Answer by  
                                                                                          John (9008)
                                                            
                          
                          
                                                          This condition can result from many different factors. Age is one major contributor to this condition, as is genetics. Diet and general health also play a role (this problem is more common in people who are obese). Some medications can also lead to the problem as a side effect. For most people, it is a combination of several factors.