Just a factoid, to support the idea that blood flow may of significance to the health of the white matter of the brain.
It came from here: http://en.wikipedia.org/wiki/White_matter
attributed to this article: http://www.ncbi.nlm.nih.gov/pubmed/2302536
Cerebral blood flow, blood volume and oxygen utilization. Normal values and effect of age.
Leenders KL, Perani D, Lammertsma AA, Heather JD, Buckingham P, Healy MJ, Gibbs JM, Wise RJ, Hatazawa J, Herold S, et al.
MRC Cyclotron Unit, Hammersmith Hospital, London, UK.
Regional cerebral blood flow (CBF), oxygen extraction ratio (OER), oxygen utilization (CMRO2) and blood volume (CBV) were measured in a group of 34 healthy volunteers (age range 22-82 yrs) using the 15O steady-state inhalation method and positron emission tomography. Between subjects CBF correlated positively with CMRO2, although the interindividual variability of the measured values was large. OER was not dependent on CMRO2, but highly negatively correlated with CBF. CBV correlated positively with CBF. When considering the values of all the regions of interest within a single subject, a strict coupling between CMRO2 and CBF, and between CBF and CBV was found, while OER was constant and independent of CBF and CMRO2. In 'pure' grey and white matter regions CMRO2, CBF and CBV decreased with age approximately 0.50% per year. In other regions the decline was less evident, most likely due to partial volume effects. OER did not change or showed a slight increase with age (maximum in the grey matter region 0.35%/yr). The results suggest diminished neuronal firing or decreased dendritic synaptic density with age.
Cerebral blood flow and cerebral blood volume and cerebral oxygen utilization decrease by .5% every year? Something to think about on my next birthday!