Preparing for retirement should include preparing for the risk of diminished mental capacity, according to noted financial writer Jane Bryant Quinn (“Losing Your Grip?”). It is an unpleasant fact of life that, as we age, we become less competent to make financial decisions. A 2009 study on financial decision-making found that this ability peaks at age 53 and declines thereafter, according to Ms. Quinn’s article. Another study at Texas Tech University revealed that what we lose 2% of what we used to know about financial matters each year after age 60, but, paradoxically, we gain confidence as we lose this knowledge. All of this makes us vulnerable to serious financial errors and even fraud, according to Ms. Quinn.