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Hirokuni Tagaya

Publications and source records attributed to Hirokuni Tagaya.

18 recordsLinked to original sources
PubMed2007

The Japanese Centenarian Study: autonomy was associated with health practices as well as physical status.

OBJECTIVES: To investigate the prevalence of centenarians who have preserved activities of daily living (ADLs) and good cognitive and psychosocial status in Japan. DESIGN: Census-based survey. SETTING: Cross-Sectional Investigation of Half of All Japanese Centenarians Study, 2000. PARTICIPANTS: A nationwide census-based study was conducted of all of the male centenarians and a random sample of half of all the female centenarians who were included in the National Census of Japan. After excluding those who had died and whose addresses could not be identified, 1,907 centenarians (53.0%) participated in the present visitation interview survey. MEASUREMENTS: ADLs, cognitive status, and psychosocial status. Centenarians who have preserved ADLs and good cognitive and psychosocial status were defined as autonomous centenarians. RESULTS: Of the study subjects, 10.4% were judged to be autonomous centenarians. Multiple logistic regression analyses revealed that autonomy in centenarians was associated with better visual acuity, getting regular exercise, spontaneous awakening regularly in the morning, preserved masticatory ability, having no history of drinking, having no history of severe falls after the age of 95, more frequent intake of protein, living at home, and being male. It was also demonstrated that autonomous centenarians were not associated with appetite, vegetable or seaweed intake, smoking habits, auditory capacity, body mass index, or present illness. CONCLUSION: These findings suggest that health practices play an important role in preserving ADLs and good cognitive and psychosocial status after reaching the age of 100 and should be useful for establishing an educational program for the ever-increasing "super elderly" population in Japan.

Activities of Daily Living↗
PubMed2006

Disappearance of memory fragments in patients with Alzheimer's disease: evidence from a longitudinal study of visual priming.

Previous studies suggested that perceptual memory as indexed by visual priming is normal in patients with Alzheimer's disease (AD). However, these studies did not specifically test the long-term effects of visual priming, which may differ significantly between Alzheimer's patients and normal subjects. To test this possibility, we examined long-term visual priming in AD patients, 1 hour, 1 month, and 3 months after training. Our results indicated a significant difference in visual priming between AD patients and normal subjects after 3 months, but not 1 month. For AD patients, there was a strong positive correlation between the 3-month priming effect and the Mini-Mental State Examination (MMSE) scores-severely demented patients were less likely to exhibit priming after 3 months. It appears that severe cortical degeneration may render AD patients unable to consolidate their perceptual memories. Our results suggest that lack of visual priming in AD patients is linked to the inability to maintain fragmented perceptual memories.

Aged↗
PubMed2005

Clinical analyses of sighted patients with non-24-hour sleep-wake syndrome: a study of 57 consecutively diagnosed cases.

STUDY OBJECTIVES: The objective of this study was to clarify the clinical features of sighted patients with non-24-hour sleep-wake syndrome. DESIGN: Clinical analyses of consecutive patients suffering from non-24-hour sleep-wake syndrome. SETTING: The sleep disorders clinic at Kohnodai Hospital, National Center of Neurology and Psychiatry, Japan. PATIENTS: Fifty-seven patients who were diagnosed consecutively as having non-24-hour sleep-wake syndrome between 1991 and 2001 were included in the study. MEASUREMENTS AND RESULTS: The clinical features and sleep characteristics of the patients were analyzed. A semistructured psychiatric interview that included the criteria for Axis I or II disorders of Diagnostic and Statistical Manual of Mental Disorders, Third Edition-Revised was conducted, and relationships between psychiatric problems and non-24-hour sleep-wake syndrome were analyzed. The patient cohort included 41 (72%) men and 16 (28%) women. The onset of non-24-hour sleep-wake syndrome had occurred during the teenage years in 63% of the cohort, and the mean ( +/-SD) period of the sleep-wake cycle was 24.9 +/- 0.4 hours (range 24.4-26.5 hours). The mean sleep length of the patients was 9.3 +/- 1.3 hours, and 44% of them had a sleep length of between 9 and 10 hours. Psychiatric disorders had preceded the onset of non-24-hour sleep-wake syndrome in 16 patients (28%); of the remaining 41 patients, 14 (34%) developed major depression after the onset of non-24-hour sleep-wake syndrome. CONCLUSIONS: These results represent the first detailed clinical review of a relatively large number of sighted patients with non-24-hour sleep-wake syndrome.

