I have got spine problems too [cervical] , i went through 5 physio therapists all claiming that they could help me, every attempt failed miserably and aggravated the condition and made it a lot more painfull, the only relief i have got is with acupuncture and magnetic therapy, using the both together at times.
I am glad to read that you don't get it a lot ,it can be such a disabling problem when its real bad.

I would love a dollar for every time i heard " i have tried magnets they didn't do a thing ", or " i paid $70 for a magnetic back support and it hardly done anything for me," or magnetic underlays, rar rar rar, personally i don't go anywhere near these type of gimmicks [my opinion only]
But if i ask " what strength were the magnets " and/or " what type of magnets were they " , i always get a blank look in their face back off them.
You see, this makes all the difference, if your going to get any relief or not, they have to be powerful to do the job properly, the longer you can leave them on the better results you get, i think its best to leave them on for 3 days, take them off wash the area and within a couple of hours put them back on if need be.

Your elderly friend has got the right idea
all the best,
Brian