This is true for me. I used chemicals to straighten my hair when I was younger. It was a fun way to change my appearance. The sort term side effects was a burned area of my scalp at the dome of my head. My scalp become more dry and itchy to the point of hair loss and bleeding.
Overtime I managed to treat the problem after having tried a multitude of hair and scalp treatment products. When I stopped using straightening products it took about 3 years for the hair to recover to a natural and healthy afro that didn't need moisturizers to look healthy - a good conditioner goes a long way in helping your hair recover.
Now, approximately 7-8 years since I first used conditioners my afro is fine, I don't have a bald-path developing on my dome, however my hair is a bit thinner than what it should be, but overall I'm happy with the hair. Again, quality shampoo and conditioners helped a long way.