, too much to do, worry over future, making choices about career, studying for examinations, amount to learn, need to do well imposed by others, and self-imposed need to do well.

The Implementation of Acute versus Chronic Animal Models for Treatment Discovery in Parkinson's Disease

Animal models for neuropsychiatric disorders are implemented for the purpose of investigating a single or multiple aspects of a specific disease entity. In Parkinsons disease (PD) several models have been utilised to study the biochemical and behavioural consequences of dopamine (DA) neurone degeneration with the intent of further understanding the aetiology of this disease and improving its treatment. While the bilateral 6-hydroxydopamine (6-OHDA) model has been used to produce a broad spectrum of neurochemical and behavioural deficits characterising DA degeneration in humans, this model is traumatic, labour intensive and is associated with high mortality due to the acute effects of the neurotoxin. Consequently, the unilateral 6-OHDA model was developed and implemented. In this model damage to the ascending DA system is produced on one side of the brain thereby inducing postural rotation. This movement is exaggerated by activating the remaining DA systems with apomorphine or amphetamine thereby making it more quantifiable. In view of the less traumatic effects on homeostasis and relative ease with which this model can be implemented it has been used routinely for the purpose of screening potential anti-Parkinsonian drugs for clinical use. However, like any model, the use of the unilateral rotation model has its limitations. It is proposed that the process of exaggerating DA function using this paradigm limits the discovery of potential anti-PD drugs to those which are effective in counteracting an exaggerated DA response. This factor may account for the high incidence of unwanted side effects including involuntary movement, tardive dyskinaesia (TD) and psychosis which are commonly observed in DA replacement therapy. Secondly, this approach limits potential drug candidates to those acting exclusively on brain DA systems. This too is a problem in the sense that PD is known to be a disease involving numerous systems in the human brain and potential therapies acting via other neurochemical systems are being excluded when this model is used exclusively. The object of the present paper is to report the discovery of a non-DA drug possessing potent anti-Parkinsonian qualities which were revealed using the bilateral 6-OHDA model of PD as a screening tool. When the same drug was retested in the traditional unilateral screening model no effect was observed, while more advanced models confirmed its efficacy. These results illustrate that the implementation of appropriate models for revealing new treatment strategies for PD should be broadly based so that single treatment entities are not exclusively pursued for diseases whose aetiologies are multifaceted. Premature extrapolation of findings from a single, early stage model to its clinical counterpart can be detrimental to advancing new treatment strategies, induce false hope, and increase morbidity in PD patients.

The relationships between insomnia, sleep apnoea and depression: Findings from the American National Health and Nutrition Examination Survey, 2005–2008:

Objective: To determine the association between insomnia, obstructive sleep apnoea (OSA), and comorbid insomnia-OSA and depression, while controlling for relevant lifestyle and health factors, among a large population-based sample of US adults. Method: We examined a sample of 11,329 adults (≥18 years) who participated in the National Health and Nutrition Examination Survey (NHANES) during the years 2005–2008. Insomnia was classified via a combination of self-reported positive physician diagnosis and high-frequency ‘trouble falling asleep’, ‘waking during the night’, ‘waking too early’, and ‘feeling unrested during the day’. OSA was classified as a combination of a positive response to a physician-diagnosed condition, in addition to a high frequency of self-reported nocturnal ‘snoring’, ‘snorting/stopping breathing’ and ‘feeling overly sleepy during the day’. Comorbid insomnia-OSA was further assessed by combining a positive response to either insomnia (all), or sleep apnoea (all), as classified above. Depressive symptomology was assessed by the Patient Health Questionnaire-9 (PHQ-9), with scores of >9 used to indicate depression. Odds ratios (ORs) and 95% confidence intervals (CIs) for sleep disorders and depression were attained from logistic regression modelling adjusted for sex, age, poverty level, smoking status and body mass index (BMI). Results: Those who reported insomnia, OSA or comorbid insomnia-OSA symptoms reported higher rates of depression (33.6%, 22.2%, 27.1%, respectively), and consistently reported poorer physical health outcomes than those who did not report sleep disorders. After adjusting for sex, age, poverty level, smoking status and BMI (kg/m2), insomnia (OR 6.57, 95% CI 3.89-11.11), OSA (OR 5.14, 95% CI 3.14–8.41) and comorbid insomnia-OSA (OR 6.67, 95% CI 4.44–10.00) were associated with an increased likelihood of reporting depression. Conclusions: Insomnia, OSA and comorbid insomnia-OSA are associated with significant depressive symptomology among this large population-based sample of adults.

