Hi Deb,
Pica in cats is a challenging and worrying condition to be concerned about. Outgrowing it is not likely something to happen let alone in the near future. If he hasn’t been thoroughly vet checked, I would start there to make sure there are no underlying issues that might cause oral or GI problems. Next, it’s time to consider environmental enrichment — safe toys for him, more play and interaction with you and family, and maybe some types of hunting games (soak some safe toy mice in dry catnip and hide them) to keep him entertained. As a last step, talk with your vet about potential behavioral medications.
I hope this helps.
Dr. Ryan Llera