Genetic and environmental influences on forced expiratory volume in African Americans: the Carolina African-American Twin Study of Aging.

OBJECTIVES Previous research found measures of pulmonary functioning to be strong predictors of cognitive functioning and mortality; however, there is considerable individual variability in performance on these measures. In the present analyses, the relative contribution of genetic and environmental influences to variability in average peak expiratory flow rate (APEFR) are examined in a sample of adult African-American twins. DESIGN Birth records from North Carolina Register of Deeds offices were used to identify participants for the Carolina African-American Twin Study of Aging (CAATSA). Participants completed an in-person interview, which included measures of health status, cognition, and psychosocial measures. PARTICIPANTS Data for the analysis come from 200 pairs of same sex twins (97 identical pairs, and 113 fraternal), with a mean age = 46.9 years (SD = 13.9), and with 39% of the sample being men. RESULTS Phenotypic correlations between APEFR, age, gender, height, and cigarette consumption (measured in pack years), were all significant, ranging from -.63 to .43. After the affects of age, gender, height, and pack years were partialled out of APEFR, quantitative genetic analyses were conducted on the residuals. Model fitting demonstrated that variance in APEFR was accounted for by shared environmental effects (30%), genetic effects (14%), and non-shared environmental effects (56%). CONCLUSION These results are discussed in relation to previous research conducted in other countries, and the importance of a complex systems approach to explanations of the impact of genes on central indices of health, such as APEFR.