Blood Flow To Brain May Be Clue To Certain Dementias

Researchers from Leiden University Medical Center in the Netherlandsused magnetic resonance imaging (MRI) to examine the brains of elderlypatients with and without dementia related to Alzheimer's orParkinson's disease. As expected, MR images showed that the patientswith late-onset dementia had more brain damage compared with youngadults and with seniors who had optimal cognitive function. Butresearchers found that the late-onset dementia group also had a muchlower rate of blood flow to the brain than the other two groups.

"Our findings not only support the hypothesis that vascularfactors contribute to dementia in the elderly, they are highlysuggestive that a diminished cerebral blood flow indeed causes braindamage," said Aart Spilt, M.D., a Leiden radiology resident and leadauthor of the study. "This gives us a clue to the genesis of dementia."

Dementia is a loss of cognitive functions, such as thinking,remembering and reasoning, that interferes with normal activities.Although many conditions can produce these symptoms, Alzheimer'sdisease is the most common cause of dementia. Some patients withParkinson's disease also develop dementia.

In the Dutch study, researchers examined 17 patients withlate-onset dementia (dementia occurring after age 75), another 16seniors of the same age with optimal cognitive function and 15 healthyyounger individuals. Researchers used MRI to measure cerebral bloodflow and the extent of structural brain damage in each person and thencompared the results of the three groups.

Average total cerebral blood flow in the healthy youngindividuals was 742 milliliters (mL) per minute. Cerebral blood flow inthe two elderly groups averaged 496 mL per minute, or 246 mL per minutelower than the younger group. In patients with dementia, averagecerebral blood flow was 443 mL per minute, or 108 mL per minute lowerthan seniors of the same age with optimal cognitive function (551 mLper minute).

Although patients with dementia have been shown to requireless cerebral blood flow as the brain becomes less active, Dr. Spilt'sresearch provides some evidence that the decreased blood flow may leadto some types of dementia.

"The findings emphasize the importance of monitoring both highand low blood pressure in older adults," Dr. Spilt said. "Possiblecauses of low cerebral blood flow include heart failure and a narrowingof cerebral or cervical arteries."

Radiology is a monthly scientific journal devoted to clinicalradiology and allied sciences. The journal is edited by Anthony V.Proto, M.D., School of Medicine, Virginia Commonwealth University,Richmond, Va. Radiology is owned and published by the RadiologicalSociety of North America, Inc. (RSNA.org/radiologyjnl)

The Radiological Society of North America (RSNA) is anassociation of more than 37,000 radiologists, radiation oncologists,medical physicists and related scientists committed to promotingexcellence in radiology through education and by fostering research,with the ultimate goal of improving patient care. The Society is basedin Oak Brook, Ill. (RSNA.org)

"Late-Onset Dementia: Structural Brain Damage and Total CerebralBlood Flow." Annelies W.E. Weverling-Rijnsburger, M.D., Huub A.M.Middelkoop, Ph.D., Wiesje M. van der Flier, Ph.D., Jacobijn Gussekloo,M.D., Anton J.M. de Craen, Ph.D., Eduard L.E.M. Bollen, M.D., Gerard J.Blauw, M.D., Mark A. van Buchem, M.D., and Rudi G.J. Westendorp, M.D.,collaborated with Dr. Spilt on this paper.