As we grow older our chances of developing Alzheimer's disease increase. This is attributed to the possible accumulation of a peptide amyloid beta in the brain. New research has shown that vitamin D is responsible for flushing out amyloid beta from the brain in addition to age-related alteration in the production of transporter proteins which move amyloid beta in and out of the brain. The research was published in BioMed Central's open access journal Fluids and Barriers of the CNS.

Age-related decline in memory and cognition, and Alzheimer's disease have all been linked to low levels of vitamin D in the body. Scientists from Tohoku University, Japan, have conducted research to understand the underlying mechanism and found that injections of vitamin D resulted in better removal of amyloid beta from the brain of mice.

Prof Tetsuya Terasaki said:

"Vitamin D appears to increase transport of amyloid beta across the blood brain barrier (BBB) by regulating protein expression, via the vitamin D receptor, and also by regulating cell signaling via the MEK pathway. These results lead the way towards new therapeutic targets in the search for prevention of Alzheimer's disease."

The movement of amyloid beta across the blood brain barrier is assisted by transporter proteins such as LRP-1, P-gp and RAGE. RAGE controls the inflow of amyloid beta whereas LRP-1 and P-gp assist in transporting it out.

After closely studying the movement of amyloid beta from blood to cerebrospinal fluid (CSF), and vice versa, scientists from Rhode Island Hospital and The Warren Alpert Medical School found that with increasing age the number of LRP-1 and P-gp transporter proteins located at the blood-cerebrospinal fluid barrier (BCSFB), also tend to increase, thus increasing removal of amyloid beta from the CSF and brain.

Prof Gerald Silverberg concluded:

"While increased production of transporter proteins at the blood CSF barrier may help amyloid beta removal from the older brain, production of these proteins eventually fails. This failure may be an important event in brain function as we age and for people with Alzheimer's disease."

"1a,25-Dihydroxyvitamin D3 enhances cerebral clearance of human amyloid-b peptide(1-40) from mouse brain across the blood-brain barrier"
Shingo Ito, Sumio Ohtsuki, Yasuko Nezu, Yusuke Koitabashi, Sho Murata and Tetsuya Terasaki
Fluids and Barriers of the CNS 2011, 8:20 doi:10.1186/2045-8118-8-20

Written by Anne Hudsmith