No, there is no external cause of hair loss. With the exception of hair that is out of condition or broken due to over processing or excessive heat- which is not strictly falling out, but many patients perceive the hairs in the brush/wash to have fallen out.
When hair loss treatment for women is sought, questions such as this are often asked as the sufferer often tries to eliminate things that may for example rub on the area. As Shuna Hammocks qualified then gained many years experience with Philip Kingsley, who mentored Shuna – there are very few conditions she hasn’t seen.
A hat would need to be very tight and worn repetitively to rub the area of contact, this would be known as “Traction Alopecia” an example of an externally caused, temporary loss of hair- if used short term.
The fact that a helmet or protective head gear (for work purposes) may cause the scalp to become sweaty or hair slightly more oily is another matter. This could potentially cause a scalp condition such as Seborrhoea Eczema for example, where the head can become itchy and sore with the appearance of blotchy red areas or even tiny pustules around the follicular mouths.
In Afro and black hair loss situations, certain types of braids, weaves, extensions and corn rows can cause permanent scarring hair loss. This condition is rather complex as the individual with very curly hair, often seeks ways to style their hair. They often find it easier with a quick fix such as this- used long term to the detriment of their own hair