Aging process analyzed by time series analysis

Research Project

Project/Area Number	04670325
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	公衆衛生学
Research Institution	Tamagawa University (1993-1994) The University of Tokyo (1992)
Principal Investigator	OKAJIMA Yoshiki Tamagawa University, Faculty of Literature, Lecturer, 文学部, 講師 (90194349)
Co-Investigator(Kenkyū-buntansha)	TOGO Masami University of Tokyo, Faculty of Education, Professor, 教育学部, 教授 (70041283)
Project Period (FY)	1992 – 1994
Project Status	Completed (Fiscal Year 1994)
Budget Amount *help	¥1,900,000 (Direct Cost: ¥1,900,000) Fiscal Year 1994: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1993: ¥600,000 (Direct Cost: ¥600,000) Fiscal Year 1992: ¥900,000 (Direct Cost: ¥900,000)
Keywords	Aging / Time series analysis / Monthly data / Body weight / Blood pressure / Fluctuation / Auto Regressive model / Seasonal variation / DECOMP / 月次測走 / 周期性 / 自己回帰(AR)式
Research Abstract	Time series analysis was carried out in order to analyze the monthly data of body weight and blood pressure from 29 to 65 years old by the program X-11, and trend series, seasonal series, irregular series were calculated.Body weight and blood pressure of trend series fluctuated enormously with age.Spectral analysis was carried out in order to analyze these fluctuations.In body weight more than one year cycle (for example, 20-months-cycle)was detected in these fluctuations.Such a cycle was observed in another subjects and in the original data. The non-stationary time series program DECOMP was used to analyze the same data.The fluctuations which were observed in the trend series of X-11 were approximated by the Auto Regressive process in DECOMP.In younger ages 4 order Auto Regressive equation was fitted best to the body weight and systolic pressure, but in older ages 1 or 2 order Auto Regressive equation was fitted best.In older ages body weight and systolic pressure of one month may be affected by another factor other than the values of previous months. Monthly data of body temperature, red blood cell count, hemoglobin, hematocrit were also analyzed by the program X-11.These variables also fluctuated with age.And more than 1 year cycles were also detected. Seasonal series of body weight, blood pressure and body temperature changed with age in the same subjects.For example, in some subject in younger ages the peak of body weight appeared in summer, but in order ages it appeared in winter.