White hair. Causes

White hair are usually associated with senility. But it is not always correct. Sometimes, white hair may occur in young people or even children. Hair and skin color are conditioned by melanin producing cells melanocytes. The lack of activity of following cells leads to whitening of hair. The causes may include:
•genetic predisposition 
•vitamin deficiency 
•endocrin disorders 
•certain diseases: vitiligo, alopecia areata
•excessive smoking
•certain medication (chloroquine, tocopherol)
Facts about white hair
•Black hair may whiten earlier 
•First, hair on the scalp may whiten, than on the other parts (beard, eyebrows, chest)
•White hair grow faster
Is it possible to return hair color❓
When white hair appear due to senility, stress or genetic factor, of course no treatment can help to get the color back. When the cause is lack of vitamins or due to medication, usually they may return to its normal color. If you notice white hair, its recommended to see a dermatologist or trichologist.