Time series analysis of monthly body weight and blood pressures of one man from 29 to 65 years.

Time series analysis was carried out on monthly data of body weight and blood pressure of one male subject from 29 to 65 years of age by the program Census X-11 and DECOMP. Body weight increased from 55 kg to 70 kg from 30 to 50 years, then decreased to 60 kg afterward. The trend factor of body weight obtained by X-11 fluctuated markedly even after the removal of seasonal and irregular components. The trend factor of systolic blood pressure increased from 120 mmHg to 140 mmHg from 40 to 55 years, while diastolic blood pressure increased from 70 mmHg to 90 mmHg around 40 years of age. These changes were also accompanied by many fluctuations. The program DECOMP suggested that the fluctuations observed in X-11 were expressed by an autoregressive model. From the viewpoint of the most appropriate autoregressive model, it is possible that at younger ages body weight and systolic blood pressure may be affected by the values of the previous several months. On the other hand, they may be affected by the values of the previous month or two at older ages. Spectral analysis was also applied to the autoregressive model. Peaks at about 20, 30, or 40 months were observed in body weight changes. The pattern of the seasonal factor changed with age in body weight and blood pressure. In body weight, the peak appeared in the summer at younger ages, but in the autumn or winter at older ages. In blood pressure, the peak did not always appear in the winter. Am. J. Hum. Biol. 12:526-541, 2000. Copyright 2000 Wiley-Liss, Inc.