t was known that skin cells produce such substances as they age, becoming "rotten apples" that can affect other cells near them, but it was thought that neurons would age in a completely different way, the researchers said. skin cells, such as fibroblasts, which are involved in repairing wounds, maintain their ability to divide, whereas most neurons in adults can't divide. "This study provides us with a new concept as to how damage can spread from the first affected area to the whole brain," said study researcher Thomas von zglinicki, a professor of cellular gerontology at Newcastle University.