Biomedical subjects

Leonid Kayumov

Publications and source records attributed to Leonid Kayumov.

15 recordsLinked to original sources

PubMed2006

Dim light melatonin onset (DLMO): a tool for the analysis of circadian phase in human sleep and chronobiological disorders.

The circadian rhythm of melatonin in saliva or plasma, or of the melatonin metabolite 6-sulphatoxymelatonin (aMT6S) in urine, is a defining feature of suprachiasmatic nucleus (SCN) function, the endogenous oscillatory pacemaker. A substantial number of studies have shown that, within this rhythmic profile, the onset of melatonin secretion under dim light conditions (the dim light melatonin onset or DLMO) is the single most accurate marker for assessing the circadian pacemaker. Additionally, melatonin onset has been used clinically to evaluate problems related to the onset or offset of sleep. DLMO is useful for determining whether an individual is entrained (synchronized) to a 24-h light/dark (LD) cycle or is in a free-running state. DLMO is also useful for assessing phase delays or advances of rhythms in entrained individuals. Additionally, it has become an important tool for psychiatric diagnosis, its use being recommended for phase typing in patients suffering from sleep and mood disorders. More recently, DLMO has also been used to assess the chronobiological features of seasonal affective disorder (SAD). DLMO marker is also useful for identifying optimal application times for therapies such as bright light or exogenous melatonin treatment.

Animals↗

PubMed2006

Psychomotor disturbance in depression: assessment using a driving simulator paradigm.

BACKGROUND: Psychomotor disturbance is an essential feature of Major Depressive Disorder (MDD) and has been associated with impaired functioning on cognitively demanding tasks. Given the psychomotor demands required to navigate a motor vehicle and the disastrous effects of motor vehicles accidents, patients with MDD present a population of clinical interest. The goal of this investigation was to examine the association between MDD and driving ability assessed within a simulated driving paradigm. METHODS: 18 outpatients currently meeting diagnostic criteria for MDD and 29 control participants completed four 30-min simulated driving trials at 10:00 am, 12:00 pm, 2:00 pm, and 4:00 pm. Participants also completed the Beck Depression Inventory (BDI) to assess for depression severity and the Epworth Sleepiness Scale (ESS) to assess for everyday sleepiness. RESULTS: After controlling for age and sleepiness, the depressed sample exhibited slower steering reaction times across trials (p<.05) and an increased number of crashes across trials (p<.05) when compared to controls. These differences were characterized by a medium effect size. No significant time-of-day effects were found. LIMITATIONS: MDD patients were free of anti-depressant medication and findings may not generalize to medicated populations. Also, a rural highway driving route was used which may not generalize well to urban driving settings. CONCLUSIONS: Patients with untreated MDD demonstrate impaired simulated driving performance. Further research into whether these findings translate into on-the-road impairment is important for public health and safety.

Accidents, Traffic↗

PubMed2006

Simulator performance, microsleep episodes, and subjective sleepiness: normative data using convergent methodologies to assess driver drowsiness.

OBJECTIVE: Our objective was to examine a novel standardized assessment methodology of detecting impaired driving performance due to drowsiness in a normative cohort. METHODS: Thirty-one healthy subjects with no significant sleep, medical, and psychiatric pathology were assessed in a driving simulation paradigm. Thirty-minute simulations were repeated at two-hourly intervals (i.e., at 1000, 1200, 1400, and 1600 h). Convergent data sources included drivers' subjective ratings of sleepiness and alertness, electroencephalogram-verified microsleep (MS) episodes, and a variety of real-time driving simulator performance measures such as speed, lane tracking, reaction time (RT), and off-road events (crashes). RESULTS: Significant diurnal fluctuations were noted on objective measures of RT, velocity, tracking, and MS events, indicating the highest risk of impairment in the afternoon. By contrast, subjective ratings of sleepiness and alertness did not demonstrate significant circadian variation. The mean incidence of MS episodes and crash risk correlated highly (r = .748). CONCLUSIONS: This prospective study demonstrates the relevance of multiple convergent measures for comprehensive assessment. The divergence of subjective and objective assays of impairment implies that healthy individuals may not have full insights into neurophysiologically mediated performance deficits. These results will serve as normative comparators to patients presenting with daytime somnolence and may allow a more accurate prediction of potential crash risk than noninteractive daytime polysomnogram tests such as the mean sleep latency test or the maintenance of wakefulness test.

