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   Brain's inability to repair DNA may explain dementia, memory loss   
      
   Last updated: 10 Feb 2015 at 3am PST   
   Neurology / Neuroscienceadd your opinionemail   
      
   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.   
   DNA strands   
   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   
      
      
      
      
   http://www.medicalnewstoday.com/articles/289191.php   
      
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