https://www.nih.gov/news-events/nih-research-matters/hearing-aids-slow-cognitive-decline-people-high-risk This link will take you to some information about hearing loss and cognitive decline.

Recent research studies have shown that untreated hearing loss is sometimes associated with cognitive decline. There are a lot of questions related to this topic, including one that asks whether this relates to 'untreated' hearing loss or hearing loss in general.

Hearing loss makes it difficult for people to understand conversation, especially in social settings where there is background noise. Sometimes that leads to withdrawal from social settings one always enjoyed. Responding out of context in conversation is embarrassing (and common with hearing loss). That can appear as if a person cannot think clearly. That can also lead to isolation, loneliness and even depression.

I encourage your husband to get hearing aids.

Has his hearing loss been diagnosed by a qualified audiologist?