OBJECTIVE: The purpose of the present investigation was to examine the age-dependency of blood pressure heritability by use of the twin method in different age groups.

DESIGN: In 272 (150 monozygous and 122 dizygous) twin pairs, aged 18 to 76 years, both conventional and ambulatory blood pressure were measured. After correction for possible confounders, model fitting was used to estimate heritability and 95% confidence limits in three age groups of similar size, i.e. 18-29, 30-39 and > or = 40 years.

RESULTS: Heritability estimates were significant in each age group, ranging from 35 to 67% for the various blood pressure measurements. The estimates tended to decrease with increasing age, except for conventional diastolic blood pressure, but the intergroup differences did not reach statistical significance, despite adequate power.

CONCLUSIONS: In conclusion, blood pressure heritability is significant in various age groups, but does not substantially change with advancing age. Twin analysis does not indicate that models for blood pressure regulation in various age groups should take into account the possibility of age-related changes in the expression of relevant genes, in the presence of relevant environmental agents, or in the susceptibility to the latter (gene-environment interaction).