The reason why old people's toenails get thick is due to the growth rate of the nail plate slowing down and the natural aging process.
Other factors that can cause an older persons toenails to become thick are poor circulation, fungal infections and reduced blood flow.
A common skin condition called psoriasis can also cause cells to buildup rapidly on the surface of the skin and potentially lead to thick toenails.
And as you age, your toenail growth also slows down and also reduced blood flow to the extremities can cause toenail thickening.
Fungal infections are also more common in older adults and can lead to the toenails becoming brittle, discolored and thicker.
As we age, the circulation to our feet and hands can decrease and affect the health and growth of our fingernails and toenails and lead to thick toenails and thick fingernails.
A fungal infection that can cause thick toenails is onychomycosis which is a common fungal infection that can cause the toenails to become brittle, discolored, painful and thick.
Other things that can lead to thick toenails are poor fitting shoes that put pressure on the toenails and cause thickening and trauma to the toes and toenails.
Injuries to your toes like stubbing your toes can also lead to toenail thickening and conditions like diabetes can also affect the growth of the toenails and fingernails and lead to thickening.