My first grey hairs appeared at the age of 16. Was already in a meaningful long-term teenage relationship even at that age, yet which suddenly ended by mail post a few years later.Transit Saturn conjoined natal 11th house Pluto in Leo.
As they appeared, increasingly more grey hairs were pulled out regularly in the following years, yet I was still basically a brunette
Saturn rules hair, whilst Leo is associated with the mane. Natal Saturn is in Gemini. Its rules natal 5th and (traditional) 6th houses.
When sec. progr. Sun, ruler 12th house, exactly conjoined natal Saturn in 10th my father died. Circumstances brought ex-boyfriend (then beginning his mid-life crisis!), through his instigation, 'back from the dead'. With transits Saturn, Uranus, and Neptune all harshly aspecting my natal Sun, I was totally silver-white within 3 years. We gradually lost touch during my own Uranus opposition.
I have never forgotten the next door's then 4 year old little boy saying
"You're old", and then attempting to rectify it with, "You are not old; your hair is old!"
My silver hair was like a cart horse's tail, thick and unmanageable to me.
Circumstances occured yet again when tr. Saturn's next round conjoined natal Pluto. Finalisation of what ever had been.
The thick white hair became thinner and more manageable.
From a personal point of view, there is no doubt in my mind that Saturn affects 'ageing' of the hair.
Possibly confirming what Sweet Pea wrote; I have Venus semi-square Saturn!