Yes, it is part of the disease. My father would always try to hit on me, my sister and his grandkids. It made us very uncomfortable because he didn't know who we were. So, we just ignored it and finally it stopped.

My husband has frontotemporal dementia with behavioral variant, and hypersexuality is his most disturbing symptom. He makes highly inappropriate sexual comments to both staff and residents in his long term care facility. He was put on estrogen, which helped tremendously. When estrogen was discontinued, his hypersexuality returned. Now he is back on estrogen. The staff is trained to deal with this issue, but he made a nasty comment to another resident who understood what he was saying. In my mind, that is totally unacceptable, and I insisted that he resume the estrogen. I don’t want his behavior to determine his placement elsewhere, in all likelihood a psychiatric facility. For the most part, I have relinquished his care to the staff, but I did intervene with this issue.

Yes, this can be a part of dementia. Others have had to deal with issues of hypersexuality. There are meds to help with it. Talk to his doctor about it. Wishing you the best.