My husband with vascular dementia is much worse all of a sudden. He has a cold. Could that make him less verbal and confused?

It might, illness can be scary and suck the energy right out of someone with cognitive impairment. You might want to make sure that he's not getting any over the counter cold medications that might interfere with his prescription medications. I have heard so many cases where someone took a common cold medication and it reacted with their Prescriptions. I avoid dangerous interactions by always checking with the pharmacy before giving any medications for common ailments.