The relationship between excessive daytime sleepiness and depressive and anxiety disorders in women

Objective: Excessive daytime sleepiness (EDS) is a common clinical symptom that affects women more than men. However, the association of excessive sleepiness with depressive and anxiety disorders in the broader population is unclear. The aim of this study was, therefore, to examine the association between excessive daytime sleepiness as measured by the Epworth Sleepiness Scale, and depressive and anxiety disorders in a population-based sample of women. Methods: Using the Structured Clinical Interview for DSM-IV Disorders (Non-Patient) (SCID-I/NP), 944 women aged 20–97 years (median 49 years, IQR 33–65 years) were assessed for depressive and anxiety disorders as part of the Geelong Osteoporosis Study. EDS was assessed using the Epworth Sleepiness Scale (ESS, cut-off > 10). Lifestyle factors were documented by self-report, height and weight were measured, and socioeconomic status categorised according to the Index of Relative Socio-Economic Advantage and Disadvantage. Results: Overall, 125 (13.2%) of the women were identified with EDS. EDS was associated with an increased likelihood for both current (OR = 2.11, 95% CI 1.10–4.06) and lifetime history (OR = 1.95, 95% CI 1.28–2.97) of depressive disorders, but not anxiety disorders, independent of age and alcohol consumption. These findings were not explained by antidepressant or sedative use, body mass index, physical activity, smoking, or socioeconomic status. Conclusions: These results suggest that excessive daytime sleepiness is associated with current and lifetime depressive, but not anxiety disorders. Clinically, this highlights the need to take into account the possible bidirectional relationship between depressive disorders and excessive sleepiness when assessing mental health issues in patients with EDS.

Mental disorders in asylum seekers: the role of the refugee determination process and employment.

Abstract The refugee determination process (RDP) and social factors putatively impact on the psychiatric morbidity of adult asylum seekers (ASs) living in the community. Clinical and sociodemographic data relevant to AS experience in the RDP were collected using self-report measures to assess posttraumatic stress (Harvard Trauma Questionnaire–Revised) and depressive and anxiety symptoms (25-item Hopkins Symptom Checklist), and the Mini-International Neuropsychiatric Interview 6.0 psychiatric interview was used to establish a cutoff for caseness. The prevalence of major depressive disorder (MDD) and posttraumatic stress disorder (PTSD) was 61% and 52%, respectively. Unemployment and greater numbers of both potentially traumatic events and RDP rejections were predictors of symptom severity. Unemployed ASs were more than twice as likely to have MDD (odds ratio, 2.61; 95% confidence interval [CI], 1.11– 6.13; p = 0.03), and ASs with at least one RDP rejection were 1.35 times more likely to develop PTSD for each additional rejection (95% CI, 1.00–1.84; p = 0.05). Reducing the asylum claim rejection rate and granting work rights are likely to reduce the rate of PTSD and MDD in community-based ASs.

Prevalence of excessive daytime sleepiness in a sample of the Australian adult population

OBJECTIVES Excessive daytime sleepiness (EDS) is associated with significant personal and medical burden. However, there is little indication of the impact of these symptoms in the broader population. PARTICIPANTS AND METHODS We studied 946 men ages 24-92 years (median age, 59.4 [interquartile range {IQR}, 45-73 years]) and 1104 women ages 20-94 years (median age, 50 [IQR, 34-65 years]) who resided in the Barwon Statistical Division, South-Eastern Australia, and participated in the Geelong Osteoporosis Study (GOS) between the years of 2001 and 2008. EDS was defined as an Epworth Sleepiness Scale (ESS) score of ⩾ 10. Lifestyle factors, history of medical conditions, and medication history were documented by self-report. RESULTS For men, the age-specific prevalence of EDS was 5.1% (ages 20-29 years), 6.4% (ages 30-39 years), 9.8% (ages 40-49 years), 15.5% (ages 50-59 years), 12.0% (ages 60-69 years), 12.0% (ages 70-79 years), and 29.0% (ages ⩾ 80 years). For women, the age-specific prevalence of EDS was 14.7% (ages 20-29 years), 8.7% (ages 30-39 years), 15.0% (ages 40-49 years), 16.0% (ages 50-59 years), 12.6% (ages 60-69 years), 13.2% (ages 70-79 years), and 17.0% (ages ⩾ 80 years). Overall standardized prevalence of EDS was 10.4% (95% confidence interval, 9.7-11.2) for men and 13.6% (95% confidence interval, 12.8-14.4) for women. CONCLUSIONS The prevalence of EDS increased with age, affecting approximately one-third of those aged ⩾ 80 years. Because EDS has been associated with poorer health outcomes in the older age strata, these findings suggest that routine screening may be beneficial in ongoing health assessments for these individuals. Overall, more than one-tenth of the Australian adult population has EDS, which is indicative of possible underlying sleep pathology.

The utility of automated measures of ocular metrics for detecting driver drowsiness during extended wakefulness.

