Application de l'analyse spectrale pour l'etude de certaines relations entre l'activité E.E.G. occipitale et l'age

Abstract

Experience amassed over many years indicates that the human E.E.G. undergoes characteristic changes with advancing age. To study these phenomena a spectral analytic investigation was carried out. Results obtained from the E.E.G. by spectral analysis (lead O2-CZ, 3-minute resting E.E.G., n = 739, age range 20-95 years) show that a slowing of the dominant occipital alpha frequency occurs increasingly in old age. Slow activities, delta and theta, increase in percentage to the entire spectrum, while at the same time there is a decrease in percentage in alpha and beta activities (statistical evaluation: polynomial regression analysis). Another investigation was carried out in 619 subjects ranging in age between 20 and 95 years, in order to identify the E.E.G. variable most closely correlated with age. All the subjects had a normal alpha E.E.G. and were in a state of physical and mental health normal for their chronological age. Because of the mutual dependency of the E.E.G. parameters and the possible existence of substructures within the data that are not related to age, factor analyses were performed. Three factors account for about 80% of the total variance, on the which can be considered age-related. In this factor the variable age has the highest loading and the dominant (alpha) frequency shows -- negatively correlated with age -- the second highest loading. It is therefore assumed that, among the various E.E.G. variables correlated with age, the slowing of the dominant (alpha) frequency represents the most characteristic symptom of the E.E.G. in senescence.