Adult↗
PubMed2005

Diurnal fluctuation of time perception under 30-h sustained wakefulness.

Previous studies have reported that time perception in humans fluctuates over a 24-h period. Behavioral changes seem to affect human time perception, so that the fluctuation in human time perception may be the result of such changes due to self-determined activities. Recently, we carried out a study in which a healthy human cohort was asked to perform simultaneously loaded cognitive tasks under controlled conditions, and found that time perception decreased linearly from morning to evening. In addition, the variations in time perception were not a consequence of behavioral changes. It remains to be elucidated whether diurnal variations in time perception are a consequence of circadian rhythm or of some homeostatic changes that are attributable to accumulated wake time. The effects of circadian rhythm on time perception were investigated in eight healthy young male volunteers by conducting 10-s time production tasks under 30-h constant-routine conditions. Core body temperature and serum melatonin and cortisol levels were measured during the course of the study. Produced time exhibited a diurnal variation and was strongly correlated with circadian variations in core body temperature and serum melatonin levels. These results suggest that human short-term time perception is under the influence of the circadian pacemaker.

Adult↗
PubMed2004

Dreaming during non-rapid eye movement sleep in the absence of prior rapid eye movement sleep.

STUDY OBJECTIVES: There is a long-standing controversy surrounding the existence of dream experiences during non-rapid eye movement (NREM) sleep. Previous studies have not answered the question whether this "NREM dream" originates from the NREM sleep mechanism because the subject might simply be recalling experiences from the preceding rapid eye movement (REM) sleep. METHODS: We scheduled 11 healthy men to repeat 20-minute nap trials separated by 40-minute periods of enforced wakefulness across a period of 3 days. At the end of the nap trial, each participant answered questions regarding the formal aspects of his dream experiences during the nap trial, using the structured interviews. RESULTS: We obtained a total of 172 dream reports after naps containing REM sleep (REM naps) and 563 after naps consisting of only NREM sleep (NREM naps). Dream reports from NREM naps were less remarkable in quantity, vividness, and emotion than those from REM naps and were obtained more frequently during the morning hours when the occurrences of REM sleep were highest. CONCLUSIONS: These results suggest that the polysomnographic manifestations of REM sleep are not required for dream experiences but that the mechanisms driving REM sleep alter experiences during NREM sleep in the morning. A subcortical activation similar to REM sleep may occur in human NREM sleep during the morning when REM sleep is most likely to occur, resulting in dream experiences during NREM sleep.

Adult↗
PubMed2004

Time estimation during nocturnal sleep in human subjects.

It has been postulated that time estimation during nocturnal sleep in humans can be explained by an interval timing clock inside the brain. However, no systematic investigations have been carried out with respect to how the human brain perceives the passage of time during sleep. The brain mechanisms of over- or underestimation of time spent in sleep have not yet been clarified. Here, we carried out an experimental study in which 11 healthy volunteers participated in time estimation trials scheduled six times during 9 h nocturnal sleep periods, under carefully controlled conditions. The time estimation ratio (TER: a ratio of subjective passage of time to actual time interval) decreased significantly from the first to the sixth trial. Individual TER was positively correlated with slow wave sleep prior to the trial, while it was negatively correlated with REM sleep. Our results indicate that the human brain has an ability to estimate the passage of time during nocturnal sleep without referring to time cues, and that the accuracy of this function fluctuates from overestimation in the early hours of sleep to underestimation in the last hours of sleep.

Adolescent↗
PubMed2004

Deficits in long-term retention of learned motor skills in patients with cortical or subcortical degeneration.

We investigated the acquisition and long-term retention of new skills in patients with cortical (Alzheimer's disease, AD) and subcortical (progressive supranuclear palsy, PSP; Parkinson's disease, PD) degeneration. The motor skill task performance of the PD and PSP patients improved with training, but the improvement disappeared within a few months, whereas AD patients retained learned skills for 3-18 months. The results of our experiments show that subcortical dysfunction induces a retention deficit for newly learned motor skills. Our present study suggests that a normal striatum is necessary for the formation of long-lasting motor skills, and that the striatum plays an important role as a motor skill consolidation system.

Alzheimer Disease↗
PubMed2004

Acute cortisol administration promotes sleep intensity in man.

