MRI shows blood flow to brain may play key role in dementia
4 October 2005
The amount of blood flowing into the brain may play a larger role in the
development of dementia than previously believed, according to a study by
researchers at Leiden University in the Netherlands. The study was published
in the September issue of the journal Radiology.
Researchers from Leiden University Medical Center in the Netherlands used
magnetic resonance imaging (MRI) to examine the brains of elderly patients
with and without dementia related to Alzheimer's or Parkinson's disease. As
expected, MR images showed that the patients with late-onset dementia had
more brain damage compared with young adults and with seniors who had
optimal cognitive function. But researchers found that the late-onset
dementia group also had a much lower rate of blood flow to the brain than
the other two groups.
"Our findings not only support the hypothesis that vascular factors
contribute to dementia in the elderly, they are highly suggestive that a
diminished cerebral blood flow indeed causes brain damage," said Aart Spilt,
M.D., a Leiden radiology resident and lead author 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's disease is the most
common cause of dementia. Some patients with Parkinson's disease also
In the Dutch study, researchers examined 17 patients with late-onset
dementia (dementia occurring after age 75), another 16 seniors of the same
age with optimal cognitive function and 15 healthy younger individuals.
Researchers used MRI to measure cerebral blood flow and the extent of
structural brain damage in each person and then compared the results of the
Average total cerebral blood flow in the healthy young individuals was
742 milliliters (mL) per minute. Cerebral blood flow in the two elderly
groups averaged 496 mL per minute, or 246 mL per minute lower than the
younger group. In patients with dementia, average cerebral blood flow was
443 mL per minute, or 108 mL per minute lower than seniors of the same age
with optimal cognitive function (551 mL per minute).
Although patients with dementia have been shown to require less cerebral
blood flow as the brain becomes less active, Dr. Spilt's research provides
some evidence that the decreased blood flow may lead to some types of
"The findings emphasize the importance of monitoring both high and low
blood pressure in older adults," Dr. Spilt said. "Possible causes of low
cerebral blood flow include heart failure and a narrowing of cerebral or