Washington, Aug. 30 -- As a consequential week played out in world affairs and economic anxieties grew, exclamation points kept sprouting on President Donald Trump's tweets. But they were about other things. Like bedbugs.

His tweets railed about the "incompetent Mayor of San Juan!" in the unnerving hours before the gathering hurricane, Dorian, brushed past Puerto Rico en route to the mainland. When the stock market took a dive, he poked fun at a little known Democratic presidential contender. Getting ready for dinner with world leaders, he took on critics who think he has a "Messiah complex."

Trump's Twitter feed is rarely normal. But over the last seven days, it has revealed a striking disconnect between matters of gravity and his triv...