however , because arteries stiffen with higher age and because of differences in wave travel distance and wave reflections , the age - related increase in systolic blood pressure does not occur uniformly across the whole arterial tree ( orourke and kelly , 1993 ) .
indeed , during systole , the heart generates a forward running pressure wave , which is reflected at various sites in the peripheral arterial system ( orourke and kelly , 1993 ) .
as the arteries become stiffer with advancing age , the reflected waves may cause an augmentation of late systolic pressure .
in addition geometric changes of the aorta with aging may also contribute to age - related increase in systolic blood pressure ( redheuil et al .
additionally aortic reservoir function and other elastic changes markedly with aging , which accounts for the age - related changes in the aortic pressure waveform ( davies et al . , 2010 ) .
because of this phenomenon , there might be differences in the age dependency of peripheral systolic blood pressure , as measured at the brachial artery , and central systolic blood pressure , as estimated non - invasively by pulse wave analysis .
however , the initial evidence supporting the principle of the age dependency of the amplification of the central blood pressure came from animal experiments ( orourke , 1994 ) and invasive studies in selected subjects ( murgo et al . , 1980 ; orourke , 1994 ) . among the published population studies on the age dependency of arterial stiffness ( avolio et al . , 1983 , 1985 ; wilkinson et al .
, 2001 ; mitchell et al . , 2004 ; mceniery et al . , 2005 ; li et al . , 2008 ) ,
, 1983 , 1985 ; mitchell et al . , 2004 ; mceniery et al . , 2005 ) , the ratio of pulse pressure in peripheral vs. central arteries ( wilkinson et al . , 2001 ) , or the augmentation index ( mceniery et al . , 2005 ; li et al . , 2008 ) in selected healthy subjects ( wilkinson et al . , 2001
; mitchell et al . , 2004 ; mceniery et al . , 2005 ; li et al . ,
2008 ) and patients at increased cardiovascular risk ( mceniery et al . , 2008 ) . the predictive value of central pressure ( both measured invasively and non - invasively ) was proved in several studies ( roman et al .
we previously reported reference values for the central and peripheral pulse pressures and augmentation indexes by age in healthy european ( wojciechowska et al . , 2006 ) and chinese ( li et al . , 2008 ) reference populations . in the present review
, we focused on the changes with age in central and peripheral systolic blood pressures , based on data collected from randomly recruited european ( wojciechowska et al . , 2012 ) and chinese ( li et al . ,
these age - related changes were assessed cross - sectionally and in a subsample also longitudinally . only participants without antihypertensive drug treatment
peripheral and central blood pressures were assessed among 1420 participants [ 731 women ( 51.5% ) and 278 ( 19.6% ) hypertensive patients ] in europe and 2044 [ 1066 women ( 52.2% ) and 556 ( 27.2% ) hypertensive patients ] in china ( wojciechowska et al . , 2012 ; li et al . , 2012 ) . in cross - sectional analyses of both populations , the peripheral and central systolic blood pressures increased with age ( p for trend    0.01 ; figure 1 for europe ; wojciechowska et al . , 2012 ) .
in single regression analysis , the cross - sectionally assessed age - related increase in central systolic blood pressure was larger than that in peripheral systolic pressure both in women and in men . additionally , in a subanalysis of the chinese sample , systolic blood increased more with age in the central than peripheral arteries in women below age 50 ( 1.21 vs. 1.01  mm hg per year ; p  <  0.001 ) and in men below age 60 ( 0.73 vs. 0.48  mm hg per year ; p  <  0.001 ) , whereas in older women ( 0.64 vs. 0.58  mmhg per year ; p  =  0.27 ) and older men ( 0.45 vs. 0.44  mm hg per year ; p  =  0.79 ) , the slopes of central and peripheral systolic blood pressures on age were similar ( li et al .
association with age of peripheral and central systolic blood pressures ( a , b ) , peripheral , and central non - augmented systolic blood pressures ( a , b ) , pressure amplification ( c , d ) , and peripheral and central systolic augmentation ( e , f ) in women ( a , c , e ) and men ( b , d , f ) . peripheral systolic blood pressure was the average of three blood pressure readings at the brachial artery .
