MIL was born and raised in Kenya and came to England in the 70s. She speaks English perfectly fine and raised both her children who both speak English perfectly. Neither child actually speaks Swahili and also don't understand it as MIL and FIL only ever spoke English to them.
Yesterday I was on a videocall with MIL as I am on mat leave and she likes to see DC as she can't visit very regularly. She was singing the alphabet and said 'A B C D' paused for a few seconds and sang 'E F G' and then paused and then laughed and said 'granny doesn't know ABCs'. All of this was addressed to DC and I was sitting nearby. I didn't say anything as I didn't want to embarrass her..
She is 66 and generally healthy but could this be an early sign of dementia?
I don't actually know much about growing up in Kenya and how much English is taught in their schools so it could be that she doesn't actually know it? She was a very traditional housewife by the sounds of it and I feel like it might be plausible she doesn't know her alphabet because sometimes I hear DH tell her things like how far away a country is, like you might explain it to a little child or for example how she will need to leave the house at 1pm if she wants to arrive at ours for 2pm because it's an hour away etc. I suspect she could be ND sometimes. I've tried to speak to DH about that in the past but I think he feels a bit offended by it..
Back to the dementia suspicion. I could be wrong. But also DH is so avoidant and I feel like MIL is very anti-healthcare (she thinks the NHS make money by killing people) and I think it's important to deal with these things.