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May 28, 2002 -- There's new evidence that a substance found in blood can cause the type of brain and blood vessel deterioration that leads to dementia. But those same studies also show that taking certain vitamins can lower levels of this substance -- homocysteine -- and ward off the damage, possibly preventing Alzheimer's disease.
Both studies and an accompanying editorial appear in the May 28 issue of Neurology.
Homocysteine is an amino acid -- the building blocks of protein -- that circulates in our bloodstream. Alzheimer's patients tend to have elevated homocysteine levels, as do 5%-7% of the general population. High homocysteine levels have been linked to heart disease and stroke.
In the first study, Joshua W. Miller, PhD, from the University of California, Davis, School of Medicine in Sacramento, and colleagues found that elevated levels of homocysteine were linked to blood vessel damage, and that having low levels of vitamin B-6 in the blood was common among Alzheimer's patients, suggesting a relationship between B-6, homocysteine, and Alzheimer's. But what that relationship may be is unknown.
The findings need to be confirmed, and "it remains to be determined if elevated homocysteine or low vitamin B-6 directly influence Alzheimer's disease progression," Miller says in a news release. "But it is interesting. Vitamin B-6 has been shown to play a role in brain function and memory, so it's possible that taking B-6 supplements could help Alzheimer's patients."
In the second study, Perminder Sachdev, MD, PhD, of Prince of Wales Hospital in Randwick, Australia, and colleagues looked at the brains and homocysteine levels of 36 healthy seniors. They found that those with high homocysteine levels were twice as likely as those with normal levels to show loss of brain cells.
Whether the excess homocysteine is actually causing the brain deterioration remains to be seen.
"This is exciting information, because homocysteine levels can be reduced by taking the vitamins B6, B12, and folic acid," says editorial author James Toole, MD, in a news release. He is a neurologist at Wake Forest University School of Medicine, in Winston-Salem, N.C.
Good sources of folic acid include citrus fruits and juices, tomatoes, vegetables, and grain products such as bread, cereal, and pasta. Vitamin B-6 is found in meat, poultry, fish, fruits, vegetables, and grain products, and vitamin B-12 is plentiful in meat, poultry, fish, and dairy products. You can get a sufficient amount of all three nutrients if you eat a varied, well-balanced diet.