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Dive into the research topics where Masako Okawa is active.

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Featured researches published by Masako Okawa.


Acta Psychiatrica Scandinavica | 1994

Morning bright light therapy for sleep and behavior disorders in elderly patients with dementia

Kazuo Mishima; Masako Okawa; Yasuo Hishikawa; S. Hozumi; H. Hori; Kiyohisa Takahashi

Fourteen inpatients with dementia showing sleep and behavior disorders (average age = 75 years), and 10 control elderly people (average age = 75 years) were carefully observed for 2 months. Four weeks of morning light therapy markedly improved sleep and behavior disorders in the dementia group. The measurement of sleep time and the serum melatonin values suggests that sleep and behavior disorders in the dementia group are related to decreases in the amplitude of the sleep‐wake rhythm and decreases in the levels of melatonin secretions. Morning light therapy significantly increased total and nocturnal sleep time and significantly decreased daytime sleep time. These results indicate that morning bright light is a powerful synchronizer that can normalize disturbed sleep and substantially reduce the frequency of behavior disorders in elderly people with dementia.


Neurology | 1995

Incidental Lewy body disease in a patient with REM sleep behavior disorder

Makoto Uchiyama; Kunihiro Isse; Katsutoshi Tanaka; N. Yokota; M. Hamamoto; S. Aida; Y. Ito; M. Yoshimura; Masako Okawa

Article abstract-We studied an 84-year-old man with a 20-year history of nocturnal violent behavior during sleep, but no other clinically evident neuropsychiatric disorders. Polysomnographic investigations confirmed that he suffered from REM sleep behavior disorder (RBD). Histopathologic examination revealed that he had Lewy body disease with a marked decrease of pigmented neurons in the locus ceruleus and substantia nigra. These histologic findings represent the first documented evidence of a loss of brainstem monoaminergic neurons in clinically idiopathic RBD and suggest that Lewy body disease might provide an explanation for idiopathic RBD in the aged. NEUROLOGY 1995;45: 709-712


Biological Psychiatry | 1999

Melatonin secretion rhythm disorders in patients with senile dementia of Alzheimer's type with disturbed sleep-waking.

Kazuo Mishima; Tozawa Tozawa; Kohtoku Satoh; Yasuhiro Matsumoto; Yasuo Hishikawa; Masako Okawa

BACKGROUND There is growing evidence that the dysregulation of circadian rhythms may play an important role in irregular sleep-waking in demented elderly. In this study, we investigated daily variation of the pineal hormone melatonin, which has been reported to possess hypnogenic and synchronizing effects, in patients with senile dementia of Alzheimers type. METHODS Serum melatonin secretion rhythms in inpatients with senile dementia of Alzheimers type (SDAT group, n = 10, average age = 75.7 years) with disturbed sleep-waking and nondemented elderly (ND group, n = 10, age = 78.3 years) without clinical sleep disorders in the same facility were monitored under a dim light condition without excessive physical exercise. RESULTS The SDAT group showed a significantly higher degree of irregularities in actigraphically recorded rest-activity (R-A) rhythm during the 7-day baseline period compared with the ND group. The SDAT group simultaneously showed significantly reduced amplitude, larger variation of peak times, and diminished amount of total secretion in the melatonin secretion rhythm compared with the ND group. There were significantly positive correlations between the severity of R-A rhythm disorder and the reduced amplitude as well as diminished amount of total melatonin secretion. CONCLUSIONS The SDAT patients with disturbed sleep-waking possessed melatonin secretion rhythm disorders that may play an important role in irregular sleep-waking in demented elderly.


Journal of Clinical Psychology | 2000

Life events, locus of control, and behavioral problems among Chinese adolescents.

