title: Diffusion tensor imaging, intracranial vascular resistance and cognition in middle-aged asymptomatic subjects.
abstract: BACKGROUND
  The contribution of traditional vascular risk factors to cognitive impairment and dementia is well known. However, in order to obtain possible targets for prevention of vascular cognitive impairment (VCI), it may be important to identify other early and noninvasive markers in asymptomatic middle-aged adults. The calculation of middle cerebral artery-pulsatility index (MCA-PI) is an ultrasonologic, noninvasive, validated and easily reproducible technique to assess increased distal resistance to blood flow. This study aims to assess the relationship between MCA-PI, microstructural white matter (WM) integrity and cognition in a middle-aged asymptomatic population.
  
  
  METHODS
  Ninety-five participants from the Barcelona-Asymptomatic Intracranial Atherosclerosis (AsIA) neuropsychology study were included. Subjects were 50-65 years old, free from dementia and without history of vascular disease. Transcranial color-coded duplex ultrasound examination was performed to assess MCA-PI as a measure of vascular resistance. WM integrity was evaluated by fractional anisotropy (FA) measurements of diffusion tensor images (DTI) acquired on a 3T-MRI. The neuropsychological battery was specifically selected to be sensitive to VCI, and included tests that were grouped into six cognitive domains: executive functioning, attention, verbal fluency, memory, visuospatial skills and psychomotor speed. A multivariate linear regression model adjusted for age, gender, years of education, diabetes and hypertension was performed.
  
  
  RESULTS
  MCA-PI was significantly associated with WM disintegration in different tracts (fornix, corticospinal and anterior thalamic), all p < 0.05 uncorrected. Both mean MCA-PI and mean FA of those significant tracts were independently associated with poor performance in attention, psychomotor speed, and visuospatial skills after adjustment for age, gender, years of education, and vascular risk factors (all p < 0.05). MCA-PI was independently associated with lower scores in all cognitive domains, except for visuospatial skills.
  
  
  CONCLUSIONS
  Our data suggest that MCA-PI may be related to WM disintegration and early vascular cognitive impairment in middle-aged subjects. Although further prospective studies are needed to provide evidence for its validity in longitudinal studies, our results support the proposal of including MCA-PI as part of clinical assessment in order to identify targets for VCI prevention.
authors.affiliation: Department of Psychiatry and Clinical Psychobiology, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: López-Olóriz
authors.forename: Elena
authors.initials: E
authors.lastname: López-Cancio
authors.forename: Juan F
authors.initials: JF
authors.lastname: Arenillas
authors.forename: María
authors.initials: M
authors.lastname: Hernández
authors.forename: Laura
authors.initials: L
authors.lastname: Dorado
authors.forename: Rosalía
authors.initials: R
authors.lastname: Dacosta-Aguayo
authors.forename: Maite
authors.initials: M
authors.lastname: Barrios
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Soriano-Raya
authors.forename: Júlia
authors.initials: J
authors.lastname: Miralbell
authors.forename: Núria
authors.initials: N
authors.lastname: Bargalló
authors.forename: Cynthia
authors.initials: C
authors.lastname: Cáceres
authors.forename: Pere
authors.initials: P
authors.lastname: Torán
authors.forename: Maite
authors.initials: M
authors.lastname: Alzamora
authors.forename: Antonio
authors.initials: A
authors.lastname: Dávalos
authors.forename: Maria
authors.initials: M
authors.lastname: Mataró
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000503:physiopathology*; D056324:Diffusion Tensor Imaging / Q000379:methods; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D011446:Prospective Studies; D014655:Vascular Resistance / Q000502:physiology*