Early onset Dementia and seizures?

This is my first time on this site or any site for support. I care for my brother who is being treated for dementia. Recently, he started having these moments of unresponsiveness. He's awake and standing, but just blanks out like he's not there. He just seems to stare off and doesn't respond to my voice. After a minute or two, he blinks and is back, but he's exhausted and flushed red in the face. I took him to the ER. They did a CT scan and urine dip. No evidence of stroke or UTI. And sent us home with a referral to a neurologist. Could this be seizure or TIA?