Xianchen Liu; Hiroshi Kurita; Makoto Uchiyama; Masako Okawa; Lianqi Liu; Dengdai Ma

This study examined associations of life events and locus of control with behavioral problems among 1,365 Chinese adolescents by using the Youth Self-Report (YSR), Adolescent Self-Rating Life Events Checklist (ASLEC), and the Nowicki-Strickland Locus of Control Scale for Children. Results indicated that the overall prevalence of behavioral and emotional problems was 10.7% (95% CI = 9.9-11.5%). Logistic-regression analyses showed that a total of 13 negative life events mainly coming from academic domain and interpersonal relationships, high life-stress score, and high external locus score significantly increased the risk for behavioral problems. Life stress and locus of control significantly interacted with behavioral problems. These findings support the linkage between stressful life events and psychopathology in a general population of adolescents from mainland China, and demonstrate the stress-moderating effects of locus of control on psychopathology as well.


Chronobiology International | 2000

SUPPLEMENTARY ADMINISTRATION OF ARTIFICIAL BRIGHT LIGHT AND MELATONIN AS POTENT TREATMENT FOR DISORGANIZED CIRCADIAN REST- ACTIVITY AND DYSFUNCTIONAL AUTONOMIC AND NEUROENDOCRINE SYSTEMS IN INSTITUTIONALIZED DEMENTED ELDERLY PERSONS

Kazuo Mishima; Masako Okawa; S. Hozumi; Yasuo Hishikawa

Increased daytime napping, early morning awakening, frequent nocturnal sleep interruptions, and lowered amplitude and phase advance of the circadian sleep-wake rhythm are characteristic features of sleep-waking and chronobiological changes associated with aging. Especially in elderly patients with dementia, severely fragmented sleep-waking patterns are observed frequently and are associated with disorganized circadian rhythm of various physiological functions. Functional and/or organic deterioration of the suprachiasmatic nucleus (SCN), decreased exposure to time cues such as insufficient social interaction and reduced environmental light, lowered sensitivity of sensory organs to time cues, and reduced ability of peripheral effector organs to express circadian rhythms may cause these chronobiological changes. In many cases of dementia, the usual treatments for insomnia do not work well, and the development of an effective therapy is an important concern for health care practitioner and researchers. Recent therapeutical trials of supplementary administration of artificial bright light and the pineal hormone melatonin, a potent synchronizer for mammalian circadian rhythm, have indicated that these treatments are useful tools for demented elderly insomniacs. Both bright light and melatonin simultaneously ameliorate disorganized thermoregulatory and neuroendocrine systems associated with disrupted sleep-waking times, suggesting a new, potent therapeutic means for insomnia in the demented elderly. Future studies should address the most effective therapeutic design and the most suitable types of symptoms for treatment and investigate the use of these tools in preventive applications in persons in early stages of dementia. (Chronobiology International, 17(3), 419–432, 2000)


Chronobiology International | 1998

Randomized, DIM Light Controlled, Crossover test of Morning Bright Light Therapy for Rest-Activity Rhythm Disorders in Patients with Vascular Dementia and Dementia of Alzheimer's type

Kazuo Mishima; Yasuo Hishikawa; Masako Okawa

The authors compared the therapeutic effect of morning bright and dim light exposure on rest-activity (R-A) rhythm disorders in patients with vascular dementia (VD) and patients with dementia of Alzheimers type (DAT). Participants in this study were 12 patients with VD (M/F = 5/7; average age = 81 years) and 10 patients with DAT (M/F = 4/6; average age = 78 years). They were exposed to 2 weeks of bright light (BL; 5000-8000 lux) and 2 weeks of dim light (DL; 300 lux) in the morning (09:00-11:00) in a randomized crossover design in which the 2-week treatment period took place between pretreatment (1 week) and posttreatment (1 week) periods. Continuous R-A monitoring was performed at 1-minute intervals throughout the study using an actigraph around the nondominant wrist. The BL exposure for 2 weeks induced a significant reduction in both nighttime activity and percentages of nighttime activity to total activity compared with the pretreatment period, as well as compared with the DL condition in the VD group, but not in the DAT group. These findings support the assumption that the therapeutic efficacies of morning BL exposure are prominent in VD patients and are mainly due to its photic effect rather than nonphotic effects such as the intensification of social interaction accompanying light therapy.


