How Tight Does a Hat/cap Have to Be to Restrict Blood Supply to the Hair? Reduced Blood Flow Speed Up Genetic Alopecia?

Hello, I wear a cap most days and especially now that I seem to be loosing my hairline. Is it possible for the tight part of the cap (band) to reduce blood supply to the hair thus speeding up androgenic alopecia? I have a large head so caps fit reasonably snug but how tight are we talking? I'd really appreciate a doctors response as it's causing a great deal of anxiety with the question un answered and I'm getting mixed views online . Thanks.