Time Structure of Blood Pressure and Aging: the Brno Database
| Authors | |
|---|---|
| Year of publication | 2016 |
| Type | Article in Proceedings |
| Conference | Noninvasive methods in cardiology 2016 |
| MU Faculty or unit | |
| Citation | |
| Web | https://is.muni.cz/do/med/noninvasive_methods_in_cardiology/noninvasive_methods_in_cardiology_2016.pdf |
| Description | The circadian system tends to weaken with advancing age. The circadian amplitude of many physiological variables is reduced and the circadian acrophase becomes more labile, often occurring earlier in older people. The Brno database consists of 297 7-day/24-hour records from men (N=219) and women (N=78), 20-84 years of age, obtained by ambulatory blood pressure monitoring between January 2000 and June 2011. Subjects resided in Brno, Czech Republic, and were mostly clinically healthy at the time of monitoring. All but 23 records covered a week. Data from the 274 complete records were analyzed by the extended cosinor. Least squares spectra were computed in the frequency range from 1 cycle per week to 7 cycles per day. Population-mean cosinor spectra were obtained to assess the infradian-to-circadian (frequencies of 1 to 7 cycles per week) and circadian-to-ultradian (frequencies between 1 and 7 cycles per day) spectral domains. The circadian period was estimated by the nonlinear fit of a cosine curve with a trial period of 24 hours. With increasing age, the circadian amplitude of blood pressure was reduced and the circadian acrophase of blood pressure was advanced. In men, but not in women, the circadian period of blood pressure shortened with age. It deviated from 24 hours in over 10% of the population. There was also a transposition of the variance from the circadian to both the infradian and ultradian domains. The weakening of the circadian system was also apparent from a widening of the 95% confidence intervals of the relative amplitude, acrophase, and period. These results provide further evidence for the need to refine reference standards by accounting for changes with age in circadian (and other) rhythm characteristics. |