I think my professor is senile...

So throughout the semester ive notice my professor have weird moments in class. I’ve noticed, sometimes he just loses track of conversations or repeats things like he’s not aware. Other times, he gets really confused about where he is, or what he is saying. its a small class of 5 students and he forgets name and freezes. And honestly, he gets pretty agitated, like when he can’t recall something. He also laughs at incoherence things, i cant even explain it. I’m not totally sure, but I think he might be showing signs of dementia or something. other students in the class had him before and he wasn't this loopy.

I should note that hes older, like 70 or 80. and hes the head of the department too... idk if I should report him cause I am consern as ive seen a decline in real time. the class functions mostly....