Accidents, Traffic↗

PubMed2006

A new approach to the construct of alertness.

OBJECTIVE: There are no psychometric measures to evaluate the critical construct of alertness. We, therefore, developed two questionnaires to measure alertness, the Toronto Hospital Alertness Test (THAT) and the ZOGIM-A, and evaluated their psychometric properties. METHODS: We examined the correspondence between scores on the THAT and the ZOGIM-A in a sample of sleep clinic outpatients (n=96) with Maintenance of Wakefulness Test (MWT) results after an overnight sleep study, physiological sleep parameters, measures of subjective sleepiness, and two psychosocial variables (psychological well-being and emotional distress). Test-retest reliability was estimated based on responses from an independent sample of 295 sleep clinic outpatients who completed the instruments before and after an overnight sleep study. RESULTS: High values were observed for both the THAT (r(tt)=.79) and the ZOGIM-A (r(tt)=.70). Internal consistency reliability (coefficient alpha) was also high: .96 for THAT and .83 for ZOGIM-A. Although neither of the new scales correlated significantly with measures derived from the MWT or nocturnal physiological measures, the two alertness scales did correlate significantly and as hypothesized with subjective measures of sleepiness and other psychosocial measures. CONCLUSIONS: These results support the perspective that subjective alertness cannot be reduced to the absence of sleepiness and corroborate the psychometric adequacy of the THAT and the ZOGIM-A as unique indices of alertness that complement objective data obtained via MWT and physiological indices of sleep architecture.

Adolescent↗

PubMed2006

Melatonin in mood disorders.

The cyclic nature of depressive illness, the diurnal variations in its symptomatology and the existence of disturbed sleep-wake and core body temperature rhythms, all suggest that dysfunction of the circadian time keeping system may underlie the pathophysiology of depression. As a rhythm-regulating factor, the study of melatonin in various depressive illnesses has gained attention. Melatonin can be both a 'state marker' and a 'trait marker' of mood disorders. Measurement of melatonin either in saliva or plasma, or of its main metabolite 6-sulfatoxymelatonin in urine, have documented significant alterations in melatonin secretion in depressive patients during the acute phase of illness. Not only the levels but also the timing of melatonin secretion is altered in bipolar affective disorder and in patients with seasonal affective disorder (SAD). A phase delay of melatonin secretion takes place in SAD, as well as changes in the onset, duration and offset of melatonin secretion. Bright light treatment, that suppresses melatonin production, is effective in treating bipolar affective disorder and SAD, winter type. This review discusses the role of melatonin in the pathophysiology of bipolar disorder and SAD.

Antidepressive Agents↗

PubMed2006

Polysomnographic and symptomatological analyses of major depressive disorder patients treated with mirtazapine.

OBJECTIVE: This study aimed to characterize the effects of mirtazapine on polysomnographic sleep, especially slow wave sleep (SWS) and rapid eye movement (REM) sleep, as well as its effects on clinical symptoms in patients with major depressive disorder (MDD). METHOD: Sixteen MDD patients were treated with mirtazapine 30 mg taken 30 minutes before bedtime. Polysomnographic and subjective sleep, as well as other clinical data, were collected at baseline and on Days or Nights 2, 9, 16, 30, and 58 during treatment. We used repeated measures analysis of variance, including pairwise comparison, to analyze data statistically. RESULTS: Mirtazapine administration increased total SWS and the SWS in the first sleep cycle, but not SWS in the second sleep cycle. The medication increased REM latency and the duration of the first REM episode; it also decreased the number of REM episodes. Simultaneously, mirtazapine significantly reduced wake-after-sleep onset and scores on the Athens Insomnia Scale. After patients took the medication, scores on the Hamilton Depression Rating Scale-17 (HDRS-17) decreased rapidly and continuously. The changes on the Beck Depression Inventory-II were consistent with those on the HDRS-17. The medication has a tendency to increase weight. CONCLUSIONS: Mirtazapine significantly improved sleep quality, reversed sleep markers of depression, and reduced depressive symptoms in this group of MDD patients.

