My half-brother has always been one of the smartest people in our family. We're a family of nerds and geeks, and he's a real life nerds nerd. He's 65, and recently retired from government engineering work, if that matters. He has type 2 diabetes which is too common in our family, otherwise ordinary old people aches and pains.

He has always had and used tremendously large post-graduate level vocabulary both in his writing and verbally. He still writes, and his stuff is amazing.

We have noticed a distinct change in the last couple of years. Even my mother in her 90s has noticed. He still writes high level of coherence and competence. Still uses a fairly substantial vocabulary in his writing. But something has changed with his verbal skills, and it's very noticeable. First, it's as if he's lost confidence in speaking. He hesitates. It's like he's struggling to put the thought together with the right words. It's not stuttering, it's more like frustrating hesitation and incomplete thoughts. It's as if the right words won't come, so he's blanking.

My sister and I are thinking of speaking to him about it. Before we do, we're looking for information on whether this could be onset dementia. Then, we need to think about how best to approach him. He's, in so many ways, a bedrock fir our family. So. Is this a sign of dementia? Any information and advice can be useful. I thank you in advance.