all p - values for trend with age were statistically significant ( p  <  0.0001 ) .
significance of the difference with zero : * p  <  0.05 and p  <  0.001 . reproduced with permission from blood pressure journal .
our cross - sectional observations are in agreement with known physiologic concepts and also in line with several previously published cross - sectional population studies ( wilkinson et al . , 2001 ;
2010 ) , including the anglo - cardiff collaborative trial ( acct ; mceniery et al . , 2005 ) .
( 2005 ) studied 4001 healthy , normotensive individuals , aged 1890  years . in both women and men , central systolic pressure increased more with age than did peripheral systolic blood pressure ( p  <  0.001 ) .
as in our current cross - sectional analyses , the increase in central systolic pressure was more prominent in women than men ( p  =  0.01 ) .
these consistent results were obtained based on white european populations with a western life style , high prevalence of obesity , and relatively high cholesterol levels . we can not simply extrapolate them to other ethnicities or populations with different lifestyles .
however , our findings were similar in lean asian people , who generally have lower serum cholesterol levels .
stiffening of the large arteries underlies the age - related increase in systolic blood pressure ( staessen et al . ,
the loss of arterial elasticity over a person s life time is partly due to cyclic stress on the arterial wall with each heart beat ( orourke and hashimoto , 2007 ) . over time , this causes fracture of elastin fibers , so that stress is transferred to the more rigid collagenous components of the arterial wall . at a young age , the aorta and proximal arteries dilate by approximately 10% with each heart beat , whereas the more distal muscular arteries dilate by only 23% with each heart beat ( boutouyrie et al . , 1992 ) .
atherosclerosis and inflammation thicken the arterial wall and contribute to arterial stiffening over and beyond the mechanical stress . to differentiate natural degeneration of the arterial wall from aging from disease , avolio et al .
( 1983 ) highlighted the interest of studies of arterial properties in population studies with low cholesterol and low prevalence of atherosclerosis , such as chinese .
1985 ) contrasted the chinese living in areas with low and high prevalence of hypertension , guangzhou ( 4.9% ) and beijing ( 15.6% ) , respectively . in guangzhou subjects ,
pulse wave velocity was consistently lower in the aorta , arm , and leg , and increased to a lesser degree with age , compared with beijing subjects ( avolio et al . , 1985 ) .
the contemporary cholesterol levels were 4.34  mmol  l in guangzhou subjects and 4.49  mmol  l in beijing subjects . in our chinese population , cholesterol levels were of similar magnitude ( 4.73  mmol  l ) , but the prevalence of hypertension was much higher ( 27.2% ) .
our current observations strengthen avolio s hypothesis ( avolio et al . , 1983 , 1985 )
that slowly progressing degeneration of the arterial wall through cyclic stress is the main cause of the age - related increase in systolic blood pressure .
the slopes of peripheral and central systolic blood pressures on age were consistently steeper ( p  <  0.001 ) in women than in men in both studied populations ( li et al .
in the young and middle - aged subjects , the age - related increase in systolic blood pressure ran a steeper course in women than men .
at all ages , women have a higher heart rate than men ( smulyan et al . , 2001 ) . the smaller height of women may be a cardiovascular risk factor , because of the early return of reflected waves to the central aorta in systole .
the shorter stature of women also implies reduced length of the arterial tree , a factor believed to be responsible for the faster heart rate , a shorter diastolic period , a shorter diastolic time constant , and at the same peripheral resistance , lower arterial compliance ( smulyan et al . , 2001 ) .
in older women , menopause might contribute to the continuing rise in systolic blood pressure , although it is difficult to differentiate the effects of aging from those of estrogen deprivation ( casiglia et al .
