by Evan Duggan
VANCOUVER, Jan. 30 (Xinhua) -- A joint Canadian-Chinese research has found out that biochemical reactions that cause Alzheimer's disease could begin in the womb or just after birth if the fetus or newborn does not get enough vitamin-A.
The study also showed that supplements given to newborns with vitamin-A could be effective in slowing the degenerative brain disease.
The findings are based on studies of genetically-engineered mice. The research was announced last week by the University of British Columbia in Vancouver in western Canada.
It was conducted jointly by Dr. Weihong Song at UBC and Dr. Tingyu Li with others at the Children's Hospital of Chongqing Medical University in southwest China.
"Our study clearly shows that marginal deficiency of vitamin-A, even as early as in pregnancy, has a detrimental effect on brain development and has long-lasting effect that may facilitate Alzheimer's disease in later life," said Song, a professor of psychiatry at UBC and the Canada Research Chair for Alzheimer's Disease.
Song told Xinhua on Monday that his findings were the result of a five-year research project that built on previous studies that linked low levels of vitamin-A with cognitive impairments.
The researchers had studied 330 elderly people in Chongqing and found that 75 percent of those with either mild or significant vitamin-A deficiency had cognitive impairment, compared to 47 percent of those with normal vitamin-A levels.
"Since lower vitamin-A is correlated or associated with dementia and cognitive impairment in the elderly, we thought maybe we could check if vitamin-A deficiency at the early stage (of life) has any effect on the later stages of Alzheimer's development. That's where we started," he said.
Vitamin-A deficiency is more common in developing countries and impoverished areas, Song said.
"According to a World Health Organization survey, there are almost 200 million pre-school children who have vitamin deficiency and about 20 million pregnant women who have vitamin deficiency," he said.
The researchers examined the effects of vitamin-A deprivation in the womb and infancy on Alzheimer's model mice.
Early developmental stages are crucial periods during which brain tissue is "programmed" for the rest of a person's life.
Song said they found that even a mild vitamin-A deficiency increased the production of amyloid beta, the protein that forms plaques that smother and kill neurons in Alzheimer's disease.
They also found that their study mice, when deprived of vitamin-A, performed worse as adults on a standard test of learning and memory.
Even when the mice deprived of vitamin-A in the womb were given a normal diet as pups, they performed worse than mice who received a normal amount of the nutrient in the womb, but were deprived after birth. Song said that means the damage to the brain had already been done in the womb.
The researchers say their findings also show that some reversal is possible. Mice that were deprived of vitamin-A in utero but were given supplements immediately after birth performed better on the tests than mice who were not given supplements.
"In some cases, providing supplements to the newborn Alzheimer's disease model mice could reduce the amyloid beta level and improve learning and memory deficits," he said, "It's a matter of the earlier, the better."
Song stressed that pregnant women should not overreact to these findings. He said pregnant women should not take excessive vitamin-A supplements and should focus instead on eating a healthy, balanced diet to ensure adequate levels of nutrients.
Vitamin-A is very important for the development of the brain, eyes, skin and immune system and is found in foods such as carrots, leafy greens, sweet potatoes and liver, Song said.
"I don't suggest that a pregnant woman who has a balanced diet to take vitamin-A because too much vitamin-A is harmful to the embryonic development. It could cause birth defects," he said.
He said the next step for the research could be to study whether there are higher rates of Alzheimer's disease in developing countries and poor communities.
"If you look at the low income world, life expectancy is very short," he said, noting that cognitive diseases tend not to show up until the age 60 or later, making it a challenge to assess cognitive health in malnourished elderly patients.