The neuronal mechanisms of sleep generation, in particular synchronization of brain activity in the process of non-rapid-eye movement (non-REM) sleep, has been elucidated in the past decade. A previous study of our group showed that acute administration of cortisol is known to increase slow-wave sleep and suppress rapid-eye movement (REM) sleep in man. To further elucidate the non-REM sleep-promoting effects of cortisol with respect to the synchronization of cortical activity, it is important to establish a sleep-state-specific quantitative EEG analysis. We therefore investigated the effects of repetitive injections of hydrocortisone on spectral composition of sleep EEG in 10 healthy male young volunteers. In addition, we performed high-frequency blood samplings to assess the relation between changes in the sleep EEG and sleep-associated secretion of growth hormone (GH). Cortisol administration resulted in a significant increase in highly synchronized EEG activity including delta and theta frequencies, according to a higher amount of slow-wave sleep. This effect predominated in the first few hours of night sleep. REM sleep was decreased, which appeared to be secondary to the lengthened first sleep cycle. The cortisol-induced stimulation of GH release did not occur in correspondence with the increased slow-wave activity. In view of the sleep impairing properties of corticotropin-releasing hormone (CRH) and the sleep-promoting function of GH-releasing hormone, it appears likely that a negative feedback inhibition of endogenous CRH was the key mechanism mediating the observed results. The cortisol-induced effects on sleep intensity and sleep-associated GH secretion appeared to be driven by different mechanisms.

Adult↗
PubMed2003

Circadian rhythms in humans' delta sleep electroencephalogram.

Eight healthy young male volunteers entered a 20-40 min ultrashort sleep-wake schedule for 78 h in the time-isolation facility. Rectal temperature was continuously recorded. Sleep electroencephalograms (EEGs) obtained during 20 min nap trials were stored in the computer and later analyzed by fast Fourier transform. A two-way repeated-measures ANOVA (with day and time-of-day as the repeated measures) revealed significant circadian rhythms in the powers of sigma and delta sleep EEGs, and in rectal temperature. These results obtained under conditions in which behavioral confounding factors of retiring and rising were experimentally minimized suggest that the circadian pacemaker contributes to determining the hours of day when one can sleep deeply.

Adult↗
PubMed2003

Circadian fluctuation of time perception in healthy human subjects.

Previous studies suggested that various psychophysiological factors have influences on human time perception. In particular, working memory loads, time of day, body temperature, and mood were known as important modifiers of time perception. The purpose of this study is to elucidate factors affecting the short-term time perception under controlled condition. Fourteen healthy young male adults participated in this study. Time perception sessions (TPS) were conducted 4 times at 0900, 1300, 1700 and 2100 h. The TPS consisted of five 10-s time production trials under five different conditions (control trial, those with reward, and 3 different dual-load working memory tasks). Subjective status was assessed using visual analogue scales (VAS). To verify a participant's vigilance state, an alpha attenuation coefficient (AAC) was calculated. Two-way repeated measures ANOVA for produced time revealed a significant main effect of session, but no effect of task or interaction. Although produced time was not correlated with AACs or VAS scores, there was a significant negative correlation between produced time and core body temperature. These results suggest that human short-term time perception may be more influenced by circadian rhythm than working memory load or psychophysiological status.

Adult↗
PubMed2003

[Somniloquy].

Explore the source record for details and available documents.

Adolescent↗
PubMed2002

Non-rapid-eye-movement sleep propensity after sleep deprivation in human subjects.

The circadian modulation of occurrence of non-rapid-eye-movement sleep (NREM) was investigated in 37 volunteers under dim-light conditions after 24-h total sleep deprivation using a 26-h 10/20-min ultra-short sleep-wake schedule. The propensity of NREM showed rapid increase followed by gradual decrease during the subjective day and nocturnal bouts during the subjective night coinciding with melatonin production. The mean propensity of NREM during the subjective day was smaller than that during the subjective night, even though the sleep debt due to the 24-h sleep deprivation would have enhanced NREM more strongly during the subjective day than that during the subjective night. These results suggest that the occurrence of NREM sleep is modulated by a circadian pacemaker.

Adult↗
PubMed2002

Larger phase angle between sleep propensity and melatonin rhythms in sighted humans with non-24-hour sleep-wake syndrome.