Slowed eyelid closure coupled with increased duration and frequency of closure is associated with drowsiness. This study assessed the utility of two devices for automated measurement of slow eyelid closure in a standard poor performance condition (alcohol) and following 12-h sleep deprivation. Twenty-two healthy participants (mean age=20.8 (SD 1.9) years) with no history of sleep disorders participated in the study. Participants underwent one baseline and one counterbalanced session each over two weeks; one 24-hour period of sleep deprivation, and one daytime session during which alcohol was consumed after a normal night of sleep. Participants completed a test battery consisting of a 30-min simulated driving task, a 10-min Psychomotor Vigilance Task (PVT) and the Karolinska Sleepiness Scale (KSS) each in two baseline sessions, and in two randomised, counterbalanced experimental sessions; following sleep deprivation and following alcohol consumption. Eyelid closure was measured during both tasks using two automated devices (Copilot and Optalert™). There was an increase in the proportion of time with eyelids closed and the Johns Drowsiness Score (incorporating relative velocity of eyelid movements) following sleep deprivation using Optalert (p<0.05 for both). These measures correlated significantly with crashes, PVT lapses and subjective sleepiness (r-values 0.46-0.69, p<0.05). No difference between the two sessions for PERCLOS recorded during the PVT or the driving task as measured by the Copilot. The duration of eyelid closure predicted frequent lapses following sleep deprivation (which were equivalent to the average lapses at a blood alcohol concentration of 0.05% - area under curve for ROC curve 0.87, p<0.01). The duration of time with slow eyelid closure, assessed by the automated devices, increased following sleep deprivation and was associated with deterioration in psychomotor performance and subjective sleepiness. Comprehensive algorithms inclusive of ocular parameters may be a better indicator of performance impairment following sleep loss.

Excessive daytime sleepiness and falls among older men and women: cross-sectional examination of a population-based sample

BackgroundExcessive daytime sleepiness (EDS) has been associated with an increased risk for falls among clinical samples of older adults. However, there is little detailed information among population-representative samples. The current study aimed to assess the relationship between EDS and falls among a cohort of population-based older adults.MethodsThis study assessed 367 women aged 60-93years (median 72, interquartile range 65-79) and 451 men aged 60-92years (median 73, interquartile range 66-80) who participated in the Geelong Osteoporosis Study between the years 2001 and 2008. Falls during the prior year were documented via self-report, and for men, falls risk score was obtained using an Elderly Fall Screening Test (EFST). Sleepiness was assessed using the Epworth Sleepiness Scale (ESS), and scores of ≥ 10 indicated EDS. Differences among those with and without EDS in regard to falls were tested using logistic regression models.ResultsAmong women, 50 (13.6 %) individuals reported EDS. Women with EDS were more likely to report a fall, and were more likely to report the fall occurring outside. EDS was similarly associated with an increased risk of a fall following adjustment for use of a walking aid, cases of nocturia and antidepressant medication use (adjusted OR = 2.54, 95 % CI 1.24-5.21). Multivariate modelling revealed antidepressant use (current) as an effect modifier (p < .001 for the interaction term). After stratifying the data by antidepressant medication use, the association between EDS and falls was sustained following adjustment for nocturia among antidepressant non-users (adjusted OR = 2.63, 95 % CI 1.31-5.30). Among men, 72 (16.0 %) individuals reported EDS. No differences were detected for men with and without EDS in regard to reported falls, and a trend towards significance was noted between EDS and a high falls risk as assessed by the EFST (p = 0.06), however, age explained this relationship (age adjusted OR = 2.20, 95 % CI 1.03-1.10).ConclusionsFor women, EDS is independently associated with at least one fall during the previous year, and this is more likely to occur whilst located outside. Amelioration of EDS may assist in improving functional outcomes among these individuals by reducing the risk for falls.

Compromised circadian function in Parkinson's disease: Enucleation augments disease severity in the unilateral model

Like enucleation, lateral hypothalamic (LH) lesions sever the connection between the retina and the pineal thereby simulating ambient exposure to constant darkness. While LH lesions have been employed to study either circadian function or Parkinsons disease (PD) independently, the application of such lesions to study circadian involvement specifically in this disease has never been attempted. In the present study, unilateral lesions of the LH, which compromise nigro-striatal dopamine (NSD) function, were combined with enucleation ipsilateral or contralateral to the hemisphere where 6-hydroxydopamine was applied. In addition to the observation that hemi-enucleation produced patterns of motor function that were grossly atypical compared to visually intact rats, hemi-enucleation ipsilateral to the side of NSD system denervation produced impairment of horizontal movement, limb retraction, ambulation and spontaneous or l-dopa induced turning. This impairment was more severe than that seen in rats with unilateral 6-OHDA lesions alone. Furthermore, hemi-enucleation contralateral to the side of unilateral NSD system denervation resulted in significantly improved performance on several parameters. While the rate of mortality in rats receiving unilateral 6-OHDA plus ipsilateral enucleation was similar to that occurring after bilateral lesions, it was not accompanied by severe weight loss and wasting that typically occurs in the acute stages of experimental PD. These results demonstrate the importance of the visual and circadian systems in PD and are consistent with reports that identify impaired circadian involvement as a major component in a wide range of neurological and neuropsychiatric conditions.