Determination of bone mineral density of the hip and spine in human pedigrees by genetic and life-style factors

In 40 human pedigrees with 563 subjects, we evaluated the contribution of g enetic and Life-style factors (exercise, smoking, and alcohol consumption) and the interactions between non-genetic factors in determining bone minera l density (BMD) of the hip and spine. In our analysis, we adjusted for age, weight, height, menopausal status in females, life-style factors, and the significant interactions among these factors. For the spine and hip BMD, he ritabilities (h(2)) (+/- SE) were, respectively, 0.68 (0.21) and 0.86 (0.28 ) in males and 0.64 (0.13) and 0.67 (0.14) in females. Exercise had signifi cant beneficial effects for male spine BMD and female hip BMD. Alcohol cons umption experienced in our sample had significant beneficial effects on hip BMD in both sexes. Although the main effect of smoking was not significant , there were significant interaction effects between smoking and other impo rtant factors (e.g., exercise, weight, alcohol consumption). For example, f or female spine BMD, exercise had significant beneficial effects in smokers ; however, its effect in non-smokers was non-significant. This result indic ates that exercise may reduce deleterious effects of smoking (if any) on BM D, but may have minor effects in increasing BMD in non-smokers. The various interaction effects among risk factors explicitly revealed here for the fi rst time indicate that the detailed effects and direction of individual ris k factors may depend on the presence and magnitude of other factors. Weight invariably affected BMD of the hip and spine in both sexes. Age effects we re significant for hip BMD, but not for male spine BMD. (C) 2000 Wiley-Liss , Inc.