Morning blood pressure surge relates to autonomic neural activity in young non-dipping adults: the African-PREDICT study

Abstract

Background It is well established that an exaggerated morning blood pressure surge (MBPS) is associated with an increased risk for cardiovascular disease development in hypertensive individuals. However, in non-dipping individuals, a lower surge was reportedly associated with increased cardiovascular risk. Sympathetic nervous system activity is involved in 24-hour blood pressure fluctuations, including night-time dipping and the MBPS. To better understand this interaction, we investigated associations of MBPS with heart-rate variability and baroreceptor sensitivity in young healthy dippers and non-dippers. Methods We included black and white men and women (n = 827), aged 20-30 years and determined the MBPS using two formulas: the sleep-trough and dynamic morning surge. For autonomic function we determined baroreceptor sensitivity and heart-rate variability. Results The majority of non-dippers in this population were black (70.4%), presenting lower sleep-trough and dynamic morning surge (all p < 0.001). Heart-rate variability was comparable between dippers and non-dippers, whereas baroreceptor sensitivity was higher in non-dippers (p = 0.021). Despite a suppressed MBPS profile in non-dippers, we found both sleep-trough (β = −0.25; p = 0.039) and dynamic morning surge (β = −0.14; p = 0.047) to be inversely and independently associated with 24-hour heart-rate variability (total power). These results were absent in dippers. Conclusions In conclusion, we found a higher night-time blood pressure coupled with lower MBPS in young healthy non-dippers. Furthermore, this lower MBPS was independently and negatively associated with autonomic neural activity, suggesting increased autonomic function involvement in MBPS suppression of non-dippers. The predictive value of suppressed nocturnal dipping pattern should be investigated while taking autonomic neural activity into account