Impact of anesthesia on the cognitive functioning of the elderly.

Exposure to general anesthesia has been suggested as a possible cause of long-term cognitive impairment in elderly subjects. The present study reviews the literature in this field in order to describe postoperative cognitive impairment in elderly populations, to determine to what extent this may be attributed to anesthetic agents, and to consider evidence of a causal relationship between anesthesia and onset of senile dementia. A systematic literature search was conducted using five bibliographic databases (PASCAL, Medline, Excerpta Medica, Psychological Abstracts, and Science Citation Index). Significant cognitive dysfunction was found to be common in elderly persons 1 to 3 days after surgery, but reports of longer-term impairment are inconsistent due to the heterogeneity of the procedures used and populations targeted in such studies. Incidence rates vary widely according to type of surgery, suggesting that factors other than anesthesia explain a significant proportion of the observed variance. Anesthesia appears to be associated with longerterm cognitive disorder and the acceleration of senile dementia, but only in a small number of cases, suggesting the existence of other interacting etiological factors.

New data on the ontogeny of the child's sleep-wake rhythm.

The present study is part of a broader body of research concerning the ontogeny and regulations of the young child's sleep-wake rhythm. It was carried out with 12 children admitted to a day-care center from 4 or 5 months of age. None of the children showed any anomalies or functional disorders. The method used in this study consisted in organizing a data collection on the alternations of wakefulness and sleep as well as on the children's behavior throughout the 24-h period, both in their family and at the day-care center from 4 to 15 months of age. The main findings are (a) the circadian rhythm of wakefulness and sleep is clearly set up as early as at 4 months of age and consolidates between 6 and 7 months; (b) some ages are characterized by significant changes in the daily distribution and duration of sleep spans: 6 to 7 months; 10 to 12 months; 13 to 15 months; (c) these changes suggest the existence of several ultradian rhythmicities which become successively prevailing from one age to the next throughout child development. The longitudinal study of the young child's sleep-wakefulness rhythm allows better evaluation of the influence of developmental factors in its structuralization and formulation of new hypotheses on its disorders and dysfunction. Individual factors are under study.

[New data on the genesis of sleep-wakefulness rhythm in children aged 4-15 months]. / Données nouvelles sur la genèse du rythme veille-sommeil de l'enfant de 4 mois à 15 mois.

The present study deals with the ontogeny of the sleep-wakefulness rhythm in 12 children from the 4th to the 15 month of age. The main findings were as follows: 1. The circadian rhythm of wakefulness and sleep is clearly sep up as of 4 months of age and is characterized by 3 main parameters: a long uninterrupted night sleep period which includes the time interval from midnight to 4 a.m. The duration of this period of time is always equal to or higher than 400 min. The periodicity of the last falling asleep before midnight and the periodicity of the first awakening after midnight are equal or very close to 24 hours. Both seem to be mutually adjusted or connected to each other. 2. Some ages are characterized by significant changes in the daily distribution of the number and duration of sleep spans. 3. These changes suggest the existence of several ultradian rhythmicities which prevail successively throughout the development period under study. 4. There are many important differences between girls and boys.

[Fluctuations of biological rhythms, behavior and intellectual activity in children in different environments]. / Les fluctuations des rythmes biologiques, des comportements et de l'activité intellectuelle de l'enfant dans ses différents environnements.

We report in this paper research data which deal with the fluctuations of biological, biopsychological and intellectual variables throughout the day and week in children and adolescents attending various educational establishments. The first chapter is devoted to the evolution of sleep-arousal alternations from the second year of life and to the relations between this evolution and behavioral and physiological variations during the day. It is divided into four parts: temporal evolution of the sleep-wake rhythm of children from 2 to 5 years of age, attending kindergarten; modifications observed in the behavior and biological rhythms of children from the last year of kindergarten to the first year of primary school; the high variability of biological rhythms from one child to another; modifications observed in intellectual performances of children attending primary and secondary school. The second chapter is devoted to the evolution of the duration of night sleep during childhood and the self-regulation phenomena that it reveals. The overall data lead to suggestions for organizing school schedules throughout the day and week.