Acta Psychiatrica Scandinavica | 1996

Seasonal variation of mood and behaviour in a healthy middle‐aged population in Japan

Masako Okawa; Shuichiro Shirakawa; Makoto Uchiyama; Mitsugu Oguri; M. Kohsaka; Kazuo Mishima; K. Sakamoto; H. Inoue; K. Kamei; Kiyohisa Takahashi

A population survey of seasonality in six representative cities in Japan was conducted using the Japanese version of the Seasonal Pattern Assessment Questionnaire (SPAQ). The questionnaires were given to 951 parents (male: female ratio 1 : 1 age range 34‐59 years) of high‐school students. Significant regional differences in seasonal variations of mood, length of sleep, and weight were observed; the proportion of individuals reporting high seasonality in the two northern cities was significantly higher than that in the other areas. These results provide evidence for a northern predominance in the prevalence of seasonal affective disorder in Japan.


Neurobiology of Aging | 1997

Different )Manifestations of Circadian Rhythms in Senile Dementia of Alzheimer's Type and Multi-Infarct Dementia

Kazuo Mishima; Masako Okawa; Kohtoku Satoh; Tetsuo Shimizu; Satoshi Hozumi; Yasuo Hishikawa

Using an actigraph and a long-term body temperature (BT) monitoring system, we simultaneously monitored rest-activity (R-A) and BT rhythms in patients with senile dementia of Alzheimers type (SDAT; n = 20) or multi-infarct dementia (MID; n = 21) for 5-7 consecutive days. The SDAT group exhibited a well-organized BT rhythm with significantly higher amplitude compared with the MID group. The SDAT group also showed significant positive correlation between the total daily activity as well as percentage of nighttime activity and the degree of dementia, while no such tendency was observed in the MID group. The different properties of the biological rhythm disorders among the SDAT and MID groups possibly underlie their sleep and behavioral disorders.


Excerpta Medica International Congress Series | 2002

Functional neuroanatomy of human non-rapid eye movement sleep: A study using a positron emission tomography

Naofumi Kajimura; Makoto Uchiyama; Yutaka Takayama; Sunao Uchida; Takeshi Uema; Masaaki Kato; Masanori Sekimoto; Tsuyoshi Watanabe; Toru Nakajima; Satoru Horikoshi; Kenichi Ogawa; Masami Nishikawa; Masahiko Hiroki; Yoshihisa Kudo; Hiroshi Matsuda; Masako Okawa; Kiyohisa Takahashi

Abstract In order to clarify the neural correlates and brain functions during non-rapid eye movement (NREM) sleep, regional cerebral blood flow (rCBF) were measured using positron emission tomography (PET) in healthy male subjects. During light NREM sleep, the rCBF in the midbrain, in contrast to that in the pons and thalamic nuclei, did not decrease when compared to that during wakefulness, while rCBF decreased in the left medial frontal gyrus, left inferior frontal gyrus, and left inferior parietal gyrus of the neocortex. During deep NREM sleep, the rCBF in the midbrain tegmentum decreased and there was a marked and bilateral decrease in the rCBF in all neocortical regions except for the peri-rolandic areas and the occipital lobe. Thus, the activity of the midbrain reticular formation may be maintained during light NREM sleep. Furthermore, selective deactivation of heteromodal association cortices including those related to language, may occur during NREM sleep, which supports the recent theory that sleep is a local, use-dependent process of the brain.


Nō to shinkei Brain and nerve | 2003

[Sleep-wake rhythm disorders].

Masako Okawa; Makoto Uchiyama

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Kiyohisa Takahashi

Shiga University of Medical Science

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Xianchen Liu

National Institutes of Health

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