A Study on the Differences in Factors Affecting the Bone Density Among Age Groups

We conducted a survey on bone density of adult females living in Chichibu District, Saitama Prefecture, for the purpose of clarifying the differences in factorswhich affect bone density and contribute to prevention of osteoporosis among different age groups. Bone densities of 506 women were measured by ultrasonic bonedensitometry and their lifestyle was examined. By dividing the subjects into 5 age group, the factors associated with bone density differed among them. In the age group of 20 to 39 years old, body weight andexercise habit (at present) were significantly positively associated with bone density. In the age group of 40 to 49 years old, the positive association with body weight and exercise habit (at junior high and senior high schools) was observed. In the age group of 50 to 59 years old, bone density was significantly positively associated with regularity in menstruation and body height, and negatively with smoking habit and delivery history. In the age group of 60 years or more, body weight only was positively associated with bone density. According to the results of this study, the health education for encouraging regular exercise during the period of junior high school through up to about 40 yearsold and smoking cessation was considered to be effective for prevention of the decrease in bone density. However, it seems plausible that exercise is less effective for the individuals aged 60 or more.