Can reading make you smarter?

When I was eight years old, I still couldn't read. I remember my teacher Mrs Browning walking over to my desk and asking me to read a few sentences from a Dick and Jane book. She pointed to a word. "Tuh-hee," I said, trying to pronounce it. "The," she said, correcting me, and that's when it clicked – the moment when I learned to read the word "the".
Growing up in Teaneck, New Jersey, in the 1960s, I was what Mrs Browning called "slow". During a parent-teacher meeting, she told my mother: "Daniel is a slow learner." I sat during lunch in the gymnasium with the – forgive the term – dumb kids. I was grouped with them during reading and maths: the "slow group".
And then, a year later, I was rescued by Spider-Man. My best friend Dan, who was reading chapter books by kindergarten, had started reading Spider-Man and other comics with some other kid, and together they began drawing and writing their own comics. In response to this loathsome intruder's kidnapping of my best friend, I began reading comics, too, and then began scrawling and scribbling my own. Soon, Dan and I were happily spending every afternoon on our masterworks, while the interloper was never heard from again. We even convinced Dan's father, Dr. Feigelson (rest his soul), to film a Super-8 movie that we scripted: "Bob Cat and Bat v Disappearo!"
By age 11, I was getting straight As. Later in my teens, I took a college admissions course in the US, and scored the equivalent of 136 on an IQ test. So what happened? Was Mrs Browning right – was I actually "slow" when I was eight – and did I somehow become smarter because I immersed myself in reading and writing comic books?