Dear Doctor: I spent 5 hours gardening in extreme heat at 82 and lost the ability to speak

Dear Doctor Roach: I’m an 82-year-old man with osteoporosis, a pacemaker, and a vegetable garden, which I worked in yesterday for 5 hours in the extreme heat. I consumed a large bottle of ice water. When I came back into the cool house, I was unable to select or even pronounce the proper words.

I felt like my brain’s gears were all in neutral. My wife had me drink a sports electrolyte drink, and I got back to normal in about 15 minutes. Did I damage myself in some way yesterday?