Frank Sutton’s fifteen-year-old cat seemed to enjoy rousting him   from sleep only on Saturdays when he had the day off and could stay in bed an extra hour. Today was no exception. Fully awake, he shooed the beast from his chest with a muttered curse and dressed quickly – khakis and a starched button-down with an ink stain on the pocket. He was thinking of leaf-filled gutters, bacon and eggs, the divorce Cheryl had threatened last week right after church, for no good reason.

It is unclear whether memory gaps or lapses are primarily genetic. According to web sources, deteriorating memory conditions such as...