Adult↗

PubMed2005

Blocking low-wavelength light prevents nocturnal melatonin suppression with no adverse effect on performance during simulated shift work.

Decreases in melatonin production in human and animals are known to be caused by environmental lighting, especially short-wavelength lighting (between 470 and 525 nm). We investigated the novel hypothesis that the use of goggles with selective exclusion of all wavelengths less than 530 nm could prevent the suppression of melatonin in bright-light conditions during a simulated shift-work experiment. Salivary melatonin levels were measured under dim (<5 lux), bright (800 lux), and filtered (800 lux) light at hourly intervals between 2000 and 0800 h in 11 healthy young males and eight females (mean age, 24.7 +/- 4.6 yr). The measurements were performed during three nonconsecutive nights over a 2-wk period. Subjective sleepiness was measured by self-report scales, whereas objective performance was assessed with the Continuous Performance Test. All subjects demonstrated preserved melatonin levels in filtered light similar to their dim-light secretion profile. Unfiltered bright light drastically suppressed melatonin production. Normalization of endogenous melatonin production while wearing goggles did not impair measures of performance, subjective sleepiness, or alertness.

Adult↗

PubMed2005

What is the driving performance of ambulatory surgical patients after general anesthesia?

BACKGROUND: Ambulatory surgical patients are advised to refrain from driving for 24 h postoperatively. However, currently there is no strong evidence to show that driving skills and alertness have resumed in patients by 24 h after general anesthesia. The purpose of this study was to determine whether impaired driver alertness had been restored to normal by 2 and 24 h after general anesthesia in patients who underwent ambulatory surgery. METHODS: Twenty patients who underwent left knee arthroscopic surgery were studied. Their driving simulation performance, electroencephalographically verified parameters of sleepiness, subjective assessment of sleepiness, fatigue, alertness, and pain were measured preoperatively and 2 and 24 h postoperatively. The same measurements were performed in a matched control group of 20 healthy individuals. RESULTS: Preoperatively, patients had significantly higher attention lapses and lower alertness levels versus normal controls. Significantly impaired driving skills and alertness, including longer reaction time, higher occurrence of attention lapses, and microsleep intrusions, were found 2 h postoperatively versus preoperatively. No significantly differences were found in any driving performance parameters or electroencephalographically verified parameters 24 h postoperatively versus preoperatively. CONCLUSIONS: Patients showed lower alertness levels and impaired driving skills preoperatively and 2 h postoperatively. Based on driving simulation performance and subjective assessments, patients are safe to drive 24 h after general anesthesia.

Adjuvants, Anesthesia↗

PubMed2005

Subjective fatigue and subjective sleepiness: two independent consequences of sleep disorders?

The objective of this investigation was to evaluate subjective fatigue versus subjective sleepiness as independent consequences of sleep disorders. Furthermore, we tried to explore how these symptoms relate to alertness, depressive symptoms and illness intrusiveness. In a prospective observational study, 283 sleep-disordered patients referred to a hospital-based sleep laboratory for various indications over a 1-year period were evaluated vis-à-vis fatigue and sleepiness. All patients completed five subjective questionnaires, underwent objective sleep recording and attended a clinical interview with a sleep specialist. The subjective questionnaires included the Epworth Sleepiness Scale, the Fatigue Severity Scale, the Toronto Hospital Alertness Test, the Illness Intrusiveness Rating Scale and the Center for Epidemiologic Studies-Depression Scale. Only 4% of the total sample was referred to the sleep clinic due to a complaint of excessive fatigue compared with 17% for excessive daytime sleepiness. However, during the assessment, 64% of referred patients reported pathological fatigue without overlap of sleepiness and only 4% reported pathological sleepiness without overlap of fatigue. Pearson's correlation analysis indicated a weak association (r=0.18) between subjective fatigue and sleepiness in the total sample. Analysis of variance testing showed strong association between those patients with prominent fatigue and depressive symptoms (P<0.01) and illness intrusiveness (P<0.001). The findings support the notion that subjective fatigue and sleepiness can be independent manifestations of sleep disorders. Furthermore, predominantly fatigued individuals with sleep disorders seem vulnerable to additional negative consequences due to possible interplay between amplified fatigue and psychological distress.

