Association between growth and blood pressure during the life course in children and adolescents

Background: Little is known on the relative importance of growth at different periods between birth and adolescence on blood pressure (BP). Objective: To assess the association between birth weight, change in body weight (growth) and BP across the entire span of childhood and adolescence. Methods: School-based surveys were conducted annually between 1998 and 2006 among all children in four school grades (kindergarten, 4th, 7th, and 10th year of compulsory school) in the Seychelles, Indian Ocean. Height and weight and BP were measured. Three cohorts of children examined twice were analyzed: 1606 children surveyed at age 5.5 and 9.1, 2557 at age 9.2 and 12.5, and 2065 at age 12.5 and 15.5, respectively. Weights at birth and at one year were extracted from medical files. Weights were expressed as Z-scores and growth was defined as a change in weight Z-scores (corresponding to weight centile crossing). The association between BP (at age 5.5, 9.2, 12.5, and 15.5) and weight at different times was assessed by linear regression. Using results of regression models of BP on all successive weights, life course plots were drawn by plotting regression coefficients against age at which weight was measured. The figure shows a life course plot of systolic BP in boys aged 15.5. Results: Without adjustment for current weight (at the time of BP measurement), birth weight was not associated with current BP, irrespective of age, excepted for girls at age 15.5 for whom a modest positive association was found. When adjusted for current weight, birth weight was negatively and modestly associated with current BP. BP was strongly associated with current weight, irrespective of age. Life course plots showed that BP was strongly associated with growth during the few preceding years but not with growth during earlier years, except for growth during the first year of life which tended to be associated with systolic BP. Conclusions: Our findings suggest that BP during childhood and adolescence is mainly determined by current body weight and recent growth.

Upward hypertension trends: changes in blood pressure or in antihypertensive treatment?

Comment on: Cutler JA, Sorlie PD, Wolz M, Thom T, Fields LE, Roccella EJ. Trends in hypertension prevalence, awareness, treatment, and control rates in United States adults between 1988-1994 and 1999-2004. Hypertension. 2008 Nov;52(5):818-27. PMID: 18852389.

Blood pressure-independent cardiac hypertrophy induced by locally activated renin-angiotensin system.

Cardiac hypertrophy is frequent in chronic hypertension. The renin-angiotensin system, via its effector angiotensin II (Ang II), regulates blood pressure and participates in sustaining hypertension. In addition, a growing body of evidence indicates that Ang II acts also as a growth factor. However, it is still a matter of debate whether the trophic effect of Ang II can trigger cardiac hypertrophy in the absence of elevated blood pressure. To address this question, transgenic mice overexpressing the rat angiotensinogen gene, specifically in the heart, were generated to increase the local activity of the renin-angiotensin system and therefore Ang II production. These mice develop myocardial hypertrophy without signs of fibrosis independently from the presence of hypertension, demonstrating that local Ang II production is important in mediating the hypertrophic response in vivo.