My name is ***** ***** I am an experienced small animal veterinary surgeon, I will be very pleased to work with you today and will try my best to answer your question to your satisfaction.
This is what is termed Pica, this is when animals suddenly start to eat non food items such as dirt etc, form them to eat cat litter is something I have dealt with now and again.
This can happen because of some underlying disease or it can also happen as a sign of senility, but Nemo is only ten so this is likely not the cause or very often it happens for no obvious reason
So how to handle it? : Well the my usual approach would be to have a thorough clinical examination and perhaps a blood test to rule out any obvious disease issues, if that comes back as clear then I would simply change the cat little to another brand which is very different in terms of texture and appearance from the one you are using at present.
Eating cat litter in itself is not dangerous as long as only small amounts are involved but if it becomes a habit and larger amounts are consumed then there is a danger of intestinal tract blockage.
I hope I have covered your question fully enough but if you would like further clarification or to talk things over a bit more then I will be on-line for the next hour or so and I will be more than pleased to continue working with you.Regards,Scott