Adolescent↗

PubMed2005

The effects of nefazodone on women with seasonal affective disorder: clinical and polysomnographic analyses.

OBJECTIVE: To outline the clinical and polysomnographic changes induced by nefazodone in patients with seasonal affective disorder. METHODS: Twelve patients were enrolled, and 9 of them studied, in an open-label trial with objective and subjective measurements. The mean age of the studied patients was 45 (range 35-58) years. They met Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), criteria for major depressive disorder and current major depressive episode with seasonal patterns. The patients' mean baseline score on the Seasonal Patterns Assessment Questionnaire (SPAQ) was 15.7 (standard deviation [SD] 5.3). The total nefazodone treatment period was 8 weeks, and the daily dosages were 100 mg in week 1, 200 mg in week 2, 300 mg in week 3, and up to 400 mg in weeks 4-8. Each patient received the 29-item version of the Hamilton Rating Scale for Depression (HAM-D), the Hamilton Rating Scale for Anxiety (HAM-A) and 2-night polysomnographic assessments on 3 occasions: before treatment (baseline, W0), at the end of week 4 (W4) and at the end of week 8 (W8). RESULTS: There were statistically significant improvements in depression, anxiety, sleep latency and sleep efficiency during the 8-week treatment protocol. Repeated-measures analysis of variance results indicated that nefazodone has a time-dependent effect on both HAM-D and HAM-A scores. After 8 weeks of nefazodone therapy, HAM-D scores decreased from 33.4 (SD 8.1) to 11.6 (SD 5.6) (F(2,14) = 13.68, p = 0.001) and HAM-A decreased from 26.6 (SD 7.0) to 11.5 (SD 11.1) (F(2,14) = 13.46, p = 0.001). The results of paired t tests show that, compared with baseline, HAM-D and HAM-A scores decreased at both W4 (p = 0.004 and p = 0.002, respectively) and W8 (p = 0.002 and p = 0.005, respectively). The time-dependent effects on stage 1 sleep (F(2,16) = 6.06, p = 0.011) and periodic leg movement index (F(2,16) = 4.31, p = 0.035) were also significant. The mean sleep latency of these patients decreased from 39.9 (SD 32.7) minutes at W0 to 16.6 (SD 15.3) minutes at W8 (p < 0.05). Sleep efficiency increased from 78.8% (SD 14.6%) at W0 to 91.5% (SD 5.5%) at W8 (p < 0.05). Stage 1 sleep decreased from 4.9% (SD 1.9%) at W0 to 3.4% (SD 2.6%) at W8 (p < 0.05). CONCLUSIONS: The results of this preliminary study indicate that nefazodone not only has favourable antidepressant and anxiolytic effects but also enhances sleep efficiency and sleep latency.

Adult↗

PubMed2004

Psychiatric aspects of late-life insomnia.

Epidemiological trends towards a 'graying' population make the issue of insomnia in the elderly an increasingly important research and clinical topic. It is often challenging to determine how much of a psychiatric dimension there is to a clinical condition that is best viewed as both as a symptom and a true psychosomatic entity in its own right. To categorize insomnia as either psychiatric or medically based risks oversimplification of the complexities of sleep disruption in the elderly. Normal senescence-related changes in sleep architecture and circadian rhythms must be considered, as well as the frequent medical comorbidities that may affect sleep. Psychiatric diagnoses to consider include mood and anxiety disorders, which may be affected equally by physiological and psychological changes implicit in old age. Sleep disruption related to dementia is of particular interest to clinicians involved with patients in long-term care facilities. Insomnia may occasionally be iatrogenically induced or exacerbated, and particularly antidepressants must be carefully selected for this reason. Light therapy and behavior therapies are important in multimodal treatment of insomnia, and sleep hygiene includes both regular physical and social activities to preserve entrainment of circadian rhythms affecting sleep.

Aged↗

PubMed2004

Subjective and objective evaluation of sleep and performance in daytime versus nighttime sleep in extended-hours shift-workers at an underground mine.

