Brain's inability to repair DNA may explain dementia, memory loss

Date: Feb-10-2015 Previously, it was thought ability to repair DNA was the same throughout the

body, but new research overturns this idea and shows organs vary in the extent to which

they carry out a type of DNA repair called nucleotide excision repair.

The study investigated an important type of DNA repair.

This was the finding of a new study led by Nova Southeastern University (NSU) in Fort

Lauderdale, FL, that is published in the journal Photochemistry and

Photobiology.

For the study, the team investigated a type of DNA repair called nucleotide excision

repair (NER). It is one of five types of DNA repair used by mammalian cells, primarily to

repair damage caused by a range of cancer-causing agents, including ultraviolet (UV),

products of organic combustion, metals and oxidative stress.

NER is a complicated process that requires a high level of metabolic investment by the

cell. It mends DNA regions that contain unwanted added molecules that distort the DNA

helix and interfere with DNA copying during cell division.

Lead investigator Jean Latimer, associate professor of pharmaceutical sciences at the

College of Pharmacy at NSU, and colleagues found that the heart has the greatest ability

to repair DNA using NER, followed by the gut, the kidneys, the spleen, the testes and the

lungs.

However, the researchers found the brain appears to have no ability to carry

out this vital type of DNA repair.

One explanation could be that because they are not exposed to light, brain cells focus

their energies on more essential functions.

'Brain does not prioritize DNA repair'

Prof. Latimer says, "The human body was not designed to live past 30 or 40 years, so

our brains haven't prioritized DNA repair over other necessary functions."

"Our brains are frequently not physically prepared to last as long as medical science

is now allowing our bodies to live," she adds, and notes:

"These findings could help explain a root cause behind memory loss and

dementia."

For the study, the team carried out the research in mouse cell tissue cultures, but

they say - because of previous work they have done on human tissue - the same will be

true of humans.

The researchers used skin cells as the control to compare other cell types against.

They grew cells taken from different organs and assessed their ability to repair DNA

after exposing them to ultraviolet (UVC) light. UVC is a part of normal sunlight and

causes extensive DNA damage.

The authors note that loss of the NER type of DNA repair also occurs in

sporadic breast cancer and can influence response to therapy.

The National Cancer Institute of the National Institutes of Health and the Ruth Estrin

Goldberg Foundation helped fund the study.

Meanwhile, Medical News Today recently learned of a study that suggests meditation may slow brain aging. Researchers from the

University of California-Los Angeles found that people who meditate regularly had better-preserved gray matter in the brain.

Written by Catharine Paddock PhD

Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.