STUDY OBJECTIVES: This study was aimed to clarify phase angle between sleep propensity and the circadian pacemaker in patients with non-24-hour sleep-wake syndrome (Non-24). DESIGN AND SETTING: A case-control study was underaken. PARTICIPANTS: Sighted patient with Non-24 (4 males and 1 female, aged 16 to 39 y), and sex- and age-matched healthy controls (12 males and 3 females, aged 19 to 35 y) participated the study. MEASUREMENT AND INTERVENTION: Following an actigraphic assessment of the sleep-wake cycle in their homes, the participants entered an ultra-short sleep-wake schedule together with simultaneous measurement of dim light melatonin rhythm after 24-hour sleep deprivation. RESULTS: The period of the sleep-wake cycle observed at home was longer in the Non-24 patients (25.12 hours) than in the controls (24.02 hours, p<0.0001). The interval from sleep propensity (SP) onset to the melatonin midpoint (MLmid) was significantly shorter in the Non-24 patients than in the controls. The interval from the MLmid to the SP offset was significantly longer in the Non-24 patients than in the controls. CONCLUSIONS: It was postulated that Non-24 sufferers' delayed SP onset relative to the circadian pacemaker may accelerate the light-induced phase-delay, leading to sleep-wake cycle that is longer than 24 hours.

Adolescent↗
PubMed2002

Effects of nocturnal bright light on saliva melatonin, core body temperature and sleep propensity rhythms in human subjects.

Nine healthy male volunteers (mean age of 24) participated in two experimental sessions of random crossover design: a bright light (5000 lux for 5 h from 00:00 to 05:00 h) session and a dim light (10 lux for 5 h from 00:00 to 05:00 h) session. Subsequently participants entered an ultra-short sleep-wake schedule for 26 h, in which a sleep-wake cycle consisting of 10-min sleep EEG recording on a bed and 20-min resting awake on a semi-upright chair were repeated. Saliva melatonin level and core body temperature was measured throughout the experiment. Bright light significantly delayed rhythms of melatonin secretion (01:58 h), core body temperature (01:12 h) and sleep propensity (02:00 h), compared as dim light session. Significant positive correlation was found between bright light-induced phase change in core body temperature and that in sleep propensity rhythm. Light-induced melatonin suppression significantly positively correlated with the phase change in core body temperature and that in sleep propensity rhythm. Assuming that light-induced melatonin suppression represents an acute impact of light on the circadian pacemaker, our results suggest that such an impact may be directly reflected in phase changes of sleep propensity and core body temperature rhythms rather than in melatonin rhythm.

Adult↗
PubMed2002

Pergolide restores sleep maintenance but impairs sleep EEG synchronization in patients with restless legs syndrome.

BACKGROUND: The treatment with the long-acting dopamine D1/D2 receptor agonist pergolide has been proven as very effective in lowering the frequency of periodic leg movements (PLM) in patients with restless legs syndrome (RLS). To further investigate the influence of this potent dopaminergic drug on the microstructure of rapid eye movement (REM) and non-REM sleep EEG we established a quantitative analysis of the EEG data. METHODS: The study group consisted of 15 patients with primary RLS (mean age 57.1+/-10.1 years) who were a subgroup of patients within a double-blind randomized crossover treatment study with pergolide versus placebo. The polysomnographic recordings were analyzed visually and submitted to a quantitative EEG analysis (fast Fourier transformation). RESULTS: The pergolide treatment induced a significant reduction of the spectral power in the delta range (0.78-3.9 Hz; P<0.05; t-test) during SWS, as well as a significant reduction of PLMs. In addition, we observed a decrease in the sigma EEG activity (12.1-14.8 Hz; P<0.03) during non-REM sleep and stage 2 sleep. The visual sleep scoring revealed a significant increase in stage 2 sleep (P<0.005), whereas wakefulness was markedly diminished (P<0.001). The REM sleep parameters including the EEG power spectrum remained unchanged. CONCLUSIONS: The treatment with pergolide markedly improved the sleep quality in RLS patients but did not restore SWS including the spectral power in the lower frequencies. Our results suggest that the dopamine agonist pergolide interferes with the subcortical mechanisms regulating the process of EEG synchronization during non-REM sleep.

Clinical Trial↗
PubMed2002

Long-term rectal temperature measurements in a patient with menstrual-associated sleep disorder.

The international classification of sleep disorders has proposed menstrual-associated sleep disorder. However, few studies have investigated its pathophysiological mechanism. A 34-year-old woman complaining of insomnia in the late luteal phase underwent continuous rectal temperature measurements and simultaneous actigraphic monitoring for 146 days. The acrophase of rectal temperature rhythm was delayed in the luteal phase, compared with that in the follicular phase. Her bedtime and risetime did not differ across the menstrual cycle. These results suggest that her insomnia in the luteal phase may have been a consequence of desynchronization between her temperature rhythm and sleep phase in the luteal phase.

Adult↗