Type A behavior and blood pressure during adolescence

In The Woodlands, Texas, 346 students in grades 9-12, age 14-18 participated in a screening examination for cardiovascular risk factors. The relationships between blood pressure with Type-A-behavior and its components were evaluated. Type-A-behavior was measured using the Hunter-Wolf Type-A-behavior scale.^ The following results refer to the current 24-item version of the Hunter-Wolf Type-A-behavior scale and subscales derived in the Bogalusa study which thereafter were applied to The Woodlands population.^ No significant differences in blood pressure were observed among children in the highest vs. lowest quintile of the Type-A-behavior score or subscales scores. The correlation coefficients of blood pressure with the Type-A-behavior and its components were small and non-significant in both boys and girls. Multiple regression analyses conducted by sex, showed that after adjustment for age, weight and height, the addition of the total Type-A-behavior score or subscale scores did not increase significantly the amount of the variability explained for any of the blood pressure components.^ These analyses were repeated with results from the original 17-item version of the Hunter-Wolf Type-A-behavior scale and subscales derived in Bogalusa. Similarly, no relationship was observed between the 17-item Type-A-behavior score or subscales scores with blood pressure levels in The Woodlands population.^ Finally, it was important to determine whether subscales derived within The Woodlands population would differ from those described in Bogalusa and would relate differently to blood pressure among students in The Woodlands. The corresponding analyses showed that the subscales derived from the two studies were different, but in fact neither set of subscales was importantly related with blood pressure in The Woodlands population.^ The results of this study are largely consistent with those obtained by Hunter and Wolf in Bogalusa, who among the white population found only the factor "Eagerness-Energy" to be associated with fourth phase diastolic blood pressure among girls. Even this relationship which they observed was weak and inconsistent across sex-race groups and blood pressure components. This study does not support even this positive finding. In conclusion, evidence indicates that blood pressure is not associated with Type-A-behavior or its components as measured by the Hunter-Wolf Type-A-behavior scale among white adolescents. ^

Total cholesterol and anthropometric measurements distributions in a cross-sectional study of school children

Cross-sectional age and sex specific distributions of serum total cholesterol were described for 1091 children age 6-18 years, in The Woodlands, Texas. Associations of serum total cholesterol with five anthropometric measurements (weight, height, body mass index, arm circumference, and triceps skinfold thickness) were examined by correlation and regression analyses. Examination of serum total cholesterol distributions showed lower levels in boys than in girls for most of the age groups studied. Mean levels of total cholesterol peaked at age 9 for boys and 8 for girls. Serum total cholesterol leveled off until age 14 for boys and 11 for girls, and then dropped through age 18 for both boys and girls. These results support the hypothesis that serum total cholesterol concentration drops at pre-adolescence.^ Age adjusted correlations were observed between serum total cholesterol and triceps skinfold thickness for both boys and girls. This association was stronger in boys. Triceps skinfold thickness and arm circumference were consistently the strongest correlates for serum total cholesterol in boys. Weight and arm circumference were consistently the strongest correlates for serum total cholesterol in girls. ^

Cardiovascular diseases risk factors during the first year of life

The pattern of change in cardiovascular risk factors, blood pressure (SBP and DBP) and plasma total cholesterol (TC), over time, their tracking and their relation to anthropometric measurements during the first year of life were investigated. Also, the effect of breast feeding on TC and the relationship of blood pressure measurements and family history of CVD risk factors were examined. One hundred five newborn term, healthy infants who were seen at a pediatric clinic in The Woodlands, Texas were followed longitudinally from 2 weeks to 1 year of age. TC, blood pressure, weight and length of the infants were measured at age 2 weeks, and again at 2, 4, 6, 9 and 12 months. In addition, family history, maternal and paternal, of CVD risk factors was obtained. Data analyses included only 40 infants who completed one year of follow up.^ At 2 weeks of age, the median value for TC was 23 mg/dl higher for females than for males. This difference disappeared as infants got older. For males, most of the increase in TC median levels, from 114 to 137 mg/dl, occurred between the ages of 2 weeks and 2 months, whereas for the female group, TC levels increased moderately, about 10 mg/dl, between 9 and 12 months of age. Tracking of TC was examined by using Spearman's correlation analysis. There were strong correlations between measurements taken as early as 2 weeks of age with later measurements. These correlations were stronger and more significant for males than for females (for males, r varied between 0.51 to 0.70, whereas for females, r varied between 0.11 to 0.70). The association of body measurements with TC is no more than modest and is closer for female infants than for male infants. Analysis, also, showed that infants who received breast milk had a TC mean value 47 mg/dl higher than that for infants who received formula milk only during the period of breast feeding and this difference disappeared by age 12 months.^ In both genders, most of the increase in blood pressure (about 10-15 mmHg in both SBP and DBP) occurred during the first 4 months of life. Most of the increase for male infants occurred during the first 2 months of life, while for females, the increase in SBP and DBP was between the age of 2 and 4 months. Neither SBP nor DBP track well during the first year of life and most of the correlations between measurements at different ages were not significant for either gender. The cross-sectional relationship of blood pressure measurements and selected body measurements was assessed. For females, only at age of 12 months did DBP have positive and significant correlations with weight, length and Quetelet index (r = 0.57, 0.60 and 0.57, respectively). There were no significant correlations between blood pressure and body measurements for males. Finally, analysis showed that maternal history of CV risk factors was significantly related to SBP in the female infant group, but not for males. For DBP, neither maternal nor paternal history was related. ^