Although the primary symptom of Alzheimer’s Disease — dementia — typically does not develop until late adulthood, mouse studies led by Dr. Weihong Song suggest a connection between vitamin A deficiency in the womb and cognitive impairments that could translate to Alzheimer’s in later years.
The vitamin A deficiency led to higher levels of amyloid beta, the protein some scientists believe is responsible for killing brain cells in Alzheimer’s. Although similar studies involving human mothers and fetuses have not been done, 75 per cent of elderly people with mild to moderate vitamin A deficiency in Chongqing, China suffered from cognitive impairments, while only 47 per cent of their nutritionally balanced counterparts did.
Observations about vitamin A deficiency made in senior homes were what first suggested the importance of the nutrient to cognitive function to Song, a neuroscience professor at UBC.
“Vitamin A is a very important molecule in the body because [it converts to] retinoic acid, which is very important for embryonic development, including vision, immunity, skin and brain development,” said Song.
After the mouse pups were born, they were all fed the same nutritionally balanced diets. Those with mothers who experienced mild vitamin A deficiency during pregnancy performed worse on standard cognitive tests, demonstrating that their brain development was heavily influenced by their time in the womb.
However, Song and his research team have also observed improvements in cognitive function in pups given vitamin A supplements after birth, suggesting that early intervention can prove to be beneficial. On this note, Song cautions against ingesting large amounts of vitamin A for humans, as deficiency is rare in developed countries.
For developing countries, malnutrition is common. Studying populations in those regions presents challenges since Alzheimer’s occurs most frequently in old age.
“If you look at West Africa — with the lowest life expectancy in Sierra Leone, which is 46 years old — you are not going to expect many Alzheimer’s patients,” said Song.
Song plans to further investigate possible connections between vitamin A deficiency in later stages of life and the development of Alzheimer’s disease, and whether prevention through vitamin supplements can be effective.