Alzheimer’s linked to prenatal deficiency

Low vitamin A before birth may be factor: study

VANCOUVER • Chemical reactions in the brain that lead to Alzheimer’s disease late in life may be triggered before birth by vitamin A deficiency, according to a new study from the University of B.C.

In animal models, even mild vitamin A deficiency increased production of amyloid beta, the protein fragment that forms plaques in the brain, said lead author Weihong Song, a Canada Research Chair in Alzheimer’s disease. In people with Alzheimer’s, amyloid plaques smother and eventually kill neurons, leading to slowly worsening dementia.

“We have known for some time there is less vitamin A in the blood of people with Alzheimer’s compared with people who have normal cognitive function,” said Song. “What we didn’t know was how important it could be in early childhood development.”

Alzheimer’s is caused by gene mutations and environmental factors over decades. The study used mice engineered with a mutated human gene to make them susceptible to Alzheimer’s.

The study also found that fetal malnutrition led to long-lasting learning problems. Fetal mice deprived of vitamin A through their mother’s diet performed worse on tests of learning and memory when they reached adulthood, even when given a normal diet right after birth.

“Vitamin deficiency during pregnancy is much more harmful (to the fetus) than a vitamin deficiency later in life,” said Song.

But Song and his collaborators at the Children’s Hospital of Chongqing Medical University in China were able to “rescue” some brain function in mice with vitamin A supplements given immediately after birth.

“If you give vitamin A supplements in the first month or two of life, you can reprogram the brain and restore most of the cognitive function,” said Song. “If you wait two months, the supplements don’t work as well.”

The finding has serious implications for brain health in the developing world and even in remote parts of Canada where food choices are limited.

Vitamin A is found in fish and brightly coloured fruits and vegetables.

“The World Health Organization report says there are 250 million preschoolers in the world with vitamin A deficiency,” said Song. “In developing countries, vitamin A deficiency is quite common and likely affects many pregnant women.”

The study appeared Thursday in the journal Acta Neuropathologica.

Weihong Song