This appears as vertical beaded ridges resembling a candle's wax drippings. With nail beading, the beads seem to drip down the nail like wax, and it is associated with endocrine conditions, like diabetes mellitus, thyroid disorders, Addison's disease, Vitamin B deficiency, hormonal changes, or stress.
However, just like with our skin, these "wrinkles of the nail" are usually caused by ageing. They run from the nail bed to the tip and generally start on one or two nails. Over time, the ridges can appear on all nails. Gentle filing and buffing can help to smooth them.