in european study 208 women ( 24.4% ) and 190 men ( 27.6% ) , underwent a repeat arterial examination at a median interval of 4.79  years ( 5th95th percentile interval , 3.965.98  years ( wojciechowska et al . ,
women ( 34.6% ) and 330 men ( 33.7% ) underwent a repeat assessment of peripheral and central systolic blood pressure at a median interval of 3.60  years ( 5th95th percentile interval , 3.563.96  years ; li et al . ,
all changes from baseline to follow - up were significant ( p    0.039 ) .
in the caucasian populations , the annual increases in the peripheral and central systolic blood pressures averaged 0.91 and 1.06  mmhg in women , and 1.24 and 1.47  mmhg in men .
the p - values for the sex differences were 0.12 and 0.08 , respectively ( wojciechowska et al . , 2012 ) . in chinese population peripheral systolic pressure
increased more ( p    0.025 ) than the central systolic pressure both in women ( 2.35 vs. 2.12  mm hg ) and in men ( 1.37 vs. 1.16  mm hg ) . on a relative scale ,
the percentage increases in peripheral and central systolic blood pressure from baseline to follow - up were similar in women ( 2.14 vs. 2.16% per year ; p  =  0.76 ) , as well as in men ( 1.33 vs. 1.34% per year ; p  =  0.96 ; ) . in sensitivity analyses stratified by quartiles of the age distribution ,
the increase in peripheral systolic blood pressure was larger than that in central systolic blood pressure ( p    0.02 ) above median age in women and above the 75th percentile of age in men , whereas in all other sex  age subgroups , the increases of peripheral and central systolic pressures were similar ( p    0.08 ; figure 2 ; li et al . , 2012 ) .
peripheral and central sbps at baseline and follow - up by quartiles of the age distribution in 369 women ( a ) and 330 men ( b ) .
all p - values for trend with age were statistically significant ( p  <  0.0001 ) .
significance of the difference between baseline and follow - up : * p  <  0.05 , p  <  0.01 , and p  < 
, kannel and gordan ( 1978 ) noticed that the age - related increase in systolic blood pressure was steeper on cross - sectional than longitudinal assessment in women , whereas the opposite was the case in men .
the reasons for the difference in bp trends obtained cross - sectionally and longitudinally in the same framingham cohort were not clear .
one possible explanation is that subjects at the higher end of the distribution of systolic blood pressure are more likely to experience cardiovascular complications or die , and therefore to disappear from follow - up .
the unmeasured attrition in our populations available for cross - sectional analysis might have contributed to the larger estimates of the age - related increase in systolic blood pressure in the longitudinal analyses .
the effects of aging on arterial function have often been underestimated , because of the sole reliance on the brachial cuff systolic pressure . with aging ,
these findings support the point of view that age - related stiffness of arteries represents a vicious circle , in which increasing systolic blood pressure is , at the same time , the cause and the consequence of a self - sustaining process that leads to major cardiovascular complications . breaking
the vicious circle is the key to slowing the age - related rise in systolic blood pressure and preventing the associated cardiovascular complications .
the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest .
 as arteries become stiffer with aging , reflected waves move faster and augment late systolic pressure . 
 few studies have described the age - related changes in both peripheral and central systolic blood pressures in populations . 
 we investigated the age dependency of peripheral ( psbp ) and central ( csbp ) systolic pressure and pressure amplification ( i.e. , difference between peripheral and central sbp ) in randomly selected participants from european and chinese populations . 
 data were collected in 1420 europeans ( mean age , 41.7  years ) and 2044 ( mean age , 45.1  years ) chinese . in cross - sectional analyses of the population samples csbp consistently increased more with age than psbp with the age - related increases being greater in women than men . 
 repeat assessment of psbp and csbp in 398 europeans and 699 chinese at a median interval approximately 4  years of follow - up confirmed that also within subjects csbp rose steeper with aging than psbp . in conclusion , with aging , psbp approximates to csbp . 
 this might explain why in older subjects psbp becomes the main predictor of cardiovascular complications . 
Introduction
Cross-Sectional Studies
Longitudinal Assessment of Age-Dependent Changes in Arterial Tree
Conclusion
Conflict of Interest Statement