Low Levels of B Vitamin Linked to Alzheimer's Lesions
April 4, 2000 (New York) -- Low blood levels of the B vitamin folic acid may
play a role in increasing a woman's risk of developing Alzheimer's disease as
she ages, according to a study of Catholic nuns.
The unusual study, reported in the April issue of the American Journal of
Clinical Nutrition, found that nuns who had the lowest levels of folic acid
in their blood had more Alzheimer's-like brain lesions when they died than
their fellow sisters who had higher levels.
Folic acid is known to be important to brain development. In pregnant women,
insufficient folic acid can cause serious neurological problems in babies, such
as spina bifida, the incomplete formation of the spine. Folic acid supplements
are recommended for all women of childbearing age to minimize the risk.
While the new study is not proof that similar supplementation in elderly
women or men will decrease their risk of developing Alzheimer's in their old
age, it suggests that folic acid may play an ongoing role in protecting the
brain throughout our lifetimes, say study author David A. Snowdon, MD, and
colleagues from the Sanders-Brown Center on Aging at the College of Medicine of
the University of Kentucky in Lexington.
Snowdon studied 30 nuns from the order of the School Sisters of Notre Dame,
who provided blood samples and underwent testing of their mental abilities when
they were 78 to 99 years of age. The nuns also gave permission to be autopsied
In the autopsies, more than 50% of the sisters were found to have varying
degrees of atrophy, or wasting away, of a major area of the brain. Half had
significant numbers of the brain lesions that have been associated with
Extensive examination of the nuns' blood for indications of their
nutritional status found that the only difference between sisters with brain
wasting and those without was the level of folic acid. Those with the lowest
folic acid levels had the greatest degree of brain wasting. Among nuns with the
Alzheimer's-like lesions in their brains, there was a higher degree of mental
The mechanisms by which low folate levels may cause brain wasting or
Alzheimer's lesions are unclear, but in the body, folic acid reduces blood
levels of an amino acid known as homocysteine. Studies have shown that if
homocysteine builds up in the blood, it may cause blood-vessel disease.
In an editorial accompanying the study, Irish researchers say the findings
add to the evidence that changes in the way folic acid is metabolized as we age
may accelerate the development of brain-wasting conditions such as Alzheimer's
But a folate expert who spoke to WebMD about the findings says he believes
the study is of little value, because none of the folic acid levels found in
the participants' blood were what anyone would consider low.