Extended hours of shift work has the potential for adverse consequences for workers, particularly during the nightshift, such as poorer sleep quality during the day, increased worker fatigue, and fatigue-related accidents and decreased work performance. This study examined subjective and objective measurements of sleep and performance in a group of underground miners before and after the change from a backward-rotating 8-hour to a forward-rotating 10-hour shift schedule. The purpose of this study was to evaluate the short- and long-term impact of a shift schedule change on sleep and performance. The results demonstrated improved subjective and objective measures of sleep and performance on the new 10-hour nightshift schedule. The 10-hour nightshift workers subjectively reported more refreshing sleep, fewer performance impairments and driving difficulties than 8-hour nightshift workers. The results of the objective measures of sleep and performance on the 10-hour nightshifts were overall similar or possibly better than those measured on the 10-hour dayshifts. These are some of the first data to suggest that a nightshift that does not encompass the entire night period could have significant benefits to shift-workers. We suggest that these benefits are mostly the result of the timing of the new nightshift start and end times rather than other shift-schedule factors.

Accidents, Occupational↗

PubMed2004

Acupuncture increases nocturnal melatonin secretion and reduces insomnia and anxiety: a preliminary report.

The response to acupuncture of 18 anxious adult subjects who complained of insomnia was assessed in an open prepost clinical trial study. Five weeks of acupuncture treatment was associated with a significant (p = 0.002) nocturnal increase in endogenous melatonin secretion (as measured in urine) and significant improvements in polysomnographic measures of sleep onset latency (p = 0.003), arousal index (p = 0.001), total sleep time (p = 0.001), and sleep efficiency (p = 0.002). Significant reductions in state (p = 0.049) and trait (p = 0.004) anxiety scores were also found. These objective findings are consistent with clinical reports of acupuncture's relaxant effects. Acupuncture treatment may be of value for some categories of anxious patients with insomnia.

Acupuncture↗

PubMed2002

REM sleep latency and wakefulness in the first sleep cycle as markers of major depression: a controlled study vs. schizophrenia and normal controls.

INTRODUCTION: REM sleep latency is a clinically significant sleep variable that is found to be decreased in several psychiatric disorders. However, it is not known whether alteration of REM sleep latency is similar across disorders. In order to test whether incorporation of wakefulness in the first sleep cycle has a different outcome on REM sleep latency in different clinical groups, the authors have investigated correlation between sleep variables in the first sleep cycle in 25 patients with major depression, 24 patients with chronic schizophrenia, and in 10 healthy subjects. RESULTS: REM sleep latency correlates with the duration of wakefulness in the first cycle in patients suffering from chronic schizophrenia and in healthy subjects. This correlation does not hold true in patients suffering from major depression. CONCLUSION: Wakefulness incorporated in the first cycle influences REM sleep latency in healthy subjects and in patients suffering from chronic schizophrenia but not in patients suffering from major depression. This finding further supports the evidence that reduced REM sleep latency is a nonflexible marker of depression.

Adult↗

PubMed2000

Self-report of memory and affective dysfunction in association with medication use in a sample of individuals with chronic sleep disturbance.

Benzodiazepines produce memory disturbance after acute administration. It is not clear whether chronic use of benzodiazepines is hazardous to memory processes. Epidemiological data indicate that a large proportion (10-30 per cent) of individuals with sleep dysfunction take hypnotic aids for a year or longer. The purpose of the present study was to evaluate self-reported memory dysfunction in a sample of individuals who considered their sleep disturbance sufficiently severe to seek investigation in sleep clinics. It was hypothesized that individuals taking benzodiazepines for sleep would report greater perceived everyday memory failures than individuals taking other sleep aids or no medication. Questionnaires were given to 368 individuals referred into the study by investigators in six sleep disorders clinics. All respondents completed a lengthy (700-item) questionnaire, which included scales assessing memory difficulties, affective status and sleep disturbance. Respondents also reported any medication use for sleep problems and duration of use of the current drug. Information on medication use was reported by 289 participants. Fifty-six per cent of respondents reported using some form of psychoactive medication (antidepressants, benzodiazepines, Zopiclone). Twenty-two per cent reported using no medication. Analysis of covariance showed that these medications had no detectable effect on subjective memory difficulties during chronic use, F(4,226)=1.34, p=0.25. Copyright 2000 John Wiley & Sons, Ltd.

Journal Article↗