Anyone got any thoughts on this one...
We have an older employee, 67 years old, who's been with us for around 10 years. Of late he's been acting quite odd - not turning work round at his usual speed, making an unusual amount of errors, and getting very flustered and anxious over really trivial work stuff. The other day he locked one of his colleagues in the office, who he'd been talking to just minutes before. And when he talks he's switches subjects at the drop of a hat for no apparent reason.
We've no desire to get rid of him as he's very much part of the team and has a level of knowledge we wouldn't be able to replace.  We've mentioned to him that we're concerned but he says he's fine and that he just had a run of unusually difficult jobs (he hasn't).
He has no close family - lives alone and isn't married and the job is pretty much his life. We're probably the only people he sees who would notice anything wrong with him.
So what to do when you see there's something wrong (no idea what, and not looking for a diagnosis on here) but the person says everything's fine?