ABSTRACT
Bishop, Pek, and Ngau (2005) found a significant interaction in Singapore between anger and nocturnal dipping among Indians but not Chinese and Malays. The current study examines the role of 5-HTTLPR genotype in this relationship. Two hundred thirty-one undergraduates participated in up to 4 days of 24-h ambulatory monitoring, completed the State-Trait Anger Expression Inventory, and provided blood samples for genotyping of 5-HTTLPR. Results indicated individuals with two copies of the short allele (SS) showed reduced dipping when they were high in Outward Anger (OA) but increased dipping when they were low in OA. Further, for Indian men only, dipping was reduced for individuals having the SS genotype when they were low on Anger In and increased when they were high on Anger In. These data provide further evidence for the role of 5-HTTLPR in cardiovascular risk as well as ethnic differences in the 5-HTTLPR-phenotype relationship. They also provide further evidence for 5-HTTLPR as a "plasticity gene."
Subject(s)
Anger/physiology , Blood Pressure/genetics , Blood Pressure/physiology , Adolescent , Adult , Alleles , Asian People , Circadian Rhythm/genetics , Circadian Rhythm/physiology , Data Interpretation, Statistical , Ethnicity , Female , Genotype , Humans , Male , Serotonin Plasma Membrane Transport Proteins/genetics , Sex Characteristics , Sleep/physiology , Young AdultABSTRACT
BACKGROUND: Individuals showing less than a 10% decline in blood pressure at night ("nondippers") are known to be at increased risk for hypertension and other cardiovascular conditions. PURPOSE: This research tested the assertion by Räikkönen et al. (1) that nondippers show blunted cardiovascular responses to activities during daytime hours. METHODS: Ambulatory blood pressure and impedance monitoring was performed with 149 young adults in Singapore. At each daytime blood pressure reading, participants completed a computerized questionnaire indicating location, posture, physical activities, feelings, and social interactions. RESULTS: Significant interactions between dipper status and feeling tired, location, posture, and physical activity provided qualified support for the blunting hypothesis. However, blunting of BP responses was not attributable to blunting of either cardiac output or total peripheral resistance responses. CONCLUSION: Nondippers appear to show blunted daytime responses to certain types of daytime activities. However, these effects are limited and appear to be the result of different mechanisms than those responsible for reduced nighttime blood pressure decline.
Subject(s)
Blood Pressure/physiology , Circadian Rhythm , Adolescent , Adult , Blood Pressure Monitoring, Ambulatory/instrumentation , Electronic Data Processing , Female , Hemodynamics/physiology , Humans , Male , Sleep , Surveys and QuestionnairesABSTRACT
This study examined the relationship of trait anger to nocturnal blood pressure decline among Singaporean young adults. One hundred forty-nine participants (51 Chinese, 51 Malays, 47 Indians, 49.7% men) participated in 24-h ambulatory monitoring for blood pressure and hemodynamic measures. Significant interactions were obtained between ethnicity and trait anger for systolic blood pressure and mean arterial pressure such that trait anger was significantly and negatively related to nocturnal blood pressure decline for Indians whereas this was not true for Chinese or Malays. Significant sex x trait anger interactions were obtained for systolic blood pressure, diastolic blood pressure, and mean arterial pressure in which trait anger was negatively related to blood pressure decline for men but not for women. Overall the results suggest that trait anger is a significant factor affecting nocturnal blood pressure decline particularly among Indians and men.
