Cerebrovascular resistance is a pressure-dependent mechanism resulting from cerebral autoregulation, which is the normal buffering of changes in arterial blood pressure. Lifestyle habits are known to have an influence; however, its magnitude is still unclear. The aim of this study was to assess the contribution of additive genetic, shared and unshared environmental factors to changes in middle cerebral artery (MCA) mean flow velocities (MFVs) and pulsatility index.
One hundred and forty-three Italian twin pairs from Padua, Perugia and Rome (68 monozygotic, 75 dizygotic, 55 ± 12 years) underwent transcranial Doppler sonography of the MCA bilaterally. Univariate quantitative genetic modeling was performed to decompose the phenotypic variance of averaged MFV and pulsatility index into additive genetic, shared and unique environmental effects adjusted by age and sex.
MFV was heritable in 30.6% [95% confidence interval (CI) 0.8–67.3%], and shared and unshared environmental factors explained 47.7 and 21.6% of the variance (95% CI 14.4–71.9% and 12.6–32.0%). Pulsatility index was not genetically determined, but unique and common environmental factors were responsible for 54.2 and 38.1% of the variance (95% CI 36.3–71.8% and 0.0–57.8%).
These findings underline the importance of identification of the specific genes and common environmental factors related to MFV. Individuals with positive family history of stroke related to the atherosclerosis of MCA might take advantage from preventive ultrasound screening. More emphasis should be placed on the prevention of the known related common environmental factors on MFV and the individual lifestyle risk factors on pulsatility index.
aDepartment of Radiology and Oncotherapy, Semmelweis University, Budapest, Hungary
bDepartment ‘Paride Stefanini’, Vascular Ultrasound Investigation Unit, Vascular Surgery, Sapienza University of Rome, Rome
cDepartment of Neurological Sciences, University of Padua School of Medicine, Padua
dDepartment of Neurology, Hospital ‘S. Maria della Misericordia’, University of Perugia Medical School, Perugia
eGenetic Epidemiology Unit, National Centre of Epidemiology, Istituto Superiore di Sanità
fVascular and Interventional Radiology Unit, Department of Radiological Sciences, La Sapienza University of Rome, Rome, Italy
gThe Methodist Hospital, Methodist DeBakey Heart and Vascular Center, Houston, Texas, USA
hCentral European University, Budapest, Hungary
iUniversità di Perugia, Unità di Medicina Interna, Ospedale ‘S. Maria’, Terni, Italy
Correspondence to Adam Domonkos Tarnoki, MD, PhD, Department of Radiology and Oncotherapy, Semmelweis University, 78/a Ulloi Street, Budapest H-1082, Hungary Tel: +36 30 6401183; fax: +36 1 2780368; e-mail: email@example.com
Received 13 July, 2014
Revised 5 September, 2014
Accepted 3 September, 2014