The relative contributions of age and menopause to vertebral bone mine
ral density were evaluated based on the estimated weights for age- and
menopause-related bone loss components using a mathematical model in
177 healthy female volunteers ages 35-81 years, living in a community
in Fukui, Japan, Bone mineral density was determined by dual X-ray abs
orptiometry, The model used was that which afforded the best fit among
the eight possible models to the data observed, Each model was compos
ed of a linear function for the age-related component and a different
type of function for the menopausal component, without interaction bet
ween them, The weights for these components in each model were estimat
ed by the least-squares method, The coefficient of determination and A
kaike information criterion disclosed that among the eight models test
ed, the model affording the best fit was composed of a logarithmic dec
rease in bone density with an increase in Sears since menopause, up to
10 years postmenopausal, with no further decline thereafter, In this
model, the weights for both components were statistically significant
and the type III sum of squares of the menopausal component was greate
r than that of the age-related component, We suggest that both age and
menopause made significant contributions to the decline in vertebral
bone mineral density, with the contribution of menopause being greater
than that of age.